A Case of Acute Cerebellitis With a Unique Sequential Change on Magnetic Resonance Imaging

BACKGROUND: Acute cerebellitis with unilateral onset is rare, and magnetic resonance imaging (MRI) is a useful method for demonstrating cerebellar involvement. PATIENT: We report a 12-year-old girl with acute cerebellitis with a unique sequential change on her MRI. RESULTS: The patient’s brain MRI first revealed cortical lesions mainly in the right cerebellar hemisphere. These subsequently disappeared, and at the same time, new lesions appeared in the opposite cerebellar hemisphere. All the lesions were confined to gray matter in the cerebellum and were isotense on diffusion-weighted imaging and had high signal intensity on the apparent diffusion coefficient map, consistent with the characteristic of vasogenic edema. CONCLUSION: The sequential MRI demonstrates conversion of hemicerebellitis to bilateral cerebellitis during subacute phase, and vasogenic edema might be contributing to the pathogenesis of acute cerebellitis in this patient.