Immediate effects on electromyographic activity and pressure pain thresholds after a cervical manipulation in mechanical neck pain: a randomized controlled trial

Effect of spinal manipulation thrust duration on trunk mechanical activation thresholds of nociceptive-specific lateral thalamic neurons

OBJECTIVE

The objective of this preliminary study was to determine if high-velocity, low-amplitude spinal manipulation (HVLA-SM) thrust duration alters mechanical trunk activation thresholds of nociceptive-specific (NS) lateral thalamic neurons.

METHODS

Extracellular recordings were obtained from 18 NS neurons located in 2 lateral thalamic nuclei (ventrolateral [n = 12] and posterior [n = 6]) in normal anesthetized Wistar rats. Response thresholds to electronic von Frey anesthesiometer (rigid tip) mechanical trunk stimuli applied in 3 lumbar directions (dorsal-ventral, 45° caudal, and 45° cranial) were determined before and immediately after the delivery of 3 HVLA-SM thrust durations (time control 0, 100, and 400 milliseconds). Mean changes in mechanical trunk activation thresholds were compared using a mixed model analysis of variance.

RESULTS

High-velocity, low-amplitude spinal manipulation duration did not significantly alter NS lateral thalamic neurons' mechanical trunk responses to any of the 3 directions tested with the anesthesiometer.

CONCLUSIONS

This study is the first to examine the effect of HVLA-SM thrust duration on NS lateral thalamic mechanical response thresholds. High-velocity, low-amplitude spinal manipulation thrust duration did not affect mechanical trunk thresholds.

Scapular kinematics pre- and post-thoracic thrust manipulation in individuals with and without shoulder impingement symptoms: a randomized controlled study

STUDY DESIGN

Randomized controlled trial with immediate follow-up.

OBJECTIVES

To evaluate the immediate effects of a low-amplitude, high-velocity thrust thoracic spine manipulation (TSM) on pain and scapular kinematics during elevation and lowering of the arm in individuals with shoulder impingement syndrome (SIS). The secondary objective was to evaluate the immediate effects of TSM on scapular kinematics during elevation and lowering of the arm in individuals without symptoms.

BACKGROUND

Considering the regional interdependence among the shoulder and the thoracic and cervical spines, TSM may improve pain and function in individuals with SIS. Comparing individuals with SIS to those without shoulder pathology may provide information on the effects of TSM specifically in those with SIS.

METHODS

Fifty subjects (mean ± SD age, 31.8 ± 10.9 years) with SIS and 47 subjects (age, 25.8 ± 5.0 years) asymptomatic for shoulder dysfunction were randomly assigned to 1 of 2 interventions: TSM or a sham intervention. Scapular kinematics were analyzed during elevation and lowering of the arm in the sagittal plane, and a numeric pain rating scale was used to assess shoulder pain during arm movement at preintervention and postintervention.

RESULTS

For those in the SIS group, shoulder pain was reduced immediately after TSM and the sham intervention (mean ± SD preintervention, 2.9 ± 2.5; postintervention, 2.3 ± 2.5; P<.01; moderate effect size [Cohen d = 0.2]). Scapular internal rotation increased 0.5° ± 0.02° (P = .04; small effect size [Cohen d<0.1]) during elevation of the arm after TSM and sham intervention in the SIS group only. Subjects with and without SIS who received TSM and asymptomatic subjects who received the sham intervention had a significant increase (1.6° ± 2.7°) in scapular upward rotation postintervention (P<.05; small effect size [Cohen d<0.2]), which was not considered clinically significant. Scapular anterior tilt increased 1.0° ± 4.8° during elevation and lowering of the arm postmanipulation (P<.05; small effect size [Cohen d<0.2]) in the asymptomatic subjects who received TSM.

CONCLUSION

Shoulder pain in individuals with SIS immediately decreased after a TSM. The observed changes in scapular kinematics following TSM were not considered clinically important.

LEVEL OF EVIDENCE

Therapy, level 4. J Orthop Sports Phys Ther 2014;44(7):475-487. Epub 22 May 2014. doi:10.2519/jospt.2014.4760.

