Paroxysmal Disorders


Paroxysmal disorders can be broadly classified into epileptiform and nonepileptic events. The nonepileptic episodes are often referred to by the generic term spells . They may mimic epileptic seizures but are not associated with the typical rhythmic EEG patterns characteristic of seizures ( Table 39.1 ; see Chapter 40, Chapter 7 ). These spells can be a manifestation of myriad etiologies leading to transient loss of consciousness and can be neurologic, cardiovascular, endocrine, psychologic, or gastrointestinal in origin. Most paroxysmal neurologic symptoms can be effectively evaluated, diagnosed, and managed by following a systematic approach. A detailed history will often be sufficient to make the diagnosis or to significantly narrow the diagnostic differential. A few well-selected tests will then allow the correct diagnosis to be made and subsequently enable the appropriate treatment of the child. The principal aim in the assessment is to establish signs of serious or emergent neurologic disease, and second, to form a differential diagnosis to guide further investigations and treatment ( Fig. 39.1 ).

TABLE 39.1
Comparison of Generalized Seizures and Some Disorders That Can Mimic Them
Adapted from Obeid M, Mikati MA. Expanding spectrum of paroxysmal events in children: potential mimickers of epilepsy. Pediatr Neurol. 2007;37(5):309–316.
Condition Precipitants (May Not Apply to All Patients) Prodrome Ictal Symptoms Postictal Symptoms
Generalized seizures Sleep deprivation, television, video games, visual patterns, and photic stimulation Rarely irritability or nonspecific behavioral changes Usually 2–3 min
Consciousness might be preserved if atonic or, in some, tonic seizures
Synchronous bilateral movements
Tongue biting
Delayed recovery with postictal depression, incontinence (may be ictal also)
Syncope: vasovagal Fatigue, emotional stress, dehydration, vomiting, choking, swallowing Blurring of vision, tinnitus, dizziness, nausea, sweating, crying in breath-holding spells Loss of consciousness for seconds, pallor, and rarely reflex anoxic seizures Rapid recovery with no postictal depression
Syncope with reflex anoxic seizures Minor bump to head, upsetting surprises
Syncope: trigeminal vagal Cold water on face
Syncope: orthostatic Standing up, bathing, awakening
Hyperekplexia Auditory and tactile stimuli None Tonic stiffening, cyanosis if severe, nonfatigable nose-tap–induced startles Depending on severity, may have postictal depression
Cardiac Exercise None Loss of consciousness, often only for a few seconds, pallor Rarely
Psychogenic Suggestion, stress None Eyes closed, with active opposition to attempts to open them
Asynchronous flailing limb movements that vary between attacks
Motor activity stops and starts during a spell
Weeping and crying
No injury
May respond to suggestion during “loss of consciousness”
Usually longer than 2–3 min
No postictal depression

Fig. 39.1
Approach to the child with a suspected convulsive disorder. CNS, central nervous system; CSF, cerebrospinal fluid.

History

A careful description of the event or events from beginning to end, including re-enactments or videos by the parents of any unclear physical symptoms, is critical.

Pertinent questions include:

  • Was this the first such event, or have there been multiple events?

  • Is there a single or multiple episodes within the event?

  • What was the child doing at the time of each spell—were they awake, asleep, playing, or sitting quietly?

  • If they were asleep, how long had they been asleep, or what time of day or night did the spell occur?

  • If abnormal tone or movements were involved, was the child rigid or limp, and which limbs were involved? Were the movements rhythmic and synchronous, or were they alternating, migratory, or stop-start?

  • If the child was unresponsive or had alteration of awareness, what did the parents do to ascertain their level of responsiveness? Did the parents try touching them to regain their attention, or merely call their name?

  • How long did the event last, and how did the child behave afterward?

  • Did the child describe any symptoms prior to the onset of the actual event, or was there any abnormal behavior that the parents witnessed prior to the event?

  • Were there any signs or symptoms of illness associated with the spell? Were any fevers documented?

  • Has there been any behavioral, developmental, or academic regression since the start of the events?

  • Is the child developmentally normal? If not, has the child’s development always been abnormal, or was there a regression at some point?

  • Were there any problems during pregnancy or the delivery?

  • Has the child ever had a significant head injury or central nervous system (CNS) infection?

  • Is there any family history of similar events, or any other neurologic disorders?

Parents frequently record videos of these spells on their mobile devices, which are ideal for reviewing the episode firsthand.

Physical Examination

The physician should compare vital signs, including blood pressure and head circumference, to previous measurements if possible. Elevated blood pressure can be indicative of pain, anxiety, increased intracranial pressure, or hypertensive encephalopathy. Hypotension may suggest syncopal events or sepsis. Dramatic increases in head circumference in infants may indicate intracranial pathology.

A general physical examination, including the cardiopulmonary and abdominal examinations, should be performed; abnormalities may indicate a non-neurologic cause for spells. Dysmorphic features or cutaneous findings can provide clues toward an underlying syndromic diagnosis.

An ophthalmologic examination can be as simple as obtaining a red reflex and observation of eye movements in young children. Eye movements may be observed by having the patient track a moving object or toy; abnormalities such as deviation, nystagmus, or new-onset limitations in range of motion may indicate a structural cause for the spells such as hydrocephalus or a mass lesion. In cooperative older children, the physician should attempt a funduscopic examination. Papilledema is a clue to increased intracranial pressure but is only readily appreciable after 2–3 weeks of increased intracranial pressure; it will not be present with acute disturbances leading to increased intracranial pressure.

The child will provide important information about their mental status and developmental status through simple conversation. Conversations about toys, school, or family members in the room can provide information about orientation, aphasia, dysarthria, and fund of knowledge for age. If there are any questions about whether any facial asymmetry is new-onset, parents may be able to provide old photographs; most people have some degree of facial asymmetry at baseline that may only be noticed after a frightening event causes the parents to observe the child more closely.

Muscle strength can be ascertained by manual testing in a cooperative older child or observing natural play or strength of resistance to examination in a younger child. If a child can easily perform age-appropriate actions such as crawling, walking, running, climbing, or grabbing for objects, and strongly resists examination, they are likely to have grossly normal strength in their major muscle groups. Tone can be checked by passively moving the patient’s limbs or suspending an infant in your hands to check if they start to slide through your grip. Low tone (hypotonia) can also be detected by observing gait or observing how the child sits; “W”-sitting (sitting with knees together and heels outside of their hips) may be another clue. Low strength (weakness) should be distinguished from hypotonia or ataxia; an example of normal strength but low tone might be an infant with motor delays and head lag who vigorously opposes examination; a child with normal strength but ataxia might vigorously oppose examination but cannot accurately reach to push away the examiner.

A normal physical examination (including vital signs and mental status) does not rule out the presence of a neurologic disorder but generally indicates a disorder that does not require immediate intervention and that more time can be spent carefully evaluating all diagnostic possibilities. In children with baseline neurologic abnormalities, such as children with cerebral palsy, knowledge of their baseline physical examination, abilities, and behavior is critical in deciding how urgently they need to be evaluated further. Parents can be very helpful in determining a child’s baseline behavior in this case.

Red Flags

After obtaining a history of the events, the presence of “red flags” in the history or examination should strongly prompt referral to the emergency room:

Increased Intracranial Pressure or Large Intracranial Mass

  • Hypertension and bradycardia

  • Third or sixth nerve palsy; anisocoria, ptosis, diplopia

  • Forced-seeming and persistent downward deviation of both eyes (tonic downward gaze deviation)

  • Papilledema

  • Severe vomiting that is exquisitely positional (i.e., strongly provoked by the transition from lying to sitting)

  • Engorged scalp veins

  • Bulging fontanel or split cranial sutures in an infant

  • Presence of a ventriculoperitoneal shunt (VP shunt) with any of the aforementioned symptoms should prompt concern about shunt malfunction

Ongoing Status Epilepticus

  • Waxing and waning responsiveness after a convulsive seizure has ended, particularly with periods of complete unresponsiveness

  • Persistent eye deviation after a convulsive seizure has ended

  • Persistent tachycardia after a convulsive seizure has ended

  • Persistent confusion or delirium, even if the child is able to speak and walk

Stroke or Complicated Migraine

  • Focal weakness or numbness, particularly if accompanied by slurred speech or confusion (if the spell is remote and the patient has returned to a normal baseline, suggest expedited referral to a neurologist)

Meningitis

  • Fever

  • Nuchal rigidity

  • Positive Kernig or Brudzinski signs

  • Bulging fontanel

The following red flags should prompt an urgent or even emergent referral to a pediatric neurologist, including direct communication with a neurologist for proper triaging:

  • Infantile spasms

  • Clusters of abdominal “crunches” or “startles,” particularly when the child is falling asleep or waking up from sleep

  • Developmental plateau or regression

  • Loss of visual attentiveness

Any developmental regression in infants or toddlers that has been present for more than 1 month (or sooner, for dramatic or progressive regressions) is concerning; change in handedness after 4–5 years of age is also a red flag (see Chapter 28 ).

Paroxysmal Spells of Altered Behavior or Movement

Paroxysmal neurologic symptoms can have neurologic, psychiatric, pulmonary, cardiovascular, or gastrointestinal causes (see Table 39.1 ). For this reason, during the investigation of a paroxysmal event, generic terms such as spells , convulsions , or altered mental status are more appropriate to use rather than seizures , which implies a very specific etiology and may falsely eliminate diagnostic possibilities. Witnesses may use terms such as grand mal , petit mal , or even generalized tonic-clonic (GTC) to describe events; these descriptors should not be taken at face value or thought to only describe epileptic seizures.

Epileptic Seizures

An epileptic seizure is a paroxysmal alteration in behavior, motor function, and/or autonomic function occurring in association with excessive synchronous neuronal activity in the CNS. Seizures may be considered provoked or unprovoked , referring to whether they were precipitated by an acute cause such as illness, concussion, metabolic disorder, or toxic ingestion. The term symptomatic refers to whether the seizures represent a symptom of a known chronic disorder, such as a structural, genetic, or metabolic abnormality. Epilepsy is a disorder in which there are recurrent unprovoked epileptic seizures; Figure 39.2 outlines the contextual framework when evaluating seizure disorders and Figure 39.3 provides the classification structure. Table 39.2 provides a glossary of terms frequently encountered when considering seizure disorders.

Fig. 39.2, The International League Against Epilepsy (ILAE) 2017 Classification of the Epilepsies. ∗Denotes onset of seizure.

Fig. 39.3, The 2017 International League Against Epilepsy (ILAE) operational classification of seizure types.

TABLE 39.2
Terminology Used in Describing Paroxysmal Episodes
Adapted from Fisher FS, Cross JH, D’Souza C, et al. Instruction manual for the ILAE 2017 operational classification of seizure types. Epilepsia. 2017;58(4):531–542 ( Table 2 , p. 538).
Word Definition
Absence, typical A sudden onset, interruption of ongoing activities, a blank stare, possibly a brief upward deviation of the eyes. Usually, the patient will be unresponsive when spoken to. Duration is a few seconds to half a minute with very rapid recovery. Although not always available, an EEG would show generalized epileptiform discharges during the event. An absence seizure is a seizure of generalized onset. The word is not synonymous with a blank stare, which also can be encountered with focal onset seizures
Absence, atypical An absence seizure with changes in tone that are more pronounced than in typical absence or the onset and/or cessation is not abrupt, often associated with slow, irregular, generalized spike-wave activity
Atonic Sudden loss or diminution of muscle tone without apparent preceding myoclonic or tonic event lasting ∼1–2 sec, involving head, trunk, jaw, or limb musculature
Automatism A more or less coordinated motor activity usually occurring when cognition is impaired and for which the subject is usually (but not always) amnesic afterward. This often resembles a voluntary movement and may consist of an inappropriate continuation of preictal motor activity
Autonomic seizure A distinct alteration of autonomic nervous system function involving cardiovascular, pupillary, gastrointestinal, sudomotor, vasomotor, and thermoregulatory functions
Aura A subjective ictal phenomenon that, in a given patient, may precede an observable seizure
Awareness Knowledge of self or environment
Behavior arrest Arrest (pause) of activities, freezing, immobilization, as in behavior arrest seizure
Bilateral Both left and right sides, although manifestations of bilateral seizures may be symmetric or asymmetric
Clonic Jerking, either symmetric or asymmetric, that is regularly repetitive and involves the same muscle groups
Cognitive Pertaining to thinking and higher cortical functions, such as language, spatial perception, memory, and praxis. The previous term for similar usage as a seizure type was psychic
Consciousness A state of mind with both subjective and objective aspects, comprising a sense of self as a unique entity, awareness, responsiveness, and memory
Dacrystic Bursts of crying, which may or may not be associated with sadness
Dystonic Sustained contractions of both agonist and antagonist muscles producing athetoid or twisting movements, which may produce abnormal postures
Emotional seizures Seizures presenting with an emotion or the appearance of having an emotion as an early prominent feature, such as fear, spontaneous joy or euphoria, laughing (gelastic), or crying (dacrystic)
Epileptic spasms A sudden flexion, extension, or mixed extension-flexion of predominantly proximal and truncal muscles that is usually more sustained than a myoclonic movement but not as sustained as a tonic seizure. Limited forms may occur: grimacing, head nodding, or subtle eye movements. Epileptic spasms frequently occur in clusters. Infantile spasms are the best-known form, but spasms can occur at all ages
Epilepsy A disease of the brain defined by any of the following conditions: (1) at least two unprovoked (or reflex) seizures occurring >24 hr apart; (2) one unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 yr; (3) diagnosis of an epilepsy syndrome. Epilepsy is considered to be resolved for individuals who had an age-dependent epilepsy syndrome but are now past the applicable age or those who have remained seizure free for the last 10 years, with no antiseizure medicines for the last 5 yr
Eyelid myoclonia Jerking of the eyelids at frequencies of at least 3 per second, commonly with upward eye deviation, usually lasting <10 sec, often precipitated by eye closure. There may or may not be associated brief loss of awareness
Fencer’s posture seizure A focal motor seizure type with extension of one arm and flexion at the contralateral elbow and wrist, giving an imitation of swordplay with a foil. This has also been called a supplementary motor area seizure
Figure-of-4 seizure Upper limbs with extension of the arm (usually contralateral to the epileptogenic zone) with elbow flexion of the other arm, forming a figure-of-4
Focal Originating within networks limited to one hemisphere. They may be discretely localized or more widely distributed. Focal seizures may originate in subcortical structures
Focal onset bilateral tonic-clonic seizure A seizure type with focal onset, with awareness or impaired awareness, either motor or nonmotor, progressing to bilateral tonic-clonic activity. The prior term was seizure with partial onset with secondary generalization
Gelastic Bursts of laughter or giggling, usually without an appropriate affective tone
Generalized Originating at some point within, and rapidly engaging, bilaterally distributed networks
Generalized tonic-clonic Bilateral symmetric or sometimes asymmetric tonic contraction and then bilateral clonic contraction of somatic muscles, usually associated with autonomic phenomena and loss of awareness. These seizures engage networks in both hemispheres at the start of the seizure
Hallucination A creation of composite perceptions without corresponding external stimuli involving visual, auditory, somatosensory, olfactory, and/or gustatory phenomena. Example: “hearing” and “seeing” people talking
Immobility Activity arrest
Impaired awareness (impairment of consciousness) Impaired or lost awareness is a feature of focal impaired awareness seizures, previously called complex partial seizures
Jacksonian seizure Traditional term indicating spread of clonic movements through contiguous body parts unilaterally
Motor Involves musculature in any form. The motor event could consist of an increase (positive) or decrease (negative) in muscle contraction to produce a movement
Myoclonic Sudden, brief (<100 msec) involuntary single or multiple contractions of muscles or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus
Myoclonic-atonic A generalized seizure type with a myoclonic jerk leading to an atonic motor component. This type was previously called myoclonic-astatic
Myoclonic-tonic-clonic One or a few jerks of limbs bilaterally, followed by a tonic-clonic seizure. The initial jerks can be considered to be either a brief period of clonus or myoclonus. Seizures with this characteristic are common in juvenile myoclonic epilepsy
Nonmotor Focal or generalized seizure types in which motor activity is not prominent
Propagation Spread of seizure activity from one place in the brain to another, or engaging of additional brain networks
Responsiveness Ability to appropriately react by movement or speech when presented with a stimulus
Seizure A transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain
Sensory seizure A perceptual experience not caused by appropriate stimuli in the external world
Tonic A sustained increase in muscle contraction lasting a few seconds to minutes
Tonic-clonic A sequence consisting of a tonic followed by a clonic phase
Unclassified Referring to a seizure type that cannot be described by the ILAE 2017 classification either because of inadequate information or unusual clinical features. If the seizure is unclassified because the type of onset is unknown, a limited classification may still derive from observed features
Unresponsive Not able to react appropriately by movement or speech when presented with stimulation
Versive A sustained, forced conjugate ocular, cephalic, and/or truncal rotation or lateral deviation from the midline
ILAE, International League Against Epilepsy.

