Abstracts

Rationale: Recently, there have been improvements in imaging and the detection of Ammon’s horn sclerosis (AHS). Additionally, pharmacoresistant patients are now being asked to consider epilepsy surgery early on. One would therefore expect a shorter epilepsy duration and an increase in the number of temporal lobe epilepsy (TLE) patients with hippocampal sclerosis. However, word is spreading throughout the epilepsy community that the number of mesial temporal lobe epilepsy (mTLE) patients with (AHS) is decreasing. If this is true, it would have implications for the etiological model of AHS in TLE. Methods: Between 1987 and 2009, 1280 patients underwent temporal lobe surgery and were retrospectively evaluated with regard to age at the time of surgery and the duration of the epilepsy as a function of histopathology, and the year of surgery. Results: Of the 1280 patients, 650 (51%) were classified with AHS, 303 had tumors, 104 had gliosis, 82 had dysplasia, 81 had vascular, and 25 displayed other pathologies. Patients with AHS were among those with the earliest epilepsy onset (age 11±9 yrs.) and the longest epilepsy duration (24±12 yrs.). The age (36 ±12, min.3 max. 71 yrs.) was normally distributed in this group (Shapiro Wilk =0.997, df=650, p=0.339). Looking back over four epochs (one epoch = 5-7 years), the percentage of patients with AHS increased from 25% to 56% within the first epochs and thereafter remained constant despite varying surgical numbers. However, the AHS patient group was the only group that was significantly older over time and had significantly longer lasting epilepsies. The age increased by 7-8 years (F=10.4, df=3, p=0.000) and the duration of the epilepsy increased by about 4-7 years (F=4.0, df =3, p=0.007). In contrast, the epilepsy duration was three years shorter for the group with tumors (F=2.5, df=3 p=0.06). Conclusions: The data indicate that due to advancements in brain imaging, the percentage of AHS patients increased over the first years, but did not change thereafter despite varying surgical numbers. In contrast to those patients with other pathologies, AHS patients become increasingly older and have longer lasting epilepsies. This would indeed support the hypothesis that the incidence of mTLE is decreasing. Conjoint retrospective data collection from the major epilepsy centres in Germany has been initiated to prove this first mono-centric evidence.