- Email: [email protected]
Short-term effects of acupuncture and stretching on myofascial trigger point pain of the neck: A blinded, placebo-controlled RCT
Complementary Therapies in Medicine (2014) 22, 835—841
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevierhealth.com/journals/ctim
Short-term effects of acupuncture and stretching on myofascial trigger point pain of the neck: A blinded, placebo-controlled RCT J. Wilke a,∗, L. Vogt a, D. Niederer a, M. Hübscher a,b, J. Rothmayr a, D. Ivkovic a, M. Rickert c, W. Banzer a a
Department of Sports Medicine, Goethe University, Ginnheimer Landstraße 39, 60487 Frankfurt am Main, Germany b Neuroscience Research Australia, Sydney, Australia c Department of Spine Diseases, Goethe University, Frankfurt am Main, Germany Available online 16 September 2014
KEYWORDS Acupuncture; Myofascial trigger points; Neck pain; Stretching
∗
Summary Objectives: This trial aimed to evaluate the short-term effectiveness of acupuncture plus stretching to reduce pain and improve range of motion in patients afflicted by cervical myofascial pain syndrome. Design: Randomized, blinded, placebo-controlled crossover study. Intervention: Nineteen patients (11 females, eight males, 33 ± 14 years) with myofascial neck pain in randomized order received the following treatments with one week washout between: acupuncture, acupuncture plus stretching, and placebo laser acupuncture. Main outcome measures: Mechanical pain threshold (MPT, measured with a pressure algometer) represented the primary outcome. Secondary outcomes were motion-related pain (Visual Analogue Scale, VAS) and cervical range of motion (ROM, recorded by means of an ultrasonic 3D movement analysis system). Outcomes were assessed immediately prior as well as 5, 15 and 30 min post treatment. Friedman tests with post hoc Bonferroni—Holm correction were applied to compare differences between treatments. Results: Both acupuncture as well as acupuncture plus stretching increased MPT by five, respectively, 11 percent post treatment. However, only acupuncture in combination with stretching was superior to placebo (p < 0.05). There were no significant differences between interventions at 15 and 30 min post treatment. VAS did not differ between treatments at any measurement. Five minutes after application of acupuncture plus stretching, ROM was significantly increased in the frontal and the transversal plane compared to placebo (p < 0.05).
Corresponding author. Tel.: +49 0 69 798 245 88; fax: +49 0 69 798 245 92. E-mail address: [email protected] (J. Wilke).
http://dx.doi.org/10.1016/j.ctim.2014.09.001 0965-2299/© 2014 Elsevier Ltd. All rights reserved.
836
J. Wilke et al. Conclusions: The combination of acupuncture and stretching could represent a suitable treatment option to improve cervical movement behavior and reduce trigger point pain in the short-term. However, additional studies further discriminating the placebo effects are still warranted. © 2014 Elsevier Ltd. All rights reserved.
Introduction Musculoskeletal disorders rank among the most widespread health problems in the general population.4 Leading to more than half of all pain related medical consultations, they represent a significant cause for absenteeism from work.23,30 In up to 85% of patients seeking treatment in US primary care or specialist pain clinic settings, myofascial trigger points (MTrP) represent the primary source of musculoskeletal pain.34 MTrP are hypersensitive palpable nodules located in a taut band of a skeletal muscle fiber with symptoms including referred pain, restricted range of motion (ROM) and motor dysfunction.35 The therapy of MTrP encompasses a wide range of interventions like analgesics, manual therapy, physiotherapy, stretching and acupuncture. Acupuncture including dry needling is one of the most commonly used interventions.10,34 While classical acupuncture is based on meridians of traditional Chinese medicine, dry needling involves inserting the needles directly into myofascial trigger points. In neck pain, sham-controlled studies have proven that acupuncture and stretching are both effective at improving pain and range of motion in the short-term.11,13,18,20 Thus, researchers have combined both treatments to increase the therapeutic success. Edwards and Knowles6 found repeated dry needling plus stretching exercises to be more effective in deactivating myofascial trigger points compared to stretching in the long-term. Likewise, Ma et al.26 showed that a series of dry needling treatments in combination with stretching induces a greater long-term reduction of pain than flexibility exercises only. So far, the combination of classical acupuncture and subsequent stretching has not been studied though Irnich et al.17 demonstrated in accordance with a systematic review done by Tough et al.34 that acupuncture seems to be superior to dry needling. Moreover, as stated above, the trials of Edward and Knowles6 and Ma et al.26 focused on repeated treatments. Thus, the aim of the present study was to evaluate the short-term effects of a single treatment of acupuncture plus stretching. We hypothesized that this combination would be superior to acupuncture only and placebo laser acupuncture.
Ethical standards and study type The blinded, randomized, placebo-controlled crossover study was approved by the local ethics committee. It was conducted in accordance with the Declaration of Helsinki. Each subject signed informed consent.
Participants Patients seeking treatment for their neck pain were recruited from a local orthopedic clinic. Inclusion criteria consisted of age ≥18 to ≤65 years and presence of at least one active myofascial trigger point in the neck and shoulder region. To enhance reliability of the diagnostic process, only MTrPs with a baseline mechanical pain threshold (MPT) value of >3 kg/cm2 were considered.31,33 All patients underwent a comprehensive medical examination. Subjects were excluded when they (1) had hemophilia or fibromyalgia, (2) suffered from severe cardiovascular, pulmonary, neurological, psychiatric or inflammatory rheumatic diseases, (3) showed radicular symptoms, (4) sustained bone fracture in the preceeding six month, (5) had to take analgesics within 48 h prior to the first treatment or throughout the study and (6) received any other form of treatment (e.g. manual therapy) to alleviate their symptoms.
