Pain in Parkinson disease: a review of the literature.

Parkinson's disease (PD) is a degenerative neurological disease presenting with motor and non-motor signs and symptoms. Approximately 30-50% of the patients experience pain. There is no consensus regarding the mechanisms and classification of pain in PD. This paper reviews current data on the possible mechanisms, classifications, evaluation and potential risk factors for pain in PD. Literature searches were performed to identify clinical trials and reviews covering patho-physiology, classification, type, evaluation and risk factors associated with pain in PD. Pain in PD could be related to pathologic changes in the anatomic structures involved in nociceptive mechanisms. Studies on pain mechanisms have been mostly conducted in animals. The mechanism of pain is complicated and influenced by different factors. There are several methodological differences between the studies trying to classify pain and to characterize its subtypes. Potential risk factors for pain in PD include: age, gender, and duration of the disease. Although pain is one of the non-motor symptoms most frequency experienced by patients, it is often under recognized and inadequately treated in contrast to motor symptoms Multicenter studies are needed that include a large cohort of subjects evaluated in multiple dimensions including pain in order to obtain more data and to allow improved management of pain in patients with PD.