Extra operative intracranial EEG monitoring for epilepsy surgery in elderly patients

Abstract

Object: The objective of the study is to investigate and report our experience with extra operative intracranial EEG monitoring for evaluation of epilepsy surgery among elderly (≥60 years) patients. Methods: After IRB approval, we searched our prospectively maintained epilepsy surgery database to find patients who underwent eiEEG at the age of 60 years or older. Electronic medical records were reviewed to extract clinical and surgery-related information. Patients who underwent resective epilepsy surgery after eiEEG and had at least 1 year of clinical follow-up were assessed for seizure outcome. Categorical and continuous variables were compared using Pearson chi-square and Student's t-test, respectively. Results: A total of 21 patients, with 13 (62%) women, underwent eiEEG in our center at the age of 60 years or older. The mean age at time of implantation was 63.8 ± 2.7 years. Sub-dural grids (SDG) were implanted in five (24%) patients, whereas sixteen (76%) patients underwent stereo-EEG (SEEG) implantation. Median number of contacts in SDG were 106 (56–136) and depth electrodes in SEEG were 12 (9–14). There were 2 complications, including one mortality due to intracerebral hemorrhage. Sixteen (76%) patients underwent respective epilepsy surgery after eiEEG and eleven (69%) achieved Engel class I outcome on the last follow-up [mean follow-up duration of 2.7 (± 1.8) years]. Conclusion: We noticed an increased utilization of eiEEG in elderly patients after the introduction of SEEG at our center. Overall, we found that eiEEG can help achieve good seizure outcomes in the elderly population. However, the one eiEEG-related mortality serves a word of caution about the potential risks in this population. Keywords: Epilepsy surgery, Elderly, Intracranial recording, SEEG, Subdural electrodes, Outcome