Unilateral Idiopathic Hypertrophic Olivary Degeneration: A Case Report

Hypertrophic olivary degeneration (HOD) is a rare type of trans-synaptic degeneration affecting the inferior olivary nucleus (ION), most commonly associated with lesions in the Guillain-Mollaret triangle (GMT). Because of its rarity, HOD remains poorly understood and lacks a comprehensive classification system. We present an unusual case of unilateral, idiopathic, nonlesional HOD in an 82-year-old male who exhibited gait disturbance and cognitive impairment. MRI showed hypertrophy of the right medullary olive without the typical clinical signs usually seen in HOD. This case underscores the variability in HOD presentation and highlights the need for further research into its atypical manifestations.