Ask the Experts: Differentiating Parkinson’s disease from other parkinsonian disorders

Parkinson's disease is the most common form of parkinsonism but there are many other causes of parkinsonian symptoms, manifested chiefly by bradykinesia, rest tremor, rigidity and gait and postural abnormalities. The classification of parkinsonian disorders is constantly changing, but most parkinsonian disorders can be categorized according to pathological hallmarks.