Spinal manipulation does not affect pressure pain thresholds in the absence of neuromodulators: a randomized controlled trial

Reduction of Chronic Primary Low Back Pain by Spinal Manipulative Therapy is Accompanied by Decreases in Segmental Mechanical Hyperalgesia and Pain Catastrophizing: A Randomized Placebo-controlled Dual-blind Mixed Experimental Trial

Chronic primary low back pain (CPLBP) refers to low back pain that persists over 3 months, that cannot be explained by another chronic condition, and that is associated with emotional distress and disability. Previous studies have shown that spinal manipulative therapy (SMT) is effective in relieving CPLBP, but the underlying mechanisms remain elusive. This randomized placebo-controlled dual-blind mixed experimental trial (NCT05162924) aimed to investigate the efficacy of SMT to improve CPLBP and its underlying mechanisms. Ninety-eight individuals with CPLBP and 49 controls were recruited. Individuals with CPLBP received SMT (n = 49) or a control intervention (n = 49), 12 times over 4 weeks. The primary outcomes were CPLBP intensity (0-100 on a numerical rating scale) and disability (Oswestry Disability Index). Secondary outcomes included pressure pain thresholds in 4 body regions, pain catastrophizing, Central Sensitization Inventory, depressive symptoms, and anxiety scores. Individuals with CPLBP showed widespread mechanical hyperalgesia (P < .001) and higher scores for all questionnaires (P < .001). SMT reduced pain intensity compared with the control intervention (mean difference: -11.7 [95% confidence interval, -11.0 to -12.5], P = .01), but not disability (P = .5). Similar mild to moderate adverse events were reported in both groups. Mechanical hyperalgesia at the manipulated segment was reduced after SMT compared with the control intervention (P < .05). Pain catastrophizing was reduced after SMT compared with the control intervention (P < .05), but this effect was not significant after accounting for changes in clinical pain. Although the reduction of segmental mechanical hyperalgesia likely contributes to the clinical benefits of SMT, the role of pain catastrophizing remains to be clarified. PERSPECTIVE: This randomized controlled trial found that 12 sessions of SMT yield greater relief of CPLBP than a control intervention. These clinical effects were independent of expectations, and accompanied by an attenuation of hyperalgesia in the targeted segment and a modulation of pain catastrophizing.

Duration of Electro-Dry Needling Does Not Change the Pain Response After Repeated Nociceptive Thermal Stimuli in Asymptomatic Individuals: A Randomized Intervention Study

Objective

To assess the effects of 5 different durations of electro-dry needling (EDN) on asymptomatic individuals' pain response after repeated noxious thermal stimuli.

Design

Randomized, non-controlled intervention trial.

Setting

University laboratory.

Participants

Asymptomatic participants (N=50) were recruited for the study and randomized into 5 groups. There were 33 women with an average age of 26.8 (±4.8) years. To participate in the study, individuals had to be between the ages of 18 and 40, free of any musculoskeletal injury which prevented participation of daily activities, and not pregnant or trying to become pregnant.

Interventions

Participants were randomly assigned to receive 5 different durations of EDN: 10, 15, 20, 25, and 30 minutes. To perform the EDN, 2 monofilament needles were inserted lateral to the lumbar spinous processes of L3 and L5 on the right. Needles were left in situ with electrical stimulation at a frequency of 2 Hz and an amplitude which resulted in a 3 to 6 out of 10 intensity pain rating by the participant.

Main Outcome Measures

The change in the magnitude of pain in response to repetitive heat-pulses before and after the EDN procedure.

Results

There was a significant reduction in the magnitude of pain in response across the groups after EDN (F_(1,42)=94.12, P<.001, ƞ_p²=.691). However, the interaction between time and group was not significant (F_(4,42)=1.019, P=.409, ƞ_p²=.088), indicating that no duration of EDN was superior to another in reducing temporal summation.

Conclusions

This study suggests that in asymptomatic individuals, performing EDN beyond 10 minutes does not provide any additional benefits in the reduction of the magnitude of pain in response to thermal nociceptive stimuli. Additional study in symptomatic populations is required for generalizability in clinical settings.

