Seizures

Epidemiology

Seizures are common. It has been estimated that 9% of the population will have at least one seizure in their lifetimes and 1% to 3% of the population will develop epilepsy. A single seizure may be a reaction to an underlying disorder, part of an established epileptic disorder or an isolated event with no associated pathology. The challenge is rapidly to identify and treat life-threatening conditions as well as to identify benign conditions that require no further investigation or treatment.

The diagnosis of epilepsy requires at least two unprovoked seizures more than 24 hours apart or a single seizure with a known predisposing cause (e.g. central nervous system [CNS] structural abnormality or interictal electroencephalographic [EEG] changes). An episode of status epilepticus is considered a single seizure. Childhood febrile and neonatal seizures are usually excluded from this definition.

Classification (see video Types of seizures https://www.youtube.com/watch?v=jrYVudPCY0g )

Epileptic seizures can be classified into focal-onset and generalized types. Focal-onset seizures are further classified into simple focal (preserved consciousness) and complex focal seizures. Either may secondarily become generalized.

Generalized seizures can be divided into convulsive and non-convulsive types. Convulsive seizures are generalized tonic-clonic (grand mal) seizures. Non-convulsive generalized seizures include absence seizures (previously termed petit mal ), myoclonic, tonic and atonic (‘drop attack’) seizures. Epilepsy and epileptic syndromes are also classified as focal or generalized. Each disorder can be further classified according to its relationship to aetiological or predisposing factors. Seizures can also be classified as provoked (acute symptomatic) or unprovoked (‘unknown-onset’). The terms ‘idiopathic’ and ‘cryptogenic’ from previous classifications are discouraged.

Different seizure types are associated with differing aetiological and prognostic factors. A number of epileptic seizure classifications are supported by different bodies. The details of the classification systems are not as important in emergency medicine as the concept of recognizing the different seizure types and being aware of the accepted terminology (as outlined earlier) when cases are being discussed and referred.

Management principles

Given the high frequency of this condition in emergency departments (EDs), it is important to have an evidenced-based management strategy formulated in advance. The main management concepts are as follows:

• Altered mental state should be thoroughly assessed and not assumed to be due to a post-ictal state.

• Patients with known epilepsy who have recovered completely from a typical seizure require little further investigation. If they remain obtunded or have atypical features, they must be fully evaluated (e.g. through biochemical analysis, a computed tomography [CT] scan, etc.).

• Patients with epilepsy should be encouraged to seek continuing care.

• Patients at risk for recurrent seizures should be advised about situations of increased personal risk, such as driving, operating power machinery or swimming alone.

Differential diagnosis

Various conditions may be confused with epileptic seizures. Syncope is accompanied by some myoclonic activity in 90% of cases (see video Myoclonic activity during syncope https://www.youtube.com/watch?v=DOHGXoiS_Dk ). Migraine, transient ischaemic attacks, hyperventilation episodes and vertigo are all important conditions to consider in the differential diagnosis. Pseudoseizures are discussed further on.