Myofascial Pain Syndrome: Trigger Points

Journal of Musculoskeletal Pain, Vol. 20(2), 2012 © 2012 Informa Healthcare USA, Inc. ISSN: 1058-2452 print / 1540-7012 online DOI: 10.3109/10582452.2012.687440

LITERATURE REVIEW

Myofascial Pain Syndrome: Trigger Points Jan Dommerholt, PT, DPT, MPS1, Carel Bron, PT, PhD2,3 Bethesda Physiocare / Myopain Seminars, Bethesda, MD, USA, 2Scientific Institute for Quality of Healthcare, Radboud University Nijmegen Medical Centre, The Netherlands, 3Private Practice for Physical Therapy for Neck, Shoulder and Upper Extremity Disorders, Groningen, The Netherlands. J Muscoskeletal Pain Downloaded from informahealthcare.com by Mr. Carel Bron on 07/31/12 For personal use only.

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INTRODUCTION

The researchers were able to accurately identify TrPs with sonography and sonoelastography. Vibration elastography was effective for measuring the size of TrPs and for distinguishing active TrPs versus latent TrPs versus normal tissue. Doppler imaging revealed a retrograde diastolic flow in 55 percent of active TrP sites compared with 40 percent and 31 percent for latent TrPs and normal sites, indicating the presence of highly resistive vascular beds at or near TrPs. Interestingly, there was no correlation between pain pressure threshold and size of the TrP area, but active TrPs occupied a greater area. The authors also conducted a small pilot study to examine whether the methodology could be used to measure changes following TrP dry needling and they noted significant changes after dry needling of active TrPs. Because of the small sample size, no conclusions could be drawn, but the methodology seemed promising.

This edition of the trigger point literature review features several important basic research and clinical studies, many reviews, and a few case reports from a wide range of countries such as Australia, Canada, China, Malaysia, Spain, India, Italy, Turkey, and the USA. Each review indicates whether it was prepared by Dr. Dommerholt [JD] or Dr. Bron [CB]. RESEARCH STUDIES Ballyns JJ, Shah JP, Hammond J, Gebreab T, Gerber LH, Sikdar S: Objective sonographic measures for characterizing myofascial trigger points associated with cervical pain. J Ultrasound Med 30(10):13311340, 2011. Summary Forty-four patients [aged 22–57 years] with acute cervical pain and an active or latent trigger point [TrP] in either upper trapezius muscle were included in this study from the United States National Institutes of Health. Physical examination determined whether subjects had active or latent TrPs. Each subject underwent a sonographic examination to determine the location of TrPs, sonoelastography to assess the areas with increased tissue stiffness such as taut bands, and color Doppler imaging to evaluate the vasculature and flow velocity wave forms. The sonographers were blinded to the clinical status. A total of 169 sites were imaged. The TrPs were located more often medially in the muscle. About 83 percent of subjects had symmetrical bilateral TrPs.

Comments This is another outstanding study from the United States National Institutes of Health utilizing songraphy to further characterize TrPs. The study offers support for an older study that showed that the oxygen saturation in the core of a TrP is far below normal and increased immediately outside a TrP (1). The possibility of using this methodology in clinical outcome studies is exciting as such studies are very much needed. Combining the findings of this study with the next study in this review, one can only conclude that it is possible to objectively examine TrPs and treatment outcomes using sonography [JD].

Address correspondence to: Dr. Jan Dommerholt, Bethesda Physiocare / Myopain Seminars, 7830 Old Georgetown Road, Suite C15, Bethesda, MD 20814-2440, E-mail: [email protected] Submitted: April 4, 2012; Revisions Accepted: April 5, 2012

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Myofascial Pain Syndrome

J Muscoskeletal Pain Downloaded from informahealthcare.com by Mr. Carel Bron on 07/31/12 For personal use only.

