What is the definition or description of: parkinsonism?

Degenerative : Parkinson's disease is associated with a misfolded protein (alpha synuclein) which causes a loss of Dopamine in the basal ganglia. Symptoms include resting tremors, dementia, gait instability, rigidity, masked facies, drooling, trouble swallowing, constipation, pain, immobilization, and eventual severe disability. Deep brain stimulation may help many continue functioning.