Spinal manipulative therapy-specific changes in pain sensitivity in individuals with low back pain (NCT01168999)

Spinal manipulative therapy (SMT) is effective for some individuals experiencing low back pain; however, the mechanisms are not established regarding the role of placebo. SMT is associated with changes in pain sensitivity, suggesting related altered central nervous system response or processing of afferent nociceptive input. Placebo is also associated with changes in pain sensitivity, and the efficacy of SMT for changes in pain sensitivity beyond placebo has not been adequately considered. We randomly assigned 110 participants with low back pain to receive SMT, placebo SMT, placebo SMT with the instructional set "The manual therapy technique you will receive has been shown to significantly reduce low back pain in some people," or no intervention. Participants receiving the SMT and placebo SMT received their assigned intervention 6 times over 2 weeks. Pain sensitivity was assessed prior to and immediately following the assigned intervention during the first session. Clinical outcomes were assessed at baseline and following 2 weeks of participation in the study. Immediate attenuation of suprathreshold heat response was greatest following SMT (P = .05, partial η(2) = .07). Group-dependent differences were not observed for changes in pain intensity and disability at 2 weeks. Participant satisfaction was greatest following the enhanced placebo SMT. This study was registered at www.clinicaltrials.gov under the identifier NCT01168999.

PERSPECTIVE

The results of this study indicate attenuation of pain sensitivity is greater in response to SMT than the expectation of receiving an SMT. These findings suggest a potential mechanism of SMT related to lessening of central sensitization and may indicate a preclinical effect beyond the expectations of receiving SMT.

Immediate effects of region-specific and non-region-specific spinal manipulative therapy in patients with chronic low back pain: a randomized controlled trial

BACKGROUND

Manual therapists typically advocate the need for a detailed clinical examination to decide which vertebral level should be manipulated in patients with low back pain. However, it is unclear whether spinal manipulation needs to be specific to a vertebral level.

OBJECTIVE

The purpose of this study was to analyze the immediate effects of a single, region-specific spinal manipulation defined during the clinical examination versus a single non-region-specific spinal manipulation (applied on an upper thoracic vertebra) in patients with chronic nonspecific low back pain for the outcome measures of pain intensity and pressure pain threshold at the time of the assessment.

DESIGN

This was a 2-arm, prospectively registered, randomized controlled trial with a blinded assessor.

SETTING

The study was conducted in an outpatient physical therapy clinic in Brazil.

PATIENTS

The study participants were 148 patients with chronic nonspecific low back pain (with pain duration of at least 12 weeks).

RANDOMIZATION

The randomization schedule was generated by an independent statistician and was concealed by using consecutively numbered, sealed, opaque envelopes.

INTERVENTIONS

A single high-velocity manipulation was administered to the upper thoracic region of the participants allocated to the non-region-specific manipulation group and to the painful lumbar levels of the participants allocated to the region-specific manipulation group.

MEASUREMENTS

Pain intensity was measured by a 0 to 10 numeric pain rating scale. Pressure pain threshold was measured using a pressure algometer.

LIMITATIONS

It was not possible to blind the therapist and participants.

RESULTS

A total of 148 patients participated in the study (74 in each group). There was no loss to follow-up. Both groups improved in terms of immediate decrease of pain intensity; however, no between-group differences were observed. The between-group difference for pain intensity and pressure pain threshold were 0.50 points (95% confidence interval=-0.10 to 1.10) and -1.78 points (95% confidence interval=-6.40 to 2.82), respectively. No adverse reactions were observed.

CONCLUSION

The immediate changes in pain intensity and pressure pain threshold after a single high-velocity manipulation do not differ by region-specific versus non-region-specific manipulation techniques in patients with chronic low back pain.

The effect of spinal manipulative therapy on experimentally induced pain: a systematic literature review

BACKGROUND

Although there is evidence that spinal manipulative therapy (SMT) can reduce pain, the mechanisms involved are not well established. There is a need to review the scientific literature to establish the evidence-base for the reduction of pain following SMT.

OBJECTIVES

To determine if SMT can reduce experimentally induced pain, and if so, if the effect is i) only at the level of the treated spinal segment, ii) broader but in the same general region as SMT is performed, or iii) systemic.

DESIGN

A systematic critical literature review.

METHODS

A systematic search was performed for experimental studies on healthy volunteers and people without chronic syndromes, in which the immediate effect of SMT was tested. Articles selected were reviewed blindly by two authors. A summary quality score was calculated to indicate level of manuscript quality. Outcome was considered positive if the pain-reducing effect was statistically significant. Separate evidence tables were constructed with information relevant to each research question. Results were interpreted taking into account their manuscript quality.

RESULTS

Twenty-two articles were included, describing 43 experiments, primarily on pain produced by pressure (n = 27) or temperature (n = 9). Their quality was generally moderate. A hypoalgesic effect was shown in 19/27 experiments on pressure pain, produced by pressure in 3/9 on pain produced by temperature and in 6/7 tests on pain induced by other measures. Second pain provoked by temperature seems to respond to SMT but not first pain. Most studies revealed a local or regional hypoalgesic effect whereas a systematic effect was unclear. Manipulation of a "restricted motion segment" ("manipulable lesion") seemed not to be essential to analgesia. In relation to outcome, there was no discernible difference between studies with higher vs. lower quality scores.

