Top of the basilar syndrome in a young adult initially presenting with a convulsive seizure.

A 23-year-old man was admitted to our hospital due to loss of consciousness and a generalized convulsive seizure. He was diagnosed as having primary epilepsy and treated with antiepileptic drugs. Emergency CT scan of the head showed no abnormality. However, MRI scan of the head several days after admission revealed fresh infarctions caused by occlusion of the basilar artery, i.e., "top of the basilar" syndrome. This case indicates the need for precise differential diagnosis of convulsive seizure in an emergency situation. It should also be borne in mind that basilar occlusion with 'onset seizure' can occur even in young adults who have no risk factors for stroke.