Botulinum toxin A for myofascial trigger point injection: a qualitative systematic review.

Botulinum toxin injection is used to treat various pain conditions including muscle spasticity, dystonia, headache and myofascial pain. Results are conflicting regarding the use of Botulinum toxin for trigger point injection in terms of improvement in pain. The aim of this study was to carry out a systematic review to assess the evidence for efficacy of Botulinum toxin A (BTA) compared with placebo for myofascial trigger point injection. Electronic databases on Medline, Cochrane Library, Scopus, CINAHL were queried using key words such as "botulinum toxin", "myofascial pain", "trigger point", "chronic pain" and "musculoskeletal pain". Relevant published randomized controlled trials that described the use of BTA as injection therapy for trigger points were considered for inclusion. The five-item 0-16 point Oxford Pain Validity Scale (OPVS) was used as a selection criteria for suitable clinical trials. Trials were also assessed based on quality using the Oxford Rating Scale. Data extracted from qualified trials included outcome measures such as pain intensity and pain pressure threshold. All studies were ranked according to the OPVS and the authors' conclusions were compared. Five clinical trials met the inclusion criteria. One trial concluded that BTA was effective, and four concluded that it was not effective for reducing pain arising from trigger points. OPVS scores ranged from 8 to 14 with the negative studies corresponding with higher validity scores. The current evidence does not support the use of BTA injection in trigger points for myofascial pain. The data is limited and clinically heterogeneous.     

Botulinum toxin A versus bupivacaine trigger point injections for the treatment of myofascial pain syndrome: a randomised double blind crossover study

The treatment of myofascial pain syndrome (MPS) is diverse and includes trigger point injections of various substances including local anesthetics, steroids and Botulinum toxin A (BTX A). The purpose of this study was to compare the effectiveness of trigger point injections using BTX A versus bupivacaine, both in combination with a home-based rehabilitation program. To be enrolled, subjects first had to demonstrate responsiveness to bupivacaine trigger point injection. In this single center, double blind, randomized, cross-over trial, 18 patients with MPS received trigger point injections of either 25 units Botulinum toxin A or 0.5 ml of 0.5% bupivacaine per trigger point. A maximum of eight trigger points were injected per subject. Subjects were followed until their pain returned to 75% or more of their pre-injection pain for two consecutive weeks, after which there was a 2 week wash-out period. The subjects then crossed over and had the same trigger points injected with the other agent. All subjects participated in a home exercise program involving static stretches of the affected muscles. Both treatments were effective in reducing pain when compared to baseline (P=0.0067). There was, however, no significant difference between the BTX A and 0.5% bupivacaine groups in duration or magnitude of pain relief, function, satisfaction or cost of care (cost of injectate excluded). Considering the high cost of BTX A, bupivacaine is deemed a more cost-effective injectate for MPS.     

Botulinum toxin for the treatment of musculoskeletal pain and spasm

The impressive pain relief experienced by sufferers of dystonia and spasticity from intramuscular injections of botulinum toxin suggested that patients with other chronic, musculoskeletal pain conditions also may benefit. However, there have been relatively few placebo-controlled studies of botulinum toxin in such non-neurologic conditions as myofascial pain syndrome, chronic neck and low back pain, and fibromyalgia; the results of these studies have not been impressive. One explanation for the lack of positive findings may be the lack of clinically evident muscle spasms (overactivity), despite the presence of muscle tenderness, tightness, or trigger points. Clinical observations of pain relief from injections of botulinum toxin for dystonia and spasticity and its apparent efficacy in treating migraine suggest an anti-nociceptive action independent of its neuromuscular junction-blocking action. Evidence from animal experiments supports this notion, and other data provide plausible physiologic mechanisms in the periphery and central nervous systems. These involve modulation of the activity of the neurotransmitters glutamate, substance P, calcitonin gene-related peptide, enkephalins, and others. However, even if botulinum toxin is firmly established as an analgesic, there is insufficient clinical evidence of its efficacy in treating non-neurologic, chronic, musculoskeletal pain conditions.     

