Abstracts

Multiple hippocampal transection (MHT) is a novel surgical procedure for medial temporal epileptic focus which can preserve memory. It was developed as a hippocampal conterpart to multiple subpial transection for neocortical focus (ref). We evaluated its seizure outcome, postoperative neuropsychometry, and postoperative imaging., Series of 10 patients with temporal lobe epilepsy were evaluated who underwent MHT at University of Tokyo Hospital and followed [gt] 10 months postoperatively. No patients had hippocampal sclerosis in preoperative MRI. All patients had Wada-test. Treatment side was language-dominant in 8 patients and nondominant in 2 and was determined by chronic video-ECoG in 7 and noninvasive evaluation in 3. MHT was performed using Shimizu[apos]s method (ref). Intraoperative epileptiform discharges from hippocampus were completely abolished in 9 patients. WAIS-R, WMS-R, and Miyake Paired Word Recall (MPWR) were tested preoperatively, 1 month and 6-12 months postoperatively. FDG-PET, ECD-SPECT and IMZ-SPECT images were acquired preoperatively and 6-12 months postoperatively., Follow-up periods were 10-33 months (median 20). Engel[apos]s scores were I in 8 patients and II in 2. Six of 7 patients who underwent dominant-sided MTH and whose preoperative memory scores were normal or mildly impaired experienced transient impairment of subjective memory and deteriorated verbal memory scores at 1 months. Those scores recovered to the preoperative level at 6-12 months. Mean WMS-R verbal memory indices, delayed recall indices, and MPWR unrelated pair scores (%) of these 6 patients at these 3 points sequentially were 89.5[plusmn]16.5[rarr]64.0[plusmn]12.3[rarr]86.5[plusmn]7.6, 83.8[plusmn]22.9[rarr]54.5[plusmn]5.7[rarr]83.0[plusmn]15.4, 51.7[plusmn]19.4[rarr]20.0[plusmn]22.8[rarr]66.7[plusmn]26.6, respectively. Subjective memory impairment resolved correspondingly. The other patient with mildly impaired preoperative memory and the 2 patients who underwent nondominant-sided MTH showed postoperative improvement in memory scores without transient deterioration. One patient with severely impaired preoperative memory did not show postoperative changes. Interestingly, glucose uptake, blood flow and benzodiazepine binding in the treated medial temporal area at the last time point remained much lower than the preoperative levels., Seizure outcome of MHT was almost comparable to medial temporal resection although further follow-up is required. Those 6 patients without hippocampal sclerosis who showed transient impairment and later recovery of memory scores were supposed to have shown severe and permanent memory disturbance if they had undergone medial temporal resection. While functional recovery did not accompany recovery of glucose uptake and blood flow, further study is required to elucidate the underlying mechanisms of functional recovery.
Ref. J Clin Neurosci 13, 322-328, 2006.,