Purpose: To evaluate the degeneration of the ipsilateral substantia nigra after striatal infarction by using magnetic resonance (MR) imaging.
Materials and methods: 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.
Results: 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.
Conclusion: 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.