Botulinum Toxin Treatment of Myofascial Pain: A Critical Review of the Literature

This is a review of literature relevant to the treatment of myofascial pain syndrome by botulinum injections. The objective is to critically review the studies to see if they are appropriately designed, conducted, and interpreted to provide guidance in the management of myofascial pain. The intent is to better understand the mixed results that these studies have provided. A search was made utilizing PubMed for literature relevant to the use of botulinum toxin in the treatment of myofascial pain. All identifiable series were reviewed, including open label, single-blinded and double-blinded studies, randomized and controlled, or not. In general, small case series of only a few patients were not included unless they made a relevant point and there were no available randomized studies or larger studies. Single case reports were not included. This is not a meta-analysis. The studies were evaluated according to their design and the selection of outcome measurements, and the interpretation of results. The studies were individually critiqued, and an overall assessment and commentary was made of the studies in the field as a whole. Problems that were common to the studies were robust placebo responders, incomplete treatment of a regional myofascial pain syndrome, inappropriate or confounding control populations or treatments, and inappropriate time periods for assessment of outcomes, or misinterpretation of the time-frame of action of botulinum toxin. The studies of the effect of botulinum toxin treatment of myofascial trigger points have had mixed results. However, few studies have been designed to avoid many of the pitfalls associated with a trial of botulinum toxin treatment of trigger points. Better-designed studies may give results that can be used to guide practice based on reliable evidence. At the present time, one must conclude that the available evidence is insufficient to guide clinical practice.     

Evidence for the Use of Botulinum Toxin in the Chronic Pain Setting—A Review of the Literature

▪ Abstract:   A significant proportion of chronic pain is of musculoskeletal origin. Botulinum toxin (BTX) has been successfully used in the treatment of spasmodic torticollis, limb dystonia, and spasticity. Investigators have, thus, become interested in its potential use in treating many chronic pain conditions. Practitioners have used BTX, outside the product license, in the treatment of refractory myofascial pain syndrome and neck and low back pain (LBP). This article reviews the current evidence relating to chronic pain practice. There is evidence supporting the use of both BTX type A and type B in the treatment of cervical dystonias. The weight of evidence is in favor of BTX type A as a treatment in: pelvic pain, plantar fasciitis, temporomandibular joint dysfunction associated facial pain, chronic LBP, carpal tunnel syndrome, joint pain, and in complex regional pain syndrome and selected neuropathic pain syndromes. The weight of evidence is also in favor of BTX type A and type B in piriformis syndrome. There is conflicting evidence relating to the use of BTX in the treatment whiplash, myofascial pain, and myogenous jaw pain. It does appear that BTX is useful in selected patients, and its duration of action may exceed that of conventional treatments. This seems a promising treatment that must be further evaluated. ▪     

The effect of small doses of botulinum toxin a on neck-shoulder myofascial pain syndrome: a double-blind, randomized, and controlled crossover trial

OBJECTIVES: Myofascial pain syndrome is a common cause of muscular pain in the shoulder-neck region. Injections of large amounts of botulinum toxin A have been found to be beneficial for the alleviation of myofascial pain, but large doses of this toxin may cause paresis of the muscle and other adverse events. The aim of this work was to determine the effect of small doses (5 U) of botulinum toxin A (BTA) injected directly into the painful trigger points of the muscles, using a double-blind crossover technique. METHODS: On the basis of the empirical criteria proposed for diagnosis of myofascial pain syndrome, 31 patients suffering from myofascial pain in the neck-shoulder region were studied. The patients received either botulinum toxin A or physiological saline injections on 2 occasions 4 weeks apart. The total dose varied from 15 to 35 U of botulinum toxin A [28+/- 6 U (mean+/- SD)]. The follow-up measurements were carried out at 4 weeks after each treatment. Neck pain and result of treatment were assessed with questionnaires. The pressure pain threshold was determined using a dolorimeter. RESULTS: Neck pain values decreased from 4.3+/- 2.4 to 3.3+/- 2.0 after saline injections and from 4.1+/- 2.1 to 3.3+/- 2.2 after botulinum toxin A. The pressure pain threshold values increased from 5.2+/-1.6 to 5.9+/-1.5 and from 5.7+/-1.6 to 5.9+/-1.6 after injections with saline and botulinum toxin A, respectively. No statistically significant changes in the neck pain and pressure pain threshold values occurred between the botulinum toxin A and saline groups. After the first injections, the subjective result of treatment was significantly (P=0.008) in favor of botulinum toxin A, and after the second injections, the subjective result was better for saline, but the difference was not statistically significant (P=0.098). There was no significant difference in the prevalence of side effects between saline and botulinum toxin A. CONCLUSIONS: Our study shows that there was no difference between the effect of small doses of botulinum toxin A and those of physiological saline in the treatment of myofascial pain syndrome.     

