Musculoskeletal pain in Parkinson's disease: Association with dopaminergic deficiency in the caudate nucleus

Abstract

Background: Musculoskeletal (MSK) pain affects over 80% of People with Parkinson's (PD, PwP) and may, in part, be dopaminergic in origin, as dopaminergic medication often leads to its relief. Methods: PwP who underwent striatal dopamine transporter visualization with a radiopharmaceutical DaTscan™ (123I-Ioflupane Injection) using a single-photon emission computed tomography (SPECT) as a part of their clinical-diagnostic work up were enrolled in the “Non-motor International Longitudinal Study” (NILS; UK National Institute for Health Research Clinical Research Network Number 10084) and included in this cross-sectional analysis. The association between specific DaTscan binding ratios for each striatum, the caudate nucleus and putamen and clinical ratings for MSK pain (assessed using the King's Parkinson's Disease Pain Scale (KPPS)) were analysed. Results: 53 PwP (30.2% female; age: 63.79 ± 11.31 years; disease duration (DD): 3.32 (0.31–14.41) years; Hoehn & Yahr stage (H&Y): 2 (1–4); Levodopa Equivalent Daily Dose (LEDD): 543.08 ± 308.94 mg) were assessed and included in this analysis. MSK pain was highly prevalent (71.7% of all participants, mean KPPS Item 1 score 5.34 ± 4.76) and did not correlate with the motor symptoms burden (SCOPA-Motor total score; p = 0.783) but showed a significant correlation with quality of life (PDQ-8, rs = 0.290, p = 0.035). z-scores for the caudate nucleus (Exp (B) = 0.367, 95% CI for Exp (B) 0.148–0.910, p = 0.031) and striatum (Exp (B) = 0.338, 95% CI for Exp (B) 0.123–0.931, p = 0.036), adjusted for DD, H&Y and LEDD, were significant determinants of MSK pain. Conclusions: Our findings suggest an association between MSK pain in PwP and the severity of dopaminergic deficiency in the caudate nucleus. Significance: In People with Parkinson's, musculoskeletal pain does not arise simply as a direct sequel to motor symptoms—instead, it is linked to the severity of dopaminergic depletion in the caudate nucleus.