title: Electrical stimulation of the parahippocampal gyrus for prediction of posthippocampectomy verbal memory decline.
abstract: OBJECTIVE Epilepsy surgery is of known benefit for drug-resistant temporal lobe epilepsy (TLE); however, a certain number of patients suffer significant decline in verbal memory after hippocampectomy. To prevent this disabling complication, a reliable test for predicting postoperative memory decline is greatly desired. Therefore, the authors assessed the value of electrical stimulation of the parahippocampal gyrus (PHG) as a provocation test of verbal memory decline after hippocampectomy on the dominant side. METHODS Eleven right-handed, Japanese-speaking patients with medically intractable left TLE participated in the study. Before surgery, they underwent provocative testing via electrical stimulation of the left PHG during a verbal encoding task. Their pre- and posthippocampectomy memory function was evaluated according to the Wechsler Memory Scale-Revised (WMS-R) and/or Mini-Mental State Examination (MMSE) before and 6 months after surgery. The relationship between postsurgical memory decline and results of the provocative test was evaluated. RESULTS Left hippocampectomy was performed in 7 of the 11 patients. In 3 patients with a positive provocative recognition test, verbal memory function, as assessed by the WMS-R, decreased after hippocampectomy, whereas in 4 patients with a negative provocative recognition test, verbal memory function, as assessed by the WMS-R or MMSE, was preserved. CONCLUSIONS Results of the present study suggest that electrical stimulation of the PHG is a reliable provocative test to predict posthippocampectomy verbal memory decline.
authors.affiliation: Departments of 1 Neurosurgery and.|Department of Neurosurgery, Osaka General Medical Center, Osaka.
authors.forename: Naoki
authors.initials: N
authors.lastname: Tani
authors.affiliation: Departments of 1 Neurosurgery and.|Epilepsy Center, Osaka University Hospital, Suita.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Kishima
authors.affiliation: Departments of 1 Neurosurgery and.|Department of Neurosurgery, Yao Municipal Hospital, Yao.
authors.forename: Hui Ming
authors.initials: HM
authors.lastname: Khoo
authors.affiliation: Departments of 1 Neurosurgery and.|Epilepsy Center, Osaka University Hospital, Suita.
authors.forename: Takufumi
authors.initials: T
authors.lastname: Yanagisawa
authors.affiliation: Departments of 1 Neurosurgery and.|Epilepsy Center, Osaka University Hospital, Suita.
authors.forename: Satoru
authors.initials: S
authors.lastname: Oshino
authors.affiliation: Departments of 1 Neurosurgery and.|Department of Neurosurgery, Otemae Hospital, Osaka.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Maruo
authors.affiliation: Departments of 1 Neurosurgery and.|Epilepsy Center, Osaka University Hospital, Suita.
authors.forename: Koichi
authors.initials: K
authors.lastname: Hosomi
authors.affiliation: Departments of 1 Neurosurgery and.|Epilepsy Center, Osaka University Hospital, Suita.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hirata
authors.affiliation: Psychiatry, Osaka University Graduate School of Medicine, Suita.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kazui
authors.affiliation: Psychiatry, Osaka University Graduate School of Medicine, Suita.
authors.forename: Keiko Tokumasu
authors.initials: KT
authors.lastname: Nomura
authors.affiliation: Department of Neurosurgery, Mansoura University Hospital, Mansoura, Egypt.
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Aly
authors.affiliation: Department of Neurosurgery, Kinki University School of Medicine, Osaka-Sayama, Japan; and.
authors.forename: Amami
authors.initials: A
authors.lastname: Kato
authors.affiliation: Departments of 1 Neurosurgery and.|Epilepsy Center, Osaka University Hospital, Suita.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Yoshimine
mesh_terms: D000293:Adolescent; D000328:Adult; D000069279:Drug Resistant Epilepsy / Q000601:surgery*; D004558:Electric Stimulation; D004833:Epilepsy, Temporal Lobe / Q000601:surgery*; D005260:Female; D006624:Hippocampus / Q000601:surgery*; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000517:prevention & control*; D008875:Middle Aged; D020534:Parahippocampal Gyrus / Q000502:physiology*; D011183:Postoperative Complications / Q000517:prevention & control*; D011237:Predictive Value of Tests
keywords: ATL = anterior temporal lobectomy; EEG = electroencephalography; FDG-PET = fluorodeoxyglucose positron emission tomography; HFO = high-frequency oscillation; MEG = magnetoencephalography; MMSE = Mini-Mental State Examination; PES = parahippocampal electrical stimulation; PHG = parahippocampal gyrus; SAH = selective amygdalohippocampectomy; TLE = temporal lobe epilepsy; WMS-R = Wechsler Memory Scale-Revised; depth electrodes; entorhinal cortex; fMRI = functional MRI; functional neurosurgery; hippocampus; temporal lobe epilepsy; verbal memory function