An overview of myofascial pain syndrome with a focus on trigger point injection

ABSTRACT

Myofascial pain syndrome (MPS) is a very common condition, with an estimated lifetime prevalence of 85% in the general population. MPS is commonly underdiagnosed or misdiagnosed due to the lack of standardized diagnostic criteria and the symptoms' overlap with those of other musculoskeletal pain conditions. The most notable and bothersome feature of MPS is the presence of myofascial trigger points (MTrPs), hypersensitive areas of muscle commonly characterized as knots, nodules, or bumps that cause strain and pain with and oftentimes without stimulation. A low-risk, low-cost procedure, trigger point injection (TPI) is the gold standard for MPS treatment, and NPs can perform the procedure in an outpatient practice setting. Through administration of TPIs and use of other treatment modalities, primary care NPs can significantly impact the quality of life for those patients affected by acute and chronic MPS. This article aims to educate primary care NPs on MPS diagnosis and provide an overview of treatment options, with a focus on TPI use and administration for MPS relief.

Effect of Local Anesthetic Versus Botulinum Toxin-A Injections for Myofascial Pain Disorders: A Systematic Review and Meta-Analysis

OBJECTIVE

Myofascial pain is a chronic pain disorder characterized by the presence of painful localized regions of stiff muscle and/or myofascial trigger points. Intramuscular myofascial trigger point injections are considered first-line treatments for myofascial pain. Common injectates include local anesthetics and botulinum toxin-A (BTX-A). The objective of this systematic review was to compare the effectiveness of local anesthetics and BTX-A on pain intensity in patients with myofascial pain.

METHODS

A comprehensive systematic search of 3 databases, EMBASE, CENTRAL, and Medline was conducted. The search was comprised of words to describe "myofascial pain" and "injections." We performed a meta-analysis comparing local anesthetic and BTX-A injections across these follow-up week periods: 0 (immediately following the injection), 1 to 2, 3 to 4, 5 to 6, 7 to 8, 9 to 10, 11 to 12, 16, 18, 24 weeks with local anesthetics and BTX-A as subgroups. We also performed subgroup analyses comparing the effectiveness of local anesthetic injections and BTX-A injections at various muscle locations and comparing the effectives of single versus multiple injection sessions.

RESULTS

In total, 33 studies were included. A qualitative analysis suggested that local anesthetics and BTX-A were inconsistently effective at mitigating pain across all follow-up periods. The meta-analyses revealed that local anesthetic injections were more effective than BTX-A at mitigating pain intensity. Multiple injection sessions of local anesthetics were more beneficial than a single session.

CONCLUSIONS

Additional studies are needed to determine sources of heterogeneity mediating the observed differences in effectiveness of local anesthetic and BTX-A injections among the studies. Additional replicative studies are also needed to delineate the relative efficacy and effectiveness of local anesthetic and BTX-A injection. The quantitative results of this study suggest that patients overall experience more pain relief with local anesthetic injections.

Classifying Whiplash Recovery Status Using the Neck Disability Index: Optimized Cutoff Points Derived From Receiver Operating Characteristic

OBJECTIVE

Researchers often use Neck Disability Index (NDI) scores to classify recovery status in whiplash patients. The purpose of this study was to investigate the optimal cutoff point score for the NDI as a mechanism for differentiating recovery from nonrecovery after whiplash.

METHODS

Subjects (N = 123) who had previously sustained whiplash injuries were recruited from 12 clinics. Subjects rated themselves as being recovered (36%) or nonrecovered (64%). This state variable was compared with their NDI score as test variable using the receiver operating characteristic statistic. The area under the receiver operating characteristic curve and optimized cutoff points were computed for the whole group and also dichotomized for sex and age.

RESULTS

The mean NDI score for the recovered group was 7.8. It was 27.1 for the nonrecovered group. The cutoff point that optimized sensitivity and specificity for the whole group was an NDI score of 15. For women, it was 19; for older persons, it was 21.

CONCLUSION

The optimal NDI score cutoff point for differentiating the recovery state after whiplash is 15. Misclassification errors are likely when using lower values.

Confirmatory Factor Analysis and Multiple Linear Regression of the Neck Disability Index: Assessment If Subscales Are Equally Relevant in Whiplash and Nonspecific Neck Pain

OBJECTIVE

Because of previously published recommendations to modify the Neck Disability Index (NDI), we evaluated the responsiveness and dimensionality of the NDI within a population of adult whiplash-injured subjects. The purpose of the present study was to evaluate the responsiveness and dimensionality of the NDI within a population of adult whiplash-injured subjects.

