BACKGROUND: This is an updated version of the original Cochrane review published in Issue 4, 2012. Myofascial pain syndrome (MPS) is a regional muscular pain syndrome characterised by the presence of trigger points, which are painful points in one or more muscles. The pain can be felt at the site where the trigger point is located or it can be felt away from that place when the muscle is pressed (referred pain). Botulinum toxin is a protein produced by the bacterium Clostridium botulinum and is a potent neurotoxin that eventually inhibits muscle contractions. It is capable of selectively weakening painful muscles and interrupting the pain cycle.
OBJECTIVES: To assess the effectiveness and safety of botulinum toxin A (BTXA) in the treatment of myofascial pain syndrome (MPS), excluding MPS in neck and head muscles.
SEARCH METHODS: This is an updated version of the original Cochrane review published in Issue 4, 2012. The search strategy for the update was the same as in the original review and we searched CENTRAL in The Cochrane Library (2013, Issue 11 of 12), MEDLINE (Ovid) (2012 to 29 November 2013) and EMBASE (Ovid) (2012 to 27 November 2013). The search strategy was composed of terms for myofascial pain and botulinum toxin. For the original review, we also searched the Cochrane Pain, Palliative and Supportive Care (PaPaS) Review Group Specialised Register until December 2011, PubMed (from 1966 to 2011) and LILACS (from 1982 to 2011). There was no language restriction.
SELECTION CRITERIA: We included randomised controlled trials (RCTs) involving botulinum toxin for treating participants with MPS. We excluded studies with MPS of the neck and head from this review as they have already been assessed in existing systematic reviews. We considered a diagnosis of MPS to be based on the identification of trigger points in the taut band through palpation of sensitive nodules, local twitch response and specific patterns of referred pain associated with each trigger point.
DATA COLLECTION AND ANALYSIS: Two review authors independently screened identified studies, extracted data, assessed trial quality and analysed results using the Cochrane PaPaS Review Group criteria.
MAIN RESULTS: Four studies with a total of 233 participants, comparing BTXA with placebo, met the inclusion criteria. In one study with 145 participants, significant improvement rates of pain intensity scores and duration of daily pain were demonstrated when comparing BTXA with placebo. The three other studies showed that there was no statistically significant difference between BTXA and placebo in pain intensity.
AUTHORS' CONCLUSIONS: Since the first publication of this review, no new studies were found. There is inconclusive evidence to support the use of botulinum toxin in the treatment of MPS based on data from four studies with a total of 233 participants, which we considered were of sufficient quality to be included in this review. Meta-analyses were not possible due to the heterogeneity between studies. We suggest that in future studies the same methodology to assess pain, a standardised dose of treatment, follow-up of at least four months (to observe the maximum and minimum curve of the drug effect) and appropriate data presentation should be used. More high-quality RCTs of botulinum toxin for treating MPS need to be conducted before firm conclusions on its effectiveness and safety can be drawn.
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.
This is an updated version of the original Cochrane review published in Issue 4, 2012. Myofascial pain syndrome (MPS) is a regional muscular pain syndrome characterised by the presence of trigger points, which are painful points in one or more muscles. The pain can be felt at the site where the trigger point is located or it can be felt away from that place when the muscle is pressed (referred pain). Botulinum toxin is a protein produced by the bacterium Clostridium botulinum and is a potent neurotoxin that eventually inhibits muscle contractions. It is capable of selectively weakening painful muscles and interrupting the pain cycle.
OBJECTIVES:
To assess the effectiveness and safety of botulinum toxin A (BTXA) in the treatment of myofascial pain syndrome (MPS), excluding MPS in neck and head muscles.
SEARCH METHODS:
This is an updated version of the original Cochrane review published in Issue 4, 2012. The search strategy for the update was the same as in the original review and we searched CENTRAL in The Cochrane Library (2013, Issue 11 of 12), MEDLINE (Ovid) (2012 to 29 November 2013) and EMBASE (Ovid) (2012 to 27 November 2013). The search strategy was composed of terms for myofascial pain and botulinum toxin. For the original review, we also searched the Cochrane Pain, Palliative and Supportive Care (PaPaS) Review Group Specialised Register until December 2011, PubMed (from 1966 to 2011) and LILACS (from 1982 to 2011). There was no language restriction.
SELECTION CRITERIA:
We included randomised controlled trials (RCTs) involving botulinum toxin for treating participants with MPS. We excluded studies with MPS of the neck and head from this review as they have already been assessed in existing systematic reviews. We considered a diagnosis of MPS to be based on the identification of trigger points in the taut band through palpation of sensitive nodules, local twitch response and specific patterns of referred pain associated with each trigger point.
DATA COLLECTION AND ANALYSIS:
Two review authors independently screened identified studies, extracted data, assessed trial quality and analysed results using the Cochrane PaPaS Review Group criteria.
MAIN RESULTS:
Four studies with a total of 233 participants, comparing BTXA with placebo, met the inclusion criteria. In one study with 145 participants, significant improvement rates of pain intensity scores and duration of daily pain were demonstrated when comparing BTXA with placebo. The three other studies showed that there was no statistically significant difference between BTXA and placebo in pain intensity.
AUTHORS' CONCLUSIONS:
Since the first publication of this review, no new studies were found. There is inconclusive evidence to support the use of botulinum toxin in the treatment of MPS based on data from four studies with a total of 233 participants, which we considered were of sufficient quality to be included in this review. Meta-analyses were not possible due to the heterogeneity between studies. We suggest that in future studies the same methodology to assess pain, a standardised dose of treatment, follow-up of at least four months (to observe the maximum and minimum curve of the drug effect) and appropriate data presentation should be used. More high-quality RCTs of botulinum toxin for treating MPS need to be conducted before firm conclusions on its effectiveness and safety can be drawn.
