A 42-year-old man is brought to the hospital by his family after a reported seizure. The patient was found on the floor, unresponsive, and suffering convulsions lasting less than a minute. He suffered no apparent trauma before or during the event. He has no history of seizures. His mental status quickly improved; he experienced oriented lucidity with slight drowsiness. His neurological exam is nonfocal, and his vital signs and laboratory values are normal. A noncontrast head computed tomogram (CT) is normal.
What is the appropriate approach to diagnosis and management for this patient with a new-onset seizure?
A patient with a first seizure presents a dilemma. Underlying causes for seizure are potentially life-threatening, and must be identified if present. A patient whose first seizure is unprovoked is at risk for future seizures (i.e., epilepsy). However, long-term therapy with anticonvulsant medication has morbidity, side effects, and expense. Advising a patient on whether to drive has public safety and legal implications, as well as major lifestyle changes for the patient.
Seizures may be focal (limited to one area of the brain) or generalized (involving both hemispheres). For the most part, focal (also known as partial) seizures do not impair consciousness; generalized seizures do. Approximately 70% of first seizures are partial focal seizures.1 Such provoking causes as head trauma, stroke, alcohol withdrawal, brain tumors, and infections can be identified in about one-third of cases.1
Electroencephalogram (EEG) and computed tomogram (CT) of the brain should be obtained, but insufficient evidence exists to recommend other testing, which should be pursued according to the clinical context.2
Unprovoked seizures recur in about 25% to 50% of patients, resulting in a diagnosis of epilepsy.1,2,4-7
Therapy is unnecessary in patients whose seizures will not recur, but reliably identifying these patients is a challenge. Whether antiepileptic drug (AED) therapy should be initiated in patients with a first unprovoked seizure is controversial and will be reviewed below.
Review of the Data
History: No test or finding can reliably differentiate unwitnessed seizures from other events (e.g., syncope).2 History from a reliable observer often is necessary to determine whether the event actually was a seizure.2 In as many as 50% of patients with a “first” seizure, thorough history will likely reveal previously unrecognized seizures.1 Although most epilepsy syndromes begin in childhood or adolescence, a significant number of patients will experience their first seizure in adulthood.2
A thorough neurologic examination should be performed. In a minority of cases, an exam will suggest a focal lesion. An impaired level of consciousness might represent a post-ictal state or delirium.2