Late-onset subacute chorea

A 71-year-old woman presented with late-onset behavioural change initially diagnosed as bipolar disorder, followed 4 years later by generalised chorea and weight loss. Examination showed hyperkinetic movements with frontal and oculomotor features. An MR scan of the brain showed bilateral striatal T2 FLAIR hyperintensities. Serum and cerebrospinal fluid were positive for anticollapsin response mediator protein 5/CV2 and anti-neuronal nuclear antibody type 1/Hu antibodies, and imaging identified an underlying thoracic malignancy. She did not respond to immunotherapy and died shortly afterwards. This case highlights paraneoplastic striatal encephalitis as an important cause of late-onset chorea. Psychiatric symptoms may precede neurological features by several years, and red flags such as subacute progression, systemic symptoms and characteristic MR imaging changes should prompt early investigation for neuronal antibodies and malignancy.