Hafizah WM, Soh JZE, Supriyanto E,Nook SM: Automatic classification of muscle condition based on ultrasound image morphological differences. Int J Biol Biomed Eng 6(1):87–96, 2012. Summary The main objective of this study was to design a software system [MATLAB] that can detect trigger points [TrPs] using ultrasound images of muscles. Observation revealed that the muscle layer of normal muscles appears flat and parallel to the surface, while in muscles with TrPs a peak appears at the TrP. One hundred subjects [aged between 20 and 50 years; 50 with a TrP and 110 without a TrP] were imaged with sonography using a low-cost machine and a much more expensive unit. The images obtained by the machines were analyzed separately. After image acquisition, image processing was completed using a MATLAB Image-processing Toolbox, including cropping the image, converting the gray scale image to a binary image, and eliminating isolated pixel groups. The purpose of this image processing was to obtain the upper boundary of the muscle layer. Finally, the curve of the muscle was detected and the image was classified using a threshold value. Signals with values exceeding the threshold were considered as muscle with a TrP and signals that did not exceed the threshold value were considered as muscle without a TrP. The results showed that the standard deviation of the signal was suitable for detection of a TrP in both machines, while the mean value of the signal was only suitable for images obtained with the more expensive machine. The authors conclude that this method of detection of TrPs provides quantitative data that is more reliable compared with physical examination. However, the system is highly dependent on the quality of the ultrasound images and the method of image processing used. Comments To better understand the clinical picture of TrPs, there is a need for objective [imaging] techniques to identify anatomic, physiological, and morphological abnormalities associated with TrPs. This may help to establish objective diagnostic criteria for identification and classification of TrPs, and changes in objective measures in treatment responses, including size and appearance of TrPs. Several studies have shown promising results, including ultrasound imaging (2,3). This study adds an alternative method of detecting TrPs by ultrasound imaging [CB].

CLINICAL STUDIES Rodríguez-Fernández AL, Garrido-Santofimia V, Güeita-Rodríguez J, Fernández-de-las-Peñas C: Effects of burst-type transcutaneous electrical nerve stimulation on cervical range of motion and latent myofascial trigger point pain Sensitivity. Arch Phys Med Rehabil 92:1353-1358, 2011. Summary To assess the effects of a burst application of transcutaneous electrical nerve stimulation [TENS] on cervical range of motion and pressure point sensitivity of latent trigger points [TrPs], a single-session, singleblind randomized trial was undertaken. Seventy-six volunteers [45 men, 31 women; aged 18–41 years, 23 ± 4 years] out of a total of 100 eligible subjects were recruited from a pain-free population by advertisement in a local newspaper. Subjects were included when either the right or left trapezius muscle harbored a latent TrP. Twelve subjects were excluded because no latent TrPs were found on either side. Twelve other subjects were also excluded due to previous neck trauma [n = 8] or a history of migraine [n = 4]. The subjects were randomly assigned to either the treatment group [n = 38] or the control group [n = 38] by flipping a coin. Outcome measures included passive cervical rotation range of motion in supine measured with a goniometer and the referred pressure pain threshold [RPPT]. Measurements were taken before treatment, one minute after the treatment, and five minutes after the treatment. The treatment consisted of 10 min of TENS, with a pulse width of 200 μs, a pulse frequency of 100 Hz, and a burst frequency of 2 Hz. The active electrode [size 3.2 cm2] was placed over the TrP and the ground electrode [size 24 cm2] was placed over the deltoid region. The control group received a sham TENS application for 10 min. The subjects were informed that they would receive an electrical current at a subliminal level. The intervention group exhibited a greater increase in RPPT than the control group 1 min after the intervention [mean difference 0.3; 95 percent confidence interval [95% CI] 0.1–0.4] and 5 min after the intervention [mean 0.6; 95% CI 0.3–0.8], although the differences were small. The increase in cervical rotation was greater for the intervention group than for the control group, but again, the differences were small [mean difference for cervical rotation to the ipsilateral side after 1 min 2.0; 95% CI 1.0–2.8] and after 5 min 2.7; 95% CI 1.7–3.8 and mean difference for the contralateral side after 1 min 0.7; 0.1–1.4 and after 5 min 1.1; 95% CI 0.2–2.0].