Hypoalgesic effects of specific vs non-specific cervical manipulation in healthy subjects: a randomized crossover trial

BACKGROUND

Joint manipulation is generally used to reduce musculoskeletal pain; however, evidence has emerged challenging the effects associated with the specificity of the manipulated vertebral segment. The aim of this study was to verify immediate hypoalgesic effects between specific and non-specific cervical manipulations in healthy subjects.

METHOD

Twenty-one healthy subjects (18-30 years old; 11 males, 10 females) were selected to receive specific cervical manipulation at the C6-7 segment (SCM) and non-specific cervical manipulation (NSCM) in aleatory order. A 48h interval between manipulations was considered. Pressure pain threshold (PPT) was measured pre- and post-manipulation with a digital algometer on the dominant forearm.

RESULTS

The SCM produced a significant increase in the PPT (P < 0.001) however no difference was observed in the PPT after the NCSM (P = 0.476). The difference between the two manipulation techniques was 37.26 kPa (95% CI: 14.69 to 59.83, p = 0.002) in favor of the SCM group CONCLUSION: Specific cervical manipulation at the C6-7 segment appears to increase PPT on the forearm compared to non-specific cervical manipulation in healthy subjects.

Hypoalgesic Effects of Transcutaneous Electrical Nerve Stimulation Combined With Joint Manipulation: A Randomized Clinical Trial

OBJECTIVE

The objective of this study was to compare the hypoalgesic effects of isolated or combined use of transcutaneous electrical nerve stimulation (TENS) and cervical joint manipulation (JM) in asymptomatic participants.

METHODS

One hundred and forty-four healthy participants aged 18 to 30 years old were randomly assigned to 1 of 4 groups (n = 36 per group): active TENS + active JM, active TENS + placebo JM, placebo TENS + active JM, and placebo TENS + placebo JM. Active or placebo TENS was applied to the dominant forearm. JM was applied to the C6-7 segments. The pressure pain threshold was measured pre- and postintervention and after 20 minutes on the forearm and tibialis anterior of the dominant side.

RESULTS

Segmental hypoalgesia was greater in the group active TENS + active JM compared with active TENS + placebo JM (P = .002), placebo TENS + active JM (P < .0001), and placebo TENS + placebo JM (P < .0001). For the extrasegmental hypoalgesia, active TENS + active JM had greater hypoalgesic effect compared with active TENS + placebo JM (P = .033), placebo TENS + active JM (P = .002), and placebo TENS + placebo JM (P < .0001).

CONCLUSION

TENS and JM produced hypoalgesia when used alone and, when the treatments were combined, a higher segmental and extrasegmental hypoalgesic effect was obtained in asymptomatic participants.

Neurophysiological mechanisms of chiropractic spinal manipulation for spine pain

Together, neck pain and back pain are the first cause of disability worldwide, accounting for more than 10% of the total years lived with disability. In this context, chiropractic care provides a safe and effective option for the management of a large proportion of these patients. Chiropractic is a healthcare profession mainly focused on the spine and the treatment of spinal disorders, including spine pain. Basic studies have examined the influence of chiropractic spinal manipulation (SM) on a variety of peripheral, spinal and supraspinal mechanisms involved in spine pain. While spinal cord mechanisms of pain inhibition contribute at least partly to the pain-relieving effects of chiropractic treatments, the evidence is weaker regarding peripheral and supraspinal mechanisms, which are important components of acute and chronic pain. This narrative review highlights the most relevant mechanisms of pain relief by SM and provides a perspective for future research on SM and spine pain, including the validation of placebo interventions that control for placebo effects and other non-specific effects that may be induced by SM. SIGNIFICANCE: Spinal manipulation inhibits back and neck pain partly through spinal segmental mechanisms and potentially through peripheral mechanisms regulating inflammatory responses. Other mechanisms remain to be clarified. Controls and placebo interventions need to be improved in order to clarify the contribution of specific and non-specific effects to pain relief by spinal manipulative therapy.

