[Patho-MR imaging study in the putaminal margin in multiple system atrophy]

The slit hyperintensity of the lateral margin of the putamen in T2 weighted MRI is a characteristic finding in those patients with multiple system atrophy (MSA) involving extrapyramidal system. In spite of some speculations such as demyelination, gliosis, iron deposition or increased extracellular fluid, the nature of the abnormal signal intensity has still been remained uncertain. In this paper, we report the coincidental findings of pathology and magnetic resonance imaging of the putaminal margin in a case of MSA. The patient was sixty three years old woman with nine years history of intreatable parkinsonism, mild ataxia and dysautonomia. At six months prior to her death, 0.5T MRI showed the pontocerebellar system atrophy, slit hyperintensity in the bilateral outer margin and left inner margin of the putamen in T2 weighted image as well as linear hypointensity in T1 weighted image. The neuropathological examinations showed severe degeneration in the olivopontocerebellar and striatonigral systems, and glial cytoplasmic inclusion in widespread regions in the brain. The putamen showed severe degeneration with rarefaction. The intertissue space was observed at the outer putaminal margin in both sides and inner margin in left side, which seemed to be caused by severe shrinkage and rarefaction of the putamen. Thus, slit hyperintensity in the putaminal margin in MSA was disclosed to represent widened intertissue space.