Lacosamide, an antiepileptic drug prescribed for children with refractory focal epilepsy, is generally well tolerated, with dose-dependent adverse effects. We describe 4 children who developed a movement disorder in conjunction with the initiation and/or uptitration of lacosamide. Three patients developed dyskinesias involving the face or upper extremity whereas the fourth had substantial worsening of chronic facial tics. The patients all had histories suggestive of opercular dysfunction: 3 had seizure semiologies including hypersalivation, facial and upper extremity clonus while the fourth underwent resection of polymicrogyria involving the opercula. Onset, severity, and resolution of dyskinesias correlated with lacosamide dosing. These cases suggest that pediatric patients with dysfunction of the opercular cortex are at increased risk for developing drug-induced dyskinesias on high-dose lacosamide therapy. Practitioners should be aware of this potential side effect and consider weaning lacosamide or video electroencephalography (EEG) for differential diagnosis, particularly in pediatric patients with underlying opercular dysfunction.
Keywords: dyskinesia; focal epilepsy; intractable epilepsy; lacosamide; operculum.