Analgesic Effect of Botulinum Toxin A in Myofascial Pain Syndrome Patients Previously Treated with Local Infiltration of Anesthetic and Steroids

The purpose of this study was to evaluate the analgesic effect of botulinum toxin A (BoNTA) injections in patients with myofascial pain syndrome (MPS) who were previously treated with the local infiltration of anesthetic and steroids (LIAS). The study included a retrospective phase and a longitudinal open-label prospective phase, which were conducted on consecutive patients with MPS previously treated with the local infiltration of anesthetic (levobupivacaíne 0.25%) and steroids (triamcinolone 40 mg). Eligible patients were treated with a single intramuscular injection of BoNTA (Botox; Allergan, Inc., Irvine, CA). The treatment efficacy was determined according to the degree of pain relief obtained. Eighty-two patients met the inclusion/exclusion criteria and were included in the study. Successful results were obtained for 32 (39.0%) and 30 (36.6%) patients, during treatment with BoNTA and LIAS, respectively. The mean (standard deviation) length of the analgesic effect was significantly longer with BoNTA (29.6 [SD = 17.7] weeks) than with LIAS (8.5 [SD = 6.4] weeks), P <.0001. As regards the side effects, 19 (23.2%) patients reported transient soreness at the injection site for 2 to 3 days with BoNTA. The MPS patients previously treated with a local infiltration of anesthetic and steroids who then received a single injection of BoNTA experienced significantly reduced pain for a relatively long time.     

Are "cervicogenic" headaches due to myofascial pain and cervical spine dysfunction?

The purpose of this investigation was to evaluate whether the pain of cervicogenic headache could be due to referred symptoms from myofascial trigger points. The presence or absence of cervical spine dysfunction was also of interest. Eleven patients with cervicogenic headaches were systematically examined for myofascial trigger points and cervical spine dysfunction. All patients had at least three myofascial trigger points on the symptomatic side. In eight of these patients, trigger point palpation clearly reproduced their headache. There were 70 myofascial trigger points (35 "very tender", 35 "tender") and 17 non-myofascial tender points on the symptomatic side, compared to 22 myofascial trigger points (one "very tender", 21 "tender") and 19 non-myofascial tender points on the asymptomatic side. These differences were statistically significant [chi-square (2df) = 22.04, p less than 0.0001]. All patients had some evidence of cervical dysfunction. Ten patients (91%) had specific segmental dysfunction of occiput on atlas and/or atlas on axis. Five patients were entered into a non-invasive, interdisciplinary pain management program designed to treat cervical spine dysfunction and myofascial pain. Treated patients reported a significant decrease in the frequency and intensity of their headaches during a median two-year follow-up. It is concluded that myofascial trigger points may be an important pain producing mechanism in cervicogenic headache and that segmental cervical dysfunction is a common feature in such patients. Conservative, non-surgical treatment appears to be effective in reducing the frequency and intensity of cervicogenic headache. These data suggest that surgical approaches should be reserved only for those patients who fail conservative therapy.     

激痛点缺血性压迫治疗颈肩肌筋膜疼痛综合征疗效观察

目的:观察激痛点缺血性压迫法治疗颈肩肌筋膜疼痛综合征的疗效。方法:选择颈肩肌筋疼痛膜综合征患者20例,按照随机数字表法分为对照组和治疗组,每组10例。对照组仅接受健康宣教;治疗组在对照组基础上实施激痛点缺血性压迫疗法。首先通过Booster Pro3筋膜枪渐次提高振动频率的方法松解斜方肌上束,提高痛阈,达到放松并激活上斜方肌的目的,随后使用缺血性压迫激痛点的方法进行干预,治疗1次/d,连续治疗2周。分别在治疗前、后,采用肌力与脊柱活动度测量仪测量颈部关节活动度与肌力,采用疼痛视觉模拟评分法(VAS)评价颈肩部的疼痛程度,采用颈椎功能障碍指数(NDI)评价颈部功能障碍水平。结果:与治疗前比较,治疗第1次结束即刻治疗组左右侧肌力明显增加,治疗后2周治疗组颈部关节活动度(前屈方向)、左右侧肌力明显增加,左屈、右屈、右旋方向上的VAS评分与NDI评分明显降低,差异有统计学意义(P<0.05);与对照组比较,治疗后2周治疗组颈部关节活动度(前屈方向)、左右侧肌力更高,左屈、右屈、右旋方向上的VAS评分与NDI评分更低,差异有统计学意义(P<0.05)。结论:激痛点缺血性压迫疗法治疗颈肩肌筋膜疼痛综合征,可以有效提高MPS患者颈部关节活动度、左右侧肌力,缓解颈部肌肉僵硬不适和疼痛,改善颈椎功能障碍状态,值得临床推广应用。     

