Differential diagnosis of Parkinson's disease

Most patients present with clinical clues to guide the neurologist's diagno stic assessment. In many cases, however, the exact diagnosis cannot be made without an autopsy to provide pathology. Only about 80% of parkinsonism ca ses are correctly diagnosed with idiopathic PD during life. A definite neur odiagnostic test for PD is not yet available. Therefore, the clinical exami nation, supplemented by tests to rule out other causes, forms the basis of diagnosis. This article discusses differential diagnosis, concentrating on distinguishing clinical characteristics and useful diagnostic tests.