METHODS

Subjects who had sustained whiplash injuries of grade 2 or higher completed an NDI questionnaire. There were 123 subjects (55% female, of which 36% had recovered and 64% had chronic symptoms. NDI subscales were analyzed using confirmatory factor analysis, considering only the subscales and, secondly, using sex as an 11th variable. The subscales were also tested with multiple linear regression modeling using the total score as a target variable.

RESULTS

When considering only the 10 NDI subscales, only a single factor emerged, with an eigenvalue of 5.4, explaining 53.7% of the total variance. Strong correlation (> .55) (P < .0001) between all variables was found. Multiple linear regression modeling revealed high internal consistency with all coefficients reaching significance (P < .0001). The 4 NDI subscales exerting the greatest effect were, in decreasing order, Sleeping, Lifting, Headaches, and Pain Intensity.

CONCLUSION

A 2-factor model of the NDI is not justified based on our results, and in this population of whiplash subjects, the NDI was unidimensional, demonstrating high internal consistency and supporting the original validation study of Vernon and Mior.

WITHDRAWN: Botulinum toxin for subacute/chronic neck pain

Withdrawn due to non‐compliance with The Cochrane Collaboration’s Commercial Sponsorship Policy

The editorial group responsible for this previously published document have withdrawn it from publication.

WITHDRAWN: Medicinal and injection therapies for mechanical neck disorders

Withdrawn due to non‐compliance with The Cochrane Collaboration’s Commercial Sponsorship Policy

The editorial group responsible for this previously published document have withdrawn it from publication.

Physician-delivered injection therapies for mechanical neck disorders: a systematic review update (non-oral, non-intravenous pharmacological interventions for neck pain)

Background:

Controversy persists regarding medicinal injections for mechanical neck disorders (MNDs).

Objectives:

To determine the effectiveness of physician-delivered injections on pain, function/disability, quality of life, global perceived effect and patient satisfaction for adults with MNDs.

Search Methods:

We updated our previous searches of CENTRAL, MEDLINE and EMBASE from December 2006 through to March 2012.

Selection Criteria:

We included randomized controlled trials of adults with neck disorders treated by physician-delivered injection therapies.

Data Collection and Analysis:

Two authors independently selected articles, abstracted data and assessed methodological quality. When clinical heterogeneity was absent, we combined studies using random-effects models.

Results:

We included 12 trials (667 participants). No high or moderate quality studies were found with evidence of benefit over control. Moderate quality evidence suggests little or no difference in pain or function/disability between nerve block injection of steroid and bupivacaine vs bupivacaine alone at short, intermediate and long-term for chronic neck pain. We found limited very low quality evidence of an effect on pain with intramuscular lidocaine vs control for chronic myofascial neck pain. Two low quality studies showed an effect on pain with anaesthetic nerve block vs saline immediately post treatment and in the short-term. All other studies were of low or very low quality with no evidence of benefit over controls.

Authors' Conclusions:

Current evidence does not confirm the effectiveness of IM-lidocaine injection for chronic mechanical neck pain nor anaesthetic nerve block for cervicogenic headache. There is moderate evidence of no benefit for steroid blocks vs controls for mechanical neck pain.

Pharmacological Interventions Including Medical Injections for Neck Pain: An Overview as Part of the ICON Project

OBJECTIVES

To conduct an overview (review-of-reviews) on pharmacological interventions for neck pain.

SEARCH STRATEGY

Computerized databases and grey literature were searched from 2006 to 2012.

SELECTION CRITERIA

Systematic reviews of randomized controlled trials (RCT) in adults with acute to chronic neck pain reporting effects of pharmacological interventions including injections on pain, function/disability, global perceived effect, quality of life and patient satisfaction.

DATA COLLECTION & ANALYSIS

Two independent authors selected articles, assessed risk of bias and extracted data The GRADE tool was used to evaluate the body of evidence and an external panel provided critical review.

