Altered Mental Status

Classification Systems

Standardized language is necessary to properly diagnose and treat alterations in consciousness because terms such as lethargy , obtundation , stupor , and coma are qualitative descriptions. Rating scales permit different observers to follow the progression of the patient’s mental status over time and facilitate effective communication of clinical information. The most widely used grading system is the Glasgow Coma Scale (GCS) ( Table 41.2 ), which has been modified for children younger than 5 years of age based on their age-appropriate developmental abilities ( Table 41.3 ). This 15-point scale evaluates three areas of CNS function: eye opening, verbal response, and motor response. A score of 15 indicates full function, whereas a score of 3 indicates no function. The first area of assessment is eye opening, in which the arousability and alertness of the patient are evaluated. Spontaneous eye opening indicates intact arousal mechanisms but does not imply awareness. The second area, verbal response, requires a high degree of integration within the CNS. Oriented responses indicate awareness of person, place, and time. The third area, motor functioning, reflects mentation as well as the integrity of the major CNS pathways. For purposes of gauging global brain function, the best motor response from any limb is taken as the score. Variation in response from one side of the body to the other is indicative of an asymmetric brain lesion. Spinal cord lesions resulting in paralysis or significant orthopedic injuries to the extremities prevent evaluation of the motor portion of the GCS.

The GCS can provide a general assessment of consciousness but is not intended to take the place of a complete neurologic evaluation ( Table 41.4 ). The GCS is an objective measure of the patient’s level of consciousness and should be used serially over time to monitor improvement or worsening of consciousness. Interventions are often based on the score; for example, most patients with a score of 8 or less should undergo endotracheal intubation. Deterioration of a patient’s score by 2 or more points indicates a need for urgent re-evaluation of the patient and the possible need for further interventions such as endotracheal intubation and diagnostic studies such as a brain CT scan.

The GCS has also been shown to correlate with prognosis in patients presenting with decreased levels of consciousness. In traumatic brain injury, it may take days to weeks for patients with initial scores of 3–5 to become conscious as opposed to a few days in patients with scores of ≥6. Children presenting after near-drowning with an initial score of ≥6 have good outcomes. Patients presenting with a score of ≤5 have a high probability of mortality or profound neurologic sequelae. A score of 3 on transfer to an intensive care unit after near-drowning has been associated with a nearly 100% rate of poor outcome.

Although the GCS is a widely applied tool for assessment, it does not assess brainstem function and fails to discriminate between low scores in intubated patients. The Full Outline of Unresponsiveness (FOUR) Scale is another tool to assess consciousness and evaluates eye response, motor response, brainstem reflexes, and respiratory effort on a 4-point scale. The FOUR score eye and motor responses are defined similarly to the GCS (see Table 41.2 ). The assessment of brainstem response focuses on the pupillary and corneal reflexes. The respiratory assessment includes ways to score for an intubated patient along with respiratory effort. Because the FOUR score includes brainstem responses and differentiates between intubated and nonintubated patients, this scale is better able to discriminate between patients with a GCS score of 3. Regardless of the scoring system used, reporting the score for each element can improve the precision of the assessment of the level of consciousness to guide management decisions.

Other scales have been developed to measure the level of consciousness in specific disease states, such as poisonings and hepatic failure. The Reed classification of coma has been used in the setting of poisoning or intoxication ( Table 41.5 ) and is used to evaluate increasing depths of coma encountered with CNS-depressant drugs. The cardiovascular system is included in this classification because toxic ingestions may depress myocardial contractility or cause vasodilation. Neurologic function in a patient with hepatic encephalopathy is staged according to the scoring system of symptoms, signs, and EEG ( Table 41.6 ).

