Abstracts

Rationale: Objective:  Vigabatrin (VGB) adjunctive therapy was started in two patients with medically refractory focal dyscognitive seizures (FDS) with secondary generalization. Despite reduction of habitual seizures, VGB treatment produced atypical focal motor seizures (FMS) in both patients without loss of awareness (LOA), which resolved with VGB withdrawal.  Methods: Retrospective chart review. Results: One patient was a 23 year-old male with epilepsy since childhood in association with left mesial temporal sclerosis. Resection of the left temporal lobe resulted in moderate reduction of his habitual seizures, characterized by FDS with right facial clonic activity, occasionally spreading to his arm and leg. VGB was added (1500mg/day) to carbamazepine, lacosamide and clonazepam. Two weeks later, he developed new onset FMS without LOA, affecting only his right lower extremity.  Atypical seizures continued despite increased VGB (2000mg/day), but resolved with VGB withdrawal.            The second case is a 54 year-old woman whose epilepsy started at 19 years. She had a nonlesional right frontal lobe epilepsy, with focal seizures associated with LOA, left arm posturing, bimanual automatisms, and nonversive head turning to the right. VGB was introduced at 1500mg/day, with >50% seizure reduction. Upon increasing VGB to 2000mg/day, she developed FMS without LOA, beginning in her left face, then spreading to her left upper and lower extremities. Seizures increased further in frequency and duration on VGB at 3000mg/day. FMS resolved once VGB was withdrawn, despite increase in her habitual seizures.  Conclusions: VGB adjunctive therapy was associated with atypical, de novo FMS without LOA. While focal seizures without LOA may represent inhibited ictal propagation, but as neither patient demonstrated the same type focal motor semiology off VGB, alteration of   propagation is more likely. The mechanisms underlying relative excitability of the motor cortices during VGB therapy requires further investigation. Funding: None