Abstracts

Rationale: Current literature documents a trend towards a gradual decline in resective temporal lobe epilepsy surgery in certain high-volume epilepsy surgery centres (1,2,3). Specifically, a large scale comprehensive survey of selected European, Australian and American centres has documented the decline of resective temporal epilepsy surgery over the past two decades and an increase in extratemporal surgeries (4). This is somewhat unexpected given that there is class one evidence for the efficacy of temporal resection in medically refractory temporal lobe epilepsy. There are a number of explanations proposed for this finding including: referral patterns, better anti-epileptic drugs or even a possible decreasing incidence of mesial temporal sclerosis from better treatment of febrile seizures.The Montreal Neurological Institute has been performing epilepsy surgery since 1934. Here we examine the cases of two epilepsy surgeons at the MNI, one in practice since 2004 (JH) and one in practice since 1971 (AO). This retrospective review was undertaken to establish if similar trends to those mentioned above can be confirmed at our centre and, if possible, to identify related factors. Methods: The records of all epilepsy surgery procedures performed by one of the authors (JH) were analysed from 2004 to 2017. Relevant data collected included; the type of surgery (resective vs. neuromodulatory) as well as  breakdown of the specific surgical target (temporal vs. extratemporal) and intracranial investigations with subdural strips/grids or intracerebral electrodes. This data will be also collected from the patients of the second author (AO). Results: JH performed 287 procedures for epilepsy over this time period. One hundred and eleven (39%) were for the surgical treatment of temporal lobe pathologies. Seventy nine (28%) were for intracranial investigations. Within the remaining cases, there is a clear trend, over time, for an increase in extratemporal resections and neuromodulatory procedures. Temporal resections have remained largely stable over this interval. Conclusions: It appears that our data are similar to the results reported by other groups suggesting a greater number of extra-temporal cases over time (4). The number of temporal cases by author JH seem to be stable over a practice interval of 14 years.  A detailed analysis of the of caseload of author AO with a practice interval of over 40 years will establish the nature of this trend over a greater time period than currently reported in literature.References:1.           Carlson C. The changing face of epileptology? Results of the initial Q-PULSE survey. Epilepsy Curr. 2013;13:305–307.2.           Neligan A, Haliasos N, Pettorini B, et al. A survey of adult and pediatric epilepsy surgery in the United Kingdom. Epilepsia. 2013;54:e62–e65.3.           Kumlien E, Mattsson P. Attitudes towards epilepsy surgery: a nationwide survey among Swedish neurologists. Seizure. 2010;19:253–255.4.           Jehi L, Friedman D, Carlson C, et al. The evolution of epilepsy surgery between 1991 and 2011 in nine major epilepsy centers across the United States, Germany, and Australia. Epilepsia. 2015;56(10):1526–1533. doi: 10.1111/epi.13116 Funding: No funding to disclose.