[Brain activities during maximum voluntary clenching with and without soft splint in patients with hemimasticatory spasms by functional magnetic resonance imaging].
OBJECTIVE
Functional magnetic resonance imaging (fMRI) was used to detect the cerebral cortical somatotopy during maximum voluntary clenching with and without soft splint in patients with hemimasticatory spasms (HMS) and the central mechanisms of HMS and the rule of the splint therapy.


METHODS
Four HMS patients were selected and the spasms sides were right in two cases and left in the other two cases. FMRI images were obtained on Elscint/GE 2.0 Tesla MR system. Block design was used and the movement pattern was the onset of spasms after maximum voluntary clenching with and without soft splint. The fMRI data were analyzed by SPM99 software.


RESULTS
With the onset of spasms after maximum voluntary clenching, the activation of motor cortex in 3 HMS patients was found lateral dominance on the left side, and the other one showed bilateral activation. All the 4 patients were found activation in cingulate area. With the onset of spasms after maximum clenching wearing soft splints, the activation of motor cortex showed no lateral dominance on the left side, and 3 patients were not found activation in cingulate area.


CONCLUSIONS
The changes of the activation in motor cortex and cingulate area during the onset of spasms after clenching with and without soft splint might be the central mechanisms of the rule of splint therapy, through which the soft splint might function in alleviating muscle pain.
Wang
Yu-wei
YW
Department of Stomatology, The General Hospital of Rocket Army, Beijing 100088, China.
Ma
Xu-chen
XC
Jin
Zhen
Z
Zhang
Lei
L
D001921:Brain / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008410:Masticatory Muscles / Q000473:pathology* / Q000503:physiopathology; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009064:Mouth Protectors; D009128:Muscle Spasticity / Q000473:pathology* / Q000503:physiopathology