Importance Parkinson disease is the most common form of parkinsonism, a group of
neurological disorders with Parkinson disease–like movement problems such as rigidity,
slowness, and tremor. More than 6 million individuals worldwide have Parkinson disease.
Observations Diagnosis of Parkinson disease is based on history and examination. History
can include prodromal features (eg, rapid eye movement sleep behavior disorder,
hyposmia, constipation), characteristic movement difficulty (eg, tremor, stiffness, slowness) …