A 69 year old lady with COPD presented with a 3-week history of progressive worsening involuntary movements of her right limbs, beginning in her right hand, and spreading to involve her right leg after 1 week. Three days prior to admission, she had an episode of dysarthria and orolingual numbness lasting five minutes. On examination, she was hypertensive (200/105mmHg), and had marked right hemiballismus/hemichorea, with subtle orolingual chorea. Her neurological and cognitive examination was otherwise normal. The hemichorea worsened with commencement of antihypertensive therapy.

It seemed likely that our patient’s presentation with subacute hemichorea/hemiballismus and a superim- posed recent TIA-like event was due to an ischaemic stroke affecting the left basal ganglia. However, CT and MRI brain imaging did not demonstrate acute ischaemia or a prior stroke of the left basal ganglia. But on further investigation, CT angiogram revealed short segment 95% stenosis of the left internal carotid artery. The patient underwent a left carotid endarterectomy. Six weeks later, there was complete resolu- tion of hemichorea.

The progressive nature of her clinical signs over three weeks, the transient worsening with antihypertensive therapy, and the gradual resolution post-operatively suggests that critical cerebral hypoperfusion due to severe internal carotid artery (ICA) stenosis can present unusually as progressive hemichorea.