Sample size calculation Since the immediate effects of acupuncture and stretching exercise have not been studied, detectable postintervention differences between dry needling and sham dry needling in patients with MTrP pain served as a basis for the calculation.9 In the study, the mean MPT values 5 min post intervention were 176.5 kPA in the dry needling group and 100.00 kPA in the sham needling control group. The standardized effect size (0.7) was calculated as the difference between the post-treatment (dry needling) and sham-control means (76.5 kPA) divided by the pooled preintervention SD (111.1 kPA22 ). The sample size calculation was performed by the algorithm given in G*Power 3.8 A matched-pairs t-test with a two-sided significance level (p < 0.05) has 80% power to detect an effect size of 0.7 between a treatment group and the placebo control group underlying a total sample size of 19.
Randomization All subjects received the following treatments in randomized order (Figure 1) with seven-day breaks in between: verum acupuncture, verum acupuncture plus stretching, placebo laser acupuncture (laser needles were fixed on the skin but the device remained switched off). A randomization list determining the treatment order was generated electronically using BiAs 10.04 (Goethe University, Frankfurt, Germany). Administration and management of the randomization process was carried out by an independent, blinded investigator.
Short-term effects of acupuncture and stretching
Figure 1
837
Flow chart of the study.
Intervention Acupuncture interventions were performed by a licensed acupuncturist (German Medical Association of Acupuncture/DÄGfA). For the treatments, sterile disposable needles with a diameter of 0.3 × 30 mm2 (DongBang Acupuncture Inc., Korea) were used. GB20, BL10, BL43, TE15, SI13 and GV14 served as near points. TE5, SI3 and GB34 were selected as far points. Needling these points has been shown to be effective in chronic neck pain, cervical syndrome and whiplash.7,18,24 Far points were treated bilaterally, whereas near points were needled unilaterally according to the location of the primary trigger point. At all points except GV14 (needled skew upward) needling was carried out perpendicular. The depth of needle insertion depended on the subjects (e.g. skin thickness and subcutaneous fat layer) and ranged between 5 and 10 mm. De qi sensation was elicited by manual stimulation (rotation) at the beginning of each 20min-session. During the treatment, subjects adopted a prone position. When receiving acupuncture plus stretching, participants subsequently performed passive static stretches for the upper trapezius and scalene muscles, levator scapulae muscle, sternocleidomastoid muscle, posterior neck musculature, middle trapezius and rhomboid muscles.6,14 Each stretching exercise was hold for 20 s in a position of mild discomfort and repeated three times. To ensure blinding of the acupuncturist, subjects were instructed by a separate investigator. Placebo laser acupuncture was applied using the Laserneedle System (Laserneedle Systems GmbH, Glienicke/Nordbahn, Germany). It contains several optical
fibers having an ending that resembles a needle. The endings were not inserted into the skin but fixed on it at the above mentioned acupuncture points by adhesive tape. To ensure double blinding, subject and acupuncturist were not informed that the laser source remained switched off during the treatment.18 Only the laser device was activated to provide visual and acoustic signals. The acupuncturist and the subject had to put on protective glasses being told that the device emits invisible infrared laser light. Subject position and treatment duration were identical to those during acupuncture.
Outcome measurements and data collection Outcome assessments were carried out immediately before and 5, 15 and 30 min after the treatment. Mechanical pain threshold (MPT) was used as the primary outcome. At the beginning of each session, an investigator blinded for treatment allocation and experienced in the palpation of trigger points screened the neck and upper back at or above T6. Diagnostic criteria for the detection of MTrP consisted of: (1) presence of a tender spot in a taut band, (2) referred pain pattern on palpation, (3) patient pain recognition on palpation and (4) positive jump sign. Each MTrP was marked, the one with the lowest MPT represented the primary MTrP. A handheld mechanical pressure algometer (diameter 1 cm2 ; PDT, New York, USA) was used to capture MPT. The investigator applied increasing pressure to the MTrP at a rate of approximately 1 kg/cm2 /s until the subject reported a painful sensation. The corresponding force value (kg/cm2 )
838 Table 1
J. Wilke et al. Baseline values of MPT, ROM and VAS before interventions.. Acu
MPT [kg/cm2 ] VAS ROM sagittal [deg] ROM transversal [deg] ROM frontal [deg]
1.9 1.7 125.5 145.2 89.0
AcuStretch ± ± ± ± ±
0.7 1.7 30.3 23.9 20.7
was recorded. The lower the score (and thus MPT) the higher is the tenderness of the tissue in the tested area. The primary MTrP was measured three times with 10-s time intervals. The mean of the two last measurements was employed for further analysis.28 Sufficient repeated-measures reliability of the device has been demonstrated by Nussbaum and Downes.28 Secondary outcomes were motion-related pain and cervical range of motion (ROM). Self-perceived motion-related pain intensity was assessed using a visual analogue scale (VAS) ranging from 0 to 10 cm with 0 representing no pain and 10 extreme pain. Subjects performed one movement cycle in each plane (flexion/extension, left/right rotation and left/right lateral flexion) and respectively rated pain intensity by means of the scale. A total score was calculated averaging across movement directions.17 Sufficient reliability of the VAS in assessing pain has been confirmed by Jensen et al.21 and Bijur et al.3 Cervical range of motion in all three planes (flexion/extension, rotation and lateral flexion) was measured with an ultrasonic movement analysis system (Zebris CMS 70, Zebris Meditechnic GmbH, Isny, Germany). After three familiarization trials,1 subjects performed 10 self-paced maximal movement cycles in the sagittal, transversal and frontal plane. Maximum oscillation angles [deg] were calculated for all three planes. This movement analysis system collects external kinematic data with an accuracy of >0.6 mm15 and has demonstrated excellent test—retest reliability.37
Statistical methods Collection of data and statistical analysis were performed blinded to treatment allocation. For each treatment, mean differences between baseline and the three postintervention measurements were calculated. Friedman tests were computed to compare the treatments. In case of significance, post hoc tests with Bonferroni—Holm correction were carried out. A two-sided p value of less than 0.05 was considered as significant. All statistical calculations were made with BiAs 10.04 (Goethe University, Frankfurt, Germany).
