Late onset levodopa responsive Huntington's disease with minimal chorea masquerading as Parkinson plus syndrome

Huntington's disease is characterised by hyperkinetic movements, mainly cho rea, cognitive dysfunction, and psychiatric abnormalities. Non-dopa respons ive parkinsonism occurs in the later stages of choreic disease or as the pr edominant feature of juvenile patients (Westphal variant). Late onset Hunti ngton's disease presenting as levodopa responsive parkinsonism is rare. A s eries of four patients with late onset Huntington's disease presenting as l evodopa responsive parkinsonism and cardiovascular dysautonomia, initially misdiagnosed as multiple system atrophy (MSA) in three patients, is reporte d. Levodopa treatment did not unmask significant chorea. These cases sugges t the presence of a distinct phenotypic variant of Huntington's disease to be added to the differential diagnosis of other akinetic rigid syndromes.