Hypertrophic olivary degeneration: Case series and review of literature

Hypertrophic Olivary Degeneration (HOD) is a rare neurological condition caused by trans-synaptic degeneration in the brainstem and cerebellum, resulting in varied clinical symptoms, classical being palatal tremors, along with characteristic imaging presentation. Large number of pathologic lesions can cause this condition, ranging from ischemic stroke to neoplasm. The most common conditions include hemorrhage, vascular malformations and infarct. Magnetic resonance scan (MRI) is the imaging modality of choice which shows signal changes with hypertrophy of the inferior olivary nucleus, as well as the primary underlying pathology. Through this pictorial essay, we present the imaging and clinical findings in a number of patients with HOD secondary to varied causes and explain the mechanism behind the changes.