Purpose: To assess magnetic resonance (MR) imaging findings of hypertrophic olivary degeneration (HOD) due to hemorrhage and correlate them with pathologic findings.
Materials and methods: MR imaging was performed in 11 patients--eight with pontine tegmental hemorrhages (THs) and three with cerebellar hemorrhages in the dentate nuclei. The interval from hemorrhagic ictus to the MR studies was 3 weeks to 49 months. Pathologic specimens came from a woman who died of brain stem hemorrhage.
Results: Involvement of the central tegmental tract produced ipsilateral HOD; that of the dentate nucleus or superior cerebellar peduncle produced contralateral HOD. Bilateral olivary changes occurred only when the TH also involved the superior cerebellar peduncle. In bilateral THs, HOD was limited to the dominant bleeding side because of the lateral position of the central tegmental tract. Hyperintense areas of the oliva appeared 3 weeks after ictus. Hypertrophy appeared after 5-15 months. Microscopically, vacuolar degeneration of neurons and hypertrophy of astrocytes with gliosis were seen.
Conclusion: MR images may depict very early neuronal changes in the oliva and are well correlated with pathologic staging.