Epileptic seizures must be clearly distinguished from non-neurologic paroxysmal disorders caused by psychiatric, cardiovascular, pulmonary, or gastrointestinal causes. There are also paroxysmal disorders that are neurologic but nonepileptic in nature, such as tics, dystonias, stereotypies, or other movement disorders. The correct diagnosis is critical to avoid unnecessary testing, interventions, and medication trials. However, multiple types of events, both epileptic and nonepileptic, may occur in the same patient, necessitating that each spell be properly characterized.

Epidemiology and Causes of Seizures and Epilepsy

If febrile seizures are included, approximately 3.5% of children experience some kind of seizure by the age of 15 years; most seizures occur before the age of 3 years. Most children who present with a seizure do not have or will not develop epilepsy. Many children presenting with a seizure have febrile convulsions, which are a provoked, age-dependent paroxysmal neurologic condition; 13% of children with seizures have acute symptomatic seizures other than febrile convulsions; and 8% have single, unprovoked seizures of unknown cause. The incidence of acute symptomatic seizures is highest in the first year of life; the most common causes of these predominantly neonatal seizures are genetic, infection, and metabolic disorders. After age 4 years, head trauma is the most common cause of acute symptomatic seizures, and infection is the next most common.

The incidence of epilepsy among children younger than 15 years is 45–85/100,000 in developed countries. It is highest in younger children; in those younger than 1 year, it is ∼100/100,000. The prevalence of active epilepsy in patients taking antiepileptic drugs (AEDs) is between 4.3 and 9.3/1,000, or about 0.5–1% of the population. Traditionally, ∼60% of children with epilepsy have no identifiable etiologic factors for the disease; next-generation gene sequencing technology has moved the estimated underlying genetic etiology to approximately 40%. Of those children in whom a cause is identified, population-based studies report the following presumed causes: infection in 5%, head trauma in 3%, and miscellaneous causes (tumors, malformations of cortical development, vascular malformations, and cerebral infarction) in 2%. Epilepsy is found in association with other long-standing neurodevelopmental abnormalities in 13% of children.

Genetics

It is estimated that a genetic etiology underlies epilepsy in approximately 40% of individuals. There are certain patterns and ages of onset that might guide specific genetic consideration ( Tables 39.3 and 39.4 ), but given the wide genetic and phenotypic heterogeneity, it is more practical to do gene sequencing broadly as opposed to trying to narrow down the genetic sequencing unless there is a very clear diagnostic consideration such as Angelman or Rett syndrome. Neonatal-onset seizures require both a metabolic ( Table 39.5 ) and a genomic approach to the diagnostic evaluation because there are several epileptic encephalopathic syndromes that could be treatable and genetic testing generally has a 2–3-month turnaround for results. If rapid genome sequencing is an option, this would supplant the need for metabolic testing as the results of genomic sequencing will be available within a short enough period of time to allow for timely implementation of treatment. Molybdenum cofactor deficiency is a rare example that has a lifesaving orphan drug treatment that needs to be initiated as early as possible to prevent irreversible cystic encephalopathy. Table 39.6 outlines several of the recognizable syndromic genetic disorders as defined by the underlying pathoetiology.

TABLE 39.3
Clinical Conditions for Targeted Gene Sequencing
Modified from Ream MA, Patel AD. Obtaining genetic testing in pediatric epilepsy. Epilepsia. 2015;56:1505–1514.
Targeted Gene Sequencing Clinical Condition Advantage of Testing
SCN1A Dravet syndrome. Consider testing for recurrent episodes of febrile status epilepticus, intractable tonic-clonic seizures during the first year of life, epileptic encephalopathy attributed to vaccination, and adults with a history consistent with Dravet syndrome Avoidance of sodium channel blockers, aggressive seizure management, justification of stiripentol, bromides, etc.
PCDH19 Females presenting with multiple clusters of brief febrile seizures and developmental delay or regression, particularly if there is a family history consistent with paternal transmission Prognosis and potential forthcoming treatment options
SLC2A1 Onset of absence seizures at younger than 4 yr old, particularly if there is a family history of paroxysmal exercise-induced dyskinesia Initiation of a ketogenic diet
POLG Prior to starting valproic acid in patients with drug-resistant seizures and developmental delay or regression Avoidance of potentially fatal liver failure starting as early as 2 mo after initiation of valproic acid therapy
HLA-B∗1502 Prior to starting carbamazepine, oxcarbazepine, phenytoin, and lamotrigine in patients of Asian descent Avoidance of a potentially fatal reaction (Stevens-Johnson syndrome/toxic epidermal necrolysis)

TABLE 39.4
Identified Genes for Epilepsy Syndromes
Epilepsy Type Gene Protein
Infantile Onset
Benign familial neonatal seizures KCNQ2 Potassium voltage-gated channel
KCNQ3 Potassium voltage-gated channel
Benign familial neonatal infantile seizures SCN2A Sodium channel protein type 2α
Early familial neonatal infantile seizures SCN2A Sodium channel protein type 2α
Early infantile epileptic encephalopathy (EIEE) CDKL5 (EIEE2) Cyclin-dependent kinase-like 5
ARX (EIEE1) Aristaless-related homeobox
TSC1 Hamartin
TSC2 Tuberin
SCN1A (EIEE6) Sodium channel protein type 1α
PCDH19 (EIEE9) Protocadherin-19
KCNQ2 (EIEE7) Potassium voltage-gated channel
STXBP1 (EIEE4) Syntaxin binding protein 1
SLC2A1 Solute carrier family 2, facilitated glucose transporter member 1
ALDH7A1 α-Aminoadipic semialdehyde dehydrogenase (antiquitin)
POLG DNA polymerase subunit γ1
SCN2A (EIEE11) Sodium channel protein type 2α
PLCβ1 (EIEE12) Phospholipase C β1
ATP6AP2 Renin receptor
SPTAN1 (EIEE5) α 2 -Spectrin
SLC25A22 (EIEE3) Mitochondrial glutamate carrier 1
PNPO Pyridoxine-5′-phosphate oxidase
Generalized epilepsy with febrile seizures plus (early onset) SCN1A Sodium channel protein type 1α
SCN1B Sodium channel protein type 1β
GABRG2 γ-Aminobutyric acid receptor subunit γ2
SCN2A Sodium channel protein type 2α
Childhood Onset
Childhood-onset epileptic encephalopathies SCN1A Sodium channel protein type 1α
PCDH19 Protocadherin-19
SLC2A1 Solute carrier family 2, facilitated GTM1
POLG DNA polymerase subunit γ1
SCN2A Sodium channel protein type 2α
Early-onset absence seizures, refractory epilepsy of multiple types, at times with movement disorder GLUT-1 deficiency syndrome, SLC2A1 gene Solute carrier family 2, facilitated GTM1
Generalized epilepsy with febrile seizure plus SCN1A Sodium channel protein type 1α
SCN1B Sodium channel protein type 1β
GABRG2 γ-Aminobutyric acid receptor subunit γ2
SCN2A Sodium channel protein type 1α
Juvenile myoclonic epilepsy (more commonly presents in adolescence) EFHC1 EF-hand domain-containing protein 1
CACNB4 Voltage-dependent L-type calcium channel
GABRA1 γ-Aminobutyric acid receptor subunit α1
Progressive myoclonic epilepsy (different forms present from infancy through adulthood) EPM2A Laforin
NHLRC1 NHL repeat-containing protein 1 (malin)
CSTB Cystatin-B
PRICKLE1 Prickle-like protein 1
PPT1, TPP1, CLN3, CLN5, CLN6, CLN8, CTSD, DNAJC5, MFSD8 Multiple proteins causing neuronal ceroid lipofuscinosis
Autosomal dominant nocturnal frontal lobe epilepsies (presents in childhood through adulthood) CHRNA4 Neuronal acetylcholine receptor α4
CHRNB2 Neuronal acetylcholine receptor β2
CHRNA2 Neuronal acetylcholine receptor α2
Adolescent Onset
Juvenile myoclonic epilepsy (JME) See Childhood-Onset JME
Progressive myoclonic epilepsy (PME) See Childhood-Onset PME
Autosomal dominant nocturnal frontal lobe epilepsies (AD-NFLE) See Childhood-Onset AD-NFLE
Autosomal dominant lateral temporal lobe epilepsy (usually presents in adulthood) LGI1 Leucine-rich glioma-inactivated protein 1

Note that the same gene (different variants) often appears as causing different epilepsy syndromes.

Most of these genes can be tested for through commercially available targeted single-gene sequencing or through commercially available gene panels or through exome sequencing ( http://www.ncbi.nlm.nih.gov/sites/GeneTests/review?db=genetests ).

TABLE 39.5
Inborn Errors of Metabolism (IEMs) Identified by Each of the Tier 1 Diagnostic Tests
From van Karnebeek CDM, Sayson B, Lee JJY, et al. Metabolic evaluation of epilepsy: a diagnostic algorithm with focus on treatable conditions. Front Neurol. 2018;9:Article 1016 ( Table 3 ). https://doi.org/10.3389/fneur.2018.01016 .
Source Diagnostic Test Related IEM
BLOOD Comprehensive metabolic panel Glucose (low in FAODs and HIHA)
Anion gap (elevated in organic acidemias)
Liver transaminases (elevated in CDGs and mitochondrial depletion syndromes)
Alkaline phosphatase (low in hypophosphatasia, elevated in GPI biosynthesis defects)
Blood gases Organic acidemias (low pH)
Urea cycle disorders (high pH)
Ammonia Urea cycle disorders
Organic acidemias
HIHA
HHH syndrome
Lysinuric protein intolerance
Pyruvate carboxylase deficiency
Creatine kinase FAODs
Dystroglycanopathy type-CDG
Uric acid Molybdenum cofactor deficiency (low)
Lactate/pyruvate PDH deficiency
Pyruvate carboxylase deficiency
Biotinidase deficiency
Mitochondrial respiratory chain defects
Lipoic acid synthesis defects
Plasma amino acids Urea cycle defects (elevated Glu)
MSUD (elevated branched-chain amino acids)
Tetrahydrobiopterin deficiencies (elevated Phe)
Lactic acidemias (elevated Ala)
Pyruvate carboxylase deficiency (elevated Cit, Pro, and Lys; low Glu)
PNPO deficiency (high Gly and Thr)
PDE (high Gly and Thr)
Nonketotic hyperglycinemia (elevated Gly)
Hyperprolinemia type 2 (elevated Pro)
Lipoic acid synthesis disorders (elevated Gly)
Serine biosynthesis disorders (low Ser)
Glutamine synthetase deficiency (low Gln)
Asparagine synthetase deficiency (low Asn)
GABA transaminase (elevated GABA, elevated β-Ala)
Mitochondrial glutamate transporter deficiency (elevated Pro)
Molybdenum cofactor deficiency (low Cys, high Tau)
Blood—cont’d Isolated sulfite oxidase deficiency (low Cys, high Tau)
Plasma acylcarnitines FAODs
Organic acidemias
Ethylmalonic encephalopathy
Copper and ceruloplasmin Menkes disease (low)
Wilson disease (low)
Plasma total homocysteine Cobalamin C disease (high)
MTHFR deficiency (high)
Molybdenum cofactor deficiency (low)
Isolated sulfite oxidase deficiency (low)
URINE Urinalysis Organic acidemias (elevated ketones)
MSUD (elevated ketones)
Urine AASA PDE
Molybdenum cofactor deficiency
Isolated sulfite oxidase deficiency
Urine purines and pyrimidines Adenylosuccinate lyase deficiency (high succinyladenosine)
Molybdenum cofactor deficiency (high xanthine and hypoxanthine)
Creatine metabolites AGAT deficiency (low GAA and creatine)
GAMT deficiency (high GAA, low creatine)
Creatine transporter deficiency (high creatine)
Urine organic acids PNPO deficiency (vanillactate)
Organic acidurias
OTC deficiency (orotic acid)
Cobalamin C deficiency (MMA)
Biotinidase deficiency and holocarboxylase synthetase deficiency (3-hydroxypropionic acid, 3-hydroxyisovaleric acid, 3-methylcrotonylglycine, methylcitrate)
Fumarate hydratase deficiency (fumarate)
SSADH deficiency (4-hydroxybutyric acid)
Ethylmalonic encephalopathy (EMA)
Mitochondrial short-chain enoyl-CoA hydratase 1 deficiency (methacryloylglycine, 3-hydroxyisobutyric acid, S -2-carboxypropyl-cysteine, and S -2-carboxypropylcysteamine)
AASA, α-aminoadipic semialdehyde; AGAT, arginine:glycine amidinotransferase; CDG, congenital disorders of glycosylation; EMA, ethylmalonic acid; FAODs, fatty acid oxidation disorders; GAA, guanidinoacetate; GABA, γ-aminobutyric acid; GAMT, guanidinoacetate methyltransferase; GPI, glycosylphosphatidylinositol; HHH, hyperornithinemia-hyperammonemia-homocitrullinuria; HIHA, hyperinsulinism-hyperammonemia syndrome; MMA, methylmalonic acidemia; MSUD, maple syrup urine disease; MTHFR, methylenetetrahydrofolate reductase; OTC, ornithine transcarbamylase; PDE, pyridoxine-dependent epilepsy; PDH, pyruvate dehydrogenase; PNPO, pyridox(am)ine 5’-phosphate oxidase; SSADH, succinic semialdehyde dehydrogenase.

