Pain as a nonmotor symptom of Parkinson disease: evidence from a case-control study

Objective: To determine whether pain is more frequent among people with Parkinson disease (PD) than among age-matched controls. Design: Case-control study Patients and Methods: Logistic regression models taking into account type of pain, time between pain and PD onset, and possible confounders were used to compare 402 PD patients with 317 age-matched healthy control subjects. Results: The overall frequency of pain was significantly greater in PD patients than in controls (281 [69.9%] vs 199 [62.8%]; P=.04), mainly because the healthy control group lacked dystonic pain. Conversely, the frequency of nondystonic pain was similar among PD patients and controls (267 [66.4%] vs 199 [62.8%]; P=.28). Nevertheless, we observed a significant association between PD and nondystonic pain, beginning after the onset of parkinsonian symptoms (odds ratio, 2.1; 95% confidence interval, 1.4-2.9). Cramping and central neuropathic pain were more frequent among PD patients than controls. About one-quarter of patients who experienced pain reported pain onset before starting antiparkinsonian therapy. Conclusion: These data support the hypothesis that pain begins at clinical onset of PD or thereafter as a nonmotor feature of PD.