Characteristics of pain and its relationship with functional limitations in individuals with Parkinson's disease

Abstract

Introduction: Pain is one of the most common nonmotor symptoms in individuals with Parkinson's disease (PD), although it is a still poorly understood and underreported phenomenon. Objective: This study aimed to analyze the relationship between pain, functioning limitations and motor impairments in individuals with PD and to characterize pain using complementary instruments
for its evaluation. Methods: This was a cross-sectional study enrolling outpatients recruited from local rehabilitation centers. Fiftyfour individuals with PD were screened [Hoehn & Yahr = 2.5 (1-4); [median (min-max)], 66 (44-85) years of age in the ON period of the anti-Parkinson medication. Pain was assessed by the King's Parkinson's disease pain scale (KPPS) and the Brief Pain Inventory (BPI). Participants were also evaluated for performance in routine activities and motor function using the Unified Parkinson Disease Rating Scale (UPDRS parts II and III), gait (Dynamic gait index), and balance (Mini-BESTest). Results: Thirty-eight participants (70.3%) reported mild to moderate pain. All demographic and functional characteristics of individuals with and without pain were similar, except to tremor that presented lower scores in pain participants. The Spearman's rank correlation coefficient showed a positive correlation between the types of pain (KPPS) and performance in general activities, as measured by UPDRS II (rho = 0.29, p = 0.04); a negative correlation between pain intensity (BPI intensity) and motor function as measured by the UPDRS III (rho = -0.28, p = 0.04), and a negative correlation between pain intensity (BPI intensity) and bradykinesia subscore of the UPDRS III (rho =-0.29, p =0.04). There was no correlation between pain and gait performance or balance. The musculoskeletal pain was the predominant type (81.5%), followed by nocturnal pain (52.6%) and fluctuationrelated pain (47.3%). The most painful areas were lower limbs (33.0%) and
shoulders/cervical (31.0%). Twenty-one (55.3%) out 38 participants reported pain interference in their working, walking ability and general activities. Participants were evaluated only during the ON period of anti-Parkinson medication. Conclusion: Pain was weakly correlated with the performance in general activities and with bradykinesia but was not correlated with the remaining classic motor PD symptoms neither with gait or balance performance. Pain was a prevalent symptom in the present sample and the individuals reported its interference on functioning.