Differential Diagnosis

The differential diagnosis in AMS is extensive. When AMS is associated with decreased level of consciousness, the differential can be broadly categorized as structural brain disease, nonstructural or medical disease, and psychogenic causes. Structural etiologies can result in either focal or nonfocal neurologic signs and include traumatic head injuries, hydrocephalus, tumors, intracranial hemorrhages, and cerebral vascular accidents. Nonstructural etiologies usually are associated with nonfocal neurologic exams and result in a decreased level of consciousness through diffuse neuronal injury. Nonstructural etiologies include infections, metabolic encephalopathies, toxic ingestion, hypoxic-ischemic events, inflammatory brain diseases, and seizures ( Table 41.7 ). The age of the patient can help the clinician differentiate the likely causes of coma, although there is considerable overlap ( Table 41.8 ). Patients with delirium must be differentiated from an acute psychotic event ( Table 41.9 ) (see Chapter 31 ). In addition, in patients who are awake but presenting with AMS, performing an appropriate mental status exam may help evaluate the degree of impairment and potential etiology ( Table 41.10 ). The mental status exam is most abnormal with medical (encephalopathy, encephalitis) causes of altered behavior and mental status. In primary psychiatric disorders, the neurologic exam is nonfocal and level of wakefulness often remains intact despite changes in behavior, orientation, and/or responses.

Simultaneous Diagnosis and Management Approach

Many causes of AMS are life-threatening medical emergencies. Rapid assessment and diagnosis are therefore crucial and must happen simultaneously alongside management of identified life-threatening etiologies. The approach to the child with AMS can be divided into four parts: (1) stabilization, (2) rapid clinical assessment, (3) reversal of immediately treatable toxic or metabolic causes, and (4) detailed investigation including determination of the level of CNS function and of the cause of the coma ( Fig. 41.1 ).

Rapid Physical Exam

After quickly collecting the available historical information, the next phase in management is completing a focused physical exam including a rapid neurologic assessment, which should take no more than a few minutes.

General Physical Exam

The general physical exam should include assessment of vital signs with emphasis on the cardiovascular, respiratory, and head and neck exams as well as a general assessment. Special attention should be paid to identify any physical exam findings that may suggest a specific toxidrome. The absence of a history of trauma or physical findings suggestive of a rapidly progressive intracranial process does not preclude a traumatic or an anatomic cause of coma. Traumatic injuries can result in life-threatening illnesses at any age, including in newborns. The head and neck should be carefully inspected, and the skull palpated for evidence of trauma ( Table 41.11 ). In infants, a bulging fontanel suggests raised intracranial pressure, which may have various causes. A bulging fontanel in the absence of a febrile illness should raise the suspicion of trauma, including abusive head trauma. Retinal hemorrhages are often present on funduscopic examination in children with abusive head trauma. In addition to abusive head trauma, a child may have a subarachnoid hemorrhage (ruptured aneurysm, arteriovenous malformation) or hydrocephalus without any of the aforementioned signs or symptoms of raised intracranial pressure. An ear exam should be performed to evaluate hemotympanum. Hemotympanum, clear drainage from the nose or ear, Battle sign (bruising behind the ear), and raccoon eyes may indicate a basilar skull fracture (see Table 41.11 ).

TABLE 41.11

Signs of Head Trauma Possibly Associated with Intracranial Disease

General	Signs of Basilar Skull Fracture
Lacerations	Hemotympanum
Hematomas	CSF rhinorrhea
Ecchymosis	CSF otorrhea
Swelling	“Raccoon eyes”
Palpable crepitations	Battle sign
Step-off of skull

CSF, cerebrospinal fluid.

Hyperventilation can be observed in midbrain structural lesions but also in toxic-metabolic encephalopathies as a primary response to stimulation of the respiratory center (salicylates, theophylline, hyperammonemia, hepatic coma) or as a compensatory response to a metabolic acidosis. This pattern is also seen with raised intracranial hypertension. Hypoventilation with a normal rhythm, particularly if associated with a symmetrically depressed motor examination, usually implies global CNS depression secondary to drug ingestion such as opioids or benzodiazepines ( Fig. 41.2 ).

