Focal inhibitory seizures: a cause of recurrent transient weakness

Focal seizures are usually manifest with stereotyped positive phenomena. However, seizures may also give negative phenomena, such as paralysis, speech arrest, neglect, atonia and numbness. We report a 39-year-old man with neurofibromatosis 2 who had recurrent stereotyped episodes of weakness affecting his right leg and right arm. His MR scan of brain showed numerous meningiomas, the largest of which was near the vertex, adjacent to the left side of the falx. Interictal electroencephalogram, MR cerebral angiogram and Doppler carotid artery ultrasound scan were normal. He was diagnosed with epilepsy and started on levetiracetam, with no subsequent attacks. We postulate his negative motor seizures related to a meningioma overlying the supplementary negative motor area in the mesial superior frontal gyrus, and discuss diagnostic criteria for inhibitory seizures.