Experimental Pain Responses Support Peripheral and Central Sensitization in Patients With Unilateral Shoulder Pain

Abstract

Objective The aims of this study were to 1) examine the pattern of experimental pain responses in the affected and non-affected extremities in patients with shoulder pain and 2) explore the intra-individual association between sensitization states derived from experimental pain testing. Methods Experimental pain responses from 58 patients with shoulder pain (17 females, ages 18 to 52) were compared to those from 56 age- and sex-matched healthy volunteers (16 females, ages 21 to 58). Experimental pain responses included pressure pain threshold (PPT), thermal pain threshold and tolerance, and suprathreshold heat pain response (SHPR). Comparisons were made between the affected and non-affected extremity of clinical participants and the average response of extremities in healthy participants. Peripheral and central sensitization indexes were computed for clinical participants using standardized scores and percentile cut-offs based on the data from the healthy control sample. Experimental pain responses in clinical participants observed beyond the 25th and 75th percentile of healthy control sample responses were used for investigation of intra-individual association of sensitization states. Results PPT on the affected side acromion and masseter of clinical participants were diminished compared to their non-affected side (p < 0.015). Bilateral sensitivity in clinical participants was noted for PPT at the acromion and SHPR (p < 0.015). Peripheral and central sensitization indexes demonstrated that individuals with shoulder pain present with variable patterns of peripheral and central sensitization. Conclusions Collectively, experimental pain responses supported peripheral and central sensitization in response to pressure and thermal stimuli. No clear association was made between individuals exhibiting peripheral or central sensitization and suggests heterogeneity in pain processing in this clinical population.

Topographical pressure pain sensitivity maps of the shoulder region in individuals with subacromial pain syndrome

“…The presence of central and peripheral sensitization mechanisms as responsible for the changes of mechanical pain sensitivity observed in unilateral shoulder pain has been previously reported (Coronado et al, 2011(Coronado et al, , 2014. Some authors suggest changes in central (Hidalgo-Lozano et al, 2010;Paul et al, 2012) and peripheral (Alburquerque-Sendín et al, 2013) nervous systems in individuals with unilateral SAPS.…”

“…Furthermore, increased mechanical sensitivity can also occur on the nonaffected side as a sign of central sensitization . Although bilateral hyperalgesia has already been identified in unilateral shoulder pain (Hidalgo-Lozano et al, 2010;Paul et al, 2012;Coronado et al, 2014;Sanchis et al, 2015), results are still conflicting which increases the interest of research in this area.…”

Peripheral and Spinal Mechanisms of Pain and Dry Needling Mediated Analgesia: A Clinical Resource Guide for Health Care Professionals

“…Previous studies have demonstrated increased sensitivity to mechanical stimulation and receptive field expansion in dorsal horn neurons following injection of bradykinen into the lumbar multifidus [69,70]. By recording pain threshold following repeated stimuli to peripheral C-fibers, a number of studies have also reported wind-up related, central sensitization in patients with low back pain [71][72][73] TMJ pain [74] shoulder pain [75] and fibromyalgia [76]. Subacute or chronic C-fiber mediated pain increases the release of glutamate and substance-P from sensory afferents in spine, leading to hypersensitivity of second order, dorsal horn neurons.…”

Immediate changes in pressure pain sensitivity after thoracic spinal manipulative therapy in patients with subacromial impingement syndrome: A randomized controlled study

“…Characterizing mechanisms and outcomes following multiple doses would more closely mirror clinical practice and may yield different results. We also did not assess subjects enrolling into this study for peripheral or central sensitization to pain, and prior research (Coronado et al, 2014) suggests that there may be a heterogeneous mix of patients with shoulder pain exhibiting peripheral and/or central pain sensitization.…”