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Dommerholt and CarelBron

The authors concluded that although the differences in RPPT and passive range of motion were statistically significant, the results were of potentially limited relevance.


Comments This well-designed study shows that treating latent TrPs with an application of burst-type TENS has an immediate and possibly short-term hypoalgesic effect on latent TrPs, but the clinical relevance of this short-term treatment effect still remains to be uncovered [CB]. Doraisamy MA: The effect of upper trapezius latent myofascial trigger points on neck pain and disability. Global J Health Sci 3(2):134–139, 2011. Summary In this study from Malaysia, 42 subjects with mechanical neck pain of at least three months duration were divided into an experimental group [n = 27] and a control group [n = 15]. Subjects in the experimental group had latent trigger points [TrPs] in the upper trapezius muscle and subjects in the control group did not. All subjects completed the Northwick Park Neck Pain Questionnaire and the scores were compared between the two groups. Subjects with latent TrPs had significantly higher scores on the Northwick Park Neck Pain Questionnaire. The author concluded that latent TrPs do contribute to neck pain and disability. Comments While this is a potentially interesting study of the impact of latent TrPs, it is not at all clear why the author opted to include only subjects with chronic mechanical neck pain rather than asymptomatic individuals. As was reviewed in the paper, by definition latent TrPs do not cause spontaneous pain. How did the researcher determine that the subjects did not have active TrPs, which would seem likely given their diagnosis of chronic mechanical neck pain? In the experience of this reviewer, it is very rare to not find any TrPs in the upper trapezius muscle, but in this study 35 percent of the subjects did not have any [JD]. REVIEWS Majlesi J, Unalan H: Effect of treatment on trigger points. Curr Pain Headache Rep 14:353–360, 2010. Turkish physicians Majlesi and Unalan prepared a clear review article focusing on effective treatment options of trigger points. They emphasized that under-recognition of myofascial pain will lead to

overuse of laboratory and imaging studies, overtreatment, and possibly even to the development of chronic pain syndrome. The paper includes a brief review of the clinical characteristics and pathophysiology of trigger points, before a succinct description of various treatment options, such as modalities, stretching, injections and dry needling, ultrasound, including high-power pain threshold ultrasound [JD]. Giamberardino MA, Affaitati G, Fabrizio A, Costantini R: Myofascial pain syndromes and their evaluation. Best Pract Res Clin Rheumatol25:185– 198, 2011. This comprehensive review article from Italy covers the current understanding of trigger point [TrP] research and clinical application of TrP therapy in much detail. The authors discuss the lack of uniform criteria, the clinical assessment and the sensory aspects of TrPs, the pathophysiology, the role of TrPs as pain generators in concurrent pain conditions, such as headache, fibromyalgia syndrome, and visceral pain. The authors concluded with a brief review of the management of individuals with myofascial pain. This is an excellent introduction to myofascial pain and TrPs [JD]. Chandola HC, Chakraborty A: Fibromyalgia and myofascial pain syndrome – a dilemma. Indian J Anaesth 53(5):575–581, 2009. Although the authors of this review paper from India recognized that there are differences between myofascial pain and fibromyalgia syndrome [FMS], they suggested that myofascial pain is a subtype of FMS. They erroneously stated that both conditions feature taut bands, although taut bands are not part of the diagnostic criteria for FMS. They also consider trigger points to be the same as FMS tender points. The authors described the typical characteristics of trigger points and various treatment options for myofascial pain and FMS. Interestingly, in this section the treatment options are separated for the two clinical entities. Overall, this paper is a bit confusing [JD]. Vázquez-Delgado E, Cascos-Romero J, Gay-Escoda C: Myofascial pain associated to trigger points: a literature review. Part 2: differential diagnosis and treatment. Med Oral Patol Oral Cir Bucal 15(4): e639–e643, 2010. It is rare to come across an article in the dental literature about myofascial pain that considers the importance of trigger points. More commonly, dental literature uses a very restricted definition of myofascial pain dysfunction syndrome based on the criteria by Dworkin et al. (4,5), or the updated criteria by

