[Seizure exacerbation caused by antiepileptic drugs]

In certain types of epilepsy, antiepileptic drugs can exacerbate the disease instead of improving it.

This review is based on a non-systematic literature search in Medline for the time-period 1990-2007, and our own clinical experience.

As a consequence of treatment with antiepileptic drugs, patients with epilepsy may have more frequent and severe seizures of the type they had before, but also new seizure types or patterns, and even series of seizures or status epilepticus. Both old and new antiepileptic drugs may exacerbate seizures, but carbamazepine-induced generalized seizures (such as absence and myoclonic) are best documented. More than one pathophysiological mechanism is probably involved in drug-related exacerbation of seizures, such as sedative and pro-convulsive effects of high serum levels, drug-associated encephalopathy, and a paradoxical pharmacodynamic effect. Accurate epilepsy- and seizure classification is important in the treatment of all types of epilepsy. Atypical absences are sometimes mistaken for complex partial seizures. Such patients may be given drugs with a narrow spectrum such as sodium channel blockers (e.g. carbamazepine, phenytoin, oxcarbazepine) or GABAergic agents (e.g. vigabatrin, tiagabine) with an increased risk of seizure exacerbation. Those at greatest risk of experiencing drug-related seizure exacerbation are learning-disabled patients, children with severe epileptic encephalopathies, those with high seizure frequency and several seizure types, and those using polytherapy.