Objective:

To describe the first known case of autoimmune cerebellitis with concurrent anti-Tr/DNER and anti-mGluR1 antibodies and highlight diagnostic and therapeutic implications.

Background:

Anti-Tr/DNER and anti-mGluR1 antibodies both target Purkinje cells but differ in oncologic associations and treatment responsiveness. Dual positivity has not been previously reported.

Design/Methods:

Case report of a 45-year-old woman presenting with subacute vertigo, oscillopsia, and gait ataxia. MRI was normal, CSF showed lymphocytic pleocytosis with CSF-specific oligoclonal bands, and paraneoplastic/encephalitis panels revealed high-titer anti-Tr/DNER and anti-mGluR1 antibodies in both serum and CSF. Oncologic evaluation was negative.

Results:

Plasma exchange and symptomatic therapy yielded limited improvement. Four months after onset, rituximab induced rapid functional recovery, with restored independent ambulation and sustained stability at 3-month follow-up.

Conclusions:

This case expands the autoimmune cerebellitis spectrum by demonstrating coexistence of a classic paraneoplastic antibody (anti-Tr/DNER) and a potentially reversible cell-surface antibody (anti-mGluR1). It underscores the importance of comprehensive antibody testing to guide malignancy screening and early escalation to B-cell–directed therapy when first-line treatments fail.