Motor System and Focal Findings

The presence of focal findings can be determined by comparison of either side of the child’s body. Careful attention should be paid to asymmetry of tone and movement between extremities, asymmetry of the face either at rest or with movement, and asymmetry of reflexes, such as the pupillary and deep tendon reflexes. Examination of the motor system includes observation first of body position, then spontaneous movements, and finally response to noxious stimuli ( Fig. 41.3 ). Throughout the exam, the examiner should note asymmetry between sides and muscle tone.

A normal body position usually denotes an intact brainstem, as do spontaneous, nonposturing movements. Hemiparesis or hemiplegia implies a structural lesion in the contralateral hemisphere or subcortical region or an ipsilateral spinal cord injury. The presence of hypertonia or hyperreflexia suggests previous corticospinal tract disease or an acute brainstem injury at the midbrain-pontine level. It can also be observed in patients with severe metabolic derangements, such as hepatic coma, hypoglycemia, anoxia, and uremia. Hypotonia implies bilateral hemispheric dysfunction or a medullary or spinal cord lesion. In patients with severe depression of brain function, motor function can be assessed only after the application of a noxious stimulus, such as a sternal rub or increasing subungual pressure to the fingernails or toenails. If the response to a noxious stimulus includes verbalization, eye opening, or a normal motor response (e.g., localization of the stimulus, withdrawal of the limb, or movement away from the stimulus), this indicates that the ascending sensory pathways to the cerebral hemispheres are intact, and descending motor pathways are functioning.

Signs of Increased Intracranial Pressure

Indications of clinically significant intracranial hypertension can be assessed through the pupillary responses ( Fig. 41.4 ), vital signs, and motor responses ( Tables 41.12 and 41.13 ). The cranial vault contains brain, blood, and cerebrospinal fluid (CSF), and an increase in volume in one area necessitates a decrease in volume in another area. This increase in volume may occur secondary to space-occupying lesions, edema, intracranial hemorrhage, or hydrocephalus. The volume compensation mechanisms within the cranial vault are limited, and if volume cannot be decreased in another area, intracranial pressure increases. The first signs of increasing intracranial pressure are often headache and vomiting followed by decreased consciousness, which is then followed by posturing, and finally vital sign changes followed by death. Sixth cranial nerve palsy or inability to abduct the eye can be an early sign of increased intracranial pressure caused by stretching of the sixth cranial nerve. Papilledema is also associated with increased intracranial pressure but takes ≥12 hours to develop and therefore may be absent in acute increased intracranial pressure. As intracranial pressure continues to increase, it eventually leads to brain herniation and the vital sign changes of Cushing triad : hypertension, bradycardia, and irregularities of respiration.

Brain herniation can occur at several different locations. The most common type of herniation is transtentorial herniation, which can be divided into uncal and central herniation. Uncal herniation occurs when the uncus (the inner part of the temporal lobe) herniates over the tentorium. This puts pressure on the midbrain, which contains the third cranial nerve. Pressure on the third cranial nerve impairs its parasympathetic fibers, leading to ipsilateral pupillary dilatation. Therefore, a unilaterally fixed and dilated pupil in a patient who is not awake represents uncal herniation. Central herniation occurs when central brain structures (diencephalon and temporal lobes) herniate through the tentorium cerebelli. Pressure on the hypothalamus at first causes small reactive pupils, which then progress to pupils that are fixed at midposition. Other types of herniation include subfalcine herniation, in which the cingulate gyrus herniates under the falx cerebri and presents with unilateral or bilateral weakness and can progress to central herniation. Tonsillar herniation or foramen magnum herniation results from the cerebellar tonsils being forced through the foramen magnum causing compression on the medulla oblongata and the cervical spinal cord leading to downbeat nystagmus, bradycardia, bradypnea, and hypertension. These signs can sometimes be worsened with neck flexion and improved with neck extension.

Brainstem Functioning

Brainstem function is evaluated by observing the child’s respiratory pattern, pupillary reflexes, corneal reflexes, and eye movement reflexes. Dysfunction of brainstem reflexes implies disruption of the ARAS and is a red flag indicating a serious and life-threatening disease process.