Clinical aspects of Parkinson disease.

Parkinson disease is a slowly progressive neurodegenerative disorder with a varied clinical picture and a variable rate of progression. Recently, there have been some studies conducted to assess the diagnostic accuracy and other clinical aspects of the disease. In the absence of a biomarker the clinical diagnosis is imprecise. This leads to a significant number of misdiagnoses, especially in early disease. Assessment of the clinical features suggests that an accuracy of 90% may be the highest that can be expected using current diagnostic criteria. In addition to bradykinesia, which is a core symptom, different types of tremors occur. Whereas the rest tremor is characteristic, action tremor, re-emergent tremor and orthostatic tremor may occur in Parkinson disease. Symptomatic treatments are quite effective in early disease but clinical course is complicated by the appearance of motor fluctuations and dyskinesias in more advanced disease. Non-motor complications, such as cognitive, psychiatric and autonomic problems, become bothersome and disabling in some patients.