TABLE 39.6
Epilepsy Genes and Phenotypes Catalogued in Online Mendelian Inheritance in Man (OMIM) Since 2016
From Hebbar M, Mefford HC. Recent advances in epilepsy genomics and genetic testing. F1000Res. 2020;9(F1000 Faculty Rev):185; last updated Mar 12 2020 ( Table 1 ). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7076331/pdf/f1000research-9-23530.pdf .
Gene Phenotype OMIM
Chromatin Remodeling
ACTL6B Epileptic encephalopathy, early infantile, 76 618470
SMARCC2 Coffin-Siris syndrome 8 618362
STAG2 Neurodevelopmental disorder, X-linked, with craniofacial abnormalities 301022
Intracellular Signaling
CSF1R Brain abnormalities, neurodegeneration, and dysosteosclerosis 618476
YWHAZ Popov-Chang syndrome 618428
CHP1 Spastic ataxia 9, autosomal recessive 618438
Ion Channels and Neurotransmitter Receptors
CACNA1E Epileptic encephalopathy, early infantile, 69 618285
GABRG2 Epileptic encephalopathy, early infantile, 74 618396
CACNA2D2 Cerebellar atrophy with seizures and variable developmental delay 618501
HCN1 Generalized epilepsy with febrile seizures plus, type 10 618482
CACNA1B Neurodevelopmental disorder with seizures and nonepileptic hyperkinetic movements 618497
KCNK4 Facial dysmorphism, hypertrichosis, epilepsy, intellectual/developmental delay, and gingival overgrowth syndrome 618381
SLC25A42 Metabolic crises, recurrent, with variable encephalomyopathic features and neurologic regression 618416
ATP1A1 Hypomagnesemia, seizures, and intellectual disability 618314
SLC28A1 Uridine-cytidineuria 618477
SCN8A Myoclonus, familial, 2 618364
SLC9A7 Intellectual developmental disorder, X-linked 108 301024
Metabolism
GLS Epileptic encephalopathy, early infantile, 71 618328
PARS2 Epileptic encephalopathy, early infantile, 75 618437
RNF13 Epileptic encephalopathy, early infantile, 73 618379
FCSK Congenital disorder of glycosylation with defective fucosylation 2 618324
PPP3CA Arthrogryposis, cleft palate, craniosynostosis, and impaired intellectual development 618265
PPP2CA Neurodevelopmental disorder and language delay with or without structural brain abnormalities 618354
MTHFS Neurodevelopmental disorder with microcephaly, epilepsy, and hypomyelination 618367
P4HTM Hypotonia, hyperventilation, impaired intellectual development, dysautonomia, epilepsy, and eye abnormalities 618493
DHPS Neurodevelopmental disorder with seizures and speech and walking impairment 618480
MAST1 Mega-corpus-callosum syndrome with cerebellar hypoplasia and cortical malformations 618273
DEGS1 Leukodystrophy, hypomyelinating, 18 618404
MYORG Basal ganglia calcification, idiopathic, 7, autosomal recessive 618317
ALKBH8 Intellectual developmental disorder, autosomal recessive 71 618504
NAXD Encephalopathy, progressive, early onset, with brain edema and/or leukoencephalopathy, 2 618321
KDM6B Neurodevelopmental disorder with coarse facies and mild distal skeletal abnormalities 618505
HS6ST2 Paganini-Miozzo syndrome 301025
TRMT1 Intellectual developmental disorder, autosomal recessive 68 618302
COLGALT1 Brain small vessel disease 3 618360
IREB2 Neurodegeneration, early onset, with choreoathetoid movements and microcytic anemia 618451
PIGB Epileptic encephalopathy, early infantile, 80 618580
Mitochondrial Metabolism
MICOS13 Combined oxidative phosphorylation deficiency 37 618329
GFM2 Combined oxidative phosphorylation deficiency 39 618397
Neuronal Development
NFASC Neurodevelopmental disorder with central and peripheral motor dysfunction 618356
NHLRC2 Fibrosis, neurodegeneration, and cerebral angiomatosis 618278
Nucleoplasmic Transport
NUP133 Galloway-Mowat syndrome 8 618349
NUP214 Susceptibility to acute infection-induced encephalopathy 9 618426
Regulation of Cell Morphology and Motility
BICD2 Spinal muscular atrophy, lower extremity predominant, 2b, prenatal onset, autosomal dominant 618291
DOCK3 Neurodevelopmental disorder with impaired intellectual development, hypotonia, and ataxia 618292
PHACTR1 Epileptic encephalopathy, early infantile, 70 618298
MACF1 Lissencephaly 9 with complex brainstem malformation 618325
DYNC1I2 Neurodevelopmental disorder with microcephaly and structural brain anomalies 618492
Synaptic Vesicle Cycle
NEUROD2 Epileptic encephalopathy, early infantile, 72 618374
MAPK8IP3 Neurodevelopmental disorder with or without variable brain abnormalities 618443
Transcriptional Regulation
ATN1 Congenital hypotonia, epilepsy, developmental delay, and digital anomalies 618494
RORB Susceptibility to idiopathic generalized epilepsy 15 618357
ZNF142 Neurodevelopmental disorder with impaired speech and hyperkinetic movements 618425
RSRC1 Intellectual developmental disorder, autosomal recessive 70 618402
TCF20 Developmental delay with variable intellectual impairment and behavioral abnormalities 618430
EIF3F Intellectual developmental disorder, autosomal recessive 67 618295
ZBTB11 Intellectual developmental disorder, autosomal recessive 69 618383
CNOT1 Holoprosencephaly 12 with or without pancreatic agenesis 618500
NFIB Macrocephaly, acquired, with impaired intellectual development 618286
SOX4 Coffin-Siris syndrome 10 618506
TRRAP Developmental delay with or without dysmorphic facies and autism 618454
Transmembrane Protein
TMEM94 Intellectual developmental disorder with cardiac defects and dysmorphic facies 618316
Structural Protein
COL3A1 Polymicrogyria with or without vascular-type Ehlers-Danlos syndrome 618343
Nuclear DNA Polymerase
POLE Intrauterine growth retardation, metaphyseal dysplasia, adrenal hypoplasia congenita, genital anomalies, and immunodeficiency 618336
Multiple Functions
WDR4 Microcephaly, growth deficiency, seizures, and brain malformations 618346
Intracellular Trafficking
TRAPPC2L Encephalopathy, progressive, early onset, with episodic rhabdomyolysis 618331

In some circumstances, unique clinical phenotypes can guide the initial clinical differential diagnosis. Severe metabolic acidosis resulting in shock and requiring intubation and ventilation is seen in metabolic epileptic encephalopathic syndromes such as nonketotic hyperglycinemia, pyridoxine-5′-phosphate oxidase deficiency, molybdenum cofactor deficiency, pyridoxine-dependent epilepsy, and Leigh syndrome. Table 39.7 provides an overview of the clinical associations of metabolic disorders associated with epilepsy. The characteristic syndactyly of the second and third toes is seen in steroid metabolism disorders, Smith-Lemli-Opitz syndrome in particular, which additionally has associated genitourinary tract abnormalities. Skin exanthems are highly suggestive of biotinidase deficiency. Atypical coarse or thin hair and wormian bones are seen in copper disorders such as Menkes syndrome. Cardiomyopathy is characteristic of mitochondrial disorders including Barth syndrome and fatty acid oxidation disorders and is also seen in RASopathies and cobalamin C deficiency. Atypical fat distribution and a prominent suprapubic fat pad are seen in congenital disorders of glycosylation. The circumstances in which genetic testing is offered varies widely between centers. Gene panels are offered by several laboratories and do not all include the same genes. It is thus important to understand the benefits and limitations of the test requested. Exome sequencing should not be considered “end of the line” or “last resort,” as the window of opportunity for targeted intervention may pass while more conventional options are investigated. This is particularly relevant in new-onset intractable or refractory seizures. In addition, there are several cases with digenic seizure disorders or rare metabolic disorders that will not be easily detected through more routine analysis but benefit from early targeted intervention to reduce morbidity and improve overall quality of life. The consensus for evaluating patients with suspected congenital disorders of glycosylation, mitochondrial disorders, or otherwise complex atypical disorders is to utilize exome sequencing as a first-line diagnostic test, with yields of up to 30% in these circumstances.

TABLE 39.7
Summary of Clinical, Laboratory, EEG, and Neuroimaging Findings of Metabolic Epilepsy
From van Karnebeek CDM, Sayson B, Lee JJY, et al. Metabolic evaluation of epilepsy: a diagnostic algorithm with focus on treatable conditions. Front Neurol. 2018;9:Article 1016 ( Table 2 ). https://doi.org/10.3389/fneur.2018.01016 .
IEM Neurologic Non-neurologic Laboratory EEG Brain MRI Brain MRS
Urea cycle disorders Encephalopathy Liver disease (sometimes) Hyperammonemia
Respiratory alkalosis
Increased glutamine
Slow background Cortical and subcortical edema
BG T2 hyperintensity with thalamic sparing
Scalloped ribbon of DWI restriction at insular gray-white matter interface
Prominent Glx peak
Organic acidemias Encephalopathy
Choreoathetosis
Cytopenias
Pancreatitis
Cardiomyopathy (PA)
Renal disease (MMA)
Hyperammonemia
High anion gap metabolic acidosis
Ketotic hyperglycinemia
Slow background
Burst-suppression possible
Diffuse swelling neonatally; delayed myelination and globi pallidi lesions later Decreased Glx peak (PA)
Disorders of biotin metabolism Encephalopathy Erythroderma or ichthyosis Hyperammonemia
High anion gap metabolic acidosis
Lactic acidosis
Ketosis
Burst-suppression Intraventricular hemorrhage
Subependymal cysts
Lactate peak
MSUD Encephalopathy
Opisthotonos
Bicycling/fencing movements
Sweet (“maple syrup”) smell Ketosis
Hypernatremia
Increased BCAAs and BCKAs
Comblike rhythm Increased signal and cytotoxic edema myelinated structures, vasogenic edema of unmyelinated tracts BCAA/BCKA peak (0.9 ppm)
Fatty acid oxidation defects Encephalopathy (“Reye syndrome”) Lipid storage myopathy
Liver disease
Renal cysts (GA2)
Hypoketotic hypoglycemia Slow background T2 hyperintensities in periventricular and subcortical WM (GA2) Lipid peak (0.9 and 1.3 ppm)
Primary lactic acidosis Encephalopathy
Infantile Parkinsonism (PC deficiency)
Dysmorphic features (PDH deficiency) Lactic acidosis Slow background, multifocal spikes T2 hyperintensities and DWI restriction of dorsal brainstem, cerebral peduncles, corticospinal tracts; subependymal cysts Lactate peak
Glycine encephalopathy Seizures None High CSF glycine and CSF/plasma glycine ratio Burst-suppression Dysgenesis of the CC
T2 hyperintensities and DWI restriction of myelinated tracts
Glycine peak (3.55 ppm)
Molybdenum cofactor/sulfite oxidase deficiency Seizures
Hyperekplexia
None Elevated S-sulfocysteine; low cysteine, high taurine
Increased AASA and pipecolic acid
Burst-suppression Diffuse swelling followed by cystic changes S-sulfocysteine peak (3.61 ppm); taurine peak (3.24
and 3.42 ppm)
Disorders of GABA metabolism Seizures
Hypersomnolence
Choreoathetosis
Overgrowth (GABAT) Elevated urine
4-hydroxybutyric acid (SSADH); elevated GABA, β-alanine, and homocarnosine (GABAT)
Slow background, multifocal spikes, burst-suppression T2 hyperintensities of globi pallidi, dentate and subthalamic nucleus (SSADH) GABA peak (2.2–2.4 ppm; GABAT)
PDE Seizures None Increased AASA and pipecolic acid Slow background, multifocal spikes, burst-suppression Usually normal; can have dysgenetic CC Decreased NAA peak (over time)
Serine biosynthesis disorders Microcephaly
Seizures
Ichthyosis
Ectropion, eclabion (Neu-Laxova)
Low serine in plasma and CSF Multifocal spikes; hypsarrhythmia Hypomyelination Decreased NAA peak; increased choline peak
Lysosomal storage disorders Neurodegeneration Hydrops fetalis
Dermal melanosis
Ichthyosis (Gaucher type 2)
Decrease in specific enzyme activity
Vacuolated lymphocytes (CLN3 disease)
Fast central spikes (Tay-Sachs); vertex sharp waves (sialidosis) Hypomyelination (GM1 and GM2 gangliosidosis, fucosidosis, Salla disease)
Subdural fluid collections (NCLs)
Broad peak centered around 3.7 ppm
Peroxisomal disorders Hypotonia
Seizures
Cholestasis; renal cysts; epiphyseal stippling
Dysmorphic features
Elevated VLCFA, phytanic acid, bile acid intermediates, pipecolic acid, low plasmalogens Multifocal spikes; hypsarrhythmia Perisylvian polymicrogyria and pachygyria; hypomyelination; subependymal cysts Lipid peak (0.9 and 1.3 ppm)
Congenital disorders of glycosylation Hypotonia
Seizures
Inverted nipples Abnormal fat pads Elevated transaminases; coagulopathy; endocrine abnormalities Multifocal epileptic discharges Pontocerebellar hypoplasia Decreased NAA peak
Disorders of copper metabolism Seizures Pili torti
Cutis laxa
Bladder diverticula
Metaphyseal lesions
Wormian bones
Low serum copper and ceruloplasmin; high urine copper Burst-suppression Arterial tortuosity
Subdural collections
Decreased NAA peak
GLUT1 deficiency Seizures
Abnormal eye movements
Hemolytic anemia, pseudohyperkalemia, cataracts (specific variants) Low CSF glucose and lactate; low CSF/serum glucose ratio Variable depending on type of seizure Normal Normal
AASA, α-aminoadipic semialdehyde; BCAAs, branched-chain amino acids; BCKAs, branched-chain ketoacids; BG, basal ganglia; CC, corpus callosum; CSF, cerebrospinal fluid; DWI, diffusion-weighted imaging; GA2, glutaric aciduria type 2; GABA, γ-aminobutyric acid; GABAT, GABA transaminase; Glx, glutamine/glutamate; IEM, inborn error of metabolism; MMA, methylmalonic acidemia; MRS, magnetic resonance spectroscopy; MSUD, maple syrup urine disease; NAA, N-acetylaspartate; NCLs, neuronal ceroid lipofuscinosis; PA, propionic acidemia; PC, pyruvate carboxylase; PDE, pyridoxine-dependent epilepsy; PDH, pyruvate dehydrogenase; SSADH, succinic semialdehyde dehydrogenase deficiency; VLCFA, very long-chain fatty acids; WM, white matter.

