[Motor paresis with cheiro-oral topography due to small infarct in the internal capsule or the corona radiata].
We reported five patients having presented only with clumsy hand and dysarthria which resulted from motor paresis confined to one side of the fingers and the ipsilateral face and tongue. All of them were right-handed, and their manifestation was transient. They had no abnormalities of muscle tonus and sensation, and no ataxia. The features of these cases differed from those of the dysarthria-clumsy hand syndrome because of absence of ataxia, and could be distinguished from pure motor hemiplegia by a motor paresis with cheiro-oral topography. MRI examinations showed a localized lesion at the border between internal capsule and corona radiata (two cases), or in the corona radiata just over this region (three cases). In the former cases in which the internal capsule was involved, we confirmed the lesion in the genu and anterior half of the posterior limb of the internal capsule. The lesion was on the left side in all five patients. It has been known that the pyramidal tract consists of the large and small fibers. The large ones are localized in the posterior part of the posterior limb of the internal capsule, and the damage of them produces sustained and serious motor paralysis. The small ones are widely distributed in the genu and the posterior limb of the internal capsule. The findings of our study suggest that the small fibers have adjacent somatotopy for the hand and mouth in the region of the genu and the anterior part of the posterior limb of the internal capsule, and that the damage of them may lead to mild, transient motor paresis without spasticity.
Takahashi
N
N
Department of Neurology, School of Medicine, Chiba University.
Kawamura
M
M
Hirayama
K
K
D000328:Adult; D002540:Cerebral Cortex / Q000098:blood supply*; D002544:Cerebral Infarction / Q000150:complications*; D004401:Dysarthria / Q000209:etiology; D005145:Face; D005260:Female; D005385:Fingers; D006801:Humans; D008297:Male; D008875:Middle Aged; D010291:Paresis / Q000209:etiology*; D014059:Tongue