Abstracts

Rationale: The performance of surface EEG can be challenging in patients who are unable to cooperate with the procedure. We present one year's experience of the performance of EEG under general anesthesia with sevoflurane. Methods: All EEGs were performed at the Barrow Neurological Institute between 5/30/07 and 5/30/08. A similar protocol was used throughout, consisting of sevoflurane alone to a mean alveolar concentration (MAC) of 7-8% sufficient to produce unconsciousness. Surface EEG electrodes were then applied using the international 10-20 system of electrode placement. The EEG was then recorded as the anesthesia was turned off, oxygen applied, and the MAC dropped to zero. The recordings were then evaluated by staff epileptologists. Results: A total of 45 studies were performed. None of the patients was neurologically normal and all had some degree of encephalopathy. There were 29 males (64%) and 16 females (36%) ranging in age from 2 to 17 years, with one female of 22 years. 22 studies (49%) were read as normal, with normal defined as : lack of asymmetry or epileptiform discharges (EPDs) and a normal mix and distribution of frequencies once the sevoflurane MAC had reached zero and the anesthesia effect of background slowing and increased beta rhythms had resolved. 23 studies (51%) were read as abnormal. 21 of these (91%)showed EPDs, both with and without focal slowing. 1 showed focal slowing alone, and another showed diffuse background slowing. 21 patients (47%) had an established diagnosis of epilepsy at the time of the study. The studies of 8 (38%) of these patients were normal and 13 (62%) were abnormal. All of the abnormals had EPDs. 24 patients (53%) did not have a pre-existing diagnosis. The studies of 14 of these patients (58%) were normal and 10 (42%)were abnormal. 8 of these abnormal studies showed EPDs, with the remaining 2 showing either focal or diffuse background slowing. 33 studies (73%) were ordered by pediatric neurologists and 12 (27%) were ordered by pediatricians. Of those ordered by neurologists, 20 (61%) were abnormal, while of those ordered by pediatricians 3 (25%) were abnormal due to EPDs. 2 of the neurologist-ordered abnormal studies demonstrated either focal or diffuse background slowing without EPDs. All of the patients tolerated the procedure well and were discharged home in good condition without complications. Conclusions: 1. This method of performing an EEG under general anesthesia with sevoflurane produces readable results which allow for the identification of epileptiform discharges and focal or diffuse slowing. 2. The yield of epileptiform abnormalities was higher in those patients with established diagnoses of epilepsy than in those without. 3. No complications occurred. 4. EEG under general anesthesia with sevoflurane is a safe and effective method of acquiring data on encephalopathic and uncooperative patients.