Differentiating Parkinson's disease from other parkinsonian disorders.

In 1817, James Parkinson formally described the shaking palsy that is now known as idiopathic Parkinson's disease (PD). Symptoms of PD, however, existed for thousands of years before that time. Descriptions evolved significantly until the term PARKINSONISM was eventually coined to describe neurologic disorders characterized by the presence of tremor, rigidity, and bradykinesia in addition to loss of postural reflexes and freezing. In this article, we present some useful clinical pearls in distinguishing idiopathic PD from atypical parkinsonism or drug-induced parkinsonism.