Seizure Classification and Terminology

Seizures are characterized according to their clinical semiology and presumptive etiology (see Figs. 39.2 and 39.3 ). Seizures can be difficult to classify and identify without a careful description of their onset, unfolding, and aftermath. Multiple seizure types may have the same brief general description, such as “twitching” or “staring.” Without further details as to duration, additional symptoms, and postictal behavior, they may be incorrectly classified as to type, even if they are accurately determined to be seizures. This is clinically relevant because improper classification can lead to inappropriate treatment; for example, some antiepileptic medications for focal seizures will exacerbate generalized seizures. Table 39.8 aligns some of the older terminology with the newer classification.

TABLE 39.8
Mapping of Old to New Seizure Classifying Terms
From Fisher FS, Cross JH, D’Souza C, et al. Instruction manual for the ILAE 2017 operational classification of seizure types. Epilepsia. 2017;58(4):531–542 ( Table 3 , p. 540).
Old Term for Seizure New Term for Seizure [Choice] (Optional)
Absence (Generalized) absence
Absence, atypical (Generalized) absence, atypical
Absence, typical (Generalized) absence, typical
Akinetic Focal behavior arrest, generalized absence
Astatic [Focal/generalized] atonic
Atonic [Focal/ generalized] atonic
Aura Focal aware
Clonic [Focal/generalized] clonic
Complex partial Focal impaired awareness
Convulsion [Focal/generalized] motor [tonic-clonic, tonic, clonic], focal to bilateral tonic-clonic
Dacrystic Focal [aware or impaired awareness] emotional (dacrystic)
Dialeptic Focal impaired awareness
Drop attack [Focal/generalized] atonic, [focal/generalized] tonic
Fencer’s posture (asymmetric tonic) Focal [aware or impaired awareness] motor tonic
Figure-of-4 Focal [aware or impaired awareness] motor tonic
Freeze Focal [aware or impaired awareness] behavior arrest
Frontal lobe Focal
Gelastic Focal [aware or impaired awareness] emotional (gelastic)
Grand mal Generalized tonic-clonic, focal to bilateral tonic-clonic, unknown-onset tonic-clonic
Gustatory Focal [aware or impaired awareness] sensory (gustatory)
Infantile spasms [Focal/generalized/unknown] onset epileptic spasms
Jacksonian Focal aware motor (Jacksonian)
Limbic Focal impaired awareness
Major motor Generalized tonic-clonic, focal-onset bilateral tonic-clonic
Minor motor Focal motor, generalized myoclonic
Myoclonic [Focal/ generalized] myoclonic
Neocortical Focal aware or focal impaired awareness
Occipital lobe Focal
Parietal lobe Focal
Partial Focal
Petit mal Absence
Psychomotor Focal impaired awareness
Rolandic Focal aware motor, focal to bilateral tonic-clonic
Salaam [Focal/generalized/unknown onset] epileptic spasms
Secondarily generalized tonic-clonic Focal to bilateral tonic-clonic
Simple partial Focal aware
Supplementary motor Focal motor tonic
Sylvian Focal motor
Temporal lobe Focal aware/impaired awareness
Tonic [Focal /generalized] tonic
Tonic-clonic [Generalized/unknown] onset tonic-clonic, focal to bilateral tonic-clonic
Uncinate Focal [aware impaired awareness] sensory (olfactory)
Note that there is not a one-to-one correspondence, reflecting reorganization as well as renaming.
The most important terms are set in bold.

Anatomic classification may still be useful for some purposes, for example, in evaluation for epilepsy surgery.

Clonic movements are rhythmic, nonsuppressible, position-independent jerking movements (low frequency, high amplitude) caused by involvement of the motor cortex. They can be unilateral or bilateral and can start with one body part and spread. If bilateral, they are synchronous and do not alternate from one side to the other in a bicycling fashion. This should be distinguished from clonus , which is rhythmic twitching of a limb, generally the foot, caused by hyperreflexia and lack of descending cortical inhibition due to CNS injury such as is seen in cerebral palsy or stroke. This is generally provoked by movement, excitement, and positioning and can be suppressed or halted by gently repositioning the affected limb. There is no alteration of alertness with clonus. In newborns, jitteriness (high frequency, low amplitude) may also be mistaken for clonic seizure activity; this tends to be stimulus-provoked and suppressible.

The term tonic refers to a change in tone as a manifestation of seizure activity, which clinically presents as stiffening or arching. This can occur as the only manifestation of a seizure (tonic seizure) or may be followed by clonic jerking, which is the generalized tonic-clonic seizure (GTC or grand mal). Atonic seizures refer to seizures where a sudden, brief loss of tone in the neck or entire body causes a head nod or fall to the ground. This type of seizure must be distinguished from falls due to complete loss of consciousness or those due to tonic stiffening of the entire body. With atonic seizures, the loss of tone is sudden but brief, and the patient is quickly responsive afterward.

Automatisms are semipurposeful movements that usually occur with impairment of consciousness either during or after a seizure and can be very useful for identifying a spell as a seizure. They may be a perseveration of an activity in progress at ictal onset, such as turning pages of a book, or novel semipurposeful movements arising during the seizure. These novel movements are most often a mixture of masticatory, oral, and lingual movements (lip smacking or grimacing) and simple fragmentary limb movements, such as fidgeting with a held object or pulling at clothing. In infants, orofacial automatisms are more likely than complex gestures and must be distinguished from the normal behavior of infants. Automatisms can be seen both in focal seizures, specifically those of temporal lobe onset, and in some generalized seizures, specifically absence epilepsy, so they are not specific to a broad category of seizure.

Impairment of consciousness , defined as an alteration in awareness of external stimuli, may be combined with a complete loss or impairment of responsiveness to external stimuli. Assessment of consciousness during seizures is often difficult, particularly in young children. It is possible to be unresponsive because of an inability to speak or articulate clearly (aphasia, apraxia, or paralysis). It is also possible to be responsive to external stimuli but to have altered awareness, often demonstrated by complete amnesia for events immediately before, during, or after the seizure, which implies that memory was not acquired during the seizure because of ongoing neuronal dysfunction. It is possible to have complex motor behaviors without loss of complete awareness or amnesia; frontal lobe seizures commonly have this presentation and must be carefully distinguished from nonepileptic events. Both focal and generalized seizures can be associated with impairment of consciousness; the term dyscognitive is used to describe this symptom (see Table 39.2 ).

Seizure etiology was previously divided into idiopathic, cryptogenic, and symptomatic . There were also separate categories for infantile spasms and neonatal seizures. The terms genetic, structural, metabolic, and unknown are currently used to characterize presumptive etiologies ( Table 39.9 ).

TABLE 39.9
Suggested Scheme for an Etiologic Classification of Epilepsy
From Shorvon SD. The etiologic classification of epilepsy. Epilepsia. 2011;52:1052–1057.
Main Category Subcategory Examples
Idiopathic epilepsy Pure epilepsies due to single-gene disorders Benign familial neonatal convulsions; autosomal dominant nocturnal frontal lobe epilepsy; generalized epilepsy with febrile seizures plus; severe myoclonic epilepsy of childhood; benign adult familial myoclonic epilepsy
Pure epilepsies with complex inheritance Idiopathic generalized epilepsy (and its subtypes); benign partial epilepsies of childhood
Symptomatic epilepsy
Predominantly genetic or developmental causation
Childhood epilepsy syndromes West syndrome; Lennox-Gastaut syndrome
Progressive myoclonic epilepsies Unverricht-Lundborg disease; dentato-rubro-pallido-luysian atrophy; Lafora body disease; mitochondrial cytopathy; sialidosis; neuronal ceroid lipofuscinosis; myoclonus renal failure syndrome
Neurocutaneous syndromes Tuberous sclerosis; neurofibromatosis; Sturge-Weber syndrome
Other neurologic single-gene disorders Angelman syndrome; lysosomal disorders; neuroacanthocytosis; organic acidurias and peroxisomal disorders; porphyria; pyridoxine-dependent epilepsy; Rett syndrome; urea cycle disorders; Wilson disease; disorders of cobalamin and folate metabolism
Disorders of chromosomes Down syndrome; fragile X syndrome; 4p− syndrome; isodicentric chromosome 15; ring chromosome 20
Developmental anomalies of the cerebral structure Hemimegalencephaly; focal cortical dysplasia; agyria-pachygyria-band spectrum; agenesis of the corpus callosum; polymicrogyria; schizencephaly; periventricular nodular heterotopia; microcephaly; arachnoid cyst
Predominantly acquired causation Hippocampal sclerosis Hippocampal sclerosis
Perinatal and infantile causes Neonatal seizures; postneonatal seizures; cerebral palsy
Cerebral trauma Open head injury; closed head injury; neurosurgery; epilepsy after epilepsy surgery; nonaccidental head injury in infants
Cerebral tumor Glioma; ganglioglioma and hamartoma; DNET; hypothalamic hamartoma; meningioma; secondary tumors
Cerebral infection Viral meningitis and encephalitis; bacterial meningitis and abscess; malaria; neurocysticercosis; tuberculosis; HIV
Cerebrovascular disorders Cerebral hemorrhage; cerebral infarction; degenerative vascular disease; arteriovenous malformation; cavernous hemangioma
Cerebral immunologic disorders Rasmussen encephalitis; SLE and collagen vascular disorders; inflammatory and immunologic disorders
Degenerative and other neurologic conditions Alzheimer disease and other dementing disorders; multiple sclerosis and demyelinating disorders; hydrocephalus and porencephaly
Provoked epilepsy Provoking factors Fever; menstrual cycle and catamenial epilepsy; sleep-wake cycle; metabolic and endocrine-induced seizures; drug-induced seizures; alcohol- and toxin-induced seizures
Reflex epilepsies Photosensitive epilepsies; startle-induced epilepsies; reading epilepsy; auditory-induced epilepsy; eating epilepsy; hot water epilepsy
Cryptogenic epilepsies
DNET, dysembryoplastic neuroepithelial tumor; SLE, systemic lupus erythematosus.

These examples are not comprehensive, and in every category there are other causes.

By definition, the causes of the cryptogenic epilepsies are “unknown.” However, these are an important category, accounting for at least 40% of epilepsies encountered in adult practice and a lesser proportion in pediatric practice.

Focal Seizures

Localization-Related Seizures, Partial Seizures

Focal seizures are seizures in which the first clinical and EEG changes indicate initial activation of a system of neurons limited to part of one cerebral hemisphere. The clinical symptoms and signs of focal seizures reflect the functional anatomy of the region of the brain undergoing the abnormal neuronal discharge.

When consciousness is impaired, this was historically known as a complex partial seizure; if there is no apparent loss of consciousness, this was known as a simple partial seizure. These terms have been replaced by the more descriptive terms focal seizure with impairment of consciousness or focal dyscognitive seizure in the case of complex partial seizures, and focal seizure without impairment of consciousness for simple partial seizures (see Table 39.8 ).

An aura is the portion of a seizure that is experienced before any loss of consciousness. Some auras can be difficult for a patient to describe; asking them if they know a seizure will happen before it happens, even if they cannot articulate precisely what they are experiencing, is one way to approach the topic. Examples of auras include an epigastric rising sensation; nausea; visual, auditory, or olfactory hallucinations; or limbic symptoms such as fear or a sensation of déjà vu. An aura may be suspected in very young children if there is a change in behavior before seizures, such as interrupting an activity to seek out parents or complaining of abdominal pain. The presence of an aura is traditionally thought to be indicative of a focal seizure without impairment of consciousness, as it implies focal cortical dysfunction, but some studies have reported that up to 64% of patients with documented idiopathic generalized epilepsy experience some form of aura, possibly due to asymmetric propagation of the discharges through the thalamocortical networks.

Nonepileptic events such as migraines or syncope may also have a prodrome, further highlighting the value of a comprehensive history in distinguishing types of events.

The progressive symptoms of some seizures after the initial aura reflect the spread of the abnormal electrical discharge beyond the region of onset, which is why a detailed history is critical for evaluating paroxysmal spells and determining the likelihood that they represent seizure activity.

Focal seizures can have motor and/or sensory components, depending on which areas of what is termed eloquent cortex become involved in the seizure. However, the seizure may originate in a portion of the cortex that does not produce obvious physical symptoms (termed the silent or noneloquent cortex ), and physical signs of the seizure only develop if the seizure discharge spreads to involve eloquent cortex. Seizures with clear electrical abnormalities but minimal or absent physical symptoms are commonly referred to as electrographic seizures or subclinical seizures . Subclinical electrographic seizures, particularly during sleep, can be associated with deterioration in development, behavior, attention, and learning.

Focal motor seizures produce rhythmic jerking (clonic) movements of the limb or limbs contralateral to the primary motor cortex involved. Other focal motor seizures include involuntary turning of the head and eyes in one direction (version), vocalization, and speech arrest. There may be tonic stiffening and extension of the arm ipsilateral to the seizure onset.

Involvement of the sensory cortex produces simple somatosensory experiences such as paresthesia or numbness, often with a dysesthetic quality, and visual, auditory, olfactory, or gustatory phenomena. Some of these sensory phenomena can be quite complex, including structured visual hallucinations, sensations of depersonalization, and affective symptoms such as anxiety or fear. Epileptic phenomena are a rare cause for such phenomena, and a broad differential diagnosis should be considered for paroxysmal spells where the primary symptoms are sensory or affective.