1.7 1.8 127 144.7 86.5
± ± ± ± ±
0.5 1.5 19 18.7 18.5
Placebo 1.7 1.5 135 147.0 90.6
± ± ± ± ±
0.4 1.3 22 20.5 18.7
Figure 2 Change of mechanical pain threshold in response to the treatments (mean values with confidence intervals). * = significant difference between AcuStretch and Placabo.
study enrolment and rendered participants ineligible (e.g. disc prolapse). Two subjects withdraw after acupuncture or acupuncture plus stretching due to illness (uncomplicated cold, thus not categorized as serious adverse event). There were no significant differences between the three disposed treatments at baseline (Table 1). Five minutes after treatment, both acupuncture as well as acupuncture plus stretching reduced pressure pain: acupuncture increased mechanical pain threshold by 0.08 (5%) while acupuncture combined with stretching exercises led to an increase of 0.17 (11%). However, only acupuncture plus stretching was more effective in reducing pain compared to placebo treatment (p < 0.05, Figure 2). At 15 and 30 min post intervention, a slight pain reduction was still measurable though not significant. With respect to motion-related pain, all three treatments resulted in a decrease of pain indicated by lower scores
Results Nineteen adults with myofascial neck pain (11 females, eight males, 33 ± 14 years) participated in the study. The cumulative drop-out rate was 29% which is equivalent to eight subjects (Figure 1). Reasons for drop-out comprised scheduling problems and health problems that occurred after
Figure 3 Change of motion-related pain in response to the treatments (mean values with confidence intervals).
Short-term effects of acupuncture and stretching
Figure 4 Change of cervical mobility in response to the treatments (mean values with confidence intervals). * = significant difference between AcuStretch and Placabo.
on the visual analogue scale. Nonetheless, there were no significant differences between treatments (Figure 3). Analysis of ROM revealed short-term differences among the interventions: after 5 min, acupuncture plus stretching increased cervical spine mobility (lateral flexion and rotation) significantly more than placebo (p < 0.05, Figure 4). However, there were no differences at 15 and 30 min posttreatment.
Discussion This study aimed to evaluate the short-term effects of combined acupuncture and stretching in patients with myofascial neck pain. Post treatment, subjects displayed a slight but significant reduction in MPT and increased cervical ROM concerning the frontal and transversal plane. We thus demonstrated for the first time that classical acupuncture plus stretching is suited to temporarily alleviate symptoms of myofascial neck pain. Our main finding of a short-term pressure pain reduction is partly in line with the work of Edwards and Knowles6 who showed that a combination of dry needling and stretching leads to a greater long-term reduction in pain than stretching only. The authors suggest that exercise causes a better effect if a prior needling treatment has deactivated MTrP. However though plausible, there is no evidence for this assumption. Also Ma et al.26 found dry needling and stretching to be superior to stretching in the long-term. The pain relief of our patients ceased with time and was no more significant at 15 and 30 min after treatment. This raises the question that why the effects in the present study did not persist. As our patients received only a single treatment, it could be hypothesized that repeated stimulation of the trigger points is necessary to induce long lasting effects.
839 Nonetheless, present studies’ patients may benefit from the short-term pain relief in different ways. Myofascial neck pain has been shown to lead to worse sleep quality and increased disability during activities of daily living.27 A longterm treatment might help to reduce such restrictions. Also, patients with chronic tension-type headache may profit from an intervention. This type of headache is associated with presence of MTrP and their deactivation seems to be effective in treating the patients.2 In general, a prior treatment with acupuncture and stretching could enhance success of movement therapy. The brief reduction in pain provides a time window enabling the patient to exercise with less paindriven compensatory movements. Besides mitigating pain, acupuncture and stretching improved cervical range of motion in the transversal and sagittal plane more than the other treatments. A gain in flexibility could be advantageous for patients because restrictions of ROM are thought to cause pathological hypermobility in adjacent joints.12 Moreover, previously impaired daily functions as turning the head when looking to the side could be restored. In any case, attributing the change in ROM to the combined application of acupuncture and stretching needs to be discussed. It is well established that the gain in flexibility induced by an acute bout of stretching starts to diminish after a few minutes in healthy subjects.5,32 This is consistent with the assumption that stretching might have adopted a dominant role in our study. Otherwise, it is conceivable that in myofascial pain, the specific combination with acupuncture represents the driving force. An explanation for this theory could be that in subjects with MTrP, a prior deactivation of the points is necessary to enable the patients to benefit from the flexibility exercises. In this case, stretching only interventions would not be capable of increasing range of motion. Evidence with regard to this is conflicting. Edwards and Knowles6 implemented a stretching group but did not assess cervical mobility as an outcome. The stretching group of Ma et al.26 did not improve the range of motion after two weeks though exercising