Possible transcallosal seizure induction by paired pulse transcranial magnetic stimulation in a patient with frontal lobe epilepsy.

Case report We report an 18 year old patient with right frontal lobe epilepsy due to paramedian focal cortical dysplasia (FCD). The patient’s usual seizure semiology consisted of a somatosensory aura of the left hand followed by a tonic seizure of the left arm which evolved to a bilateral asymmetrical tonic seizure without loss of consciousness. In the two years preceding the study (see below) he had rare night-time seizures only. His antiepileptic medication consisted of levetiracetam 500 mg, phenobarbital 25 mg, and carbamazepine 1600 mg daily. During presurgical videoelectroencephalogram (video-EEG) monitoring, interictal EEG showed right frontotemporal spikes. Ictal EEG revealed seizure patterns with a right frontal onset. Magnetic resonance imaging (MRI) showed FCD in the right superior frontal gyrus extending into the right precentral gyrus (fig 1A). Neurological examination was normal.