title: Chronic spatial working memory deficit associated with the superior longitudinal fasciculus: a study using voxel-based lesion-symptom mapping and intraoperative direct stimulation in right prefrontal glioma surgery.
abstract: OBJECTIVE Although the right prefrontal region is regarded as a silent area, chronic deficits of the executive function, including working memory (WM), could occur after resection of a right prefrontal glioma. This may be overlooked by postoperative standard examinations, and the disabilities could affect the patient's professional life. The right prefrontal region is a part of the frontoparietal network and is subserved by the superior longitudinal fasciculus (SLF); however, the role of the SLF in spatial WM is unclear. This study investigated a persistent spatial WM deficit in patients who underwent right prefrontal glioma resection, and evaluated the relationship between the spatial WM deficit and the SLF. METHODS Spatial WM was examined in 24 patients who underwent prefrontal glioma resection (right, n = 14; left, n = 10) and in 14 healthy volunteers using a spatial 2-back task during the long-term postoperative period. The neural correlates of spatial WM were evaluated using lesion mapping and voxel-based lesion-symptom mapping. In addition, the spatial 2-back task was performed during surgery under direct subcortical electrical stimulation in 2 patients with right prefrontal gliomas. RESULTS Patients with a right prefrontal lesion had a significant chronic spatial WM deficit. Voxel-based lesion-symptom mapping analysis revealed a significant correlation between spatial WM deficit and the region that overlapped the first and second segments of the SLF (SLF I and SLF II). Two patients underwent awake surgery and had difficulties providing the correct responses in the spatial 2-back task with direct subcortical electrical stimulation on the SLF I, which was preserved and confirmed by postoperative diffusion tensor imaging tractography. These patients exhibited no spatial WM deficits during the postoperative immediate and long-term periods. CONCLUSIONS Spatial WM deficits may persist in patients who undergo resection of the tumor located in the right prefrontal brain parenchyma. Injury to the dorsal frontoparietal subcortical white matter pathway, i.e., the SLF I or SLF I and II, could play a causal role in this chronic deficit. A persistent spatial WM deficit, without motor and language deficits, could affect the professional life of the patient. In such cases, awake surgery would be useful to detect the spatial WM network with appropriate task during tumor exploration.
authors.affiliation: Department of Neurosurgery and.
authors.forename: Masashi
authors.initials: M
authors.lastname: Kinoshita
authors.affiliation: Pharmaceutical and Health Science, Kanazawa University.
authors.forename: Riho
authors.initials: R
authors.lastname: Nakajima
authors.affiliation: Department of Anatomy II, Kanazawa Medical University; and.
authors.forename: Harumichi
authors.initials: H
authors.lastname: Shinohara
authors.affiliation: Department of Neurosurgery and.
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Miyashita
authors.affiliation: Department of Neurosurgery and.
authors.forename: Shingo
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Department of Physical Medicine and Rehabilitation, Kanazawa University Hospital, Kanazawa, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Okita
authors.affiliation: Department of Neurosurgery and.
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Nakada
authors.affiliation: Department of Neurosurgery and.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hayashi
mesh_terms: D001931:Brain Mapping / Q000379:methods*; D001932:Brain Neoplasms / Q000601:surgery*; D002908:Chronic Disease; D004558:Electric Stimulation; D005260:Female; D005910:Glioma / Q000601:surgery*; D006801:Humans; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis*; D008570:Memory, Short-Term; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis*; D017397:Prefrontal Cortex; D065852:Spatial Memory
keywords: DES = direct electrical stimulation; DTI = diffusion tensor imaging; DW = diffusion weighted; FDR = false discovery rate; MNI = Montreal Neurological Institute; SLF = superior longitudinal fasciculus; VLSM = voxel-based lesion-symptom mapping; VOI = volume of interest; WM = working memory; direct electrical stimulation; oncology; right prefrontal glioma; spatial working memory; superior longitudinal fasciculus; voxel-based lesion-symptom mapping