Hypertrophic Olivary Degeneration Postoperatively Following Pilocytic Astrocytoma Resection

A 25-year-old male presented with headaches 3 weeks after a car accident. His magnetic resonance imaging images showed a hemorrhagic vermis mass with fourth ventricle effacement. One month later, he underwent suboccipital craniotomy for removal of a pilocytic astrocytoma. A 3-month postoperative scan demonstrated a new area of medullary hyperintensity in the inferior olive, which was also present 7 months postoperatively consistent with hypertrophic olivary degeneration. This condition is caused by disruption to the dento-rubro-olivary pathway with magnetic resonance imaging enlargement of the inferior olivary nucleus and increased T2 signal. Hypertrophic olivary degeneration should be considered after cerebellar surgery and should not be mistaken for tumor recurrence.