Hypertrophic olivary degeneration is a rare and potentially confusing imaging finding with unusual histological features causing macroscopic enlargement rather than atrophy of the inferior olive. Palatal myoclonus or other movement disorders may not always occur; however, the possibility of developing HOD and its clinical sequela is a relevant concern for clinicians and patients when surgery is contemplated. Knowledge of the condition and its MR characteristics on the part of the radiologist can prevent erroneous diagnoses of more sinister pathology.

From the manuscript

Hypertrophic Olivary Degeneration After Resection of a Pontine Cavernous Malformation: A Case Report

Abstract
We report the case of a 35 year old African American female who developed hypertrophic olivary degeneration secondary to resection of a pontine cavernous malformation. The patient initially complained of headaches and diplopia. Unenhanced computed tomography (CT) and magnetic resonance images (MRI) of the brain revealed a left pontine cavernous malformation with scattered foci of recent and remote hemorrhage. The patient subsequently underwent surgical resection of the lesion. Follow up MRI 7 months post surgery demonstrated hypertrophy and T2 signal hyperintensity in the ipsilateral inferior olivary nucleus secondary to hypertrophic olivary degeneration. Familiarity with this diagnosis and its imaging characteristics is required of the radiologist to prevent erroneous diagnoses of other pathology.