Long‐term outcome and neuroradiologic changes after multiple hippocampal transection combined with multiple subpial transection or lesionectomy for temporal lobe epilepsy

Abstract

SUMMARYObjective: 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 drugresistant mesial temporal lobe epilepsy (mTLE) and were followed for more than 5 years. Indications for the procedure were the following: (1) verbally dominantsided 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.

Five-Year Neuropsychological Outcome after Stereotactic Radiofrequency Amygdalohippocampectomy for Mesial Temporal Lobe Epilepsy: Longitudinal Study

“…However, collateral damage due to access route is inevitable. Current data indicate that verbal memory functions transiently worsened immediately after surgery but recovered to the preoperative values thereafter [51]. The aim of laser ablation is MRI-controlled complete ablation of mesiotemporal structures.…”

Improvement of intellectual outcomes in 20 children with refractory epilepsy after individualized surgery

“…If the bilateral anterior temporal lobe and hippocampus are damaged, patients may suffer severe cognitive impairments, including impairments to learning and memory. [ 13 ] Fortunately, there were no lethal postoperative complications, and intellectual outcomes increased among refractory epilepsy children by reasonable surgical procedures in this study. The reasons for this are as follows:…”

Multiple hippocampal transections for mesial temporal lobe epilepsy

“…Of these, cavernous malformations were the cause of epilepsy in nine cases, and neuronal-glial tumors in four cases (three gangliogliomas and 1 DNET). [ 22 , 27 , 42 ] In this group of patients, MHT was used simultaneously with resection of the medial temporal lesions in cases when intraoperative ECoG showed epileptic discharges coming from the hippocampus after tumor removal. Our approach is consistent with the paradigm described by Ishida et al .…”

“…In general, taking into account all published data (except for publications describing single observations), after hippocampal transection, seizure control (Engel I) was achieved – from 64.7% to 94.7% of cases during a follow-up period of 12–60 months. [ 14 , 34 , 36 , 40 , 42 ] Seizure control rate is also high in the group of patients with medial temporal lobe lesions sparing the hippocampus. In the study of Usami et al .,[ 42 ] the Engel I outcome was achieved in 100% of cases by 2 years and 60% of cases by 5 years.…”