The International Parkinson and Movement Disorder Society (MDS) is a professional society of clinicians, scientists, and other healthcare professionals who are interested in movement disorders. The field of Movement Disorders includes the following areas: Parkinson's disease and parkinsonism, ataxia, dystonia, chorea and Huntington's disease, tics and Tourette syndrome, myoclonus and startle, restless leg syndrome, stiff person syndrome, tremor and essential tremor, spasticity, and gait disorders.