three times a day. Only after three months a slight advance was measurable. In contrast, Oliveira-Campelo29 found a stretching only intervention to be effective in increasing cervical ROM of patients with MTrP. An important issue for any study concerned with MTrP consists in reliably detecting the trigger points. Tough et al.34 reported a wide range of diagnostic criteria allowing numerous combinations. According to the authors, there is no consistent combination across studies. Consequently, comparing the results of studies on MTrP can be difficult. The criteria selected most often in studies are ‘‘tender spot in a taut band’’, ‘‘patient pain recognition’’, ‘‘predicted pain referral pattern’’ and ‘‘local twitch response’’.34 We decided to screen for ‘‘jump sign’’ instead of the local twitch response due to higher reliability (Kappa scores, CI 0.07—0.71 vs −0.05 to 0.57.25 Anyhow, another selection of criteria for trigger point detection could have yielded a differing population and differing results. This underlines the need for uniform standards in trigger point detection. The chosen acupuncture protocol has been proven to be effective in different cervical pain conditions.7,18,24 However, a more flexible approach with varying needle placement based on MTrP localization or pain intensity might
840 represent an alternative that might be addressed in future research. Some limitations have to be mentioned. As the selection of diagnostic criteria, positioning of the subjects may influence the results. We had the participants lying prone in order to provide a relaxed position. However, stimulation of SJ5 required subjects to externally rotate their arms what could be slightly uncomfortable. Some of the patients therefore reported that the used position hampered relaxation. Treating in the sitting position could solve this problem. Nevertheless, sitting without supporting the lower arm may also provoke discomfort then. Another issue relates to the placebo treatment. Implementing a deactivated laser device represents a suitable method for the evaluation of the treatment response due to comparable credibility and physiological inertness.16,19 We fixed the pads of the laser needles on the skin instead of using a laser pen to placebo-stimulate all points simultaneously thus providing a treatment regime that is more similar to classical acupuncture. Nevertheless, placebo laser acupuncture does not attempt to mimic acupuncture, it does not control for non-specific effects of needling. Consequently, it can only provide a partial answer to the question of efficacy.36 We further decided for a washout period of one week. Baseline values did not differ between treatments. However, some carry-over effects cannot be ruled out completely. Our study has shown that acupuncture plus stretching seems to be a promising approach to reduce mechanical hyperalgesia and improve function in the short-term. A potential field of future study consists in the long-term effects of a continued treatment. Additionally, trials should include a stretching only group to delineate relative contributions of individual treatment components.
Conflict of interest statement None declared.
Role of the funding source This research was supported by the Deutsche Gesellschaft für Muskelkranke (DGM) (Ba 4/1). The funding resource had no involvement in design, conduct and reporting of the study.
References 1. Allison GT, Fukushima S. Estimating three-dimensional spinal repositioning error: the impact of range, posture, and number of trials. Spine 2003;28:2510—6. 2. Alonso-Blanco C, Fernández-de-las-Pe˜ nas C, de-la-Llave-Rincón AI, Zarco-Moreno P, Galán- Del-Río F, Svensson P. Characteristics of referred muscle pain to the head from active trigger points in women with myofascial temporomandibular pain and fibromyalgia syndrome. J Headache Pain 2012;13:625—37. 3. Bijur PE, Silver W, Gallagher EJ. Reliability of the visual analog scale for measurement of acute pain. Acad Emerg Med 2001;8:1153—7. 4. Cimmino MA, Ferrone C, Cutolo M. Epidemiology of chronic musculoskeletal pain. Best Pract Res Clin Rheumatol 2011;25:173—83.
J. Wilke et al. 5. Depino GM, Webright WG, Arnold BL. Duration of maintained hamstring flexibility after cessation of an acute static stretching protocol. J Athl Train 2000;35:56—9. 6. Edwards J, Knowles N. Superficial dry needling and active stretching in the treatment of myofascial pain—–a randomised controlled trial. Acupunct Med 2003;21:80—6. 7. Fattori B, Ursino F, Cingolani C, Bruschini L, Dallan I, Nacci A. Acupuncture treatment of whiplash injury. Int Tinnitus J 2004;10:156—60. 8. Faul F, Erdfelder E, Lang A, Buchner A. G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav Res Methods 2007;39:175—91. 9. Fernández-Carnero J, La Touche R, Ortega-Santiago R, Galandel-Rio F, Pesquera J, Ge HY, et al. Short-term effects of dry needling of active myofascial trigger points in the masseter muscle in patients with temporomandibular disorders. J Orofac Pain 2010;24:106—12. 10. Fleckenstein J, Zaps D, Rüger LJ, Lehmeyer L, Freiberg F, Lang PM, et al. Discrepancy between prevalence and perceived effectiveness of treatment methods in myofascial pain syndrome: results of a cross-sectional, nationwide survey. BMC Musculoskelet Disord 2010;11:32. 11. Fu L, Li J, Wu W. Randomized controlled trials of acupuncture for neck pain: systematic review and meta-analysis. J Altern Complement Med 2009;15:133—45. 12. Greenman PE. Principles of manual medicine. Baltimore: Williams & Wilkins; 1996. 13. Häkkinen A, Salo P, Tarvainen U, Wirén K, Ylinen J. Effect of manual therapy and stretching on neck muscle strength and mobility in chronic neck pain. J Rehabil Med 2007;39: 575—9. 