[A clinico-MRI study of extrapyramidal symptoms in multiple system atrophy--linear hyperintensity in the outer margin of the putamen].

We did a clinico-MRI study concerning extrapyramidal symptoms and T2-weighted MRI findings of the putamen in twenty patients with multiple system atrophy (MSA) as well as twenty-five with idiopathic Parkinson's disease. Nine out of twenty MSA patients showed extrapyramidal symptoms. And we could not observe cerebellar ataxia in two of these patients because of severe rigidity and akinesia. Eight out of nine MSA patients with extrapyramidal symptoms showed linear hyperintensity in the outer margin of the putamen. This abnormal intensity was bilateral and symmetric in most patients. However, in MSA patients without extrapyramidal symptoms, only one patient showed the linear hyperintensity. We could not find such abnormal intensity in any patients with Parkinson's disease. On proton density MRI, the signal intensity in the lesion was higher than that in the gray matter, which leads the speculation that the hyperintensity is gliosis of the putamen or increased extracellular fluid space caused by severe shrinkage of the putamen. This characteristic MRI finding is useful to distinguish MSA with extrapyramidal symptoms from Parkinson's disease.