Current perception threshold and pain tolerance threshold of median nerve of Parkinson's disease patients associated with pain

Abstract

Objective To explore the role of current perception threshold and pain tolerance threshold of median serve of Parkinson's disease (PD) patients associated with pain. Methods Sixty-four PD patients and 30 healthy controls were enrolled in the study. Using the Neurometer CPT, current perception threshold and pain tolerance threshold testing at 2 000, 250, 5 Hz was performed on median nerves of both hands. PD patients were assessed by the following rating scales: Unified Parkinson's Disease Rating Scale (UPDRS), Hoehn-Yahr Scale (H-Y), Hamilton Depressive Scale (HAMD), Visual Analogue Scale (VAS), Montreal Cognitive Assessment (MoCA), and Mini Mental State Examination. Results PD patients had increased current perception threshold at 2 000, 250, 5 Hz of right hand as compared with control group (315.3±58.7 vs 290.1±38.6, t=-2.137, P=0.035; 112.3±29.3 vs 100.7±12.6, t=-2.701, P=0.008; 80.7±29.2 vs 71.1±15.1, t=-2.102, P=0.038) and had reduced pain tolerance threshold at 2 000, 250, 5 Hz of both hands(left hand: 15.6±2.6 vs 16.7±2.3, t=1.933, P=0.056; 8.9±2.7 vs 10.0±1.7, t=2.445, P=0.017; 12.1±4.1 vs 13.6±1.9, t=2.395, P=0.019; right hand: 14.6±3.5 vs 16.1±2.4, t=2.383, P=0.020; 8.9±2.3 vs 9.7±1.0, t=2.365, P=0.020; 11.5±4.5 vs 13.6±4.0, t=2.191, P=0.032). PD patients with pain had lower pain tolerance threshold at 2 000, 250, 5 Hz of both hands, compared with PD patients without pain (left hand: 14.7±2.4 vs 16.6±2.6, t=3.041, P=0.003; 8.1±2.3 vs 9.9±2.7, t=2.766, P=0.007; 10.9±4.7 vs 13.4±3.0, t=2.439, P=0.018; right hand: 13.5±3.1 vs 15.8±3.6, t=2.647, P=0.010; 8.1±2.0 vs 9.8±2.4, t=3.052, P=0.003; 10.3±3.9 vs 13.0±4.7, t=2.546, P=0.013). Compared with the PD patients without pain, PD patients with pain had higher scores of UPDRS, H-Y, HAMD and lower scores of MoCA. Conclusions In PD patients, the current perception threshold and pain tolerance threshold are abnormal, especially in the PD patients with pain. The sensory nerve function impairment may be involved in the mechanisms of pain in PD. Key words: Parkinson disease; Pain; Median nerve; Pain threshold; Sensory thresholds; Predictive value of tests