Hemimegalencephaly is a malformation of cortical development that normally manifests in childhood with seizures and cognitive impairment. We present a case of hemimegalencephaly in a 55-year-old developmentally-normal woman who developed focal impaired awareness seizures with bilateral tonic-clonic spread. Her interictal EEG showed left-sided multifocal spikes, and ictal EEG showed seizures starting in the left hemisphere. Imaging showed hemimegalencephaly. This case may represent the oldest age for a first seizure in a patient with hemimegalencephaly.
Keywords: focal epilepsy; hemimegalencephaly; malformations of cortical development.