Early diagnosis of Parkinson's disease and initiation of treatment.

The diagnosis of Parkinson's disease remains a clinical diagnosis with no confirmatory laboratory or imaging studies available. The classic diagnostic criteria include 2 of 3 cardinal motor features of parkinsonism (resting tremor, cogwheel rigidity, and bradykinesia) on examination. Interest in a "premotor diagnosis" of Parkinson's disease is based on the hope that neuroprotective therapy could be initiated earlier and affect disease course. However, there is no proven method to diagnose Parkinson's disease prior to the onset of motor signs and there is no proven neuroprotective treatment. Once the diagnosis is made, the neurologist must decide, with the patient, whether to institute treatment at the time of diagnosis or whether to institute treatment when functional disability evolves. There are multiple possible initial pharmacologic choices for the initial treatment of Parkinson's disease, including monoamine oxidase type B inhibitors, dopamine receptor agonists, and levodopa/carbidopa.