14. Hanten W, Olson SL, Butts NL, Nowicki AL. Effectiveness of a home program of ischemic pressure followed by sustained stretch for treatment of myofascial trigger points. Phys Ther 2000;80:997—1003. 15. Himmelreich H, Stefanicki E, Banzer W. Ultrasound-controlled anthropometry—–on the development of a new method in asymmetry diagnosis. Sportverletz Sportschaden 1998;12:60—5. 16. Hübscher M, Vogt L, Ziebart T, Banzer W. Immediate effects of acupuncture on strength performance: a randomized, controlled crossover trial. Eur J Appl Physiol 2010;110:353—8. 17. Irnich D, Behrens N, Gleditsch JM, Stör W, Schreiber MA, Schöps P, et al. Immediate effects of dry needling and acupuncture at distant points in chronic neck pain: results of a randomized, double-blind, sham-controlled crossover trial. Pain 2002;99:83—9. 18. Irnich D, Behrens N, Molzen H, König A, Gleditsch J, Krauss M, et al. Randomised trial of acupuncture compared with conventional massage and sham laser acupuncture for treatment of chronic neck pain. Br Med J 2001;322:1574—8. 19. Irnich D, Salih N, Offenbächer M, Fleckenstein J. Is sham laser a valid control for acupuncture trials? Evid-based Complement Altern Med: eCAM 2011;2011:485945. 20. Jaeger B, Reeves JL. Quantification of changes in myofascial trigger point sensitivity with the pressure algometer following passive stretch. Pain 1986;27:203—10. 21. Jensen MP, Karoly P, Braver S. The measurement of clinical pain intensity: a comparison of six methods. Pain 1986;27:117—26. 22. Kazis LE, Anderson JJ, Meenan RF. Effect sizes for interpreting changes in health status. Med Care 1989;27:S178—89. 23. Kohlmann T. Muskuloskelettale Schmerzen in der Bevölkerung. Der Schmerz 2003;17:405—11. 24. Kuhlemann H. Die Behandlung des HWS-Syndroms mit Akupunktur vs TENS-Placebo. Eine klinische, prospektiv kontrollierte Studie. Ruhr-Universität Bochum; 1998 (Dissertation). 25. Lucas N, Macaskill P, Irwig L, Moran R, Bogduk N. Reliability of physical examination for diagnosis of myofascial trigger points: a systematic review of the literature. Clin J Pain 2009;25:80—9.
Short-term effects of acupuncture and stretching 26. Ma C, Wu S, Li G, Xiao X, Mai M, Yan T. Comparison of miniscalpel-needle release, acupuncture needling, and stretching exercise to trigger point in myofascial pain syndrome. Clin J Pain 2010;26:251—7. 27. Mu˜ noz-Mu˜ noz S, Mu˜ noz-García MT, Alburquerque-Sendín F, nas C. Myofascial trigArroyo-Morales M, Fernández-de-las-Pe˜ ger points, pain, disability, and sleep quality in individuals with mechanical neck pain. J Manip Physiol Ther 2012;35: 608—13. 28. Nussbaum EL, Downes L. Reliability of clinical pressure-pain algometric measurements obtained on consecutive days. Phys Ther 1998;78:160—9. 29. Oliveira-Campelo NM, Melo CAde, Alburquerque-Sendín F, Machado JP. Short- and medium-term effects of manual therapy on cervical active range of motion and pressure pain sensitivity in latent myofascial pain of the upper trapezius muscle: a randomized controlled trial. J Manip Physiol Ther 2013;36: 300—9. 30. Picavet H, Schouten J. Musculoskeletal pain in the Netherlands: prevalences, consequences and risk groups, the DMC3-study. Pain 2003;102:167—78. 31. Sciotti VM, Mittak VL, DiMarco L, Ford LM, Plezbert L, Santipadri E, et al. Clinical precision of myofascial trigger
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Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevierhealth.com/journals/ctim
Short-term effects of acupuncture and stretching on myofascial trigger point pain of the neck: A blinded, placebo-controlled RCT J. Wilke a,∗, L. Vogt a, D. Niederer a, M. Hübscher a,b, J. Rothmayr a, D. Ivkovic a, M. Rickert c, W. Banzer a a
Department of Sports Medicine, Goethe University, Ginnheimer Landstraße 39, 60487 Frankfurt am Main, Germany b Neuroscience Research Australia, Sydney, Australia c Department of Spine Diseases, Goethe University, Frankfurt am Main, Germany Available online 16 September 2014
KEYWORDS Acupuncture; Myofascial trigger points; Neck pain; Stretching
∗
Summary Objectives: This trial aimed to evaluate the short-term effectiveness of acupuncture plus stretching to reduce pain and improve range of motion in patients afflicted by cervical myofascial pain syndrome. Design: Randomized, blinded, placebo-controlled crossover study. Intervention: Nineteen patients (11 females, eight males, 33 ± 14 years) with myofascial neck pain in randomized order received the following treatments with one week washout between: acupuncture, acupuncture plus stretching, and placebo laser acupuncture. Main outcome measures: Mechanical pain threshold (MPT, measured with a pressure algometer) represented the primary outcome. Secondary outcomes were motion-related pain (Visual Analogue Scale, VAS) and cervical range of motion (ROM, recorded by means of an ultrasonic 3D movement analysis system). Outcomes were assessed immediately prior as well as 5, 15 and 30 min post treatment. Friedman tests with post hoc Bonferroni—Holm correction were applied to compare differences between treatments. Results: Both acupuncture as well as acupuncture plus stretching increased MPT by five, respectively, 11 percent post treatment. However, only acupuncture in combination with stretching was superior to placebo (p < 0.05). There were no significant differences between interventions at 15 and 30 min post treatment. VAS did not differ between treatments at any measurement. Five minutes after application of acupuncture plus stretching, ROM was significantly increased in the frontal and the transversal plane compared to placebo (p < 0.05).
Corresponding author. Tel.: +49 0 69 798 245 88; fax: +49 0 69 798 245 92. E-mail address: [email protected] (J. Wilke).
http://dx.doi.org/10.1016/j.ctim.2014.09.001 0965-2299/© 2014 Elsevier Ltd. All rights reserved.
