Abstracts

Rationale: Approximately 25% of patients with epilepsy are estimated to have an age ?- 60 years. The US census bureau projects doubling of population aged > 65 over the next 30 years. This means an increasing prevalence of epilepsy in the older population in coming years. Another emerging trend is the increase in practice of extra-temporal resections for medically refractory epilepsy. Prolonged extraoperative intracranial electroencephalography (eiEEG) is an integral part of evaluation of neocortical epilepsies. With the very likely convergence of above two trends, an increasing number of elderly population may be expected to be requiring eiEEG. Recent meta-analysis of the two major eiEEG techniques, subdural grids (SDG) and stereotactic EEG (SEEG) report good safety profile with complication rates ranging from 1-4%. Since this data comes from younger adult population, traditionally < 50 years of age, we present the first report of eiEEG is elderly population above age of 60 years. Methods: After IRB approval, we searched our prospectively maintained epilepsy surgery data base from 01/01/2000 to 03/31/2016 to find patients who underwent eiEEG at ?- 60 years of age. We looked into complications from eiEEG as well as outcome of resective epilepsy surgery (RES) in patients with at least 1 year of clinical follow up. Descriptive statistical methods were used to analyze data. Results: A total of 21 patients underwent eiEEG, with first patient implanted in 2008 (Figure 1). The average age at the time of implantation was 63.8 (+/-2.8) years with 13 (61.9%) females. Five (23.8%) patients underwent SDG implantation (in combination with depth electrodes in 3 patients) and rest (76.2%) with SEEG. Average number of SDG electrodes was 111.4 (44-160) with two bilateral implantation and average duration of implantation being 9.2 (4-13) days. First SEEG implantation was in 2011 and all eiEEG since have been SEEG. The average number of stereotactically implanted electrodes was 12.8 (6-18) with 9 (56.2%) patients undergoing bilateral implantation and one undergoing two phased implantation (14+4 electrodes). Their average duration of SEEG implantation was 8.4 (5-21) days. Two patient had complications from eiEEG. One SDG implanted patient developed transient aphasia from tension pneumocephalus requiring emergent explantation and RES. One patient developed expansive intracerebral hemorrhage after SEEG electrode implantation, which was emergently evacuated but died after 48 hours as family requested non-aggressive medical treatment due to the poor neurological status. Fifteen (71.4%) patients, constituting 31.9% of all RES in this age group during this duration, underwent RES with 11 of the 14 (78.6%) with 1 year of clinical follow up having Engle 1 outcome (Table 1). Conclusions: We are presenting the first description of eiEEG evaluation in patients above 60 years of age. Despite one fatal complication, eiEEG was overall safe and led to excellent outcomes. We have seen a rapid increases in number of eiEEG evaluations in recent years in elderly population. Our unique findings are highly relevant in a rapidly growing elderly population. Funding: No funding was received in support of this abstract