Rating scale and functional prognosis of Parkinson's disease

Parkinson's disease is a progressive neurodegenerative disorder. Motor functions of patients with Parkinson's disease are determined by its cardinal symptoms: akinesia, tremor, rigidity and disturbed righting reflexes. To evaluate degree of disability and rate of its progression in Parkinson disease, simple but reliable and reproducible rating scales are essential. Those that essentially fulfil such conditions are Hoehn and Yahr Scale, Schwab and England Scale, and Unified Parkinson's Disease Rating Scale (UPDRS). Levodopa, the major anti-parkinsonian agent, has greatly improved the motor functions of the Parkinson's disease patients and prolonged their life expectancy. Studies using the above mentioned scales compared the rate of disability progression and the motor functional prognosis between pre- and post-levodopa era, and always demonstrated the levodopa's benefits for the prognosis. Side effects of long administration of levodopa such as motor fluctuation, dyskinesia, wearing-off or on-off phenomenon, and psychosis, however, are disability factors to the patients' motor functions. Rating scales that can integrate the side effects to evaluate the functions will be required.