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Objective Multiple hippocampal transection ( MHT) is a surgical procedure developed to avoid postoperative memory decline. Its efficacy has been documented in only a few small series with relatively short observation periods. We prospectively evaluated the long-term seizure and cognitive outcomes of MHT combined with multiple subpial transection or lesionectomy ( MHT + MST/L). Moreover, we quantitatively evaluated the structural and metabolic neuroradiologic changes after the procedure to elucidate the anatomofunctional correlates of memory preservation. Methods Twenty-four patients underwent MHT + MST/L for treatment of drug-resistant mesial temporal lobe epilepsy ( mTLE) and were followed for more than 5 years. Indications for the procedure were the following: (1) verbally dominant-sided surgery in patients with a radiologically normal hippocampus or normal/near normal memory, and (2) surgery for patients with concomitant epileptic activity on the contralateral side, that is, when the surgery was considered a high risk for severe postoperative memory decline. Seizure outcome was evaluated using Engel's classification 1, 2, and 3 years after surgery, and at the last visit ( LV). Three subgroups were evaluated as well: magnetic resonance imaging ( MRI) negative ( MN), hippocampal sclerosis ( HS), and normal hippocampus with extrahippocampal lesion ( NHEL). The long-term cognitive outcome was followed through to LV in patients who underwent verbally dominant-sided surgery. Hippocampal volume ( HV), diffusion tensor parameters ( DTP), and glucose utilization ( GU) were determined from MRI and fluorodeoxyglucose-positron emission tomography ( FDG- PET) studies performed before and >6 months after surgery. Results Whereas the rate of Engel class I as a whole was 71% at 1 year and 67% at LV, the rates in the MN, HS, and NHEL groups were 60%, 67%, and 100% at 1 year, respectively, and 70%, 56%, and 80% at LV, respectively. Memory indices after verbally dominant-sided surgery transiently declined at 1 month but recovered to and remained at the preoperative level through LV. The HV, DTP of the fornix, and GU of the temporal lobe on the treated side showed pathologic changes even when the transiently declined memory indices had recovered to the preoperative level. Significance The long-term outcome for complex partial seizures after MHT + MST/L was comparable to that seen after anterior temporal lobectomy. The long-term cognitive outcome was favorable, even for patients with a high risk of severe postoperative memory decline. MHT + MST/L may be a treatment option for mTLE in which resective surgery carries a risk of postoperative memory decline, particularly in patients without MRI lesion. A discrepancy between the preserved memory and the pathologic neuroradiologic changes indicates the necessity for further studies including functional MRI. [ABSTRACT FROM AUTHOR]

Background Safe entry to the inferior horn is required for a selective approach to the medial temporal region. This can be challenging sometimes for inexperienced surgeons. Our objective was to verify the usefulness of the deep medullary vein (DMV) as an intraoperative landmark for safely entering the inferior horn during the transsylvian selective approach to the mesial temporal region. Methods Videos of 8 cases of transsylvian selective amygdalohippocampectomies performed at the University of Tokyo Hospital from 2013 to 2015 were reviewed. Consistency of the DMV and time required to open the inferior horn via the temporal stem through the inferior limiting sulcus were retrospectively evaluated. Results DMVs were identified in all cases; the average number identified was 2.5 ± 0.3 (mean ± SE). The inferior horn was opened without disorientation in all cases, with mean dissecting time of 7.0 minutes ± 1.1. No complications were caused by disorientation within the temporal stem white matter. Conclusions Consideration of the venous system within the white matter and following the DMV could reduce the risk of disorientation and enable the surgeon to reach the inferior horn in a straightforward manner without accidental white matter damage. [ABSTRACT FROM AUTHOR]

Objective Resective surgery for mesial temporal lobe epilepsy ( MTLE) with a correspondent lesion has been established as an effective and safe procedure. Surgery for temporal lobe epilepsies with bilateral hippocampal sclerosis or without correspondent lesions, however, carries a higher risk of devastating memory decline, underscoring the importance of establishing the memory-dominant side preoperatively and adopting the most appropriate procedure. In this study, we focused on high gamma activities ( HGAs) in the parahippocampal gyri and investigated the relationship between memory-related HGAs and memory outcomes after hippocampal transection ( HT), a hippocampal counterpart to neocortical multiple subpial transection. The transient nature of memory worsening after HT provided us with a rare opportunity to compare HGAs and clinical outcomes without risking permanent memory disorders. Methods We recorded electrocorticography from parahippocampal gyri of 18 patients with temporal lobe epilepsy while they executed picture naming and recognition tasks. Memory-related HGA was quantified by calculating differences in power amplification of electrocorticography signals in a high gamma range (60-120 Hz) between the two tasks. We compared memory-related HGAs from correctly recognized and rejected trials (hit- HGA and reject- HGA). Using hit- HGA, we determined HGA-dominant sides and compared them with memory outcomes after HT performed on seven patients. Results We observed memory-related HGA mainly between 500 and 600 msec poststimulus. Hit- HGA was significantly higher than reject- HGA. Three patients who had surgery on the HGA-dominant side experienced transient memory worsening postoperatively. The postoperative memory functions of the other four patients remained unchanged. Significance Parahippocampal HGA was indicated to reflect different memory processes and be compatible with the outcomes of HT, suggesting that HGA could provide predictive information on whether the mesial temporal lobe can be resected without causing memory worsening. This preliminary study suggests a refined surgical strategy for atypical MTLE based on reliable memory lateralization. [ABSTRACT FROM AUTHOR]