Nonconvulsive status epilepticus during perioperative period of cerebrovascular surgery.

Nonconvulsive status epilepticus (NCSE) is generally defined as a change in behavior and/or mental process from the baseline, which is associated with ongoing seizure activity or continuous epileptiform discharges on electroencephalography (EEG) in the absence of convulsive seizures. The present study investigated NCSE incidence using serial EEG during the perioperative periods of cerebrovascular surgery at a medium-sized, local hospital. A total of 54 patients were admitted to our department and underwent various neurosurgical procedures over a course of one year. If clinical symptoms worsened without clear explanation, EEG was performed, resulting in a diagnosis of NCSE in four patients (7.4%). The EEG abnormalities included periodic lateralized epileptiform discharges in 1 patient, triphasic waves in 2 patients, and repeated ictal discharges in 1 patient. Improved mental status and consciousness level, together with disappearance of EEG abnormalities, after appropriate anticonvulsant treatment supported the diagnosis of NCSE. The present study stressed the importance of EEG if no adequate explanation for neurological deterioration can be determined from the clinical course, laboratory data, or neuroimaging examination.