Unilateral hemichorea and hemiballismus in a woman in her late 70s

Chorea is a hyperkinetic movement disorder characterised by involuntary, brief, random and irregular contractions. Acquired chorea can present acutely or subacutely and may be asymmetrical or unilateral. A detailed history and examination are crucial to identify triggering factors and underlying cause. In this case, a woman in her late 70s presented with progressively increasing involuntary movements in her right upper and lower limbs, triggered by active movements but ceasing with rest. Her medical history included a transient ischaemic attack (TIA) 3 years prior. Examination revealed choreoathetoid movements on the right side, occasionally manifesting as ballismus, which disappeared with rest. MRI showed small areas of restricted diffusion in the left parietal lobe suggestive of a microbleed, and carotid duplex ultrasonography revealed significant stenosis in the left carotid artery. The differential diagnosis included secondary paroxysmal kinesigenic dyskinesia and limb-shaking TIA/haemodynamic factors. In this report, we discuss both these differentials and how to approach.