Trigger points and myofascial pain: toward understanding how they affect headaches

Myofascial pain, referred from hyperalgesic trigger points located in skeletal muscle and its associated fascia, is a common cause of persistent regional pain. Clinical and experimental literature on manifestations, pathophysiology, and management of pain from myofascial trigger points is reviewed with priority given to how pain referred from trigger points generates, triggers, and maintains headaches—especially chronic and recurrent ones. Because treating myofascial problems may be the only way to offer complete relief from certain types of headache, clinicians must learn to diagnose and manage trigger points in neck, shoulder, and head muscles.     

Effect of botulinum toxin on endplate noise in myofascial trigger spots of rabbit skeletal muscle

OBJECTIVE: To assess the effect of botulinum toxin type A (BTX-A) on the endplate noise prevalence in rabbit myofascial trigger spots to confirm the role of excessive acetylcholine release on the pathogenesis of myofascial trigger points and to develop an objective indicator of the effectiveness of BTX-A in the treatment of myofascial trigger points. DESIGN: Eighteen adult New Zealand rabbits were divided into three groups that received a single bolus of BTX-A over a myofascial trigger spot region on one side of the biceps femoris muscle. Another 10 rabbits received multiple-point injections in a myofascial trigger spot where endplate noises were found. A control study was performed on the other side of the biceps femoris muscle. The endplate noise prevalence in a myofascial trigger spot region was assessed. RESULTS: It was found that injection of BTX-A reduced the prevalence of endplate noise. No significant differences between a single bolus injection and multiple-point injections were noted, although there was some evidence that multiple-point injections might maintain the endplate noise decreasing effect much longer than a single injection. CONCLUSIONS: This study demonstrated the suppressive effect of BTX-A on endplate noise prevalence in a myofascial trigger spot region. The prevalence of endplate noise in the myofascial trigger point region may be a useful objective indicator for evaluating the therapeutic effectiveness of BTX-A injection to treat myofascial trigger points.     

Uncovering the biochemical milieu of myofascial trigger points using in vivo microdialysis: An application of muscle pain concepts to myofascial pain syndrome

This article discusses muscle pain concepts in the context of myofascial pain syndrome (MPS) and summarizes microdialysis studies that have surveyed the biochemical basis of this musculoskeletal pain condition. Though MPS is a common type of non-articular pain, its pathophysiology is only beginning to be understood due to its enormous complexity. MPS is characterized by the presence of myofascial trigger points (MTrPs), which are defined as hyperirritable nodules located within a taut band of skeletal muscle. MTrPs may be active (spontaneously painful and symptomatic) or latent (non-spontaneously painful). Painful MTrPs activate muscle nociceptors that, upon sustained noxious stimulation, initiate motor and sensory changes in the peripheral and central nervous systems. This process is called sensitization. In order to investigate the peripheral factors that influence the sensitization process, a microdialysis technique was developed to quantitatively measure the biochemical milieu of skeletal muscle. Biochemical differences were found between active and latent MTrPs, as well as in comparison with healthy muscle tissue. In this paper we relate the findings of elevated levels of sensitizing substances within painful muscle to the current theoretical framework of muscle pain and MTrP development.     

