Clinicoradiological studies in the frontal ataxia; correlation with ataxic hemiparesis

本研究从临床放射学角度探讨了交叉性小脑萎缩和共济失调性轻偏瘫的病理机制，这两种疾病似乎与额叶共济失调有关。交叉性小脑萎缩。130例单侧幕上脑血管病中，8例CT显示交叉性小脑萎缩。其中6例为额颞叶脑梗死，2例为脑出血（分别为壳核和丘脑出血）。交叉性小脑萎缩8例中5例同时表现为小脑顶和桥脑底萎缩，未见第四脑室扩大或畸形。结论：1. CT结果提示交叉性小脑萎缩不是由齿状核-红核-丘脑通路的逆行性跨突触变性引起的，而是由皮质-桥脑-小脑通路的顺行性跨突触变性引起的，尤其是从额颞叶开始的.大脑皮质脱髓鞘病变引起的共济失调性轻偏瘫。两名多发性硬化症患者描述谁共济失调性轻偏瘫，其中磁共振成像显示局部病变，在大脑中的中脑对侧的受影响的肢体。他们没有深感觉障碍，在一个病人体感诱发电位正常。MRI显示的病变未到达中脑被盖，包括上级小脑脚交叉或红核。在这两个病人中，MRI结果提示共济失调性轻偏瘫是由于大脑皮质-脑桥通路和皮质脊髓束的中断引起的。

The pathomechanism of the crossed cerebellar atrophy and ataxic hemiparesis, which seem to correlate with frontal ataxia, was investigated clinicoradiologically.1. Crossed cerebellar atrophy. Crossed cerebellar atrophy was demonstrated by CT in 8 of the 130 patients who suffered from unilateral supratentorial cerebrovascular diseases. Of these 8 patients, 6 had cerebral infarction in the fronto-temporal lobe and 2 had cerebral hemorrhage (putaminal and thalamic hemorrhages respectively). It was observed that in 5 of the 8 patients with crossed cerebellar atrophy, atrophy was present in both crus cerebri and basis pontis and no dilatation or deformity of the fourth ventricle was seen in the 8 patients. The CT findings suggest that crossed cerebellar atrophy is not caused by the retrograde transsynapyic degeneration of the dentatorubrothalamic pathways but the anterograde trans-synaptic degeneration of the corticopontocerebellar pathways, especially from the fronto-temporal lobe.2. Ataxic hemiparesis from demyelinating lesion in the crus cerebri. Two patients with multiple sclerosis are described who had ataxic hemiparesis and in whom MRI revealed localized lesion in the crus cerebri of midbrain on the side opposite the affected limbs. They had no deep sensory disturbance, and in one patient somatosensory evoked potentials were normal. The lesion demonstrated by MRI had not reached the midbrain tegmentum including the decussation of superior cerebellar peduncles or red nucleus. In these two patients, the MRI findings suggest that ataxic hemiparesis is caused by the interruption of cortico-pontine pathways and corticospinal tract in the crus cerebri.