Whether antiepileptic drugs (AEDs) should be prescribed for a person reporting only one seizure requires the physician to estimate the likelihood of recurrent seizures. Up to 10% of the general population may have a single seizure, but a much smaller proportion will have recurrent seizures and therefore will need AEDs or other treatment.

One of the main factors in this decision is the type of seizure. As a rule, when a single absence seizure is reported and confirmed by the typical EEG pattern, the child usually has had many other staring spells that have not been noticed, so treatment is generally recommended.

Similarly, with partial seizures, a person commonly will have had several partial seizures, but one relatively prominent episode or convulsion has finally brought him or her to the doctor. If a partial seizure has definitely occurred, the probability of more seizures is high and most physicians recommend treatment.

The question is more difficult for a single tonic-clonic (grand mal) seizure. The chance of another seizure varies from 16% to 61%, depending on the circumstances surrounding the seizure and test results. Another seizure may be unlikely and treatment with an AED may not be needed if:

• The neurologic examination shows no focal abnormalities.
• Neuroimaging studies (CT, MRI) show no identifiable brain lesion.
• The EEG is normal (especially with no epileptiform abnormalities).
• The patient's history does not include brain insult or cognitive impairment.
• There is no family history of epilepsy.
• The seizure occurred during sleep.
• Factors that tend to provoke seizures, such as sleep deprivation or excessive alcohol intake, can be eliminated.

The patient's wishes also must be a factor in this decision. Some patients may be willing to take the risk of having another seizure. The choice will be based on the likelihood of more seizures, the patient's lifestyle (for example, another seizure could be disastrous if the patient must drive a lot or cares for small children), and the likely side effects of the AED.

Adapted from: Schachter SC. Treatment of seizures. In: Schachter SC, Schomer DL, eds. The comprehensive evaluation and treatment of epilepsy. San Diego, CA: Academic Press; 1997. p. 61-74.
With permission from Elsevier (www.elsevier.com).
Reviewed and revised December 2003 by Steven C. Schachter, MD, Harvard Medical School