Functional identification of the primary motor area by corticospinal tractography.
OBJECTIVE
For quick and stable identification of the primary motor area (PMA), diffusion tensor imaging (DTI) data were acquired and corticospinal tractography was mathematically visualized.


METHODS
Data sets of DTI, anatomic magnetic resonance imaging, and functional magnetic resonance imaging with finger-tapping tasks were acquired during the same investigation in 30 patients with a brain lesion affecting the motor system. Off-line processing of DTI data was performed to visualize the corticospinal tract, placing a seed area in the cerebral peduncle of the midbrain, where the corticospinal tract is densely concentrated. Somatosensory evoked magnetic fields and intraoperative cortical somatosensory evoked potentials were recorded with electrical stimulation of the median nerve to confirm the results of the corticospinal tractography.


RESULTS
Functional magnetic resonance imaging and somatosensory evoked magnetic fields failed to identify the PMA in eight patients (16.7%) and one patient (3.8%) investigated, respectively, because of cortical dysfunctions caused by brain lesions. DTI data were acquired within 3 minutes without patient tasks. Using the appropriate seed area and fractional anisotropy, corticospinal tractography successfully indicated the PMA location in all patients. The suspected PMA and central sulcus locations were confirmed by the cortical somatosensory evoked potentials.


CONCLUSIONS
Corticospinal tractography enables identification of the PMA and is beneficial, particularly for patients who present with dysfunction of the PMA.
Kamada
Kyousuke
K
Department of Neurosurgery, University of Tokyo, Hongo 7-3-1, Tokyo, Japan. kamady-k@umin.ac.jp
Sawamura
Yutaka
Y
Takeuchi
Fumiya
F
Kawaguchi
Hideaki
H
Kuriki
Shinya
S
Todo
Tomoki
T
Morita
Akio
A
Masutani
Yoshitaka
Y
Aoki
Shigeki
S
Kirino
Takaaki
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D001931:Brain Mapping / Q000379:methods*; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D015225:Magnetoencephalography / Q000379:methods; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000000981:diagnostic imaging / Q000502:physiology* / Q000601:surgery; D011712:Pyramidal Tracts / Q000502:physiology*; D011859:Radiography