836
J. Wilke et al. Conclusions: The combination of acupuncture and stretching could represent a suitable treatment option to improve cervical movement behavior and reduce trigger point pain in the short-term. However, additional studies further discriminating the placebo effects are still warranted. © 2014 Elsevier Ltd. All rights reserved.
Introduction Musculoskeletal disorders rank among the most widespread health problems in the general population.4 Leading to more than half of all pain related medical consultations, they represent a significant cause for absenteeism from work.23,30 In up to 85% of patients seeking treatment in US primary care or specialist pain clinic settings, myofascial trigger points (MTrP) represent the primary source of musculoskeletal pain.34 MTrP are hypersensitive palpable nodules located in a taut band of a skeletal muscle fiber with symptoms including referred pain, restricted range of motion (ROM) and motor dysfunction.35 The therapy of MTrP encompasses a wide range of interventions like analgesics, manual therapy, physiotherapy, stretching and acupuncture. Acupuncture including dry needling is one of the most commonly used interventions.10,34 While classical acupuncture is based on meridians of traditional Chinese medicine, dry needling involves inserting the needles directly into myofascial trigger points. In neck pain, sham-controlled studies have proven that acupuncture and stretching are both effective at improving pain and range of motion in the short-term.11,13,18,20 Thus, researchers have combined both treatments to increase the therapeutic success. Edwards and Knowles6 found repeated dry needling plus stretching exercises to be more effective in deactivating myofascial trigger points compared to stretching in the long-term. Likewise, Ma et al.26 showed that a series of dry needling treatments in combination with stretching induces a greater long-term reduction of pain than flexibility exercises only. So far, the combination of classical acupuncture and subsequent stretching has not been studied though Irnich et al.17 demonstrated in accordance with a systematic review done by Tough et al.34 that acupuncture seems to be superior to dry needling. Moreover, as stated above, the trials of Edward and Knowles6 and Ma et al.26 focused on repeated treatments. Thus, the aim of the present study was to evaluate the short-term effects of a single treatment of acupuncture plus stretching. We hypothesized that this combination would be superior to acupuncture only and placebo laser acupuncture.
Ethical standards and study type The blinded, randomized, placebo-controlled crossover study was approved by the local ethics committee. It was conducted in accordance with the Declaration of Helsinki. Each subject signed informed consent.
Participants Patients seeking treatment for their neck pain were recruited from a local orthopedic clinic. Inclusion criteria consisted of age ≥18 to ≤65 years and presence of at least one active myofascial trigger point in the neck and shoulder region. To enhance reliability of the diagnostic process, only MTrPs with a baseline mechanical pain threshold (MPT) value of >3 kg/cm2 were considered.31,33 All patients underwent a comprehensive medical examination. Subjects were excluded when they (1) had hemophilia or fibromyalgia, (2) suffered from severe cardiovascular, pulmonary, neurological, psychiatric or inflammatory rheumatic diseases, (3) showed radicular symptoms, (4) sustained bone fracture in the preceeding six month, (5) had to take analgesics within 48 h prior to the first treatment or throughout the study and (6) received any other form of treatment (e.g. manual therapy) to alleviate their symptoms.
Sample size calculation Since the immediate effects of acupuncture and stretching exercise have not been studied, detectable postintervention differences between dry needling and sham dry needling in patients with MTrP pain served as a basis for the calculation.9 In the study, the mean MPT values 5 min post intervention were 176.5 kPA in the dry needling group and 100.00 kPA in the sham needling control group. The standardized effect size (0.7) was calculated as the difference between the post-treatment (dry needling) and sham-control means (76.5 kPA) divided by the pooled preintervention SD (111.1 kPA22 ). The sample size calculation was performed by the algorithm given in G*Power 3.8 A matched-pairs t-test with a two-sided significance level (p < 0.05) has 80% power to detect an effect size of 0.7 between a treatment group and the placebo control group underlying a total sample size of 19.
Randomization All subjects received the following treatments in randomized order (Figure 1) with seven-day breaks in between: verum acupuncture, verum acupuncture plus stretching, placebo laser acupuncture (laser needles were fixed on the skin but the device remained switched off). A randomization list determining the treatment order was generated electronically using BiAs 10.04 (Goethe University, Frankfurt, Germany). Administration and management of the randomization process was carried out by an independent, blinded investigator.
Short-term effects of acupuncture and stretching
Figure 1
837
Flow chart of the study.
Intervention Acupuncture interventions were performed by a licensed acupuncturist (German Medical Association of Acupuncture/DÄGfA). For the treatments, sterile disposable needles with a diameter of 0.3 × 30 mm2 (DongBang Acupuncture Inc., Korea) were used. GB20, BL10, BL43, TE15, SI13 and GV14 served as near points. TE5, SI3 and GB34 were selected as far points. Needling these points has been shown to be effective in chronic neck pain, cervical syndrome and whiplash.7,18,24 Far points were treated bilaterally, whereas near points were needled unilaterally according to the location of the primary trigger point. At all points except GV14 (needled skew upward) needling was carried out perpendicular. The depth of needle insertion depended on the subjects (e.g. skin thickness and subcutaneous fat layer) and ranged between 5 and 10 mm. De qi sensation was elicited by manual stimulation (rotation) at the beginning of each 20min-session. During the treatment, subjects adopted a prone position. When receiving acupuncture plus stretching, participants subsequently performed passive static stretches for the upper trapezius and scalene muscles, levator scapulae muscle, sternocleidomastoid muscle, posterior neck musculature, middle trapezius and rhomboid muscles.6,14 Each stretching exercise was hold for 20 s in a position of mild discomfort and repeated three times. To ensure blinding of the acupuncturist, subjects were instructed by a separate investigator. Placebo laser acupuncture was applied using the Laserneedle System (Laserneedle Systems GmbH, Glienicke/Nordbahn, Germany). It contains several optical
fibers having an ending that resembles a needle. The endings were not inserted into the skin but fixed on it at the above mentioned acupuncture points by adhesive tape. To ensure double blinding, subject and acupuncturist were not informed that the laser source remained switched off during the treatment.18 Only the laser device was activated to provide visual and acoustic signals. The acupuncturist and the subject had to put on protective glasses being told that the device emits invisible infrared laser light. Subject position and treatment duration were identical to those during acupuncture.
