title: Primary thumb sensory cortex located at the lateral shoulder of the inverted omega-shape on the axial images of the central sulcus.
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 N20 m 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.
authors.affiliation: Department of Neurosurgery, Tohoku University School of Medicine, Sendai.
authors.forename: T
authors.initials: T
authors.lastname: Kumabe
authors.forename: N
authors.initials: N
authors.lastname: Nakasato
authors.forename: T
authors.initials: T
authors.lastname: Inoue
authors.forename: T
authors.initials: T
authors.lastname: Yoshimoto
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology; D013003:Somatosensory Cortex / Q000502:physiology*; D013668:Technetium Tc 99m Aggregated Albumin; D013933:Thumb / Q000502:physiology*
chemical_list: D013668:Technetium Tc 99m Aggregated Albumin