Early postoperative seizures after posterior fossa surgery.

A review is reported of the seizure incidence in 726 patients who underwent 740 posterior fossa operations via a suboccipital craniectomy without prophylactic anticonvulsant agents. Thirteen patients (1.8%) experienced seizures within 2 weeks postoperatively. Five of these patients (0.7% of the series) had seizures within 24 hours after operation. The incidence was highest for patients with medulloblastoma (7.2%) followed by those with astrocytoma (2.3%). Also, a higher percentage was found in patients with preoperative ventriculoperitoneal shunt or intraoperative ventriculostomy (2.7%) than in those without (1%), but the difference was not statistically significant. Metabolic acidosis (80%) and hyponatremia (20%) were the major causes of the seizures that developed within 24 hours after operation. Follow-up computerized tomography showed no definite lesion in these patients. Hydrocephalus (75%) and supratentorial hemorrhage remote from the operative site (25%) were detected in the patients who developed seizures between the 2nd and 14th postoperative day. Two of these patients also had postoperative bacterial meningitis. This review suggests that seizures are a possible complication in the early postoperative period after suboccipital craniectomy for posterior fossa lesions.