Acupuncture for myofascial pain

  • Protocol
  • Intervention



This is the protocol for a review and there is no abstract. The objectives are as follows:

This systematic review aims to assess whether acupuncture is superior to placebo, sham acupuncture, chemical drugs, or other complementary therapies in the treatment of MP. In addition, we also plan to compare the effect difference between traditional acupuncture and western medical acupuncture.


Description of the condition

Myofascial pain (MP) is a form of muscle pain arising from myofascial trigger points (MTrPs). MTrPs are hyperirritable points within muscle taut bands that are painful to palpation, reproduce the patient's symptoms, and cause referred pain (Borg-Stein 2002). Patients may experience regional pain, and may also suffer from an inability to work, mood changes, and reduced quality of life (Borg-Stein 2002). In some cases, the discomfort usually resolves in a few weeks without any medical intervention. When pain persists or worsens, it is referred to as a myofascial pain syndrome (Bennett 2007; Borg-Stein 2002).

MP is a common disorder mainly caused by acute muscle injury, overuse or repetitive strain (Bennett 2007). The prevalence varies from 30% to 93% in clinics of different specialities and pain management centres (Cummings 2007; Fishbain 1986; Fricton 1985; Han 1997; Skootsky 1989).

The precise pathophysiological basis of MP is complex and still unclear. Currently-available evidence suggest that abnormal neurophysiology and a perturbed biochemical milieu are relevant to MTrPs (Bennett 2007). An important finding in the pathophysiology of MP is a pathologic increase in release of acetylcholine by the nerve terminal of an abnormal motor endplate (Mense 2003; Simons 2002). Increased release of acetylcholine can result in sustained depolarisation of the postjunctional membrane of the muscle fibre and produce sustained sarcomere shortening and contracture. The abnormality may greatly increase local energy consumption and reduce local circulation that produces local ischemia and hypoxia. Mechanical, chemical, or other noxious stimuli or injury may mediate the abnormal release of acetylcholine (Liley 1956). Compared to normal muscle, the active trigger points have an acidic milieu and elevated levels of several biologically relevant molecules such as tumour necrosis factor-alpha, interleukin-1b, calcitonin-gene-related polypeptide, substance P, bradykinin, serotonin and norepinephrine (Shah 2005). These active factors can also stimulate the local autonomic nervous system fibres to release more acetylcholine, completing a "positive feedback loop" (Mense 2001; Simons 1999).

Description of the intervention

Many pharmacologic and nonpharmacologic treatments are used in the management of MP. Drugs such as analgesics (e.g. tramadol), non-steroidal anti-inflammatory drugs, tricyclic antidepressants (e.g. amitriptyline), alpha-2 adrenergic agonists (such as tizanidine), and anticonvulsant drugs. Recently, botulinum toxin has also been used for the treatment of MP (Bennett 2007; Borg-Stein 2002; Borg-Stein 2006; Fleckenstein 2010; Leite 2009; Soares 2012). However, the effectiveness of these drugs and treatments can often be unsatisfactory and the adverse effect of synthetic drugs is common. As a consequence, non-pharmacologic therapies, including acupuncture, dry needling, local injection, low-power laser, muscle-stretching technique and massage, are often used as alternative complementary therapies (Borg-Stein 2002; Borg-Stein 2006; Renan-Ordine 2011; Sun 2010; Tough 2009).

Acupuncture originated in China, and has become popular both in eastern and western countries. Acupuncture is a traditional remedy involving the insertion of acupuncture needles into specific sites (acupuncture points) located in the body for treating a variety of symptoms and conditions. There are several types of needling therapies evolved for traditional Chinese acupuncture, such as western medical acupuncture, dry needling, electro-acupuncture, laser acupuncture and acupoint injection. Western medical acupuncture can not adhere to concepts of Traditional Chinese Medicine but according to current knowledge of anatomy, physiology and pathology (Filshie 1999; White 2009).

How the intervention might work

The mechanism of acupuncture analgesia remains not completely understood. Nevertheless, the neuroendocrine mechanisms have been gradually revealed since the 1970s (Sims 1997; Staud 2007; Zhao 2008). Acupuncture stimulations in skin and muscle deliver signals to the spinal cord and lead to the activation of the spinal cord, midbrain and hypothalamus-pituitary gland, which cause the release of neuroendocrine factors such as endorphin, enkephalin, serotonin, and dopamine in the plasma and brain tissue (Peng 1978; Plotnikoff 1985; Tee 2007). It has been determined that these neuroendocrine factors mediate acupuncture analgesia and have an effect on psychological adjustment (Bennett 2007; Cabýigky 2006; Han 1997; Kiser 1983; Mayer 1977; Mendelson 1977; Skootsky 1989). Furthermore, a remarkably close association has been found between acupuncture points and trigger points, with 71% of trigger points sharing location and pain distribution patterns with acupuncture points (Hong 2000; Melzack 1977). Acupuncture may break the "positive feedback loop" of MP by modifying the release of neurological and chemical factors. Acupuncture, therefore may have potential benefits for the treatment of MP.

