Degeneration of the ipsilateral substantia nigra following cerebral infarction in the striatum.

In rats, degeneration of the ipsilateral substantia nigra occurs a few weeks after occlusion of the middle cerebral artery. The aim of this study was to clarify whether similar change is observed in stroke patients. Eighteen patients with striatal infarction and six patients with cortical infarction in the territory of the middle cerebral artery were examined by means of sequential magnetic resonance imaging. In all patients with striatal infarction, T2-weighted images revealed a high-signal-intensity spot in the ipsilateral substantia nigra. Changes in the ipsilateral substantial nigra appeared at day 14 after stroke on average and then became less intense and smaller a few months after the stroke. By contrast, we observed no nigral changes in any patient with cortical infarction. The degenerative change in the ipsilateral substantia nigra initially found in the rat model similarly occurred in patients with striatal infarction. This remote change in the substantia nigra may represent magnetic resonance imaging detection of neuropathologic changes in this region through the striatonigral pathway.