Differential diagnosis of parkinsonism.

The diagnosis of Parkinson's disease is predominantly clinical, based on a combination of the cardinal features of tremor, bradykinesia and rigidity. The differential essentially lies between other conditions resulting in tremor, of which essential tremor is the commonest, and other akinetic-rigid syndromes. These include progressive supranuclear palsy, multiple system atrophy, toxins and other degenerative disorders, including diffuse Lewy body disease and corticobasal degeneration. The key clinical features of these disorders and a practical diagnostic approach are briefly reviewed in this article.