Paraneoplastic Cerebellar Degeneration Presenting as Subacute Ataxia with Normal Neuroimaging: A Diagnostic Challenge

Paraneoplastic cerebellar degeneration (PCD) is a rare immune-mediated neurological syndrome commonly associated with gynecological malignancies and anti-Yo antibodies. Diagnosis is often delayed due to nonspecific presentation and normal imaging. A 48-year-old female presented with progressive imbalance for 2 months and slurred speech for 15 days. Examination revealed cerebellar signs with pyramidal features. Magnetic resonance imaging brain was normal. Cerebrospinal fluid showed mild lymphocytic pleocytosis. Initial treatment with intravenous methylprednisolone resulted in minimal improvement. Further evaluation revealed markedly elevated CA-125 and strongly positive anti-Yo antibodies. Surgical exploration confirmed poorly differentiated squamous cell carcinoma of the ovary. PCD should be suspected in subacute cerebellar ataxia with normal imaging and poor response to steroids. Early tumor detection is critical, although neurological recovery is often limited.