Hypertrophic Olivary Degeneration Secondary to Brain Abscess: A Case Report and Literature Review

Shihan Tian¹Biqiu Tang¹Kai Zhang¹Xiaohe Tian^2*Na Hu^1,3*

• ¹Department of Radiology, West China Hospital of Sichuan University, Chengdu, China
• ²Department of Radiology, Huaxi MR Research Center (HMRRC), Institution of Radiology and Medical Imaging, West China Hospital of Sichuan University, Chengdu, China
• ³Sichuan Provincial Engineering Research Center of Intelligent Medical Imaging, West China Hospital, Sichuan University, Chengdu, China

Introduction: Hypertrophic olivary degeneration (HOD) is a rare transsynaptic neurodegenerative disorder arising from disruption of the Guillain-Mollaret triangle (GMT), a neural circuit critical for motor coordination. Classical clinical presentation includes palatal tremor. While cerebrovascular etiology dominates reported cases, HOD secondary to intracranial infections remains poorly characterized, posing diagnostic challenges. Case presentation: A 72-year-old man with diabetes and hypertension presented with a 7-day history of fever, headache, and vomiting. Initial neuroimaging revealed right cerebellar hematoma with multiple brain abscesses. Antibacterial treatment achieved symptomatic improvement, but follow-up was lost. Seven months later, readmission occurred due to memory decline and personality changes. Magnetic resonance imaging (MRI) showed T2-weighted hyperintensity in the left anterior medulla oblongata and hemosiderosis in the right cerebellar hemisphere. Despite lacking classic HOD features, prior abscess-induced GMT involvement strongly supported the diagnosis. Symptomatic management stabilized the patient, with persistent lesions but no clinical progression at 5-month follow-up. Conclusion: This case documents a rare case of HOD following bacterial brain abscess, presenting with atypical features. It expands the etiological spectrum of HOD and underscores the need for heightened clinical suspicion in post-infectious neurological deterioration. Multimodal MRI facilitates early diagnosis and timely intervention, highlighting its critical role in managing this underrecognized entity.