Myofascial Pain Syndrome


Schiffman et al. (6), which does not really recognize the role of trigger points. This Spanish paper describes in some detail the various differential diagnoses followed by a brief review of several treatment options. Although this paper lacks the details of the review paper by Giamberardino and colleagues, it is nevertheless a welcome contribution to the dental literature on myofascial pain [JD]. Wong CS, Wong SH: A new look at trigger point injections. Anesthesiol Res Pract. 2012; Published online 2011 September 29. doi: 10.1155/2012/492452 From Hong Kong, the authors explored the use of the potential use of ultrasound in trigger point [TrP] injection therapy. After a brief introduction, the authors reviewed some thoughts about the possible mechanisms of TrP injections, but they concluded that there is a lack of literature. The authors argued that it is conceivable that TrP injections may be effective, because of their effect on nerves. For example, TrPs in the abdominal wall may be entrapped cutaneous nerves. TrP injections in the psoas muscle may be the same as a lumbar plexus block and TrPs in the levator ani may equal a pudendal nerve block. The authors recommend the use of sonography to further explore whether some TrP injections may in fact be peripheral nerve blocks and to visualize TrPs. They cited the recent TrP sonography research of the United States National Institutes of Health reviewed earlier in this column [JD]. Dommerholt J: Dry needling – peripheral and central considerations. J Man Manipul Ther 19 (4):223–237, 2011. Summary In this narrative review, the author created an up-todate picture of the current evidence concerning the pathophysiology of trigger points [TrPs] with an emphasis on peripheral and central sensitization. The advantages of dry needling include an immediate reduction in local, referred, and widespread pain, restoration of range of motion, and muscle activation patterns. The author included a succinct summary of recent microdialysis studies of the role of biochemical substances and various receptors in the pathophysiological processes of peripheral and central sensitization. Whether a TrP is latent or active depends at least partly on the level of central sensitization, caused by increasing synaptic activity in the dorsal horn. According to the author, TrP dry needling is best understood when considered from a pain science perspective. Dry needling is relatively easy to learn by qualified healthcare providers with a solid

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background and education in anatomy, physiology, and pain sciences. It requires training and practice in order to reliably identify TrPs. Complications are rare, but practitioners should carefully locate anatomic landmarks to avoid for example puncturing the lung, nerves or large blood vessels. TrPs can be visualized by means of ultrasound and magnetic resonance eleastography, but these techniques are not yet applicable for clinical use. The author highlighted some of the difficulties in designing placebo-controlled dry needling trials. It is almost impossible to develop real sham-needles that do not stimulate Adelta fibers when puncturing the skin. In the last section, the author discussed some controversial issues between acupuncturists and physical therapists, which is a growing concern especially in the USA. Comments The author has given a clear and understandable picture of the current evidence of the TrP concept and the advantages of dry needling in the management of TrPs within the context of contemporary pain sciences [CB]. Janz S, Adams J: Acupuncture by another name: dry needling in Australia. Aust J Acupunct Chin Med 6(2):3–11, 2011. Summary In this article from Australia, the authors express their concerns about non-acupuncturists using dry needling techniques in their respective practices. In spite of claims made by non-acupuncturists that dry needling is not acupuncture, dry needling has been described in both classical and contemporary Chinese acupuncture literature. Dry needling techniques are similar to one of the ancient needling methods and are just a variation of classical acupuncture; yet, descriptions of dry needling in the physical therapy literature do not include references to ancient Chinese texts. The authors maintain that the term “dry needling” is used intentionally to circumvent legal requirements as only licensed acupuncturists are allowed to practice acupuncture. Next, the article discusses that the incidence of serious adverse events is not known for dry needling. According to the authors, acupuncture is safe when practiced by well-trained practitioners, but since dry needling is taught in short courses of 16– 36 h of duration, dry needling would fall in the highrisk category. The authors state that acupuncture practice has evolved over thousands of years and during the past 50 years, the mechanisms of acupuncture have been explored from a biomedical perspective. From the authors perspective, dry needling is nothing new