The Acute Effects of Manual and Instrument-Assisted Cervical Spine Manipulation on Pressure Pain Threshold, Pressure Pain Perception, and Muscle-Related Variables in Asymptomatic Subjects: A Randomized Controlled Trial

OBJECTIVE

The purpose of this study was to compare the immediate effects in asymptomatic participants of manual and instrument-assisted cervical manipulation on pressure pain thresholds, pressure pain perception, and muscle mechanical properties (tone, stiffness, and elasticity) over muscles anatomically related and unrelated to the manipulated level.

METHODS

Fifty-nine asymptomatic participants (34 women and 25 men; age [mean ± standard deviation] = 21.1 ± 1.6 years) were randomly assigned to 4 groups in a double-blind, randomized, placebo-controlled trial. Two groups received cervical (C3/C4) manipulation, 1 manual and the other instrument-assisted; the third group received a sham manipulation; and the fourth group served as the control. Bilateral pressure pain threshold, pressure pain perception, muscle tone, stiffness, and elasticity in the upper trapezius and biceps brachii were evaluated before and immediately after the interventions.

RESULTS

At baseline, there were no differences among the groups on any variable. After the interventions, a significant increase in pressure pain threshold was observed with both manual and instrument-assisted manipulation at local and distal sites (P < .05), whereas no changes were observed in either the control or the placebo group. The perception of pain pressure did not change significantly in any group. The interventions did not promote any statistically significant differences in muscle tone, elasticity, or stiffness at any site (local or distal).

CONCLUSION

Cervical (C3/C4) manual and instrument-assisted manipulations produced an increase in pressure pain threshold bilaterally and over muscles related and unrelated to the vertebral segment, but had no effect on muscle tone, elasticity, or stiffness.

Transcutaneous electrical nerve stimulation and cervical joint manipulation on pressure pain threshold

Aim: Transcutaneous electrical nerve stimulation (TENS) and cervical joint manipulation (CJM) are often used for pain treatment. Methods: A total of 144 healthy subjects will be randomly allocated into four groups: active TENS and CJM, placebos TENS and CJM, placebo TENS and active CJM, active TENS and placebo CJM. TENS will be applied for 20 min followed by CJM. All subjects will be assessed before, during and after interventions, using a digital pressure algometer. Discussion: This is the first study to assess the combined effects of TENS and CJM on pressure pain threshold in healthy individuals. It is possible that both methods combined can enhance the hypoalgesic effect because they activate different analgesic pathways.

Study registration: NCT03531541 (ClinicalTrials.gov).

The regional effect of spinal manipulation on the pressure pain threshold in asymptomatic subjects: a systematic literature review

Background

Spinal manipulation (SM) has been shown to have an effect on pain perception. More knowledge is needed on this phenomenon and it would be relevant to study its effect in asymptomatic subjects.

Objectives

To compare regional effect of SM on pressure pain threshold (PPT) vs. sham, inactive control, mobilisation, another SM, and some type of physical therapy. In addition, we reported the results for the three different spinal regions.

Method

A systematic search of literature was done using PubMed, Embase and Cochrane. Search terms were ((spinal manipulation) AND (experimental pain)); ((spinal manipulative therapy OR spinal manipulation) AND ((experimental pain OR quantitative sensory testing OR pressure pain threshold OR pain threshold)) (Final search: June 13th 2017). The inclusion criteria were SM performed anywhere in the spine; the use of PPT, PPT tested in an asymptomatic region and on the same day as the SM. Studies had to be experimental with at least one external or internal control group. Studies on only spinal motion or tenderness, other reviews, case reports, and less than 15 invited participants in each group were excluded. Evidence tables were constructed with information relevant to each research question and by spinal region. Results were reported in relation to statistical significance and were interpreted taking into account their quality.

Results

Only 12 articles of 946 were accepted. The quality of studies was generally good. In 8 sham controlled studies, a psychologically and physiologically “credible” sham was found in only 2 studies. A significant difference was noted between SM vs. Sham, and between SM and an inactive control. No significant difference in PPT was found between SM and another SM, mobilisation or some type of physical therapy. The cervical region more often obtained significant findings as compared to studies in the thoracic or lumbar regions.

Conclusion

SM has an effect regionally on pressure pain threshold in asymptomatic subjects. The clinical significance of this must be quantified. More knowledge is needed in relation to the comparison of different spinal regions and different types of interventions.