We report the first case of acute cerebellitis caused by cytotoxic chemotherapy.

Acute cerebellitis is rare in adults. Common causes are infectious and para-infectious processes, toxins, paraneoplastic and autoimmune antibodies. Cerebellitis is confirmed by neuroimaging showing diffuse cerebellar edema.

A 56-year-old woman presented with sudden onset of generalized weakness and reduced alertness, associated with poor appetite and vomiting. She was diagnosed with stage 1A uterine carcinosarcoma in 2017 for which she underwent TAHBSO, but declined adjuvant chemotherapy. In 2019, she was found to have metastatic disease of the lung and liver and agreed to chemotherapy. She was treated with one cycle of carboplatin/paclitaxel 35 days earlier. On examination, she was encephalopathic with BP: 136/76mmHg , P: 123bpm, T: 98.3F. She was dysarthric, had generalized hypotonia, areflexia and dysmetria on finger-to-nose testing.

Contrast MRI brain showed diffuse cerebellar edema with mass effect and diffusion restriction without contrast enhancement. Lumbar puncture was not performed due to concern for herniation and she was started on dexamethasone. CBCD was normal. RPR, lyme titer, serum EBV/CMV/HSV serology and blood cultures were negative. CRP was 74(H), ESR was 132(H), C4 was 52(H) and ANA titer was 1:640 with a ribosomal pattern. Anti-dsDNA antibody was negative, serum ACE and C3 were normal. A serum paraneoplastic panel was negative. She was discharged to inpatient rehabilitation and upon follow-up referred to hospice care. She expired one month after discharge.

Our patient presented with symptoms and had neuroimaging that was pathognomonic for acute cerebellitis. The acute onset of symptoms in the absence of paraneoplastic antibodies made a paraneoplastic syndrome unlikely. Infectious etiology was considered, but she presented without a viral prodrome, and with normal temperature and CBCD. While ataxia due to a delayed neurotoxic effect of carboplatin has been reported in the literature, there are no reports of acute cerebellitis.