Neurologia medico-chirurgica
Online ISSN : 1349-8029
Print ISSN : 0470-8105
ISSN-L : 0470-8105
Original Articles
Primary Thumb Sensory Cortex Located at the Lateral Shoulder of the Inverted Omega-shape on the Axial Images of the Central Sulcus
Toshihiro KUMABENobukazu NAKASATOTakashi INOUETakashi YOSHIMOTO
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JOURNAL OPEN ACCESS

2000 Volume 40 Issue 8 Pages 393-403

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Abstract

Useful landmarks on magnetic resonance (MR) images were identified for preoperative prediction of the relationship of a tumor to the primary sensory cortex of the thumb. Functional MR (fMR) imaging and magnetoencephalography were used to retrospectively localize the hand-digit sensorimotor area in four patients who underwent tumor resection around the central sulcus with intraoperative neurophysiological mapping. fMR imaging revealed the hand-digit motor cortex in the so-called “precentral knob” inside the characteristic inverted-omega on axial MR images. Equivalent current dipoles of the N20m response in somatosensory evoked fields (SEFs) of the thumb, median nerve, and ulnar nerve stimuli were localized at the lateral portion of the inverted omega-shape from the lateral to medial directions. The SEF-based thumb sensory cortex was verified by intraoperative functional mapping with a neuronavigation system. The hand-digit somatosensory cortices were localized at the lateral shoulder of the inverted-omega, in the lateral anterior inferior position to the hand-digit motor cortices in the precentral knob. Axial MR imaging can provide useful preoperative planning information for the surgical treatment of tumors within or adjacent to the motor-somatosensory cortex.

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© 2000 by The Japan Neurosurgical Society

This article is licensed under a Creative Commons [Attribution-NonCommercial-NoDerivatives 4.0 International] license.
https://creativecommons.org/licenses/by-nc-nd/4.0/
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