Evidence for Antinociceptive Activity of Botulinum Toxin Type A in Pain Management

The neurotoxin, botulinum toxin type A, has been used successfully, in some patients, as an analgesic for myofascial pain syndromes, migraine, and other headache types. The toxin inhibits the release of the neurotransmitter, acetylcholine, at the neuromuscular junction thereby inhibiting striated muscle contractions. In the majority of pain syndromes where botulinum toxin type A is effective, inhibiting muscle spasms is an important component of its activity. Even so, the reduction of pain often occurs before the decrease in muscle contractions suggesting that botulinum toxin type A has a more complex mechanism of action than initially hypothesized. Current data points to an antinociceptive effect of botulinum toxin type A that is separate from its neuromuscular activity. The common biochemical mechanism, however, remains the same between botulinum toxin type A's effect on the motor nerve or the sensory nerve: enzymatic blockade of neurotransmitter release. The antinociceptive effect of the toxin was reported to block substance P release using in vitro culture systems. ¹
The current investigation evaluated the in vivo mechanism of action for the antinociceptive action of botulinum toxin type A. In these studies, botulinum toxin type A was found to block the release of glutamate. Furthermore, Fos, a product of the immediate early gene, c- fos , expressed with neuronal stimuli was prevented upon peripheral exposure to the toxin.
These findings suggest that botulinum toxin type A blocks peripheral sensitization and, indirectly, reduces central sensitization. The recent hypothesis that migraine involves both peripheral and central sensitization may help explain how botulinum toxin type A inhibits migraine pain by acting on these two pathways. Further research is needed to determine whether the antinociceptive mechanism mediated by botulinum toxin type A affects the neuronal signaling pathways that are activated during migraine.     

A systematic review of manual therapy techniques,dry cupping and dry needling in the reduction of myofascial pain and myofascial trigger points

IntroductionMyofascial pain with myofascial triggers are common musculoskeletal complaints. Popular treatments include manual therapy, dry needling, and dry cupping. The purpose of this systematic review was to compare the efficacy of each treatment in the short-term relief of myofascial pain and myofascial trigger points.MethodsSearch engines included Google Scholar, EBSCO Host, and PubMed. Searches were performed for each modality using the keywords myofascial pain syndrome and myofascial trigger points. The inclusion criteria included English-language, peer-reviewed journals; a diagnosis of myofascial pain syndrome or trigger points; manual therapy, dry needling, or dry cupping treatments; retrospective studies or prospective methodology; and inclusion of outcome measures.ResultsEight studies on manual therapy, twenty-three studies on dry needling, and two studies on dry cupping met the inclusion criteria. The Physiotherapy Evidence Database (PEDro) was utilized to assess the quality of all articles.DiscussionWhile there was a moderate number of randomized controlled trials supporting the use of manual therapy, the evidence for dry needling ranged from very low to moderate compared to control groups, sham interventions, or other treatments and there was a paucity of data on dry cupping. Limitations included unclear methodologies, high risk for bias, inadequate blinding, no control group, and small sample sizes.ConclusionWhile there is moderate evidence for manual therapy in myofascial pain treatment, the evidence for dry needling and cupping is not greater than placebo. Future studies should address the limitations of small sample sizes, unclear methodologies, poor blinding, and lack of control groups.     

灰阶超声联合剪切波弹性成像评估肌筋膜疼痛综合征患者肌筋膜疼痛触发点

目的 探讨灰阶超声联合剪切波弹性成像（SWE）技术评估肌筋膜疼痛综合征（MPS）患者肌筋膜疼痛触发点（MTrPs）处肌肉形态及组织学特性的价值。方法 以28例MPS患者（36个MTrPs）为病例组,33名健康志愿者（33个正常肌肉点）为对照组。由2名检查者分别测量病例组MTrPs （上斜方肌）厚度、剪切波传播速度（SWV）及杨氏模量值（E）,1名检查者测量对照组上述参数,1周后2组均重复测量。采用组内相关系数（ICC）评价2名检查者检测结果的一致性,以Pearson检验分析MPS患者疼痛视觉模拟量表（VAS）评分与上斜方肌厚度、SWV及E的相关性。结果 2名检查者重复测量一致性、时间一致性及检查者间一致性均好或优（ICC 0.73~0.98）。病例组MPS患者上斜方肌厚度、SWV及E均高于对照组,差异均有统计学意义（P均<0.05）。MPS患者VAS评分与上斜方肌厚度无相关性（r=0.016,P=0.945）,与SWV （r=0.709,P<0.001）、E （r=0.653,P=0.002）均呈正相关。结论 灰阶超声联合SWE可定量评估MPS患者MTrPs处肌肉形态及组织学特性。     

