What is the effect of spinal manipulation on the pressure pain threshold in young, asymptomatic subjects? A randomized placebo-controlled trial, with a cross-over design

Abstract

Background: Spinal manipulation (SM) has been shown to have an effect on the pressure pain threshold (PPT) in asymptomatic subjects, but SM has never been compared in studies on this topic to a validated sham procedure. We investigated the effect of SM on the PPT when measured i) in the area of intervention and ii) in an area remote from the intervention. In addition, we measured the size and duration of the effect. Method: In a randomized cross-over trial, 50 asymptomatic chiropractic students had their PPT measured at baseline, immediately after and every 12 min after intervention, over a period of 45 min, comparing values after SM and a previously validated sham. The trial was conducted during two sessions, separated by 48 h. PPT was measured both regionally and remotely from the 'treated' thoracic segment. Blinding of study subjects was tested with a post-intervention questionnaire. We used mixed linear regression with the baseline value and time as covariates. If a significant difference were found between groups, then an effect size would be calculated using Cohen's d or Hedge's h coefficient. Statistical significance was set at p < 0.05. Results: Study subjects had been successfully blinded. No statistically significant differences were found between SM and sham estimates, at any time or anatomical location. Conclusion: When compared to a valid sham procedure and with successfully blinded subjects, there is no regional or remote effect of spinal manipulation of the thoracic spine on the pressure pain threshold in a young pain-free population.

The effect of a single spinal manipulation on cardiovascular autonomic activity and the relationship to pressure pain threshold: a randomized, cross-over, sham-controlled trial

“…Our results do not suggest that a single spinal HVLA technique may specifically activate the descending pain inhibitory system projecting from the periaqueductal gray matter since we found (i) no effect on local and distal PPT [31] and (ii) no effect on cardiovascular autonomic outcomes. In addition, we found (iii) no relationship between PPT and autonomic responses after the HVLA technique.…”

“…Please note that another report deals with the assessment of the specific effect of the spinal manipulation on pressure pain threshold [31].…”

Neurophysiological mechanisms of chiropractic spinal manipulation for spine pain

“…In spite of this consensus on segmental effects of SM, it should be noted that two recent studies using a single‐blinded placebo‐controlled design obtained conflicting results (Aspinall et al., 2019; Honore et al., 2020). The quality of studies on segmental hypoalgesia resulting from SM is variable.…”

“…Nevertheless, a question that remains unanswered is whether these placebo interventions lack any therapeutic effects (Chaibi et al., 2015; Vernon et al., 2012). Indeed, these placebo interventions allowed successful blinding, but reported no significant group difference (Aspinall, Jacques, et al., 2019; Honore et al., 2020). This was interpreted as a lack of therapeutic effect of SMT, but it could be argued that the placebo intervention may not be inert and may have masked therapeutic effects.…”

Who are the chiropractic students favouring a limitless scope of practice? Exploring the relationship with personality, magical thinking, and academic achievement

“…However, a recent systematic review on whether SMT can be used to prevent or treat non-MSK disorders has shown that SMT appears to be useful but only in methodologically weak studies, whereas, in the properly conducted studies, SMT did not come out better than sham or no treatment, regardless the condition that was treated [ 4 ]. Two recent systematic reviews did not support the concept that SMT would be beneficial on the autonomic nervous system [ 5 , 6 ], neither did a more recent randomized control trial with a successful sham [ 7 ]. As for the therapeutically beneficial effect of SMT on the brain, a recent systematic review of RCTs on the subject failed to reveal any positive evidence [ 8 ].…”