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and is virtual identical to acupuncture practice. They conclude the article with quoting a report by the World Health Organization [WHO] that acupuncture practice takes at least 2,500 hours of training. Anything short of such comprehensive training would constitute a high-risk procedure. Comments This is a timely article as in the USA there is also growing opposition by some acupuncture groups to dry needling by other healthcare providers, such as physical therapists. In the humble opinion of this reviewer, physical therapists may have contributed to the perception of a growing number of acupuncturists by stating that “dry needling is not acupuncture.” The fact is that dry needling is in the scope of multiple disciplines, including osteopathic, naturopathic, podiatric, veterinary, and chiropractic medicine, acupuncture, physical therapy, dentistry, and massage therapy, among others, dependent upon the country and local jurisdictional regulations. In some cases, the term dry needling may indeed have been used intentionally to bypass acupuncture regulations, but considering the historical context of trigger point [TrP] injections, it is clear that Travell never considered the similarities between dry needling and acupuncture practice. Travell developed her concepts in the 1940s and 1950s and did not communicate with acupuncturists until the mid 1980s. When acupuncturists maintain that dry needling is only a subsystem of acupuncture, they seem to deny the notion of original thought in the Western world. The concepts of TrPs and dry needling were developed independent of already existing acupuncture concepts. The authors of this paper are right when they express concerns about the qualifications of certain healthcare providers and instructors of dry needling courses. Dry needling is gaining in popularity and inevitably, some will take advantage of this expansion and move away from the initial concepts of Travell and Simons. Others have introduced dry needling to healthcare providers with little educational background. In Ireland, for example, dry needling is offered to physical therapists with about 150 h of total education. It should be noted that in Ireland, there are marked differences between physiotherapists who are recognized by the World Federation of Physical Therapy, and physical therapists, who have less education than most massage therapists. There is no evidence that serious adverse reactions to dry needling are common; dry needling is a safe technique when practiced by trained healthcare providers with no significant risk to the public. The United States Federation of State Boards of Physical

Therapy’s Examination, Licensure and Disciplinary Database has no entries in any jurisdiction or discipline for harm caused by dry needling performed by physical therapists (7). Thousands of physical therapists in many countries have used TrP dry needling for years without any documented serious health hazards. A study of adverse events is currently being conducted in Ireland. One area of confusion is that many acupuncturists consider dry needling as a discipline rather than a technique. From this reviewer’s perspective, dry needling is indeed just another technique. The WHO’s notion that a minimum of 2,500 hours would be required to practice acupuncture is irrelevant for using a technique that is also in the scope of acupuncture practice. As a side note, many acupuncture schools in the USA have less than 2,500 hours, while the average physical therapy education program consists of 2,676 hours, which confirms that physical therapists are well prepared to add dry needling to their treatment arsenal. Overlap to offer high-quality, affordable and accessible healthcare, it is crucial that all healthcare providers can practice within the full scope of their professional competencies (8,9). The Pew Health Commission Taskforce on Health Care Workforce Regulation emphasized that near-exclusive scopes of practice lead to unreasonable barriers to high-quality and affordable care [10]. Of interest is that the WHO confirmed that “making use of acupuncture in modern medical care means taking it out of its traditional context and applying it as a therapeutic technique for a limited number of conditions for which it has been shown to be effective, without having to reconcile the underlying theories of modern and traditional medicine” and “some physicians or dental surgeons might wish to acquire proficiency in certain specific applications of acupuncture [for example, pain relief, or dental or obstetric analgesia] and for them flexibility would be needed in designing special courses adapted to their particular areas of interest” (11). Unfortunately, the arguments are too often based on misunderstanding, a lack of communication, and just plain turf wars [JD]. CASE REPORTS Koo TK, Cohen JH, Zheng Y: Immediate effect of Nimmo receptor tonus technique on muscle elasticity, pain perception, and disability in subjects with chronic low back pain. J Manipul Physiol Ther35(1):45–53, 2012. Summary In this experimental controlled multiple case study, 14 subjects [aged between 18 and 50 years] were


