Diagnostic Utility of Overnight Video Electroencephalography (VEEG) to Routine EEG in Case of Seizure Disorder

Overnight sleep EEG has been widely used for diagnosis, classification and management of seizures over routine EEG. The high sensitivity of awake and sleep EEG over routine EEG in the diagnosis of epilepsy is well known. No such study has been undertaken in patients of North East India. Therefore, the present study was performed to study the sensitivity of minimum 12 hour EEG in the diagnosis of epilepsy. The study was carried out in the Comprehensive Epilepsy Care Centre, GNRC Hospitals, Six Mile, Guwahati, from June 2011 to July 2011.129 referred patients were subjected to overnight video EEG with mean recording time of 12 hours. Usually the patients were connected between 500 PM to 1000 PM in the previous evening and the recordings were continued upto 500 AM to 1000 AM next morning. . Routine activation procedures were followed. The recorded awake and sleep EEG was reviewed and findings were observed for background activity, response to activation, presence of benign variants, and presence of epileptiform activity. Epileptiform activities were recorded in 22 of 129 cases (17.05 %) during awake record. While continuing the recording during sleep, epileptiform activities were detected in 86 of 129 (66.66 %) patients. The increased sensitivity of sleep EEG over routine EEG is comparable to previous studies.16 (12.4 %) patients were documented to have at least one episode of seizure.19 (14.72 %) patients were found to have a normal sleep EEG, who clinically had history of seizure. In conclusion, the minimum 12 hours overnight EEG during both awake and sleep states is a highly sensitive diagnostic tool in the diagnosis and management of epilepsy.