As the seizure continues to spread, both cerebral hemispheres may become engaged, and there is generalized clonic jerking of the body that closely resembles a GTC seizure. These secondarily generalized seizures may be mistaken for a generalized seizure if the onset is not witnessed. Occasionally after a seizure, there is persistent focal weakness or hemiparesis known as Todd palsy , which is strongly suggestive of a contralateral focal onset to the seizure.

Generalized Seizures

Generalized seizures are defined as seizures in which the first clinical changes indicate initial involvement of both hemispheres. Motor involvement, if present, is bilateral, as are the initial EEG changes. Consciousness is impaired in most generalized seizures, but not in all; for instance, brief myoclonic seizures and some atonic seizures may not be associated with any impairment of consciousness.

Absence (petit mal) seizures begin with sudden interruption of activity and staring; they are usually brief and end abruptly without postictal confusion. Simple absence seizures consist of only motionlessness and a blank stare lasting for several seconds, with immediate postictal reanimation. Lip-smacking, fumbling or searching hand movements, or convulsive swallowing can appear during longer seizures, or preictal activities may be continued in a slow, automatic manner. Paroxysmal alterations in autonomic function may also accompany absence seizures, including pupillary dilation, pallor, flushing, sweating, salivation, piloerection, or a combination of these. Absence seizures that are more typically accompanied by eyelid fluttering, facial twitching, or myoclonic jerks of the trunk or extremities are referred to as complicated absence seizures. Atypical absence seizures are described as absence seizures with a less abrupt beginning and end, with more pronounced changes in muscle tone, and of longer duration. Distinctions should be made between the clinical features of absence seizures, focal dyscognitive seizures, and episodic daydreaming ( Table 39.10 ). Staring spells that are prolonged beyond 15–20 seconds are less likely to represent absence seizures due to incorrect duration. Staring spells in infants and toddlers are also unlikely to represent absence seizures due to incorrect age of onset. Early-onset generalized epilepsy is associated with rare genetic syndromes. Children with prolonged staring spells, particularly starting at a young age, are at higher risk of partial-onset seizures or behavioral spells.

TABLE 39.10
Differential Diagnosis of Episodic Unresponsiveness Without Convulsions
Clinical Absence Seizures Focal Dyscognitive Seizures Staring, Inattention
Frequency Multiple daily Rarely more than one to two per day Daily, situation dependent: e.g., may occur only at school
Duration Often <10 sec, rarely >30 sec Average duration >60 sec, rarely <10 sec Seconds to minutes
Aura Not present May be present Not present
Abrupt interruption of child’s activity Yes: e.g., speech arrest midsentence; pause while eating, playing, or fighting Yes Activities such as play or eating are not abruptly interrupted, no sudden onset
Eyelid flutter Common, often with upward eye movement Uncommon, but may be present No
Myoclonic jerks Common Uncommon Not present
Automatisms Occur in longer absences, usually mild Frequent and often prominent No
Responsiveness Unresponsive Unresponsive Responds to touch
Postictal impairment None Postictal confusion and malaise is typical; drowsiness may also occur No
EEG Generalized 3-Hz spike-and-wave complexes Regional epileptic discharges (most often frontal or temporal) Normal
MRI Normal Focal structural lesions not uncommon (e.g., tumor) Normal
First-line medication Valproate, ethosuximide Carbamazepine, phenytoin, valproate None

Tonic-clonic seizures are perhaps the most dramatic of the epileptic seizures. The tonic phase begins with sudden sustained contraction of facial, axial, and limb muscle groups, and there may be an initial involuntary stridorous cry or a moan secondary to contraction of the diaphragm and chest muscles against a partially closed glottis (the ictal cry ). The tonic contraction is maintained for seconds to 10s of seconds, during which time the child falls if standing, is apneic and may become cyanotic, may bite the sides of their tongue, and may pass urine. The clonic phase of the seizure begins when the tonic contraction is repeatedly interrupted by momentary relaxation of the muscular contraction. This gives the appearance of generalized jerking as the contraction resumes after each relaxation. At the end of the clonic phase, the body relaxes, and the patient is unconscious with deep respiration. If roused, the patient is confused, may complain of muscle soreness, and usually wishes to sleep.

Myoclonic seizures are sudden, brief, shocklike contractions of muscles. They may involve the whole body or a portion of the axial musculature such as the face and trunk, or they may be limited to the limbs. They can be isolated or repetitive, irregular or rhythmic. Myoclonic seizures arise from the cortex and are associated with a distinct EEG pattern. Some forms of myoclonus are of brainstem or spinal origin; those occurring without other seizure types are not regarded as epileptic myoclonus but thought of as movement disorders .

Generalized tonic seizures begin in the same way as tonic-clonic seizures; a massive, generalized contraction produces any combination of facial grimacing, neck and trunk flexion or extension, abduction or elevation of the arms, and flexion of the hips. Subtle tonic seizures may produce only facial grimacing and slight neck and trunk flexion. Tonic seizures may be accompanied by pronounced autonomic activity with diaphoresis, flushing, pallor, and tachycardia, even when the muscular contraction is slight.

Atonic seizures are characterized by a sudden decrease or loss of postural muscle tone. The extent of muscle involvement may vary; an atonic seizure may be limited to a sudden head drop with slack jaw or may result in a fall because of loss of axial and limb muscle tone. The falls are referred to as drop attacks , and because they are unexpected and sudden in onset, they often result in injury.

Diagnostic Evaluation of a Seizure Disorder

Electroencephalographic Studies

The incidence of EEG epileptiform activity in normal children without a history of seizures is very low (<2%); such findings are associated with a strong family history of genetic epilepsy. The incidence of recurrent epileptic seizures in patients with focal EEG spikes is 83%. In a child with suspected seizures, the finding of focal or generalized epileptiform activity on the EEG supports a diagnosis of epilepsy, whereas multiple negative EEG studies capturing both wakefulness and sleep argue against such a diagnosis and should prompt the physician to consider alternative diagnoses and to attempt to record the episodes.

There are two basic types of EEGs: conventional and amplitude-integrated . A conventional EEG utilizes 19 or more electrodes distributed symmetrically over both hemispheres and along the midline. A routine outpatient EEG is run for at least 20 minutes, and more often 40–60 minutes. A prolonged EEG, or long-term monitoring, is run for over 24 hours, and can even be performed for over a week at a time. This type of prolonged study can be performed on an ambulatory basis at home or as an inpatient in an epilepsy monitoring unit. Amplitude-integrated EEG, by contrast, utilizes only two or four EEG electrodes and is primarily used in neonatal intensive care units.

An EEG should always attempt to capture sleep, and most will include hyperventilation and photic stimulation, all of which potentially activate epileptiform discharges, increasing the diagnostic yield. Hyperventilation produces absence seizures in about 80% of children with childhood absence epilepsy. Intermittent photic stimulation produces generalized epileptic discharges in several of the generalized epileptic syndromes, but photosensitivity is overall rare in epilepsy. Recording during wakefulness and sleep performed after sleep deprivation may have the highest yield. Overnight recording in the hospital provides for prolonged sampling of the interictal EEG in wakefulness and spontaneous sleep. For any patient with refractory seizures or an uncertain diagnosis, the use of video and EEG monitoring is usually helpful in clarifying the diagnosis. Defining the exact seizure type may lead to modification of drug treatment or consideration of epilepsy surgery, or a nonepileptic paroxysmal disorder may be discovered.

A single normal EEG does not definitively exclude a seizure disorder, particularly in people with infrequent seizures or seizures in specific contexts, such as illness or sleep.

Neuroimaging Studies

MRI is superior to CT for the evaluation of epilepsy. Any patient with a history or examination suspicious for focal-onset epilepsy should have MRI of the brain unless the syndrome is clearly that of benign focal epilepsy of childhood with centrotemporal spikes. MRI may also reveal an abnormality in patients with symptomatic generalized epilepsy. Functional neuroimaging is important in the assessment of candidates for surgical resection in patients with intractable seizures ( Fig. 39.4 ). When available, a 3.0 Tesla MRI of the brain with specific protocols dedicated to epilepsy evaluation (e.g., proper alignment of the imaging axis with the hippocampi) is preferred. It is important to note that generalized seizures associated with status epilepticus may also produce nonspecific and reversible findings on MRI ( Fig. 39.5 ).

Fig. 39.4, Fluorodeoxyglucose F 18 ([ 18 F]FDG) PET and ictal [ 99m Tc] ethyl cysteinate dimer ([ 99m Tc]ECD) single photon emission computed tomography (SPECT) in left frontal lobe epilepsy. This patient’s MRI scan (top row) was normal, whereas [ 18 F]FDG PET showed extensive left frontal hypometabolism (second row) . Additional ictal and interictal [ 99m Tc]ECD SPECT scans were performed for accurate localization of seizure onset. Result of a SPECT subtraction analysis (ictal-interictal; blood flow increases above a threshold of 15%, maximum 40%) was overlaid onto the MRI and [ 18 F]FDG PET scan (third and fourth rows, respectively), clearly depicting the zone of seizure onset within the functional deficit zone given by [ 18 F]FDG PET.

Fig. 39.5, Common MRI findings due to status epilepticus. Diffusion-weighted imaging (DWI) (A) sequence reveals increased intensity in the left insular and frontal cortices (white arrows) with corresponding decreased apparent diffusion coefficient (B). There are similar regions of increased intensity on fluid-attenuated inversion recovery imaging (C) and contrast enhancement (D) implying a component of vasogenic edema. These changes resolved on repeat MRI 1 week later.

Evaluation of the First Seizure

There is no clinical sign or diagnostic investigation that determines with certainty whether a child presenting with a first seizure has epilepsy or has had an isolated seizure. The assessment of patients with a first seizure must include a search for etiologic agents and features that may indicate the risk of recurrence. Factors to be considered include the circumstances of the seizure, the health of the child in the time before the seizure, the recent sleep patterns, the possibility of abuse or trauma, and the chance of ingestion of prescription or street drugs or syndromes such as the neurocutaneous disorders ( Table 39.11 ).

TABLE 39.11
Neurocutaneous Syndromes
Clinical Syndromes and Findings Investigations
Sturge-Weber Syndrome
Facial hemangioma, “port-wine stain” upper face, division of cranial nerve V; bilateral in 30%, absent in 5%, associated truncal and limb hemangiomas in 45% CT scan: calcification, MRI scan with gadolinium
EEG: attenuation of background rhythms, epileptiform discharges
Intracranial leptomeningeal angiomatosis
Epilepsy in 70–90%, usually before 2 yr and before hemiparesis, intractable in 35%
Intellectual disability in 50–60%
Hemiparesis in 30%, often with hemisensory deficit and hemianopia
Tuberous Sclerosis
Diagnostic Criteria
Any One of the Following:
Facial angiofibroma (adenoma sebaceum, nasolabial folds, and nose becomes more prominent with age) or periungual fibromas Physical examination
Cortical tubers, subependymal nodule, giant cell astrocytoma MRI examination: T1 and T2 sequences with gadolinium
Multiple retinal hamartomas (usually asymptomatic) or multiple renal angiomyolipomas (usually asymptomatic, may manifest as hematuria, hypertension, or renal failure) Funduscopic examination and renal ultrasonography, abdominal CT scan
Or Any Two of the Following:
Infantile spasms (seizures in 90%, most commonly generalized; infantile spasms and myoclonus) History and physical, EEG; focal or generalized abnormalities
Hypomelanotic papules (ash leaf spots; in 80–90%, 1–2 cm oval or leaf-shaped) Wood lamp examination in darkened room
Single retinal hamartoma Funduscopic examination
Subependymal or cortical calcification on CT scan CT scan of the brain
Single renal angiomyolipomas or cysts Renal ultrasonography or abdominal CT scan
Cardiac rhabdomyomas (single or multiple; may obstruct outflow, cause arrhythmias, or cause conduction defects) Echocardiography, ECG
First-degree relative with tuberous sclerosis (autosomal dominant disorder, 80% of cases represent new variants) Examination of parents; echocardiography, MRI scans
Also Associated:
Intellectual disability in 50–66%
Shagreen patches; hamartomatous skin lesion in lumbosacral region in 50%
Pulmonary involvement, fibrosis Chest radiograph
Skeletal abnormalities Hand, feet (cystic), long bone (sclerotic) radiographic changes
Epidermal Nevus Syndrome
Hamartomatous lesions; subclassified according to most predominant histologic and clinical features (e.g., linear nevus sebaceus, see below) Careful examination of the scalp, skin folds, and conjunctiva; funduscopic examination
Sporadic, affects both sexes equally; CNS abnormalities are common with epidermal nevus syndrome, including seizures (25% of patients), intellectual disability, and neoplasia; also, skeletal abnormalities, including kyphoscoliosis and hemiatrophy Spine and limb radiographs, as appropriate
Linear nevus sebaceus; hairless verrucous yellow-orange or hyperpigmented plaques on the face and scalp
Epilepsy in 76%
Intellectual disability in 60%
Associated neuronal migration disorders MRI scan of the brain
Malignant transformation of a skin lesion
Other Neurocutaneous Syndromes Associated with Seizures
Neurofibromatosis; cutaneous lesions include café-au-lait spots, axillary freckling, neural tumors; seizure types include generalized tonic-clonic, partial complex, and partial simple-motor MRI scan of the brain
Incontinentia pigmenti; involvement includes linear papular-vesicular cutaneous lesions at birth, later pigmentation, ocular and dental anomalies; female-to-male ratio >20:1 (boys may die in utero); seizure types include neonatal onset and later generalized tonic-clonic Skin biopsy; ophthalmology examination
Hypomelanosis of Ito (incontinentia pigmenti achromians)
CNS, central nervous system.

See http://www.tsalliance.org/healthcare-professionals/diagnosis/ .

The recurrence risk after a first unprovoked seizure, usually defined as a seizure or flurry of seizures within 24 hours in patients older than 1 month, is ∼40–50%.

The most important predictor of recurrence appears to be the existence of an underlying neurologic disorder. The existence of intellectual disability or cerebral palsy is a common antecedent to epilepsy, as is a history of significant head injury. An EEG with generalized or focal epileptiform discharges or with focal or generalized slowing is also predictive of recurrence. Focal seizures are more likely to be associated with recurrence, although patients with such seizures are also more likely to have an existing neurologic deficit or an abnormal EEG. The duration of the first seizure or a presentation in status epilepticus is not associated with a higher incidence of recurrence. A family history of epilepsy is not a predictor of recurrence. Earlier age at onset, particularly before the age of 12 months, has been associated with a higher risk of recurrent seizures.

