Prevalence, classification, and etiology of pain in Parkinson's disease: association between Parkinson's disease and fibromyalgia or chronic widespread pain.

Parkinson's disease (PD) is characterized by resting tremor, slow and decreased movement (hypokinesia and akinesia), rigidity, postural instability, problems with gait, and coordination. The prevalence of PD is between 0.1% and 0.3% in the general population and between 1 % and 2% in persons 65 years of age or older. Patients with PD are more likely to suffer from pain. Indeed, the chief complaint of patients with severe motor disturbance and severe pain is pain rather than motor disturbance. Fibromyalgia (FM) is defined by widespread pain (pain in the left and right sides of the body, pain above the waist, pain below the waist, and axial skeletal pain) for more than 3 months and the presence of at least 11 of the 18 specified tender points. FM and chronic widespread pain (CWP), which is usually an incomplete form of FM, cause pain in the musculoskeletal region, but their etiologies are unknown. Therefore, it is almost impossible to determine whether or not pain in the musculoskeletal region is in the musculoskeletal origin. We suspect that dysfunction or degeneration of the nerves that control pain, mind, and movement in the brain causes FM, depression, and PD, respectively. When pain in PD is discussed, FM and CWP should be considered because their prevalence is high. Patients with PD may be likely to suffer from FM and CWP; however, the prevalence of FM and CWP in patients with PD has not been reported. Here, we discuss the relationship between PD and FM or CWP.