Why it is important to do this review

No "gold standard" of management has been suggested for MP until now. A large number of clinical trials have now been done to test the effectiveness of acupuncture for MP. However, the clinical trials usually generate contradictory results; and the benefit of acupuncture remains controversial. Therefore, a systematic review is needed to evaluate the evidence of acupuncture for MP.


This systematic review aims to assess whether acupuncture is superior to placebo, sham acupuncture, chemical drugs, or other complementary therapies in the treatment of MP. In addition, we also plan to compare the effect difference between traditional acupuncture and western medical acupuncture.


Criteria for considering studies for this review

Types of studies

We will include randomised controlled trials (RCTs) with double-blinding. For randomised cross-over studies, we will only analyse the data of the first round. we will include studies with the treatment durations of 2 weeks and up to 16 weeks.

Types of participants

We will include participants, aged 18 years and over, with a clinical diagnosis of MP, regardless of genders, race, profession, social and economic status. The diagnosis of MP depends on the identification of active trigger points and appropriate patient feedback. An active MTrP is usually associated with a reproducible pain and restricted range of movement. Although there was no gold-standard for the diagnosis of MP, the most recent modification of diagnostic criteria was the combination of "tender spot/nodule in a taut band", "patient pain recognition" and "painful limitation to range of movement" (Simons 1999; Tough 2007). "Local twitch response" and "predicted pain referral pattern" are not essential for the diagnosis (Simons 1999).

MP may mimic a large number of other disorders (Flax 1995). In order to control confounding factors, RCTs that included participants with pain caused by specific pathological entities such as infection, metastatic diseases, neoplasm, osteoarthritis, rheumatoid arthritis, radiculopathy, tenosynovitis or fractures will be excluded.

Types of interventions

The intervention in the experimental group should be traditional manual acupuncture (inserting acupuncture needles in meridian points), and western medical acupuncture. Inserting acupuncture needles in ah-shi points (painful points) is eligible. Other stimulation methods in acupuncture points, such as electrical current, injection, low-power laser irradiation, finger pressure will be excluded.

The control interventions will be sham acupuncture, conventional drugs or other therapies. Other adjunctive treatments (e.g. drug, physiotherapy, exercise and cognitive behavioural therapy) should be the same in the experimental and control groups. Studies with different types of comparison will be analysed separately in subgroups.

Types of outcome measures

Primary outcomes

Intensity, frequency and duration of pain recorded using validated visual analogue scales or categorical scales.

Secondary outcomes
  1. Range of motion

  2. Function or quality of life

  3. Adverse events

Outcomes measured after short time (2 to 6 weeks) or long-term (7 to 16 weeks) will be analysed. According to treatment durations, we plan to carry out a sensitivity analyses.

Search methods for identification of studies

Electronic searches

To identify eligible trials we will search:

  • the Cochrane Central Register of Controlled Trials (CENTRAL);

  • PubMed (January 1966 to present date);

  • EMBASE (January 1980 to present date);

  • Chinese Journal Full-Text Database (January 1980 to present date);

  • Chinese Science and Technology Journal Database (January 1989 to present date);

  • SINOMED (January 1980 to present date).

The search strategy will be composed of terms and their synonyms for MP and acupuncture. Subject headings and free text words will be used. There will be no language restrictions. The strategy to be used for PubMed can be seen in Appendix 1. We will adapt this search strategy for each database as necessary for the full review. 

Searching other resources

The bibliographies of review articles, relevant articles, books on acupuncture and MP will be checked manually to identify any additional studies. Information of registered clinical trials will also be searched through (, ( and the WHO International Clinical Trials Registry Platform Search Portal ( We will contact specialists in the field and authors of the included studies for unpublished data.

Data collection and analysis

Two review authors (XL and JZ) will independently screen studies, extract the data and assess study quality. We will consult another review author (EE) if there is any disagreement or need for quality assurance of the process. The Cochrane Collaboration's statistical software, Review Manager 2012, will be used for data analysis.

Selection of studies

Study selection will be independently performed by two review authors (XL and JZ). Titles and abstracts of the located literature will be preliminarily examined to identify the potential to include each study. The full-text articles will then be obtained and assessed according to the selection criteria outlined above. Disagreements will be resolved by discussion and consultation with another review author. The authors of original studies will be contacted to obtain more information when needed. We will aim to include a flowchart in the review which will document the selection process as recommended by the PRISMA statement (Liberati 2009).

Data extraction and management

Two review authors (XL and JZ) will independently extract data from each included study and enter into a piloted electronic spread sheet. Discrepancies remaining in data extraction will be resolved by discussion between the two review authors and where necessary another review author will adjudicate. We will extract the following information: characteristics of the study (such as publishing date, study design and setting, methods of randomisation and blinding); patients (inclusion/exclusion criteria, duration of symptoms and criteria used for diagnosis); interventions (therapists' qualification, acupuncture points and manipulation, treatment period and frequency, and treatment methods in control groups); outcomes (types of outcome measures, original data and adverse events). For dichotomous outcomes, the number of responders and the total number of participants for each study arm will be extracted. For continuous outcomes the mean change and standard deviation in each group of the study will be extracted along with the total number. If necessary, the authors of included studies will be contacted to obtain more data.

