Secondary thalamic degeneration after cerebral infarction in the middle cerebral artery distribution: evaluation with MR imaging.

PURPOSE: To evaluate secondary degeneration of the ipsilateral thalamus after cerebral infarction in the middle cerebral artery (MCA) distribution by using magnetic resonance (MR) imaging. MATERIALS AND METHODS: Thirty patients (17 men, 13 women; aged 30-85 years) with embolic cerebral infarction in the MCA distribution underwent serial MR imaging 2 hours to 12 months after a stroke. In 23 of the 30 patients, the authors evaluated cerebral blood flow with single photon emission computed tomography (SPECT). RESULTS: T2-weighted spin-echo images disclosed a hyperintense area in the ipsilateral thalamus in 14 patients (47%) 1-12 months after stroke. The hyperintense area was confined to the dorsomedial or anterior and dorsomedial nuclei of the thalamus in nine of the 14 patients; it extended from the dorsomedial or anterior and dorsomedial nuclei to the ventral lateral nucleus or pulvinar in the remaining five patients. Hypoperfusion of the ipsilateral thalamus was observed in 21 of the 23 patients who underwent SPECT. Twelve of the 21 patients also showed a hyperintense area in the ipsilateral thalamus on the MR images. CONCLUSION: MR imaging is useful in evaluating secondary thalamic degeneration after cerebral infarction. In clinical practice, this secondary degeneration should not be mistaken for other lesions such as further cerebral infarction.