MAIN RESULTS

We found 26 reviews reporting on 47 RCTs. Most pharmacological interventions had low to very low quality methodologic evidence with three exceptions. For chronic neck pain, there was evidence of: a small immediate benefit for eperison hydrochloride (moderate GRADE, 1 trial, 157 participants);no short-term pain relieving benefit for botulinum toxin-A compared to saline (strong GRADE; 5 trial meta-analysis, 258 participants) nor for subacute/chronic whiplash (moderate GRADE; 4 trial meta-analysis, 183 participants) including reduced pain, disability or global perceived effect; andno long-term benefit for medial branch block of facet joints with steroids (moderate GRADE; 1 trial, 120 participants) over placebo to reduce pain or disability;

REVIEWERS' CONCLUSIONS

While in general there is a lack of evidence for most pharmacological interventions, current evidence is against botulinum toxin-A for chronic neck pain or subacute/chronic whiplash; against medial branch block with steroids for chronic facet joint pain; but in favour of the muscle relaxant eperison hydrochloride for chronic neck pain.

Muscle trigger points, pressure pain threshold, and cervical range of motion in patients with high level of disability related to acute whiplash injury

STUDY DESIGN

Cross sectional cohort study.

OBJECTIVE

To analyze the differences in the prevalence of trigger points (TrPs) between patients with acute whiplash-associated disorders (WADs) and healthy controls, and to determine if widespread pressure hypersensitivity and reduced cervical range of motion are related to the presence of TrPs in patients with acute WADs.

BACKGROUND

The relationship between active TrPs and central sensitization is not well understood in patients with acute WADs.

METHODS

Twenty individuals with a high level of disability related to acute WAD and 20 age- and sex-matched controls participated in the study. TrPs in the temporalis, masseter, upper trapezius, levator scapulae, sternocleidomastoid, suboccipital, and scalene muscles were examined. TrPs are defined as hypersensitive spots in a palpable taut band, producing a local twitch response and referred pain when palpated. Pressure pain threshold (PPT) was assessed bilaterally over the C5-6 zygapophyseal joints, second metacarpal, and tibialis anterior muscle. Active cervical range of motion, neck pain, and self-rated disability using the Neck Disability Index were also assessed.

RESULTS

The mean ± SD number of TrPs for the patients with acute WAD was 7.3 ± 2.8 (3.4 ± 2.7 were latent TrPs; 3.9 ± 2.5 were active TrPs). In comparison, healthy controls had 1.7 ± 2.2 latent and no active TrPs (P<0.01). In patients with acute WAD, the most prevalent sites for active TrPs were the levator scapulae and upper trapezius muscles. The number of active TrPs increased with higher neck pain intensity (P<0.001) and a higher number of days since the accident (P=.003). Patients had significantly lower PPTs in all tested locations and less active cervical range of motion than controls (P<.001). In the patient group, there were significant negative correlations between the number of active TrPs and PPT over the C5-C6 joints and cervical range of motion in flexion, extension, and rotation in both directions: the greater the number of active TrPs, the lower the bilateral PPT over the neck and the greater the cervical range of motion limitation.

CONCLUSIONS

The local and referred pain elicited from active TrPs reproduced neck and shoulder pain patterns in individuals with acute WADs with higher levels of disability. Patients with acute WADs exhibited widespread pressure hypersensitivity and reduced cervical mobility. The number of active TrPs was related to higher neck pain intensity, the number of days since the accident, higher pressure pain hypersensitivity over the cervical spine, and reduced active cervical range of motion.

Botulinum toxin for subacute/chronic neck pain

BACKGROUND

Neck disorders are common, disabling and costly. Botulinum toxin (BoNT) intramuscular injections are often used with the intention of treating neck pain.

OBJECTIVES

To systematically evaluate the literature on the treatment effectiveness of BoNT for neck pain, disability, global perceived effect and quality of life in adults with neck pain with or without associated cervicogenic headache, but excluding cervical radiculopathy and whiplash associated disorder.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE, AMED, Index to Chiropractic Literature, CINAHL, LILACS, and EMBASE from their origin to 20 September 2010.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials in which BoNT injections were used to treat subacute or chronic neck pain.

DATA COLLECTION AND ANALYSIS

A minimum of two review authors independently selected articles, abstracted data, and assessed risk of bias, using the Cochrane Back Review Group criteria. In the absence of clinical heterogeneity, we calculated standardized mean differences (SMD) and relative risks, and performed meta-analyses using a random-effects model. The quality of the evidence and the strength of recommendations were assigned an overall grade for each outcome.

