Abstracts

RATIONALE: Within mesial temporal sclerosis (MTS), which is the most common pathology in patients undergoing surgery for CPS, several different patterns of neuronal loss and gliosis have been described, including Ammon[ssquote]s horn sclerosis (AHS) and Atypical sclerosis (Atypical). The category of Atypical sclerosis includes: end folium (CA4) sclerosis, sclerosis of the dentate gyrus and CA4, and sclerosis of CA1 alone. Our research has found that Atypical patients have less successful seizure control following anterior temporal lobectomy (ATL) than classic AHS patients. We tested the verbal and nonverbal memory functioning of AHS and Atypical patients following ATL to evaluate the influence of the underlying neuropathology of AHS and Atypical sclerosis on cognitive outcome following surgical intervention for intractable CPS.
METHODS: Forty-two AHS and 11 Atypical patients underwent comprehensive preoperative and postoperative (within a year of surgery) neuropsychological evaluations. All patients underwent neurological and neurophysiological evaluations prior to ATL. The Buschke Verbal Selective Reminding Test (VSR) and the TRIMS Nonverbal Selective Reminding Test (NVSR) were administered preoperatively to aid in localization of the seizure focus and postoperatively to assess the effect of ATL on memory performance. The mean follow-up between the pre and postsurgical evaluations was 8.9 months.
RESULTS: The AHS and Atypical groups did not differ preoperatively on gender, birth weight, handedness, age at surgery, educational attainment, and age of seizure onset. Repeated measures ANOVA revealed that the NVSR scores declined significantly following surgery for the Atypical group, but not for the AHS group (P=.002). No differences were found between the AHS and Atypical patients on the VSR following surgery (P=.49).
CONCLUSIONS: The Atypical sclerosis group recalled significantly less nonverbal material following surgery than did the AHS group. The AHS and Atypical patients did not differ on verbal memory performance following ATL. The differentiation in the patterns of memory performance and seizure control following ATL raises the question of whether the classic AHS and the Atypical sclerosis groups comprise two distinct syndromes. These findings highlight the need for future research to investigate these pathology groups as separate entities.
Support: This work was supported by a NIH Postdoctoral Medical Rehabilitation Research Training Grant HDO7465 and by the Peter Kellaway, Ph.D. Endowment for Research.