Stage IV Ovarian Cancer Complicated by Anti-Yo Cerebellar Degeneration

What happened, in summary

A woman in her mid-60s presented with 2 weeks of abdominal pain and a palpable mass. CA-125 was 1767 kU/L, CT confirmed stage IV disease, and an omental biopsy showed high-grade serous adenocarcinoma of the Müllerian tract. She received 6 cycles of carboplatin and paclitaxel with interval debulking surgery. Bevacizumab was added during cycle 6 and continued every 3 weeks as maintenance.

Five months into maintenance therapy, she developed 9 days of double vision, dizziness, nausea, headache, and poor coordination. Brain CT and MRI were normal, and the symptoms were initially attributed to bevacizumab. Three weeks later, she returned with worsening vertigo, abnormal eye movements, tremor, severe unsteadiness, and inability to walk without help. Repeat evaluation did not support brain metastases, stroke, or posterior reversible encephalopathy syndrome.

A paraneoplastic neurological syndrome was suspected. She received intravenous methylprednisolone 1000 mg daily for 5 days followed by 5 plasma exchanges, but her neurological condition did not improve. Propranolol and baclofen also failed to relieve the abnormal eye movements. Four weeks after immune treatment began, anti-Yo antibodies were confirmed in both serum and cerebrospinal fluid, establishing anti-Yo paraneoplastic cerebellar degeneration. Rituximab was considered but not given because the syndrome was refractory and the underlying cancer carried a poor prognosis. Her condition continued to deteriorate, care shifted to palliation, and she died 2 months after hospital admission.