MAIN RESULTS

We included nine trials (503 participants). Only BoNT type A (BoNT-A) was used in these studies.High quality evidence suggests there was little or no difference in pain between BoNT-A and saline injections at four weeks (five trials; 252 participants; SMD pooled -0.07 (95% confidence intervals (CI) -0.36 to 0.21)) and six months for chronic neck pain. Very low quality evidence indicated little or no difference in pain between BoNT-A combined with physiotherapeutic exercise and analgesics and saline injection with physiotherapeutic exercise and analgesics for patients with chronic neck pain at four weeks (two trials; 95 participants; SMD pooled 0.09 (95% CI -0.55 to 0.73)) and six months (one trial; 24 participants; SMD -0.56 (95% CI -1.39 to 0.27)). Very low quality evidence from one trial (32 participants) showed little or no difference between BoNT-A and placebo at four weeks (SMD 0.16 (95% CI -0.53 to 0.86)) and six months (SMD 0.00 (95% CI -0.69 to 0.69)) for chronic cervicogenic headache. Very low quality evidence from one trial (31 participants), showed a difference in global perceived effect favouring BoNT-A in chronic neck pain at four weeks (SMD -1.12 (95% CI: -1.89 to -0.36)).

AUTHORS' CONCLUSIONS

Current evidence fails to confirm either a clinically important or a statistically significant benefit of BoNT-A injection for chronic neck pain associated with or without associated cervicogenic headache. Likewise, there was no benefit seen for disability and quality of life at four week and six months.

Sample size calculation in physical medicine and rehabilitation: a systematic review of reporting, characteristics, and results in randomized controlled trials

OBJECTIVE

To assess systematically the reporting of sample size calculation in randomized controlled trials (RCTs) in 5 leading journals in the field of physical medicine and rehabilitation (PM&R).

DATA SOURCES

The data source was full reports of RCTs in 5 leading PM&R journals (Journal of Rehabilitation Medicine, Archives of Physical Medicine and Rehabilitation, American Journal of Physical Medicine and Rehabilitation, Clinical Rehabilitation, and Disability and Rehabilitation) between January and December of 1998 and 2008. Articles were identified in Medline.

STUDY SELECTION

A total of 111 articles met our inclusion criteria, which include RCTs of human studies in the 5 selected journals.

DATA EXTRACTION

Sample size calculation reporting and trial characteristics were collected for each trial by independent investigators.

DATA SYNTHESIS

In 2008, 57.3% of articles reported sample size calculation as compared with only 3.4% in 1998. The parameters that were commonly used were a power of 80% and alpha of 5%. Articles often failed to report effect size or effect estimates for sample size calculation. Studies reporting sample size calculation were more likely to describe the main outcome and to have a sample size greater than 50 subjects. The study outcome (positive vs negative) was not associated with the likelihood of sample size reporting. Trial characteristics of the 2 periods (1998 vs 2008) were similar except that in 1998 there were more negative studies compared with 2008.

CONCLUSIONS

Although sample size calculation reporting has improved dramatically in 10 years and is comparable with other fields in medicine, it is still not adequate given current publication guidelines.

A research synthesis of therapeutic interventions for whiplash-associated disorder: part 1 - overview and summary

Whiplash-associated disorder (WAD) represents a significant public health problem, resulting in a substantial socioeconomic burden throughout the industrialized world, wherever costs are documented. While many treatments have been advocated for patients with WAD, scientific evidence of their effectiveness is often lacking. A systematic review was conducted to evaluate the strength of evidence supporting various WAD therapies. Multiple databases (including Web of Science, EMBASE and PubMed) were searched to identify all studies published from January 1980 through March 2009 that evaluated the effectiveness of any clearly defined treatment for acute (less than two weeks), subacute (two to 12 weeks) or chronic (longer than 12 weeks) WAD. The present article, the first in a five-part series, provides an overview of the review methodology as well as a summary and discussion of the review's main findings. Eighty-three studies met the inclusion criteria, 40 of which were randomized controlled trials. The majority of studies (n=47) evaluated treatments initiated in the chronic stage of the disorder, while 23 evaluated treatments for acute WAD and 13 assessed therapies for subacute WAD. Exercise and mobilization programs for acute and chronic WAD had the strongest supporting evidence, although many questions remain regarding the relative effectiveness of various protocols. At present, there is insufficient evidence to support any treatment for subacute WAD. For patients with chronic WAD who do not respond to conventional treatments, it appears that radiofrequency neurotomy may be the most effective treatment option. The present review found a relatively weak but growing research base on which one could make recommendations for patients at any stage of the WAD continuum. Further research is needed to determine which treatments are most effective at reducing the disabling symptoms associated with WAD.

