Heightened pain facilitation rather than impaired pain inhibition distinguishes those with moderate/severe disability in work-related neck pain

Restoration of normal central pain processing following manual therapy in nonspecific chronic neck pain

OBJECTIVE

To determine if a 4-week manual therapy treatment restores normal functioning of central pain processing mechanisms in non-specific chronic neck pain (NSCNP), as well as the existence of a possible relationship between changes in pain processing mechanisms and clinical outcome.

DESIGN

Cohort study.

METHODS

Sixty-three patients with NSCNP, comprising 79% female, with a mean age of 45.8 years (standard deviation: 14.3), received four treatment sessions (once a week) of manual therapy including articular passive mobilizations, soft tissue mobilization and trigger point treatment. Pressure pain thresholds (PPTs), conditioned pain modulation (CPM) and temporal summation of pain (TSP) were evaluated at baseline and after treatment completion. Therapy outcome was measured using the Global Rating of Change Scale (GROC), the Neck disability Index (NDI), intensity of pain during the last 24 hours, Tampa Scale of Kinesiophobia (TSK) and Pain Catastrophizing Scale (PCS). Two sets of generalized linear mixed models with Gaussian response and the identity link were employed to evaluate the effect of the intervention on clinical, psychological and psychophysical measures and the association between psychophysical and clinical outcomes.

RESULTS

Following treatment, an increased CPM response (Coefficient: 0.89; 95% credibility interval = 0.14 to 1.65; P = .99) and attenuated TSP (Coefficient: -0.63; 95% credibility interval = -0.82 to -0.43; P = 1.00) were found, along with amelioration of pain and improved clinical status. PPTs at trapezius muscle on the side of neck pain were increased after therapy (Coefficient: 0.22; 95% credibility interval = 0.03 to 0.42; P = .98), but not those on the contralateral trapezius and tibialis anterior muscles. Only minor associations were found between normalization of TSP/CPM and measures of clinical outcome.

CONCLUSION

Clinical improvement after manual therapy is accompanied by restoration of CPM and TSP responses to normal levels in NSCNP patients. The existence of only minor associations between changes in central pain processing and clinical outcome suggests multiple mechanisms of action of manual therapy in NSCNP.

Conditioned pain modulation and psychological factors in young adults with recurrent or chronic neck pain

BACKGROUND

Controversy exists with the presence of alterations in descending pain inhibition mechanisms in patients with non-specific neck pain (NSNP). The aim of the present study was to evaluate the status of conditioned pain modulation CPM, remote pressure pain thresholds (PPT), and psychological factors in a specific subgroup of patients with NSNP such as young adult students. In addition, possible associations between CPM, psychological factors, and pain characteristics were analyzed.

METHODS

Thirty students with recurrent or chronic NSNP and 30 pain-free students were included in this cross-sectional study. The following measures were assessed: CPM, remote PPT, psychological factors (depression, anxiety, pain catastrophizing, and kinesiophobia), pain characteristics (duration, intensity, severity of chronic pain, interference with daily life), and central sensitization inventory (CSI).

RESULTS

No significant differences were found in the efficacy of CPM between students with chronic or recurrent NSNP and pain-free students (β coefficient = -0.67; 95% CI = -1.54, 0.20). However, students with pain showed a significantly higher remote PPT (mean difference = -1.94; 95% CI = -2.71, -1.18). and a greater presence of anxious (mean difference = 6; 95% CI = 2, 9) and depressive symptoms (mean difference = 8.57; 95% CI = 3.97, 13.16). In addition, significant moderate or strong correlations were found between CPM and pain intensity (partial r = 0.41), pain catastrophizing and mean pain intensity (r = 0.37), grade (r = 0.50), and interference of pain (r = 0.57), kinesiophobia and disability (r = 0.38), and depression and CSI (r = 0.39).

CONCLUSIONS

Young adult students with chronic or recurrent NSNP present remote hyperalgesia and symptoms of depression and anxiety but not dysfunctional CPM.

Exercise-induced hypoalgesia in chronic neck pain: A narrative review

Chronic neck pain (CNP) is a worldwide health problem with several risk factors. One of the most widely used treatments for managing this condition is therapeutic exercise, which could generate a response called exercise-induced hypoalgesia (EIH). There is no consensus on the best exercise modality to induce hypoalgesia. Therefore, this review aims to analyze and synthesize the state-of-the-art about the hypoalgesic effect of exercise in subjects with CNP. We included articles on EIH and CNP in patients older than 18 years, with pain for more than three months, where the EIH response was measured. Articles that studied CNP associated with comorbidities or measured the response to treatments other than exercise were excluded. The studies reviewed reported variable results. Exercise in healthy subjects has been shown to reduce indicators of pain sensitivity; however, in people with chronic pain, the response is variable. Some investigations reported adverse effects with increased pain intensity and decreased pain sensitivity, others found no clinical response, and some even reported EIH with decreased pain and increased sensitivity. EIH is an identifiable, stimulable, and helpful therapeutic response in people with pain. More research is still needed on subjects with CNP to clarify the protocols and therapeutic variables that facilitate the EIH phenomenon. In addition, it is necessary to deepen the knowledge of the intrinsic and extrinsic factors that influence EIH in people with CNP.