Myofascial Pain Syndrome included with a history of at least three months of musculoskeletal pain in the lower back or legs. Subjects had at least one trigger point [TrP] in the gluteus medius muscle, a pain level of more than three points on a 10-point visual analog scale [VAS] and a score on the Oswestry Index [ODI] of at least 10 percent. The effects of two different TrP treatment approaches were compared using a within-day repeated-measures design study. After an initial session, during which only primary TrPs were addressed, the second session was used to establish baseline measurement data for muscle elasticity or stiffness in the gluteus medius muscle. The researcher used a rate-controlled mechano-acoustic indentor system, measuring muscle thickness and load–deformation response under large deformation [L–Dresponse]. During the second session, primary and secondary TrPs were treated. Since three subjects were excluded because of poor ultrasound echo signals, elasticity measurements of 11 subjects were used for analyses. All treatments were provided by the same Nimmotrained chiropractic physician, who had more than 30 years of experience in TrP management. Every subject was first treated with a simple TrP technique, which consisted of applying mild pressure on the gluteus medius muscle TrP with the thumb or index finger for 5–7 s for several cycles until the clinician perceived that the TrP was resolved. Immediately after this treatment, the L-D-response was measured, after which a full Nimmo treatment protocol was used. The Nimmo technique was described as a technique that involves locating and eliminating all primary and secondary TrPs by applying mild pressure for 5–7 s in sequence for several cycles until the TrPs resolve. Immediately following the intervention, the L–Dresponse was measured again. The VAS was scored at intake [P1] before the first treatment [P2], after the second treatment [P3], and finally 24 h after completion of the treatment [P4]. The ODI was measured at intake and 24 h after completion of the treatment. The muscle stiffness gradually decreased during the treatments, but the strongest decline was after the second treatment. The VAS scores decreased with the smallest and not statistically significant difference between P3 and P4 [during the full Nimmo treatment]. The mean ODI score difference was 9.4. This study shows that that applying pressure on primary and secondary TrPs has an effect on pain, disability scores, and tissue compliance. Comments In most cases, patients with musculoskeletal pain have multiple TrPs. This study shows that the manual

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treatment of all TrPs gives better results than the treatment of just one TrP. From this paper, it remains unclear what the special features of the Nimmo technique are. Since this paper was published in a chiropractic publication, and the authors referenced previous papers in which they described the Nimmo technique in more detail, it appears that they assumed that the readers would be familiar with the Nimmo technique [readers of this journal may want to read The Collected Writings of Nimmo & Vannerson: Pioneers of Chiropractic Trigger Point Therapy by Schneider, Cohen, and Laws]. The authors provided no information about any randomization or blinding procedures. Therefore, serious bias may have occurred. Because the first session was followed by a more comprehensive second session, the results may have been caused by the summation of effects of both sessions. It also remains unclear whether repeated measurements by themselves may cause similar effects [CB]. Usman F, Bajwa A, Shujaat A, Curry J: Retrosternal abscess after trigger point injections in a pregnant woman: a case report. J Med Case Rep 5:403, 2011. This is a case report of a 37-year-old female patient who presented with a gas-containing abscess in the retrosternal region behind the manubrium with associated sclerosis and cortical irregularity of the manubrium. They described that retrosternal abscesses may be due to staphylococcus or mycobacterium infections following mediastinitis, cardiopulmonary resuscitation, or sternal bone marrow aspiration. The patient’s history was significant for having received trigger point [TrP] injections for left-sided chest pain. Reportedly, some of the TrP injections were in the sternoclavicular joint, which by definition would not be considered a TrP injection. The authors attributed the abscess to the TrP injections, but they did not consider that possibly the patient’s abscess was not recognized by the physician who performed the TrP injections. The chest pain may have been attributed to chest wall TrPs instead of the underling abscess. Either way, this case report supports the need for a solid differential diagnostic process [JD]. Hudes K: Conservative management of a case of medial epicondylosis in a recreational squash player. J Can Chiropr Assoc 55(1):26–31, 2011. A 35-year-old male presented with forearm pain. He was an avid squash player with recurrent complaints of muscle weakness and pain associated with playing squash, but also with reaching and gripping. Physical examination by the chiropractor,