A research synthesis of therapeutic interventions for whiplash-associated disorder (WAD): part 5 - surgical and injection-based interventions for chronic WAD

Whiplash-associated disorder (WAD) represents a significant public health problem, resulting in substantial social and economic costs throughout the industrialized world. While many treatments have been advocated for patients with WAD, scientific support regarding their effectiveness is often lacking. A systematic review was conducted to evaluate the strength of evidence associated with various WAD therapies. Multiple databases (including Web of Science, EMBASE and PubMed) were searched to identify all studies published from January 1980 through March 2009 that evaluated the effectiveness of any well-defined treatment for acute (less than two weeks), subacute (two to 12 weeks) or chronic (more than 12 weeks) WAD. The present article, the fifth in a five-part series, evaluates the evidence for surgical and injection-based interventions initiated during the chronic phase of WAD. Twenty-five studies were identified that met the inclusion criteria, six of which were randomized controlled trials with 'good' overall methodological quality (median Physiotherapy Evidence Database score of 7.5). For the treatment of chronic WAD, there was moderate evidence supporting radiofrequency neurotomy as an effective treatment for whiplash-related pain, although relief is not permanent. Sterile water injections have been demonstrated to be superior to saline injections; however, it is not clear whether this treatment is actually beneficial. There was evidence supporting a wide range of other interventions (eg, carpal tunnel decompression) with each of these evaluated by a single nonrandomized controlled trial. There is contradictory evidence regarding the effectiveness of botulinum toxin injections, and cervical discectomy and fusion. The evidence is not yet strong enough to establish the effectiveness of any of these treatments; of all the invasive interventions for chronic WAD, radiofrequency neurotomy appears to be supported by the strongest evidence. Further research is required to determine the efficacy and the role of invasive interventions in the treatment of chronic WAD.

A research synthesis of therapeutic interventions for whiplash-associated disorder (WAD): part 3 - interventions for subacute WAD

Whiplash-associated disorder (WAD) represents a significant public health problem, resulting in substantial social and economic costs throughout the industrialized world. While many treatments have been advocated for patients with WAD, scientific evidence supporting their effectiveness is often lacking. A systematic review was conducted to evaluate the strength of evidence associated with various WAD therapies. Multiple databases (including Web of Science, EMBASE and PubMed) were searched to identify all studies published from January 1980 through March 2009 that evaluated the effectiveness of any clearly defined treatment for acute (less than two weeks), subacute (two to 12 weeks) or chronic (longer than 12 weeks) WAD. The present article, the third in a five-part series, evaluates the evidence for interventions initiated during the subacute phase of WAD. Thirteen studies that met the inclusion criteria were identified, six of which were randomized controlled trials with 'good' overall methodology (median Physiotherapy Evidence Database score of 6). Although some evidence was identified to support the use of interdisciplinary interventions and chiropractic manipulation, the evidence was not strong for any of the evaluated treatments. There is a clear need for further research to evaluate interventions aimed at treating patients with subacute WAD because there are currently no interventions satisfactorily supported by the research literature.

The role of botulinum toxin in management of pain: an evidence-based review

PURPOSE OF REVIEW

In the present review we discuss the role of botulinum neurotoxins (BoNTs) in the management of different pain conditions, with evidence-based data on the toxins' efficacy on pain and its mechanisms.

RECENT FINDINGS

Experimental in-vitro studies have reported promising results of a novel recombinant chimera of BoNT A and E that inhibits the calcitonin gene-related peptide exocytosis from brainstem sensory neurons. Animal studies in neuropathic pain rat models have reported an analgesic effect of BoNT A given after the neuropathic procedure and a bilateral antinociceptive effect to the unilateral noxious stimuli. There is a growing body of evidence that BoNTs are effective in myofascial pain syndrome, neuropathic pain, and joint pain. The pre-existing evidence that BoNTs are ineffective in migraine or other headache disorders has not yet been challenged. In other pain syndromes, studies published in the last review year have not contributed significantly in either demonstrating or invalidating the research that has so far proved inconclusive.

SUMMARY

The role of BoNTs in management of pain is not yet well established. Larger studies in neuropathic pain, joint pain, and myofascial pain syndrome are needed to fully ascertain the role for BoNT therapy in those areas.

Botulinum toxin intramuscular injections for neck pain: a systematic review and metaanalysis

OBJECTIVE

To assess the effect of intramuscular botulinum toxin type A (BoNT-A) injections on pain, function/disability, global perceived effect, and quality of life (QOL) in adults with neck pain (NP).