Outcome measurements and data collection Outcome assessments were carried out immediately before and 5, 15 and 30 min after the treatment. Mechanical pain threshold (MPT) was used as the primary outcome. At the beginning of each session, an investigator blinded for treatment allocation and experienced in the palpation of trigger points screened the neck and upper back at or above T6. Diagnostic criteria for the detection of MTrP consisted of: (1) presence of a tender spot in a taut band, (2) referred pain pattern on palpation, (3) patient pain recognition on palpation and (4) positive jump sign. Each MTrP was marked, the one with the lowest MPT represented the primary MTrP. A handheld mechanical pressure algometer (diameter 1 cm2 ; PDT, New York, USA) was used to capture MPT. The investigator applied increasing pressure to the MTrP at a rate of approximately 1 kg/cm2 /s until the subject reported a painful sensation. The corresponding force value (kg/cm2 )
838 Table 1
J. Wilke et al. Baseline values of MPT, ROM and VAS before interventions.. Acu
MPT [kg/cm2 ] VAS ROM sagittal [deg] ROM transversal [deg] ROM frontal [deg]
1.9 1.7 125.5 145.2 89.0
AcuStretch ± ± ± ± ±
0.7 1.7 30.3 23.9 20.7
was recorded. The lower the score (and thus MPT) the higher is the tenderness of the tissue in the tested area. The primary MTrP was measured three times with 10-s time intervals. The mean of the two last measurements was employed for further analysis.28 Sufficient repeated-measures reliability of the device has been demonstrated by Nussbaum and Downes.28 Secondary outcomes were motion-related pain and cervical range of motion (ROM). Self-perceived motion-related pain intensity was assessed using a visual analogue scale (VAS) ranging from 0 to 10 cm with 0 representing no pain and 10 extreme pain. Subjects performed one movement cycle in each plane (flexion/extension, left/right rotation and left/right lateral flexion) and respectively rated pain intensity by means of the scale. A total score was calculated averaging across movement directions.17 Sufficient reliability of the VAS in assessing pain has been confirmed by Jensen et al.21 and Bijur et al.3 Cervical range of motion in all three planes (flexion/extension, rotation and lateral flexion) was measured with an ultrasonic movement analysis system (Zebris CMS 70, Zebris Meditechnic GmbH, Isny, Germany). After three familiarization trials,1 subjects performed 10 self-paced maximal movement cycles in the sagittal, transversal and frontal plane. Maximum oscillation angles [deg] were calculated for all three planes. This movement analysis system collects external kinematic data with an accuracy of >0.6 mm15 and has demonstrated excellent test—retest reliability.37
Statistical methods Collection of data and statistical analysis were performed blinded to treatment allocation. For each treatment, mean differences between baseline and the three postintervention measurements were calculated. Friedman tests were computed to compare the treatments. In case of significance, post hoc tests with Bonferroni—Holm correction were carried out. A two-sided p value of less than 0.05 was considered as significant. All statistical calculations were made with BiAs 10.04 (Goethe University, Frankfurt, Germany).
1.7 1.8 127 144.7 86.5
± ± ± ± ±
0.5 1.5 19 18.7 18.5
Placebo 1.7 1.5 135 147.0 90.6
± ± ± ± ±
0.4 1.3 22 20.5 18.7
Figure 2 Change of mechanical pain threshold in response to the treatments (mean values with confidence intervals). * = significant difference between AcuStretch and Placabo.
study enrolment and rendered participants ineligible (e.g. disc prolapse). Two subjects withdraw after acupuncture or acupuncture plus stretching due to illness (uncomplicated cold, thus not categorized as serious adverse event). There were no significant differences between the three disposed treatments at baseline (Table 1). Five minutes after treatment, both acupuncture as well as acupuncture plus stretching reduced pressure pain: acupuncture increased mechanical pain threshold by 0.08 (5%) while acupuncture combined with stretching exercises led to an increase of 0.17 (11%). However, only acupuncture plus stretching was more effective in reducing pain compared to placebo treatment (p < 0.05, Figure 2). At 15 and 30 min post intervention, a slight pain reduction was still measurable though not significant. With respect to motion-related pain, all three treatments resulted in a decrease of pain indicated by lower scores
Results Nineteen adults with myofascial neck pain (11 females, eight males, 33 ± 14 years) participated in the study. The cumulative drop-out rate was 29% which is equivalent to eight subjects (Figure 1). Reasons for drop-out comprised scheduling problems and health problems that occurred after
Figure 3 Change of motion-related pain in response to the treatments (mean values with confidence intervals).
Short-term effects of acupuncture and stretching
Figure 4 Change of cervical mobility in response to the treatments (mean values with confidence intervals). * = significant difference between AcuStretch and Placabo.
on the visual analogue scale. Nonetheless, there were no significant differences between treatments (Figure 3). Analysis of ROM revealed short-term differences among the interventions: after 5 min, acupuncture plus stretching increased cervical spine mobility (lateral flexion and rotation) significantly more than placebo (p < 0.05, Figure 4). However, there were no differences at 15 and 30 min posttreatment.
