Pain is a key unmet need and a major aspect of non-motor symptoms of Parkinson's disease (PD). No specific validated scales exist to identify and grade the various types of pain in PD. We report an international, cross-sectional, open, multicenter, one-point-in-time evaluation with retest study of the first PD-specific pain scale, the King's PD Pain Scale. Its seven domains include 14 items, each item scored by severity (0-3) multiplied by frequency (0-4), resulting in a subscore of 0 to 12, with a total possible score range from 0 to 168. One hundred seventy-eight PD patients with otherwise unexplained pain (age [mean ± SD], 64.38 ± 11.38 y [range, 29-85]; 62.92% male; duration of disease, 5.40 ± 4.93 y) and 83 nonspousal non-PD controls, matched by age (64.25 ± 11.10 y) and sex (61.45% males) were studied. No missing data were noted, and floor effect was observed in all domains. The difference between mean and median King's PD Pain Scale total score was less than 10% of the maximum observed value. Skewness was marginally high (1.48 for patients). Factor analysis showed four factors in the King's PD Pain Scale, explaining 57% of the variance (Kaiser-Mayer-Olkin, 0.73; sphericity test). Cronbach's alpha was 0.78, item-total correlation mean value 0.40, and item homogeneity 0.22. Correlation coefficients of the King's PD Pain Scale domains and total score with other pain measures were high. Correlation with the Scale for Outcomes in PD-Motor, Non-Motor Symptoms Scale total score, and quality of life measures was high. The King's PD Pain Scale seems to be a reliable and valid scale for grade rating of various types of pain in PD.

BACKGROUND STN-DBS is well established to improve motor symptoms and quality of life in patients with PD. While non-motor symptoms are crucial for quality of life in these patients, only neuropsychiatric and neuropsychological symptoms have been systematically studied in a longitudinal design thus far. However, these are only a part of the spectrum of non-motor symptoms in PD. We hypothesized that STN-DBS is associated with a beneficial effect on a range of non-motor symptoms. METHODSIn this multicenter, open, prospective, international study we investigated non-motor effects of STN-DBS in "real-life" use. We evaluated Non-motor Symptom Scale, and Questionnaire, PD Questionnaire-8, Scales for Outcomes of PD motor examination and complications, and activities of daily living preoperatively and at 6 months follow-up in 60 consecutive patients (35 male, mean age: 61.64 ±7.84 years, mean disease duration: 10.45 ±4.22 years) undergoing STN-DBS. RESULTSAll outcomes improved significantly at 6 months follow-up (PD Questionaire-8, p=0.006; activities of daily living, p=0.012; all others, p<0.001; Wilcoxon signedrank, respectively paired t-test; Bonferroni-correction). Post-hoc analyses of Nonmotor Symptom Scale domains showed a significant reduction of sleep/fatigue and miscellaneous domains (p≤0.001), perceptual problems/hallucinations (p=0.036), and urinary (p=0.018) scores. Effect sizes were "moderate" effect for Non-motor Non-motor effects of subthalamic DBS -5 -Symptom Scale, and motor complications, "large" for motor examination, and "small" for other outcomes. CONCLUSIONSThis study provides first evidence that bilateral STN-DBS improves non-motor burden in patients with PD and opens the door to a more balanced evaluation of DBS outcomes. Further randomized studies are needed to confirm these findings and compare DBS non-motor effects to other therapies such as infusion based treatments of advanced PD.

Autonomic and somatic denervation is well established in Parkinson's disease (PD).Objectives(1) To determine whether corneal confocal microscopy (CCM) can non-invasively demonstrate small nerve fiber damage in PD. (2) To identify relationships between corneal nerve parameters, intraepidermal nerve fiber density (IENFD) and clinical features of PD.MethodsTwenty-six PD patients and 26 controls underwent CCM of both eyes. 24/26 PD patients and 10/26 controls underwent skin biopsies from the dorsa of both feet. PD patients underwent assessment of parasympathetic function [deep breathing heart rate variability (DB-HRV)], autonomic symptoms [scale for outcomes in Parkinson's disease – autonomic symptoms (SCOPA-AUT)], motor symptoms [UPDRS-III “ON”] and cumulative Levodopa dose.ResultsPD patients had significantly reduced corneal nerve fiber density (CNFD) with increased corneal nerve branch density (CNBD) and corneal nerve fiber length (CNFL) compared to controls. CNBD and CNFL but not CNFD correlated inversely with UPDRS-III and SCOPA-AUT. All CCM parameters correlated strongly with DB-HRV. There was no correlation between CCM parameters and disease duration, cumulative Levodopa dose or pain. IENFD was significantly reduced in PD compared to controls and correlated with CNFD and UPDRS-III. However, unlike CCM measures, IENFD correlated with disease duration and cumulative Levodopa dose but not with autonomic dysfunction.ConclusionCCM identifies corneal nerve fiber pathology, which correlates with autonomic symptoms, parasympathetic deficits and motor scores in patients with PD. IENFD is also reduced and correlates with CNFD and motor symptoms but not parasympathetic deficits, indicating it detects different aspects of peripheral nerve pathology in PD.

UK National Health Service.