Most authorities believe that the majority of patients with a first seizure should not be treated unless the risk of recurrence is judged to be significantly higher than average. An abnormal neurologic examination, an abnormal MRI of the brain, and abnormal EEG all increase the risk of recurrence; the greater the number of risk factors, the more likely an AED may be initiated after a first known seizure, although some neurologists will still elect to wait for a second confirmed seizure. In adults or adolescents, the issues of driving and employment may influence the decision to treat a first seizure, but in otherwise healthy and developmentally normal children, there is almost no indication for chronic AED treatment in response to a single seizure. Activities such as bathing, driving, and swimming must be carefully supervised.

The decision to begin AED therapy is usually made after a patient has had two or more seizures in a short interval of time (6–12 months). Treatment with AEDs lowers the recurrence rate by about 50% ( Fig. 39.6 ).

Fig. 39.6, Additional steps assume that seizures are not controlled despite adequate trial of well-tolerated medication. AED, antiepileptic drug; ASM, antiseizure medication; TLE, temporal lobe epilepsy; VNS, vagus nerve stimulation.

Status Epilepticus

Status epilepticus is a medical emergency where epileptic seizures are prolonged or occur in rapid succession without recovery between the seizures. There are two general categories of status epilepticus: convulsive and nonconvulsive (“subclinical”) status epilepticus. Convulsive status epilepticus may involve repetitive or prolonged GTC, myoclonic, or tonic seizures. Nonconvulsive status epilepticus may involve repeated or continuous absence seizures or focal dyscognitive seizures with an altered state of consciousness lasting hours or even days.

A common duration of a seizure defined as status epilepticus is 30 minutes or longer, but seizures continuing for more than 5–10 minutes warrant immediate attention, as they are statistically likely to progress to status epilepticus. The tonic-clonic phase of generalized seizures usually lasts <2 minutes; such seizures lasting ≥5 minutes usually evolve into status epilepticus. One third of children presenting with status epilepticus have no history of epilepsy, another third have a history of chronic epilepsy, and an acute illness or injury has caused status epilepticus in another third. One of the most common precipitants of status epilepticus in people with a known history of epilepsy is abrupt discontinuation of a daily AED.

Status epilepticus has a significant acute mortality rate, partly because of the underlying cause of the seizures; intracranial infections (meningitis, encephalitis), poisoning, acute metabolic disorders, and head injuries are some of the most common causes.

The goals of the emergency management of status epilepticus are as follows:

  • 1.

    Maintain normal cardiorespiratory function and cerebral oxygenation.

  • 2.

    Stop clinical and electrical seizure activity and prevent its recurrence.

  • 3.

    Identify precipitating factors.

  • 4.

    Correct any metabolic disturbances (hypoglycemia, hyponatremia) and prevent systemic complications such as cardiovascular collapse, cardiac arrhythmia, pneumonia, and renal failure.

Table 39.12 sets out a plan of initial assessment and management of convulsive status epilepticus. Lorazepam and diazepam are rapidly acting anticonvulsants when given intravenously but must be combined with a primary AED, as their duration of action is short. Side effects include sedation, depressed respiration, decreased ability to protect the airway, and hypotension.

TABLE 39.12
Management of Convulsive Status Epilepticus
Priority Examination and Laboratory Investigations Management
On arrival Airway patency and respiratory rate, inspect pharynx, chest auscultation, BP, pulse, temperature; level of consciousness; response to command, pain; serum Na, K, glucose, creatinine, Ca, Mg; CBC, liver function studies, AED levels; serum and urine toxins screen; arterial blood gases, chest radiograph Airway protection; suction pharynx and give supplemental oxygen
Rectal antipyretic to lower temperature if elevated, IV access and administer: 25% glucose IV, 2–4 mL/kg, and lorazepam IV, 0.1 mg/kg (to a maximum of 8 mg) as a bolus and fosphenytoin IV, 20 mg/kg at 150 mg/min with ECG monitoring and collection of serum level after loading dose
If immediate IV access is not possible, give diazepam 0.3–0.5 mg/kg rectally and fosphenytoin IM and arrange for central line or intraosseous access
After initial treatment Neck stiffness, funduscopy, signs of trauma, rashes, symmetry of motor function and reflexes If patient is febrile: appropriate cultures, other studies depending on age and other symptoms
If any suspicion of head injury: obtain urgent CT scan
If seizures continue Patient’s level of consciousness becomes depressed with lorazepam and PB, and an EEG is necessary to assess adequacy of therapy Arrange ICU bed and consider intubation; give further bolus of lorazepam 0.05–0.1 mg/kg, and push PHT serum level above 30 mg/L with further loading dose (∼10 mg/kg)
In an ICU setting, if seizures continue with PHT levels of 30–40 mg/L, then add PB 20 mg/kg IV loading over 15–30 min
Continued clinical or electrical seizures may necessitate induction of pentobarbital therapy: loading dose of 5–15 mg/kg, followed by IV infusion of 1–3 mg/kg/hr titrated by EEG monitoring to achieve burst-suppression pattern; maintain for 24–48 hr and review
Elective intubation and ventilation, arterial line, BP monitoring
After stabilization or in tandem with escalating therapy LP; if acute febrile illness with papilledema or focal neurologic signs, then CT/MRI first If LP is delayed and intracranial infection is suspected, then cover with antibiotic and antiviral therapy
AED, antiepileptic drug; BP, blood pressure; Ca, calcium; ICU, intensive care unit; IM, intramuscularly; IV, intravenously; K, potassium; LP, lumbar puncture; Na, sodium; Mg, magnesium; PB, phenobarbital; PHT, phenytoin.

Give lorazepam if actively convulsing; this may not be required in patients with serial seizures who can be quickly loaded with fosphenytoin.

Phenytoin, fosphenytoin, phenobarbital, or valproic acid could be used in conjunction with the benzodiazepines in providing longer-lasting anticonvulsive action.

Phenytoin is less commonly used. It has a rare but serious complication called purple glove syndrome, which occurs in 1.7–5.9% of intravenous administrations; within 2 hours of administration, there is pain, bluish discoloration, and swelling of the affected limb. Treatment involves discontinuation of the phenytoin and elevation and icing of the affected limb; compartment syndrome is a potential complication.

Fosphenytoin, a prodrug of phenytoin, can be administered either intravascularly or intramuscularly. Fosphenytoin has a maximum infusion rate of 150 mg PE/min; when it is infused faster, hypotension and arrhythmias may occur.

Valproate can be given intravenously and may be the appropriate therapy for patients with known idiopathic and symptomatic generalized epilepsies. It is also generally appropriate for children with a known static cerebral injury presenting with status epilepticus as their first seizure, such as a child with a history of neonatal hypoxic-ischemic encephalopathy who presents at age 4 in status epilepticus. It is contraindicated in children with known or suspected mitochondrial disease, multisystemic disease of unknown etiology, or known hepatic disease, or in children under the age of 2 years.

Nonconvulsive status epilepticus may arise when frequent focal dyscognitive seizures or absence seizures occur. In both settings, discrete seizures may not be identifiable; instead, the child may present with confusion, clouded consciousness, and partial responsiveness or a stuporous state, all of which can last hours or even days. It should be treated urgently as soon as it is identified, especially if focal dyscognitive status is suspected, in which case treatment should follow that outlined for convulsive status epilepticus. In absence status epilepticus, intravenous benzodiazepines are usually effective but should be used in conjunction with intravenous valproate or oral ethosuximide.

Classification of Epilepsies and Epileptic Syndromes

The clinician should attempt to determine whether the seizure disorder is focal or generalized, and then whether there is evidence of underlying brain dysfunction. Both the focal and generalized epilepsies in otherwise developmentally normal children respond favorably to treatment, and there is a good chance of long-term remission. Structural epilepsies may benefit from surgical intervention. Genetic and metabolic epilepsies respond less predictably to treatment, and the chance of remission is less certain.

Identification of one of the epileptic encephalopathies of infancy and childhood has grave prognostic significance ( Table 39.13 ). These epilepsies vary in the seizure types and EEG features but have certain features in common: specific age at onset and expression, intractable seizures, cognitive dysfunction, arrest in development, conspicuous interictal epileptic discharges on the EEG, and a poor response to treatment.

TABLE 39.13
Cryptogenic and Symptomatic Epileptic Encephalopathies
Neonates and Infants
  • Early infantile epileptic encephalopathy (Ohtahara syndrome)

  • Early infantile myoclonic epilepsy

  • Migratory partial seizures of infancy

  • West syndrome (infantile spasms)

  • Severe myoclonic epilepsy of infants (Dravet syndrome)

  • Epilepsy restricted to females with cognitive impairment

  • Atypical Rett syndrome with early epilepsy

  • Epilepsy in association with inherited disorders of metabolism (see Table 39.7 )

    • Lysosomal storage disorders

    • Urea cycle disorders

    • Aminoacidurias

Children and Adolescents
  • Lennox-Gastaut syndrome

  • Myoclonic-astatic epilepsy

  • Atypical benign partial epilepsy

  • Acquired epileptic aphasia (Landau-Kleffner syndrome)

  • Continuous spike-and-wave patterns in slow-wave sleep

  • Epilepsy in association with inherited disorders of metabolism

  • Mitochondrial encephalomyopathies

  • Progressive myoclonus epilepsies

  • Epilepsy in association with systemic disorders involving the central nervous system

  • Systemic lupus erythematosus, other vasculitides

Neonatal Period

The paroxysmal disorders seen in the neonatal period (birth to 8 weeks) are presented in Table 39.14 .

TABLE 39.14
Paroxysmal Disorders of the Neonatal Period
Paroxysmal Nonepileptiform Disorders
  • Jitteriness

  • Benign neonatal sleep myoclonus

Acute Symptomatic Seizures and Occasional Seizures
  • Hypoxic-ischemic encephalopathy

  • Intraventricular hemorrhage

  • Acute metabolic disorders

  • Sepsis-meningitis

Epileptic Syndromes
  • Benign idiopathic neonatal convulsions

  • Familial

  • Nonfamilial

  • Ohtahara (see EIEE) (see Table 39.18 )

  • Symptomatic focal epilepsy

  • Brain tumor

  • Malformations of cortical development

  • Inherited metabolic disease; mitochondrial disorders

  • Early-onset generalized epileptic syndromes with encephalopathy

  • Early myoclonic encephalopathy

  • Early infantile epileptic encephalopathy (EIEE)

Hypoglycemia, hypocalcemia, hypomagnesemia, hyponatremia, hypernatremia, hyperammonemia.

Paroxysmal Nonepileptic Disorders

Jitteriness

Jitteriness or tremulousness is a common movement disorder of neonates. It can be confused with seizures, especially if superimposed on normal tonic postural reflexes. Jitteriness, characterized by rhythmic alternating movements of all extremities with equal velocity in flexion and extension, only occasionally has a true synchronized clonic appearance. Jitteriness is not accompanied by eye deviation or staring, is stimulus sensitive, and can usually be stopped by gentle passive flexion of the moving limb.

Jitteriness in the newborn can be associated with hypoxic-ischemic encephalopathy, hypoglycemia, hypocalcemia, and drug withdrawal; if any of these causative factors are identified, there may also be a higher risk of epileptic seizures. In otherwise healthy infants, jitteriness seems to be a benign movement disorder, resolving by 10–14 months of age.

Benign Neonatal Sleep Myoclonus

Myoclonic jerks may appear during sleep in some healthy neonates. It has been reported within hours of birth and may disappear over the next few months or persist into childhood. The jerks can be bilateral and synchronous or asymmetric; they may migrate between muscle groups during an episode. They are repetitive but do not disturb sleep. These jerks have been described in all stages of sleep but are most prominent in quiet sleep; they are not confined to sleep onset. Features distinguishing this phenomenon from epilepsy are its presence exclusively during sleep with disappearance on awakening, normal EEGs, and normal psychomotor development.

Acute Symptomatic Seizures and Occasional Seizures

Most neonatal seizures are acute symptomatic seizures, and the number of children who continue to have seizures after the neonatal period is relatively small. Neonatal seizures have been classified according to the clinical features as subtle, tonic, clonic, and myoclonic. However, not all of these clinical seizure types have consistent ictal EEG patterns. The classification of neonatal seizures reflects the variable, poorly organized, and often subtle clinical expression of epileptic seizures at this age. Typical GTC or absence seizures are not seen at this age, perhaps because of the limited capacity of the neonatal brain for interhemispheric synchrony. Patterns include the following:

  • Clinical seizures consistently associated with an EEG seizure pattern:

    • Clonic seizures with focal or multifocal jerking of the face or extremities fit this category, as do focal tonic seizures with focal tonic posturing of a limb or asymmetric posturing of the axial musculature. Clinical seizures with consistent focal jerking or posturing of one limb are most consistently correctly identified at the bedside and are commonly associated with a focal structural defect, such as a focal perinatal stroke.

  • Clinical seizures sometimes associated with an EEG seizure pattern:

    • Myoclonic seizures consist of single or multiple flexor jerks of the upper or lower limbs. An ictal EEG pattern is not always seen in this group. Fragmentary (multifocal) myoclonus is not always associated with an ictal EEG.

  • Clinical seizures not consistently associated with an EEG seizure pattern:

    • These include motor automatisms characterized by a diversity of signs, including any of the following: wide-eyed staring, rapid blinking, eyelid fluttering, drooling, sucking, repetitive limb movements such as rowing or swimming with the arms or pedaling with the legs, apnea, hyperpnea, tonic eye deviation, and vasomotor skin color changes. This group of subtle seizures is generally associated with EEG background abnormalities such as suppression; the seizure itself may not have a consistent EEG correlate. This is reflective of diffuse cerebral dysfunction, such as seen in hypoxic-ischemic encephalopathy or metabolic disorders.

    • Generalized tonic seizures and focal and multifocal myoclonus are also often not associated with neonatal ictal EEG patterns, and when seen in stuporous or comatose children, the jerks may not be epileptic. However, if the EEG is completely normal, it is unlikely that the behaviors of concern represent subtle seizures.

Some simple clinical observations should guide the assessment of neonates with episodic abnormal behaviors. Epileptic behaviors are typically repetitive and stereotyped but are not provoked by stimulation of the child or increased with increasing intensity of a stimulus. Nonepileptic movements may disappear with repositioning of a limb or the child. Gentle restraint of a limb should be able to suppress or abort nonepileptic motor activity, whereas epileptic movements are still palpable. The association of abnormal eye movements with unusual behavior or limb movements suggests a seizure rather than nonepileptic behavior.

