Parkinson’s disease a degenerative neurological disease. The disease increases in severity over time. It is a chronic progressive neurologic disease; chronic means long duration and progressive means proceeding in steps. In Parkinson’s disease neurons of brain area known as substantia nigra are primarily affected. When neurons in substantia nigra degenerate, brain’s ability to generate body movements is disrupted and this disruption produces signs and symptoms characteristic of Parkinson’s disease. These include tremor, akinesia (lack of movement or loss of spontaneous movements), bradykinesia(slowness of gait) and postural instability.