Anticonvulsant Medication Effect in Patients With Continuous Epileptiform Discharges

Abstract

Continuous epileptiform discharges (CEDs) are often an unanticipated finding on an electroencephalogram (EEG) at times occurring after presumedly successful treatment of convulsive status epilepticus. Often no clinical seizures are evident. Implications for treatment are unclear and not necessarily the same as for convulsive status. We reviewed anticonvulsant use in 53 patients with CEDs. Clinical seizures occurred in just 21 following the EEG and were usually readily controlled. Mental status improved with anticonvulsant treatment in 16 of 20 stuporous or confused patients but in only 2 of 33 comatose patients. Benzodiazepines often controlled clinical seizures or suppressed EEG discharges but rarely led to improved alertness. Phenytoin and phenobarbital were the most useful medications in improving level of consciousness. Carbamazepine and valproic acid were almost never helpful, but drug levels were often subtherapeutic. The medication effect during the EEG did not predict which medication would produce a cognitive improvement. Recurrence of CEDs was common following tapering of medication, and most patients had complications attributed to anticonvulsants. Some patients with CEDs appear to benefit from long-acting anticonvulsants but require prolonged clinical and EEG follow-up.