The possible etiologic factors are numerous and diverse ( Tables 39.15 and 39.16 ). The most common cause is hypoxic-ischemic encephalopathy (60–65%); it is important to make a positive diagnosis of this historically and to exclude conditions such as perinatal local anesthetic toxicity, pyridoxine-dependent seizures, prenatal injury, and metabolic encephalopathies that may masquerade as perinatal asphyxia.

TABLE 39.15
Causes of Neonatal Seizures
Ages 1–4 Days
  • Hypoxic-ischemic encephalopathy

  • Drug withdrawal, maternal drug use of narcotics or barbiturates

  • Drug toxicity: lidocaine, penicillin

  • Intraventricular hemorrhage

  • Acute metabolic disorders

    • Hypocalcemia

    • Perinatal asphyxia, small for gestational age

    • Sepsis

    • Maternal diabetes, hyperthyroidism, or hypoparathyroidism

    • Hypoglycemia

    • Perinatal insults, prematurity, small for gestational age

    • Maternal diabetes

    • Hyperinsulinemic hypoglycemia

    • Sepsis

    • Hypomagnesemia

    • Hyponatremia or hypernatremia

    • Iatrogenic or inappropriate antidiuretic hormone secretion

  • Inborn errors of metabolism

    • Galactosemia

    • Glycine encephalopathy

    • Urea cycle disorders

    • Pyridoxine deficiency (must be considered at any age)

Ages 4–14 Days
  • Infection

    • Meningitis (bacterial), encephalitis (enteroviral, herpes simplex)

  • Metabolic disorders

    • Hypocalcemia

      • Diet, milk formula

    • Hypoglycemia, persistent

      • Inherited disorders of metabolism: galactosemia, fructosemia, leucine sensitivity

      • Hyperinsulinemic hypoglycemia

      • Anterior pituitary hypoplasia, pancreatic islet cell tumor

      • Beckwith syndrome

  • Drug withdrawal, maternal drug use of narcotics or barbiturates

  • Benign neonatal convulsions, familial and nonfamilial

  • Kernicterus, hyperbilirubinemia

Ages 2–8 Wk
  • Infection

    • Herpes simplex or enteroviral encephalitis, bacterial meningitis

  • Head injury

    • Subdural hematoma, child abuse

  • Inherited disorders of metabolism

    • Aminoacidurias, urea cycle defects, organic acidurias

    • Neonatal adrenoleukodystrophy

  • Malformations of cortical development

    • Lissencephaly

    • Focal cortical dysplasia

  • Tuberous sclerosis

  • Sturge-Weber syndrome

TABLE 39.16
Inherited Disorders of Metabolism and Neurodegenerative Diseases Associated with Seizures in Infants
Disorder Clinical Features and Laboratory Findings Investigations
Neonates
These disorders are rare. The clinical features are nonspecific and usually do not distinguish between the inherited disorders of metabolism; however, they may suggest that a search for these conditions is warranted:

  • Metabolic or degenerative disorder in another sibling

  • Normal immediately after birth with symptoms and signs developing in the first days to weeks of life

  • Food intolerance; vomiting, diarrhea, not settling after feedings

  • Lethargy, may become stuporous after feeding

  • Hypotonia

  • Seizures; tonic, clonic, subtle neonatal seizures; myoclonus in some disorders

  • Late signs: weight loss, failure to thrive, psychomotor retardation

Initial investigations in neonatal seizures:

  • Glucose, urinalysis, ketones

  • Serum glucose, Na + , K + , Ca 2+ , Mg 2+ , blood urea nitrogen, creatinine

  • Serum ammonia, lactate, and pyruvate

  • Liver function tests, complete blood cell count, arterial blood gas measurements

  • Lumbar puncture and CSF analysis

  • EEG

  • CT or MRI scan may be indicated

  • Maple syrup urine disease

An unusual maple syrup odor of the urine may be detected; severe metabolic acidosis and increased anion gap; urine positive for ketones; boiled urine reacts with 2,4-DNPH to give yellow precipitate Serum amino acid analysis; elevated serum leucine, isoleucine, and valine
Organic acidurias
  • Propionic acid

  • Methylmalonic acid

  • Isovaleric acid

  • Glutaric acid

Hyperammonemia, metabolic acidosis and increased anion gap, ketosis, low blood urea nitrogen; secondary elevation of lactate and hypoglycemia may be present and secondary carnitine deficiency may occur; glycine level may be elevated in these disorders
Thrombocytopenia, neutropenia, and anemia
Characteristic body odor in some of these disorders
Urine organic acid analysis
Serum carnitine measurement
Serum acylcarnitine profile
Urea cycle disorders Hyperammonemia without hypoglycemia, ketoacidosis or hematologic abnormalities Serum ammonia. Plasma amino acids and urine orotic acid can help define the specific urea cycle defect
Nonketotic hyperglycinemia d -glyceric acidemia (glycine encephalopathy) Intractable seizures and severe encephalopathy, often with coma, within the first weeks of life; may have the clinical syndrome of early myoclonic encephalopathy; myoclonic seizures, burst suppression on EEG, severe psychomotor retardation Elevated urine and plasma glycine levels, normal organic acid pattern and ammonia level. Ratio of CSF:serum glycine necessary to make the diagnosis
Pyridoxine dependency No specific clinical features; must be suspected in all neonatal seizures without alternative cause and especially in those not responding to simple measures Therapeutic trial of pyridoxine; high dosage must be given for a period of weeks
Peroxisomal diseases
  • Zellweger syndrome

  • Adrenoleukodystrophy

  • Refsum disease

Characteristic facies
Neonatal form
Infantile form
Screen with serum very-long-chain fatty acid analysis, specific measurement of phytanic acid, pristanic acid, pipecolic acid, red cell plasmalogens, and bile acids for biochemical diagnosis. Molecular diagnostics using comprehensive gene panels
Infants
Pyruvate dehydrogenase deficiency
Pyruvate carboxylase deficiency
Metabolic acidosis and increased anion gap, lactic acidosis, with normal lactate-to-pyruvate ratio (10:20); hyperammonemia may be seen; normoglycemic; serum and CSF alanine levels may be elevated
Lactate-to-pyruvate ratio is normal or elevated
The clinical features are nonspecific: encephalopathy, hypotonia, and seizures; intermittent hyperventilation may be present. Both these disorders can manifest later in childhood with developmental delay and episodic symptoms such as ataxia and vomiting
Serum lactate and pyruvate measurement
Serum and CSF amino acids measurement
Biotinidase deficiency Refractory seizures, rash, alopecia; lactic and organic acidosis
  • Phenylketonuria

Onset in infancy with developmental delay and seizures; seizures occur in about 25%, and the infant may have severe epilepsy with West syndrome; deficiency of phenylalanine hydroxylase causes the accumulation of phenylalanine and phenylacetic acid Nearly 100% identified through newborn screening. Plasma amino acids will identify elevated phenylalanine in affected individuals
  • Phenylketonuria variant with biopterin deficiency

Hypotonia and seizures develop at or after 6 mo of age; generalized motor seizures, erratic myoclonus, and oculogyric seizures Nearly 100% identified through newborn screening. Plasma amino acids will identify elevated phenylalanine in affected individuals
Tay-Sachs disease
GM 2 gangliosidosis
Abnormalities appear in the first weeks to months of life with irritability and acoustic startle or myoclonus, not seizures, in the first months; developmental delay and cherry-red macular spots are present; seizures develop in the second year of life; erratic myoclonus, focal seizures, and slowing of background rhythms on EEG Blood sample and skin biopsy; hexosaminidase A deficiency detectable in blood lymphocytes and cultured fibroblasts
Sandhoff disease
GM 2 gangliosidosis type II
Similar in phenotype to Tay-Sachs disease Hexosaminidase B deficiency detectable in blood lymphocytes and cultured fibroblasts
GM 1 gangliosidosis Dysmorphic features; three clinical subtypes, infantile with rapid progression in first 6 mo of life, seizures are frequent without specific characteristics; cherry-red spots on the maculae; juvenile or late-onset form (6 mo–3 yr); chronic form (4–30 yr). Dysmorphic features and skeletal changes similar to Morquio mucopolysaccharide storage disorder Skin biopsy, blood β-galactosidase deficiency found in blood lymphocytes and cultured fibroblasts
Leigh disease (subacute necrotizing encephalopathy) A clinical syndrome resulting from various abnormalities of mitochondrial oxidative phosphorylation
Usually manifesting in infancy with regression of motor skills, hypotonia, lethargy, respiratory disorders (typically hyperventilation and apnea), and seizures; other features are nuclear and supranuclear oculomotor paralysis, brainstem dysfunction, choreoathetosis, cerebellar ataxia, and pyramidal signs
CSF lactate measurement; MRI of the brain (may show midbrain periaqueductal signal abnormalities)
Muscle biopsy for oxidative metabolism analysis and DNA studies
Menkes disease Sex-linked inheritance on long arm of X chromosome; hypotonia, failure to thrive, abnormal temperature regulation, hypothermia or hyperthermia, fragile wiry hair, poor pigmentation, generalized seizures, often infantile spasms Deficiency of serum copper and ceruloplasmin
Krabbe disease Appears before 3–6 mo of age; rigidity develops in an irritable, crying infant; opisthotonic posturing of the neck and trunk; generalized motor seizures may occur, but must be distinguished from tonic spasms; affected children become blind with optic atrophy Skin biopsy and blood galactocerebrosidase deficiency
Angelman syndrome Developmental delay from birth, characteristic facies, ataxia with jerky limb movements, inappropriate laughter (“happy puppet”), seizures in 86% of patients Abnormal methylation of maternally inherited imprinted region of chromosome 15q11.2. Four known genetic mechanisms can cause Angelman syndrome; approximately 70% of cases result from de novo maternal deletions involving chromosome 15q11.2-q13; approximately 2% result from paternal uniparental disomy of 15q11.2-q13; a subset of the remainder result from other imprinting defects and pathogenic variants in the gene encoding the ubiquitin-protein ligase E3A gene ( UBE3A )
Early infantile type of ceroid-lipofuscinosis
Batten disease
Severe myoclonus at 3–18 mo; hypotonia, ataxia, impaired vision, dementia; diffuse cerebellar and cerebral atrophy on EEG; no enzymatic defect identified; diagnosis must be based on clinical features and skin biopsy showing ceroid Skin biopsy, inclusion bodies on electron microscopy of peripheral lymphocytes (buffy coat EM), rectal biopsy; genetic testing available
Other Rare Metabolic Disorders with Encephalopathy Seizures in Infancy
Glutaric aciduria type II, multiple acyl-CoA dehydrogenase deficiency
Medium-chain acyl–CoA dehydrogenase deficiency
Canavan–van Bogaert disease
Molybdenum cofactor deficiency
Specific testing based on suspected diagnosis
CoA, coenzyme A; CSF, cerebrospinal fluid; DNPH, dinitrophenylhydrazine; EM, electron microscopy.

Diagnostic Investigations

EEG monitoring is useful in the evaluation of suspicious fluctuations in vital signs in neonates who are paralyzed and intubated or comatose, or in neonates with subtle but repetitive episodes of unusual behavior.

Many neonatal intensive care units have the capability to perform amplitude-integrated EEG (aEEG), which is a reduced electrode monitoring method that uses time-compressed baseline trends of two or four channels of EEG to allow the bedside practitioner to look for changes suspicious for seizure. However, both the sensitivity and specificity of aEEG are lower than that of full-montage conventional EEG: <50% if only a single channel of aEEG is available, but up to 76% and 78%, respectively, when two channels of raw EEG are available for comparison and direct review by expert aEEG interpreters. Conventional EEG is recommended over aEEG when both are available; however, the use of aEEG is associated with lower total seizure duration in neonates compared to no monitoring.

Proper treatment must include a thorough search for the cause of the seizures because many conditions necessitate specific treatment.

Prognosis

The prognosis for normal development after neonatal seizures depends on the cause of the seizures. Approximately 50% of neonates with seizures develop normally, 30% have neurologic sequelae, and 15–20% die. Neonates with seizures caused by CNS infection, hypoglycemia, structural brain malformations, intraventricular hemorrhage, and hypoxic-ischemic encephalopathy have a higher risk of poor outcome due to the prevalence of global brain injury in these conditions. Fifty percent of neonates with hypoxic-ischemic encephalopathy–related seizures develop normally, but fewer than 10% of neonates with seizures and intraventricular hemorrhage develop normally. In contrast, those infants with seizures caused by hypocalcemia (in the absence of asphyxia), drug withdrawal (from maternal drug use), and focal arterial ischemic stroke usually do well, as these are either caused by reversible, transient, or focal etiologies. The likelihood of recurrent seizures is 15–30% overall.

The EEG may add prognostic information; neonates with a normal background pattern are unlikely to have any neurologic deficits and are less likely to have seizures as a cause for their paroxysmal events, but persistent severe abnormalities of the background rhythms, such as burst-suppression patterns, suppression of background rhythms, and electrocerebral silence, have over 90% chance of a poor outcome, including death. Moderate abnormalities of the EEG in the form of amplitude asymmetries and patterns immature for the patient’s conceptional age are associated with intermediate outcomes and are of less value in isolation from other clinical data; these will require long-term neurologic follow-up. Table 39.17 lists neonatal and childhood epileptic disorders with a typically good prognosis.

TABLE 39.17
Childhood Epileptic Syndromes with Generally Good Prognosis
Modified from Deonna T. Management of epilepsy. Arch Dis Child. 2005;90:5–9; and Seneviratne U. The prognosis of idiopathic generalized epilepsy. Epilepsia. 2012;53(12):2079–2090.
Syndrome Comment
Benign neonatal familial convulsions Dominant, may be severe and resistant during a few days
Febrile or afebrile seizures (benign) occur later in a minority
Infantile familial convulsions Dominant, seizures often in clusters (overlap with benign partial complex epilepsy of infancy)
Febrile convulsions plus syndromes In some families, febrile and afebrile convulsions occur in different members, GEFS+
The old dichotomy between febrile convulsions or epilepsy does not always hold
Benign myoclonic epilepsy of infancy Often seizures during sleep, one rare variety with reflex myoclonic seizures (touch, noise)
Partial idiopathic epilepsy with rolandic spikes Seizures with falling asleep or on awakening; focal sharp waves with centrotemporal location on EEG; genetic
Idiopathic occipital partial epilepsy Early childhood form with seizures during sleep and ictal vomiting; can occur as status epilepticus
Later forms with migrainous symptoms; not always benign
Petit mal absence epilepsy Cases with absences only, some have generalized seizures; 60–80% full remission
In most cases, absences disappear on therapy but there are resistant cases (unpredictable)
Juvenile myoclonic epilepsy Adolescence onset, with early morning myoclonic seizures and generalized seizures during sleep; often history of absences in childhood
GEFS+, generalized epilepsy with febrile seizures plus.

