[Analysis of hemiparesis with homolateral ataxia by single photon emission CT]

Case 1. A 46-year-old man suddenly developed mild gait disturbance and left hemiparesis. On examination, gross strength was slightly reduced in the left extremities. The finger-to-nose and heel-to-knee tests disclosed moderate dyssynergia and dysmetria on the left side that could not be explained by the muscular weakness. Deep tendon reflexes were more brisk in the left extremities. There was no Babinski sign. Magnetic resonance imaging showed a region of high signal intensity in the right posterior limb of internal capsule with extension into lateral thalamus. The lesion involved the cortico-ponto-cerebellar pathway and partly the dentato-rubro-thalamo-cortical pathway. No lesions were seen in the brainstem. Single photon emission CT with 123I-IMP showed left cerebellar hypoperfusion termed crossed cerebellar diaschisis by Baron et al. Case 2. A 65-year-old female developed weakness of the left extremities and gait disturbance. On examination, there was a horizontal nystagmus on lateral gaze to each side. She showed dysarthria, mild left hemiparesis and slight left hypesthesia. The finger-nose and heel-knees tests revealed moderate dysmetria and dyssynergia on the left side. Deep tendon reflexes were hyperactive in the left extremities with left Babinski sign. CT showed a low density area in the right basis pontis at about middle level. Intravenous digital subtraction angiography revealed a slight stenosis of right vertebral artery, but no other abnormality. The lesion involved the cortico-ponto-cerebellar pathway. Single photon emission CT with 123I-IMP showed left cerebellar hypoperfusion. The right cerebellar blood flow was normal.(ABSTRACT TRUNCATED AT 250 WORDS)