Parkinson's disease. Update in diagnosis and symptom management.

Parkinson's disease (PD) is a progressive neurodegenerative disorder with a high burden of morbidity. Because no diagnostic test exists for PD, clinical knowledge and skill are key to making an early, accurate diagnosis. Diagnostic criteria for PD require at least two of three motor signs: tremor, rigidity, or bradykinesia. Levodopa and the dopamine agonists are considered first-line drug therapy. Recent studies have shown a lower incidence of dyskinesia in patients who began therapy with a dopamine agonist, although levodopa may be better tolerated by patients age 70 or older. Combinations of medications and rehabilitative, alternative, and surgical therapies can often help patients achieve adequate control of PD motor symptoms and maintain a high quality of independent living.