Previous Injury and Chronic Pain are Associated with Side of Onset in Parkinson's Disease.

BACKGROUND Parkinson's disease (PD) motor symptoms are frequently asymmetric and the factors that influence the side of onset are unclear. OBJECTIVE To explore whether peripheral injury and associated chronic limb pain may influence the side of onset. METHODS We administered a questionnaire to 128 PD patients in a tertiary movement disorder clinic. Handedness, date and type of limb injury(s) and duration of associated pain, and date and side of onset were ascertained. RESULTS Sixty-two subjects reported limb injuries prior to the onset of PD symptoms, 30 with and 32 without chronic pain (i.e., ≥ 2 months). There was no association between injury and PD onset side overall (p=0.334). In subjects with chronic pain associated with limb injuries, however, side of injuries was associated with the side of PD symptom onset (p=0.030). CONCLUSIONS Limb injury with chronic pain may be related to the side of PD symptom onset. Future studies may shed light on the nature of this observation.