Myofascial component of cancer pain review

BackgroundPain is a common complaint of cancer patients, experienced by 38%–85% of patients. Some studies have shown a high incidence of myofascial pain syndrome (MPS) in cancer patients.Aims1) To estimate the prevalence of MPS in cancer patients; 2) to examine the efficacy of current treatment options for MPS in cancer patients.MethodsNarrative review. PubMed, CINAHL, PEDro, and Google Scholar databases were searched from inception until November 2017, for the keywords: cancer; cancer pain; breast cancer; mastectomy; lumpectomy; myofascial pain; trigger points. Trials of any methodological quality were included. All published material with an emphasis on randomized control trials was analyzed.ResultsMPS is prevalent in cancer patients who suffer from pain, with a prevalence of between 11.9% and 44.8% in those diagnosed either with neck or head or breast cancer. Clinical studies showed conflicting results. Four interventional studies found that specific treatment for MPS may reduce the prevalence of active myofascial trigger points and therefore decrease pain level, sensitivity, and improve range of motion (in shoulder) in cancer patients. Two recent randomized control trials showed that pressure release of trigger points provides no additional beneficial effects to a standard physical therapy program for upper limb pain and function after breast cancer surgery.ConclusionsWe recommend including the evaluation of myofascial pain in routine clinical examination of cancer patients suffering from pain. Future studies are needed to investigate the long- and short-term effect of MPS treatments in cancer patients.     

Botulinum Toxin A, Adjunctive Therapy for Refractory Headaches Associated With Pericranial Muscle Tension

Pericranial muscle tension may contribute to the development of facial discomfort, chronic daily headache, and migraine-type headache. Elimination of pericranial muscle tension may reduce associated myalgia and counteract influences that can trigger secondary headaches which fall within the migraine continuum. Four patients with chronic, predominantly tension-type headaches and associated pericranial muscles tension failed prolonged conventional treatment and, therefore, symptomatic areas were treated with botulinum toxin A. This alleviated myalgia and reduced the severity and frequency of migraine-type headaches with a concomitant reduction in subsequent medical and physical therapy interventions. Judicious use of botulinum toxin A into defined areas of pericranial muscle tension may be useful for reducing primary myalgia and secondary headache.     

Expert consensus on the diagnosis and treatment of myofascial pain syndrome

Myofascial pain syndrome (MPS) is characterized by myofascial trigger points and fascial constrictions. At present, domestic and foreign scholars have not reached a consensus on the etiology and pathogenesis of MPS. Due to the lack of specific laboratory indicators and imaging evidence, there is no unified diagnostic criteria for MPS, making it easy to confuse with other diseases. The Chinese Association for the Study of Pain organized domestic experts to formulate this Chinese Pain Specialist Consensus on the diagnosis and treatment of MPS. This article reviews relevant domestic and foreign literature on the definition, epidemiology, pathogenesis, clinical manifestation, diagnostic criteria and treatments of MPS. The consensus is intended to normalize the diagnosis and treatment of MPS and be used by first-line doctors, including pain physicians to manage patients with MPS.     

Pathophysiology of Trigger Points in Myofascial Pain Syndrome

Questions from patients about pain conditions and analgesic pharmacotherapy and responses from authors are presented to help educate patients and make them more effective self-advocates. Trigger point pathophysiology in myofascial pain syndrome, which involves muscle stiffness, tenderness, and pain that radiates to other areas of the body, is considered. The causes of trigger points and several theories about how they develop are reviewed, and treatment approaches, including stretching, physical therapy, dry needling, and injections, are offered.     

Subacromial impingement syndrome as a consequence of botulinum therapy to the upper trapezii: a case report

Scapular upward rotation is predominantly achieved via a force coupling involving the upper and lower trapezius and the serratus anterior. Although studies have shown a relationship between abnormal scapular motion and subacromial impingement, it has been unclear whether the altered scapular biomechanics represent a cause, or consequence, of impingement. We present a 49-year-old woman with refractory myofascial pain of many years duration who developed subacromial impingement syndrome (SIS) following a series of botulinum toxin injections to the bilateral upper trapezii. Although botulinum therapy effectively reduced the patient's refractory myofascial pain, signs and symptoms of SIS developed in association with the upper trapezii weakness after the third set of injections. Botulinum therapy was discontinued and nonsteroidal anti-inflammatory medication markedly reduced the new symptoms, which completely resolved within 3 months. This case, which afforded a unique opportunity to follow the consequences of weakening scapular stabilizers over time, provides evidence for the etiologic role of scapular dyskinesis in SIS and shows that SIS is a potential complication of botulinum therapy for myofascial pain involving the scapular stabilizers.