Treatment

The primary treatment for neonatal seizures is the treatment of the underlying cause. All neonates with seizures should have a trial of pyridoxine and folinic acid treatment if the cause is not identified and seizures persist. Some neonates also require treatment with an AED, traditionally phenobarbital, but levetiracetam and fosphenytoin are also used. Protein binding is lower in neonates than in older children, and the speed of hepatic metabolism changes significantly in the first few days of life, so frequent serum levels of protein-bound, hepatically metabolized AEDs such as phenobarbital or fosphenytoin are necessary for the first several days of treatment, or when making dose adjustments.

At an intravenous loading dose of 18–20 mg/kg, phenobarbital should produce a serum level of approximately 18–20 mg/L. A daily maintenance dose of 3–5 mg/kg, either administered once daily or in two divided doses daily, keeps serum levels in this range. The serum level can be increased to 40–60 mg/L with further loading doses before consideration of a second drug for persistent seizures.

If a self-limited or correctable short-term insult is the cause, the clinician may administer a loading dose with phenobarbital and give no maintenance therapy, simply observing for recurrent seizures. Alternative management would be to administer a loading dose of phenobarbital and give maintenance doses throughout an illness or to treat for a maximum of 3–6 months if the time during which the child is at risk for seizures is uncertain.

Epileptic Syndromes

Benign idiopathic neonatal convulsions, familial and nonfamilial

Some neonatal seizures occur in otherwise healthy neonates without perinatal risk factors or identifiable causes that remit spontaneously and are not followed by developmental delay; these include benign idiopathic neonatal convulsions and benign familial neonatal convulsions. These are diagnoses of exclusion and a complete work-up for other causes of neonatal seizures must be performed before deciding upon these etiologies.

Benign idiopathic neonatal convulsions are common and may account for 2–7% of neonatal seizures. The disorder is sometimes referred to as fifth-day fits , although the seizures may begin between 1 and 7 days of age. The seizures are typically focal and multifocal clonic seizures that may, in rare cases, develop into status epilepticus. The seizures remit within hours or days. Although normal at the onset of seizures, affected neonates may become drowsy and hypotonic during the seizures and for a few days after the seizures remit. Long-term follow-up data are not yet complete, but the majority of affected children appear to have normal psychomotor development and no increased risk for the development of epilepsy.

Benign familial neonatal convulsions are less common. There is a distinctive family history of transient neonatal seizures that shows autosomal dominant inheritance. The onset of seizures is usually between 2 and 4 days after birth, but in some cases, onset may occur at 1–3 months of age. The neonates are otherwise healthy without risk factors for seizures. The seizures are usually brief clonic seizures, but some neonates have tonic seizures. This group differs from the nonfamilial cases in that the seizures may persist longer, the interictal EEG is generally nonspecific, and later seizures occur more frequently in approximately 10–15% of children. Abnormalities in two potassium channel genes, KCNQ2 on chromosome 20 and KCNQ3 on chromosome 8, have been found in some kindreds (see Table 39.4 ).

Vitamin-dependent seizures

There are rare metabolic disorders that present in the first few days of life with encephalopathy and refractory seizures; a smaller percentage of these disorders can be treated with early diagnosis and administration of the correct vitamin. Pyridoxine-dependent and folinic acid–dependent seizures are two such disorders; pyridoxine is essential for amino acid metabolism, and folinic acid is necessary for DNA synthesis and repair. Multidisciplinary care with a geneticist and a neurologist is ideal for children with these rare disorders.

Pyridoxine-dependent seizure is a rare autosomal recessive disorder in which seizures usually appear within the first 3 months of life, often within hours of birth, but in rare cases, as late as 2–5 years of age. The EEG may show focal, multifocal, and generalized epileptiform activity, and the child is encephalopathic. The seizures (myoclonic, GTC, and partial) and EEG discharges disappear over hours in response to 100 mg of intravenous pyridoxine (vitamin B 6 ), which can be repeated 3–5 times as necessary. The children require long-term pyridoxine, 50–100 mg/day.

Folinic acid–responsive seizures present very similarly to pyridoxine-dependent seizures, with medically intractable, relentless seizures of multiple types, often within the first days of life. The seizures respond to 2.5–5 mg of folinic acid twice daily.

These are rare disorders, but as they are neurologically devastating or fatal if untreated, it is reasonable to administer a trial dose of pyridoxine and/or folinic acid to seizing, encephalopathic infants where no other cause has been found for their seizures and encephalopathy. If there is a clinical, and ideally electrographic, response to the vitamin trial, then it is also reasonable to continue the supplement. Nonetheless, even with early diagnosis and treatment, these children may have developmental delays.

Biotin-responsive basal ganglia disease is a subacute encephalopathy syndrome manifest with episodes of dystonia, confusion, seizures, and coma that responds to acute and chronic biotin and thiamine therapy. SLC19A3 is the responsible gene.

Structural focal epilepsy

Malformations of cortical development . Disorders of cell migration within the CNS may result in profound anatomic abnormalities and dysfunction or a spectrum of lesser abnormalities, ranging from focal areas of cortical dysgenesis or dysplasia and clinical deficits to subcortical collections of neurons (heterotopia) seen only under the microscope. Migrational abnormalities are rare but are commonly associated with seizures. Although these abnormalities are present from birth, seizures may develop at any age.

Lissencephaly , or agyria, is a profound abnormality characterized by a smooth brain without development of the normal gyral pattern and sulci; there are often large heterotopias in the white matter, and neuroimaging studies may reveal the appearance of a double cortex.

Hemimegalencephaly is characterized by gross enlargement of one hemisphere with no normal cortical development within that hemisphere. More restricted abnormalities may occur in the form of a limited area of gyral enlargement and distortion called pachygyria.

Schizencephaly refers to unilateral or bilateral clefts in the cerebral hemispheres, usually with abnormal arrangement (polymicrogyria) of the cortical gray matter lining the clefts.

Porencephaly refers to fluid-filled cavities within the brain. Porencephalic cysts communicate with both the subarachnoid space and the ventricular system and are lined not by cortical gray matter but rather by white matter because they result from loss of tissue as a consequence of insults, typically infarction or hemorrhage, during development.

Early-onset generalized epileptic syndromes with encephalopathy

Early myoclonic encephalopathy appears in neonates before 2–3 months of age, usually within the first 2 weeks of life. Myoclonus appears at the onset but may be fragmentary. Partial motor seizures, massive myoclonus, or infantile spasms may also occur. The EEG shows a suppression-burst pattern that may later evolve into a hypsarrhythmic pattern. There is a failure or arrest of psychomotor development and a high rate of mortality before 12 months of age. A number of patients have an inborn error of metabolism, including nonketotic hyperglycinemia, d -glyceric acidemia, propionic acidemia, and methylmalonic acidemia; some have a pathologic genetic variant ( Table 39.18 ).

TABLE 39.18
Genetic Variants Associated with Epileptic Encephalopathies
From Beal JC, Cherian K, Moshe SL. Early-onset epileptic encephalopathies: Ohtahara syndrome and early myoclonic encephalopathy. Pediatr Neurol. 2012;47:317–323 ( Table 2 , p. 321).
Variant Site Ohtahara Syndrome EME West Syndrome SMEI Atypical RTT with Early Epilepsy EFMR
ARX Yes Yes
CDKL5 Yes Yes
ErbB4 Yes
MAGI2 Yes
PCDH19 Yes Yes
PNKP Yes Yes
SCN1A Yes
SLC25 A22 Yes
STXBP1 Yes Yes
Only epileptic encephalopathy syndromes presenting during infancy are included. Some variants may also be associated with other conditions; for example, the SCN1A variant is associated with generalized epilepsy with febrile seizures.
EFMR, epilepsy and cognitive impairment limited to females; EME, early myoclonic encephalopathy; RTT, Rett syndrome; SMEI, severe myoclonic epilepsy of infancy (also known as Dravet syndrome).

Early epileptic encephalopathy with suppression-burst EEG pattern (Ohtahara syndrome) has an onset during the same period. The affected child experiences intractable tonic seizures or epileptic spasms, and the EEG shows a suppression-burst pattern. Affected children have a severe encephalopathy, and the prognosis for remission from seizures or for normal development is very poor. Many of these patients have pathologic gene variants or malformations of cortical development (see Table 39.18 ).

There appear to be neonates in whom the EEG features and clinical course of these two syndromes overlap; these syndromes may evolve into West syndrome and Lennox-Gastaut syndrome.

Infancy

The paroxysmal disorders of infancy (8 weeks to 2 years) are shown in Tables 39.4 and Table 39.19 .

TABLE 39.19
Paroxysmal Disorders in Infants
Nonepileptiform Disorders
  • Infantile syncope

  • Cyanotic breath-holding spells

  • Pallid syncope

  • Shivering attacks

  • Paroxysmal torticollis

  • Extrapyramidal drug reactions, dystonia

  • Gastroesophageal reflux with dystonia

  • Rumination

  • Stereotypical movements, autism, Rett syndrome, coexisting deafness and blindness

  • Withholding, constipation

  • Masturbation

  • Spasmus nutans

  • Opsoclonus

  • Benign paroxysmal vertigo

  • Myoclonus

  • Nonepileptic; anxiety, excitement, acute metabolic encephalopathy

  • Benign myoclonus of early infancy

  • Hyperexplexia

  • Alternating hemiplegia of childhood

  • Sleep disorders

  • Jactatio capitis, head banging

Acute Symptomatic Seizures, Occasional Seizures
  • Febrile convulsions

  • Meningitis, encephalitis

  • Head injury, child abuse

  • Poisoning

  • Intercurrent medical illness, renal and liver disease, cardiac left-to-right shunt, and embolism

  • Metabolic disease, rickets

Epileptic Syndromes
  • Symptomatic focal epilepsy

  • West syndrome

  • Early myoclonic encephalopathy

  • Early infantile encephalopathic epilepsy

  • Malformations of cortical development

  • Neurocutaneous disorders (see Table 39.11 )

    • Tuberous sclerosis

    • Sturge-Weber syndrome

    • Incontinentia pigmenti

    • Epidermal nevus syndrome

  • Severe myoclonic epilepsy in infancy (Dravet syndrome and its mimics)

Common.

See childhood section for discussion.

See neonatal section for discussion.

Paroxysmal Nonepileptic Disorders

Infantile syncope

Cyanotic infant syncope (breath-holding spells)

Cyanotic infant syncope consists of episodes of loss of consciousness followed by tonic stiffening in crying infants. The peak incidence is between 6 and 18 months of age, but it may occur in neonates or in children as old as 6 years of age. The typical clinical picture is an infant who is frightened, frustrated, or surprised; begins to cry vigorously; and then becomes apneic and cyanotic before becoming unconscious, stiff, or limp. In rare cases, typical infant syncope may evolve into a brief GTC seizure. The child regains consciousness rapidly after being positioned horizontally or stimulated without a prolonged postictal state, although there may be a tendency to sleep.

These episodes have also been called breath-holding spells, anoxic seizures, and convulsive syncope, but cyanotic infant syncope may be a better term because the loss of consciousness appears to be the result of transient impairment of cerebral perfusion. The subsequent tonic posturing in the typical attack is not epileptic but is thought to have the same brainstem origin as decerebrate or decorticate posturing.

Cyanotic infant syncope is common and is seen in 4.6% of a large cohort of children monitored from birth. A thorough history is usually sufficient for diagnosing this condition. The crucial diagnostic point is the history of an external event precipitating the episode. The differential diagnosis is noted in Table 39.20 .

TABLE 39.20
Differential Diagnosis of Infantile Syncope
Clinical Cyanotic Infantile Syncope Pallid Syncope Tonic-Clonic Seizures Infantile Spasms
Age range 1–6 yr; peak, 6–18 mo 1–6 yr All ages 4–12 mo
Precipitating factors Present (e.g., minor trauma, frustration, fright) Present (e.g., minor trauma, frustration, fright) Usually none None
Occurrence in sleep Never Never Common At transition from awake to sleep and sleep to awake
Sequence of events Crying → exhale; apnea → cyanosis, loss of consciousness; opisthotonos → relaxation, resumption of breathing Upset, usually not crying → sudden pallor → limp fall with fainting → tonic posture, or clonic jerks may occur Sudden loss of consciousness → increased tone, followed by synchronous jerking of body and limbs → unconsciousness; duration, 1–2 min Sudden sustained flexion or extension of proximal limbs and trunk; duration, 2–20 sec; seizures usually occur multiple times daily
Postictal symptoms Usually minimal; infant may be lethargic and irritable Usually minimal; quick return to normal Usually marked; unconsciousness initially, then confusion and lethargy Rapid return to preictal state
Interictal EEG Normal Normal Frequently abnormal with epileptiform discharges Abnormal background and epileptiform discharges
Ictal EEG Reflects global cerebral hypoxia, diffuse rhythmic slowing → suppression → slowing with return of consciousness Reflects global cerebral hypoxia; diffuse, rhythmic slowing → suppression → slowing with return of consciousness EEG seizure patterns; postictal diffuse suppression, then slowing High-amplitude slow transient waves → diffuse suppression
Pathophysiology Respiratory arrest without asystole Vagal bradycardia or temporary asystole Primary CNS event Primary CNS event, age-related epileptic seizure
CNS, central nervous system.

Although the spells appear to be unpleasant for the child and can be frightening to the parents, they do not result in neurologic sequelae and do not necessitate intensive investigation. The child should be evaluated for anemia; treatment of iron-deficiency anemia reduces the frequency of syncopal events. Treatment with carbamazepine, phenytoin, or valproate may decrease the frequency or severity of postsyncopal convulsions in the rare child with epileptic seizures triggered by the anoxic event. Children with known brainstem or posterior fossa malformations may also be at higher risk of prolonged syncope and clinically significant anoxia due to their abnormal respiratory drive, and these children may benefit from treatment.

Pallid infant syncope

Pallid infant syncope occurs in response to transient cardiac asystole in children with a hypersensitive cardioinhibitory reflex. This form is much less common than cyanotic syncope but more alarming. There is minimal crying, perhaps only a gasp, and no obvious apnea before the loss of consciousness. Again, there is a precipitating event; the child appears to lose consciousness after minimal injury or fright, collapses limply, and then may have posturing and clonic movements before regaining consciousness (see Table 39.20 ).

Pallid infant syncope, if frequent and troublesome or if followed by prolonged GTC convulsions, can be treated with atropine, which blocks the vagus nerve–mediated asystole. Most affected children require no medical treatment.

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