Parkinsonism is the syndrome of having a combination of slowness of movement, stiffness and tremor. Many related diseases can cause parkinsonism, or parkinsonian symptoms, including Parkinson’s disease, vascular parkinsonism and atypical parkinson’s syndromes such as multiple-systems atrophy (MSA) and corticobasal degeneration (CBD). Parkinson’s disease specifically refers to patients who have parkinsonism, do not have any atypical features, and who have an essentially normal MRI that excludes other causes for their parkinsonian symptoms. In many cases, Parkinson’s disease is referred to as “idiopathic” Parkinson’s disease, meaning that all other causes of parkinsonism have been eliminated. Of all patients with parkinsonism, patients with Parkinson’s disease respond best and the longest to medications and are potential candidates for deep brain stimulation surgery.