Abstracts

Rationale: To evaluate changes in Posterior Fornix (PF) and Mamillary Bodies (MB) before and after temporal lobe surgery in patients with Mesial Temporal Lobe Epilepsy (MTLE), and to correlate their evolution (MRI signs of wallerian degeneration) with postoperative memory statusMethods: 17 Patients with (8 right and 9 left) Hippocampal Sclerosis (HS) operated between 1999 and 2003 were enrolled in this retrospective study. The volume of PF and MB were qualitatively evaluated by MRI in pre and postoperative (at least 2 years after surgery). Size and signal changes on FLAIR images were depicted and correlated with patient memory status, comparing Wechsler memory scale (WMS) before and at least one year after standardized temporal lobectomy Results: Preoperatively, MRI showed size symmetry of PF (in 8 patients) and MB (in 12 patients). On postoperative MRI, ipsilateral PF size was symmetrical in 2 patients, mildly decreased in 8 and severely reduced in 7. Ipsilateral MB size was symmetrical in 5 patients, mildly decreased in 7 and markedly reduced in 5. Post operatively, 12 patients showed ipsilateral PF hypersignal on FLAIR images (mild reduced size in 8 and severe decreased in 2) not detectable on preoperative MRI. The WMS analysis showed postoperative improvement in 11,8,9,13 and 8 patients for Verbal memory, Visual memory , General memory, Attention/Concentration and Delayed Recall scores respectively, negative differences after surgery for the same WMS subtest where noted in 6,8,8,4 and 8 patients correspondingly. Two patients demonstrated equals pre and postoperative scores for visual memory and delayed recall. There was no correlation between MB and PF atrophy or PF hypersignal with memory performance test (ANCOVA, p=0.001). Also, there was no correlation between temporal surgery side and memory test performance.Conclusions: Ipsilateral PF and MB atrophy is often associated with hippocampal sclerosis in MTLE patients. This atrophy is stressed in variable degree after temporal lobe surgery and seems to represent Wallerian degeneration of limbic system fibres. Although limbic system is extensively related to cognitive function, this work does not demonstrate any correlations between increased atrophy or FLAIR hypersignal on MRI and postoperative memory deficit