Physical exercise, manual therapy, and other interventions may modulate pressure pain thresholds (PPTs) in patients with shoulder pain, a study published in Pain Medicine suggests.
The study was a systematic review and meta-analysis of 19 prospective trials that investigated shoulder pain interventions. These studies used quantitative sensory testing (QST) to examine patients with shoulder pain. Approximately 78% of the studies used PPT as the QST assessment. Exercise, the most frequent pain intervention, was used in 55% of the studies.
In a meta-analysis of the acute effects of local and remote PPT, the investigators found an overall effect in favor of local decreased PPTs (standardized mean difference [SMD], -0.38; 95% CI, -0.54 to -0.23; P <.0001) and an overall effect in favor of remote decreased PPTs (SMD, -0.33; 95% CI, -0.6 to -0.06, P =.02).
Surgery had no significant effect on the conditioned pain modulation (CPM) effect at 3 months, according to pooled data from 3 prospective cohort studies (SMD, 0.01; 95% CI, -0.26 to 0.29; P =.94). Pooled data from 2 other prospective cohort studies found no significant effect of surgery on CPM effect at 6-month follow-up (SMD, -0.09; 95% CI, -0.39 to 0.22; P =.58).
Although the investigators found no significant heterogeneity for local PPT (χ2=18.9, I2=21%; P =.21), they did observe significant heterogeneity for remote PPT (χ2=25.31, I2=60%; P =.005). Additional heterogeneity was found for the CPM effect at 3-month follow-up (I2=70%, P =.04).
A limitation of this meta-analysis was the lack of studies that investigated central pain mechanisms, including temporal summation of pain and conditioned pain modulation.
The study investigators concluded that their findings provide “preliminary evidence for a modulatory ability of localized and widespread pressure hyperalgesia after pain relieving interventions in patients with shoulder pain.”
Lyng KD, Thorsen JBB, Boye Larsen D, Kjær Petersen K. The modulatory effect of QST in shoulder pain: a systematic review and meta-analysis. Pain Med. Published online April 27, 2021. doi:10.1093/pm/pnab155