Pain in Parkinson's disease.

Parkinson's disease is characterized primarily as a neurodegenerative disorder that leads to disabling motor and cognitive impairment. PD is less widely appreciated as a disease causing a substantial variety of pain syndromes, although the prevalence of pain in PD is approximately 40%. In a minority of patients, pain is so severe and intractable that it overshadows the motor symptoms of the disorder. In recent years, descriptive surveys of non-motor symptoms in PD have led to a classification of painful sensations into one or more of several categories: musculoskeletal pain, radicular or neuropathic pain, dystonia-related pain, akathitic discomfort, and primary, central parkinsonian pain. A framework for diagnosing and treating painful PD is described in this review, together with recent insignts into the neurophysiological mechanisms and substrates of pain in PD.