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who prepared this article, revealed a tender point in the pronator teres muscle. He was diagnosed with medial epicondylosis. He was treated with various soft tissue mobilization techniques, including fascial stripping, trigger point compression, and general mobilizations of the scaphoid joints, combined with eccentric exercises, which resolved his pain. The author concluded the paper with a lengthy discussion section, in which she contemplated various considerations for the successful outcome. As a case report, no definitive conclusions can be drawn, why this patient benefitted from the soft tissue techniques and exercise program. The treatment of trigger points was one of the interventions [JD]. Gonzalez-Iglesias, J, Cleland, JA, Del Rosario Gutierrez-Vega, M and Fernández- de lasPeñas, C: Multimodal management of lateral epicondylalgia in rock climbers: a prospective case series. J Manipulative Physiol Ther 34:635–642, 2011. This prospective case series from Spain describes the treatment of lateral epicondylalgia in nine rock climbers, who presented with a chief complaint of lateral elbow pain. Physical examination included an assessment of cervical and thoracic spinal segments, an evaluation of trigger points [TrPs], and pain pressure threshold measurements. Treatment was provided three times per week for three weeks and included manual therapy of the cervical spine, elbow and wrist, kinesio taping, and TrP dry needling. The researchers employed the Patient-Rated Tennis Elbow Evaluation as the main outcome measure. There was an improvement in all outcome measures at each follow-up period. Since this study was designed as a case series, the researchers did not include a control group. Yet, it appeared that in this

small sample, a multi-modal approach, that included TrP dry needling, was beneficial [JD]. Declaration of interest: The author reports no conflict of interest. The author alone is responsible for the content and writing of this paper. REFERENCES 1 Brückle W, Sückfull M, Fleckenstein W, Weiss C, Müller W: Gewebe-pO2-Messung in der verspanntenRückenmuskulatur (m. erector spinae). Z Rheumatol 49:208–216, 1990. 2 Ballyns JJ, Shah JP, Hammond J, Gebreab T, Gerber LH,Sikdar S: Objective sonographic measures for characterizing myofascial trigger points associated with cervical pain. J Ultrasound Med 30(10): 1331–1340, 2011. 3 Sikdar S, Shah JP, Gebreab T, Yen RH, Gilliams E, Danoff J, Gerber LH: Novel applications of ultrasound technology to visualize and characterize myofascial trigger points and surrounding soft tissue. Arch Phys Med Rehabil 90(11):1829–1838, 2009. 4 Dworkin SF, LeResche L: Research diagnostic criteria for temporomandibular disorders: review, criteria, examinations and specifications, critique. J Craniomandib Disord Facial Oral Pain 6:301–355, 1992. 5 Dworkin SF, Sherman J, Mancl L, Ohrbach R, LeResche L, Truelove E: Reliability, validity, and clinical utility of the research diagnostic criteria for Temporomandibular Disorders Axis II Scales: depression, non-specific physical symptoms, and graded chronic pain. J OrofacPain 16(3):207–220, 2002. 6 Schiffman EL, Truelove EL, Ohrbach R, Anderson GC, John MT, List T,Look JO: The research diagnostic criteria for temporomandibular disorders. I: Overview and methodology for assessment of validity. J Orofac Pain 24(1):7–24, 2010. 7 Adrian L: Intramuscular manual therapy (dry needling), Federation of State Boards of Physical Therapy: Alexandria, 2010 8 Safriet BJ: Impediments to progress in health care workforce policy: license and practice laws. Inquiry 31(3):310–317, 1994. 9 Schmitt MH: Collaboration improves the quality of care: methodological challenges and evidence from US health care research. J Interprof Care 15(1):47–66, 2001. 10 Finocchio LJ, Dower CM, McMahon T, Gragnola CM: Taskforce on health care workforce regulation: reforming health care workforce regulation: policy considerations for the 21st century, Pew Health Professions Commission: San Francisco, 1995. 11 World Health Organization: Guidelines on basic training and safety in acupuncture. Geneva, 1999.