Degeneration of the ipsilateral substantia nigra after striatal infarction: evaluation with MR imaging.

Abstract

To evaluate the degeneration of the ipsilateral substantia nigra after striatal infarction by using magnetic resonance (MR) imaging. Twenty-five adult patients with embolic cerebral infarction of the middle cerebral artery distribution underwent MR imaging 0-4, 5-9, 12-15, and 27-29 days after the stroke. Sixteen of them also underwent follow-up MR imaging 2-12 months after the stroke. Ten patients had an infarct in the striatum with or without a cortical infarct (striatal infarction group); the other 15 patients had an infarct in the cerebral cortex of the middle cerebral artery distribution without a striatal infarct (cortical infarction group). In all 10 patients with striatal infarction, a hyperintense spot appeared in the ipsilateral substantia nigra on T2-weighted fast spin-echo images 7-12 days after the onset. This area became less intense and smaller 3 months later. In the cortical infarction group, no hyperintense spot in the ipsilateral substantia nigra was observed at any time. Degeneration of the substantia nigra ipsilateral to the striatal infarction was clearly demonstrated at MR imaging. This finding should not be mistaken for further cerebral infarction.