Discussion This study aimed to evaluate the short-term effects of combined acupuncture and stretching in patients with myofascial neck pain. Post treatment, subjects displayed a slight but significant reduction in MPT and increased cervical ROM concerning the frontal and transversal plane. We thus demonstrated for the first time that classical acupuncture plus stretching is suited to temporarily alleviate symptoms of myofascial neck pain. Our main finding of a short-term pressure pain reduction is partly in line with the work of Edwards and Knowles6 who showed that a combination of dry needling and stretching leads to a greater long-term reduction in pain than stretching only. The authors suggest that exercise causes a better effect if a prior needling treatment has deactivated MTrP. However though plausible, there is no evidence for this assumption. Also Ma et al.26 found dry needling and stretching to be superior to stretching in the long-term. The pain relief of our patients ceased with time and was no more significant at 15 and 30 min after treatment. This raises the question that why the effects in the present study did not persist. As our patients received only a single treatment, it could be hypothesized that repeated stimulation of the trigger points is necessary to induce long lasting effects.
839 Nonetheless, present studies’ patients may benefit from the short-term pain relief in different ways. Myofascial neck pain has been shown to lead to worse sleep quality and increased disability during activities of daily living.27 A longterm treatment might help to reduce such restrictions. Also, patients with chronic tension-type headache may profit from an intervention. This type of headache is associated with presence of MTrP and their deactivation seems to be effective in treating the patients.2 In general, a prior treatment with acupuncture and stretching could enhance success of movement therapy. The brief reduction in pain provides a time window enabling the patient to exercise with less paindriven compensatory movements. Besides mitigating pain, acupuncture and stretching improved cervical range of motion in the transversal and sagittal plane more than the other treatments. A gain in flexibility could be advantageous for patients because restrictions of ROM are thought to cause pathological hypermobility in adjacent joints.12 Moreover, previously impaired daily functions as turning the head when looking to the side could be restored. In any case, attributing the change in ROM to the combined application of acupuncture and stretching needs to be discussed. It is well established that the gain in flexibility induced by an acute bout of stretching starts to diminish after a few minutes in healthy subjects.5,32 This is consistent with the assumption that stretching might have adopted a dominant role in our study. Otherwise, it is conceivable that in myofascial pain, the specific combination with acupuncture represents the driving force. An explanation for this theory could be that in subjects with MTrP, a prior deactivation of the points is necessary to enable the patients to benefit from the flexibility exercises. In this case, stretching only interventions would not be capable of increasing range of motion. Evidence with regard to this is conflicting. Edwards and Knowles6 implemented a stretching group but did not assess cervical mobility as an outcome. The stretching group of Ma et al.26 did not improve the range of motion after two weeks though exercising three times a day. Only after three months a slight advance was measurable. In contrast, Oliveira-Campelo29 found a stretching only intervention to be effective in increasing cervical ROM of patients with MTrP. An important issue for any study concerned with MTrP consists in reliably detecting the trigger points. Tough et al.34 reported a wide range of diagnostic criteria allowing numerous combinations. According to the authors, there is no consistent combination across studies. Consequently, comparing the results of studies on MTrP can be difficult. The criteria selected most often in studies are ‘‘tender spot in a taut band’’, ‘‘patient pain recognition’’, ‘‘predicted pain referral pattern’’ and ‘‘local twitch response’’.34 We decided to screen for ‘‘jump sign’’ instead of the local twitch response due to higher reliability (Kappa scores, CI 0.07—0.71 vs −0.05 to 0.57.25 Anyhow, another selection of criteria for trigger point detection could have yielded a differing population and differing results. This underlines the need for uniform standards in trigger point detection. The chosen acupuncture protocol has been proven to be effective in different cervical pain conditions.7,18,24 However, a more flexible approach with varying needle placement based on MTrP localization or pain intensity might
840 represent an alternative that might be addressed in future research. Some limitations have to be mentioned. As the selection of diagnostic criteria, positioning of the subjects may influence the results. We had the participants lying prone in order to provide a relaxed position. However, stimulation of SJ5 required subjects to externally rotate their arms what could be slightly uncomfortable. Some of the patients therefore reported that the used position hampered relaxation. Treating in the sitting position could solve this problem. Nevertheless, sitting without supporting the lower arm may also provoke discomfort then. Another issue relates to the placebo treatment. Implementing a deactivated laser device represents a suitable method for the evaluation of the treatment response due to comparable credibility and physiological inertness.16,19 We fixed the pads of the laser needles on the skin instead of using a laser pen to placebo-stimulate all points simultaneously thus providing a treatment regime that is more similar to classical acupuncture. Nevertheless, placebo laser acupuncture does not attempt to mimic acupuncture, it does not control for non-specific effects of needling. Consequently, it can only provide a partial answer to the question of efficacy.36 We further decided for a washout period of one week. Baseline values did not differ between treatments. However, some carry-over effects cannot be ruled out completely. Our study has shown that acupuncture plus stretching seems to be a promising approach to reduce mechanical hyperalgesia and improve function in the short-term. A potential field of future study consists in the long-term effects of a continued treatment. Additionally, trials should include a stretching only group to delineate relative contributions of individual treatment components.
Conflict of interest statement None declared.
Role of the funding source This research was supported by the Deutsche Gesellschaft für Muskelkranke (DGM) (Ba 4/1). The funding resource had no involvement in design, conduct and reporting of the study.
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