Seizures, including generalized convulsions and simple and complex partial seizures, rarely occur after surgical clipping of unruptured cerebral aneurysms. We conducted a detailed investigation of cases of seizures after clipping for unruptured aneurysms. A total of 235 patients (78 men and 157 women; mean age, 63.0±9.1 years) with 251 aneurysms underwent surgical clipping of unruptured aneurysms. Intravenous administration of prophylactic antiepileptic drugs was continued for 1 or 2 days after surgery. Seventeen patients (6.7%) had seizures after surgery. Patients who underwent surgery through a transsylvian approach developed seizures significantly more frequently when compared with patients treated through other approaches, such as an interhemispheric approach (p=0.008). Onset of seizures occurred 3.5±2.5 days after surgery, and 13 patients (76.4%) developed seizures within 4 days. Three patients developed generalized seizures, 2 developed secondarily generalized seizures, and 12 developed partial seizures. Magnetic resonance imaging was obtained in 14 patients immediately after a seizure; 4 patients (28.5%) had high signals on diffusion-weighted imaging. Most of the patients discontinued antiepileptic drug therapy within 1 year after surgery. Because most patients with unruptured aneurysms are asymptomatic, seizures after surgery should be prevented whenever possible. Therefore, it is necessary to use appropriate prophylactic treatment for postoperative seizures.