Assessment of risk of bias in included studies

Quality in a systematic review refers essentially to the absence of biases. We will evaluate probable sources of bias in included studies according to the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). In addition, we will adopt the factors described in the traffic light classification system suggested by the Cochrane Pain, Palliative and Supportive Care (PaPaS) Review Group (Moore 2010).

We will also check for other potential factors of bias:

  1. patient expectations of benefit across arms of the trial;

  2. credibility to patients of trial arms;

  3. details of training, manualisation, adherence to the manual and therapists (Eccleston 2010).

Each included study will be independently evaluated by two review authors (JZ and XL). Disagreements will be resolved by consultation with a third review author (EE).

Measures of treatment effect

For dichotomous data, we will use relative risk (RR) and 95% confidence interval (CI) as the effect measure. In case there are statistically significant estimate effects, we will calculate the number needed to treat (NNT) for beneficial outcomes and number needed to treat to harm (NNH) for undesirable outcomes. For continuous data, we will use weighted mean difference (WMD) or standardised mean difference (SMD) with their respective 95% CIs as appropriate.

Unit of analysis issues

For cross-over studies we will only analyse the results of the first round. In RCTs which tested multiple interventions, we will include only the treatment groups which met our criteria for inclusion.

Dealing with missing data

If withdrawal existed in a clinical trial, we will attempt intention-to-treat (ITT) analysis. We will assume participants who dropped out were non-respondents (Unnebrink 2001). For dichotomous data, the baseline observation carried forward (BOCF) method will be adopted if necessary.

Assessment of heterogeneity

We will evaluate heterogeneity from two aspects. Clinical heterogeneity will be firstly checked based on the information (patients' characteristics, intervention and control methods, treatment times and outcome measures) reported in each included study. Chi2 tests and I2 will be performed to identify statistical heterogeneity. Heterogeneity is considered as significant when P < 0.10 and/or I2 > 50%.

Assessment of reporting biases

We will assess publication bias using a funnel plot when there are sufficient included trials. If possible, we will calculate how many patients in zero treatment effect trials would make a NNT exceed a predetermined utility limit according to the methods described in (Moore 2008).

Data synthesis

If there are more than two clinically homogeneous studies, we will perform meta-analyses. When there is no substantial statistical heterogeneity (P > 0.1 and/or I2< 50%), we will use fixed-effect model in meta-analysis. When there is significant statistical heterogeneity (P < 0.1 and/or I2 > 50%), we will try the random-effects model. If substantial clinical and statistical heterogeneity is present, data will not be combined but presented with a narrative synthesis.

Subgroup analysis and investigation of heterogeneity

Subgroup analyses can control the clinical heterogeneity during meta-analysis. If a sufficient number of studies can be retrieved, we will perform subgroup analyses according to four factors:

  • medical history of participants;

  • type of acupuncture;

  • treatment frequency, period and follow-up;

  • different treatment in control group.

Sensitivity analysis

We will carry out sensitivity analysis to explore the robustness of the results, by re-performing meta-analyses by excluding studies with high risks of bias (e.g. less than 50 participants in each treatment arm).


The authors thank Yaozu Xiang and Li Zhang for their help with the literature search.


Appendix 1. PubMed search strategy

#1 "myofascial pain syndromes"[MeSH]

#2 myofascial pain [tiab]

#3 "trigger points"[MeSH]

#4 myofascial trigger point [tiab]

#5 trigger Area [tiab]

#6 trigger point [tiab]

#7 #1 OR #2 OR #3 OR #4 OR #5 OR #6

#8 acupuncture [tiab]

#9 "acupuncture Therapy"[MeSH]

#10 "acupuncture"[MeSH]

#11 "acupuncture points"[MeSH]

#12 acupoint* [tiab]

#13 "acupuncture analgesia"[MeSH]

#14 needling [tiab]

#15 #8 OR #9 OR #10 OR #11 OR #12 OR #13 OR #14

#16 randomized controlled trial [pt]

#17 controlled clinical trial [pt]

#18 randomized [tiab]

#19 placebo [tiab]

#20 drug therapy [sh]

#21 randomly [tiab]

#22 trial [tiab]

#23 groups [tiab]

#24 #16 OR #17 OR #18 OR #19 OR #20 OR #21 OR #22 OR #23

#25 animals [mh] NOT humans [mh]

#26 #24 NOT #25

#27 #7 AND #15 AND #26

Contributions of authors

Xuemei Li: Study design,data extract, and data interpretation.

Junhua Zhang: Study design, literature search, data extract, statistical analysis, data interpretation and review updating.

Edzard Ernst: Manuscript preparation, quality assessment and data interpretation.

Declarations of interest

None known.

Sources of support

Internal sources

  • No sources of support supplied

External sources

  • National Natural Science Foundation (81102733), China.