METHODS

We searched Central, Medline, and Embase databases up to June 2010. A minimum of 2 authors independently selected articles, abstracted data, and assessed risk of bias and clinical applicability. We estimated standard mean differences (SMD) with 95% CI, relative risks (RR), and performed metaanalyses (SMD(p)) using a random-effects model for nonheterogeneous data. The approach of the Grading of Recommendations Assessment, Development, and Evaluation working group summarizes the quality of evidence.

RESULTS

We selected 14 trials. High-quality evidence suggested BoNT-A was no better than saline at 4 weeks [4 trials/183 participants; SMD(p) -0.21 (95% CI -0.50 to 0.07)] and 6 months for chronic NP. Moderate-quality evidence showed a similar effect for subacute/chronic whiplash-associated disorder (WAD) on pain [4 trials/122 participants; SMD(p) -0.21 (95% CI -0.57 to 0.15)], disability, and QOL. Very low-quality evidence indicated BoNT-A combined with exercise and analgesics was not significant for chronic NP reduction at 4 weeks [3 trials/114 participants; SMD(p) -0.08 (95% CI -0.45 to 0.29)] but was at 6 months [2 trials/43 participants; SMD(p) -0.66 (95% CI -1.29 to -0.04)].

CONCLUSION

Current evidence does not confirm a clinically or statistically significant benefit of BoNT-A used alone on chronic NP in the short term or on subacute/chronic WAD pain, disability, and QOL. Larger trials, subgroups, and predictors of responses defined a priori (to facilitate selection of patients most likely to benefit) and factorial designs to explore BoNT as an adjunct treatment to physiotherapeutic exercise and analgesics are needed.

The efficacy of botulinum toxin type A in managing chronic musculoskeletal pain: a systematic review and meta analysis

BACKGROUND

Botulinum toxin type A (BoNTA) is a neurotoxin that acts by inhibiting the release of neurotransmitters acetylcholine at neuromuscular junctions, thus reducing muscular contractions. Recent evidence suggests that BoNTA can reduce nociceptive activities of sensory neurons in animal models by inhibiting release of certain neuropeptides. Despite the therapeutic benefit of BoNTA in alleviating painful muscle spasms, its efficacy in other musculoskeletal pain conditions is less clear.

OBJECTIVE

We aim to examine the efficacy of BoNTA in reducing chronic musculoskeletal pain.

METHODS

Studies for inclusion in our report were identified using MEDLINE, EMBASE, PUBMED, Cochrane Central Register of Controlled Trials, CINAHL, and reference lists of relevant articles. Studies were considered eligible for inclusion if they were randomized controlled trials (RCTs), evaluating the efficacy of BoNTA injections in pain reduction. All studies were assessed and data were abstracted independently by paired reviewers. The outcome measures were baseline and final pain scores as assessed by the patients. The internal validity of trials was assessed with the Jadad scale. Disagreements were resolved through discussions.

MAIN RESULTS

Twenty-one studies were included in the systematic review and 15 of them were included in the final meta-analysis. There was a total of 706 patients in the meta-analysis, represented from trials of plantar fasciitis (n = 1), tennis elbow (n = 2), shoulder pain (n = 1), whiplash (n = 3), and myofascial pain (n = 8). Overall, there was a small to moderate pain reduction among BoNTA patients when compared to control (SMD = -0.27, 95% CI: -0.44 to -0.11). When the results were analyzed in subgroups, only tennis elbow (SMD = -0.44, 95% CI: -0.86 to -0.01) and plantar fasciitis (SMD = -1.04, 95% CI: -1.68 to -0.40) demonstrated significant pain relief. Although not in the meta-analysis, one back pain study also demonstrated positive results for BoNTA. Lastly, BoNTA was effective when used at ≥ 25 units per anatomical site or after a period ≥ 5 weeks.

CONCLUSION

In our meta-analysis, BoNTA had a small to moderate analgesic effect in chronic musculoskeletal pain conditions. It was particularly effective in plantar fasciitis, tennis elbow, and back pain, but not in whiplash or shoulder pain patients. However, more evidence is required before definitive conclusions can be drawn. On the other hand, there is convincing evidence that BoNTA lacks strong analgesic effects in patients with myofascial pain syndrome. A general dose-dependent and temporal response with BoNTA injections was also observed.