CONCLUSIONS

These results indicate that SMT has a direct local/regional hypoalgesic effect on experimental pain for some types of stimuli. Further research is needed to determine i) if there is also a systemic effect, ii) the exact mechanisms by which SMT attenuates pain, and iii) whether this response is clinically significant.

Assessment of the upper trapezius muscle temperature in women with and without neck pain

OBJECTIVE

The purpose of the study was to analyze the upper trapezius muscle temperature using thermography in women with and without neck pain.

METHODS

Thirty-six female university students were classified through the Neck Disability Index (NDI) into 2 groups: the neck pain group comprised 18 volunteers diagnosed with mild disability, and the control group, 18 healthy volunteers. All subjects were submitted to evaluation by thermography, which registered the skin surface temperature of the upper bilateral trapezius muscle. Student t test and Mann-Whitney U test were used for the comparison between the groups, and the Spearman correlation coefficient was used for the appropriate correlations between the NDI score and the temperature values. A significance level of 5% was set.

RESULTS

No significant difference was found between the groups regarding the temperature values of the upper left (P = .565) and right (P = .917) trapezius muscles, as well as in comparisons of temperature asymmetry (P = .542). In addition, no significant association was found between the study variables (P > .05).

CONCLUSION

Women with neck pain, diagnosed with mild disability by NDI, did not present with reduction or asymmetry of upper trapezius muscle temperature when compared with a group without neck pain.

Changes in pain sensitivity following spinal manipulation: a systematic review and meta-analysis

Spinal manipulation (SMT) is commonly used for treating individuals experiencing musculoskeletal pain. The mechanisms of SMT remain unclear; however, pain sensitivity testing may provide insight into these mechanisms. The purpose of this systematic review is to examine the literature on the hypoalgesic effects of SMT on pain sensitivity measures and to quantify these effects using meta-analysis. We performed a systematic search of articles using CINAHL, MEDLINE, PsycINFO, and SPORTDiscus from each databases' inception until May 2011. We examined methodological quality of each study and generated pooled effect size estimates using meta-analysis software. Of 997 articles identified, 20 met inclusion criteria for this review. Pain sensitivity testing used in these studies included chemical, electrical, mechanical, and thermal stimuli applied to various anatomical locations. Meta-analysis was appropriate for studies examining the immediate effect of SMT on mechanical pressure pain threshold (PPT). SMT demonstrated a favorable effect over other interventions on increasing PPT. Subgroup analysis showed a significant effect of SMT on increasing PPT at the remote sites of stimulus application supporting a potential central nervous system mechanism. Future studies of SMT related hypoalgesia should include multiple experimental stimuli and test at multiple anatomical sites.

Randomized Controlled Pilot Study: Pain Intensity and Pressure Pain Thresholds in Patients with Neck and Low Back Pain Before and After Traditional East Asian "Gua Sha" Therapy

Gua Sha is a traditional East Asian healing technique where the body surface is "press-stroked" with a smooth-edged instrument to raise therapeutic petechiae that last 2–5 days. The technique is traditionally used in the treatment of both acute and chronic neck and back pain. This study aimed to measure the effects of Gua Sha therapy on the pain ratings and pressure pain thresholds of patients with chronic neck pain (CNP) and chronic low back pain (CLBP). A total of 40 patients with either CNP or CLBP (mean age 49.23 ± 10.96 years) were randomized to either a treatment group (TG) or a waiting list control group (WLC). At baseline assessment (T1), all patients rated their pain on a 10 cm visual analog scale (VAS). Patients' pressure pain thresholds (PPT) at a site of maximal pain (pain-maximum) and an adjacent (pain-adjacent) site were also established. The treatment group then received a single Gua Sha treatment. Post-intervention measurements were taken for both groups at T2, seven days after baseline assessment (T1), using the same VAS and PPT measurements in precisely the same locations as at T1. Final analysis were conducted with 21 patients with CNP and 18 patients with CLBP. The study groups were equally distributed with regard to randomization. Patients in both the CNP and the CLBP treatment groups reported pain reduction (p < 0.05) and improved health status from their one Gua Sha treatment, as compared to the waiting list group. Pain sensitivity improved in the TG in CNP, but not in CLBP patients, possibly due to higher pressure sensitivity in the neck area. No adverse events were reported. These results suggest that Gua Sha may be an effective treatment for patients with chronic neck and low back pain. Further study of Gua Sha is warranted.