Thoracic outlet syndrome (TOS) results from compression of the neurovascular bundle in the thoracic outlet. Several etiologies can contribute to the development of thoracic outlet syndrome, including both congenital and acquired causes. Historically, trapezius pathology has not been considered a cause of TOS; however, here we report a patient with neurogenic TOS plus ipsilateral trapezius hypertonicity and hypertrophy who had significant symptomatic improvement following botulinum toxin injections to trapezius

Jeong, Won Jae

Paily, Paul

Philp, Jamie

English

DigitalCommons@The Texas Medical Center

The Texas Medical Center Library DigitalCommons@TMC Faculty and Staff Publications Baylor College of Medicine 7-1-2024 An Uncommon Culprit: Trapezius Dystonia as a Cause of Thoracic Outlet Syndrome: A Case Report Jamie Philp Won Jae Jeong Paul Paily Follow this and additional works at: https://digitalcommons.library.tmc.edu/baylor_docs  Part of the Medical Sciences Commons, Pediatrics Commons, Physical Therapy Commons, and the Sports Medicine Commons Review began 06/17/2024 Review ended 06/29/2024 Published 07/04/2024© Copyright 2024Philp et al. This is an open access articledistributed under the terms of the CreativeCommons Attribution License CC-BY 4.0.,which permits unrestricted use, distribution,and reproduction in any medium, providedthe original author and source are credited.An Uncommon Culprit: Trapezius Dystonia as aCause of Thoracic Outlet Syndrome: A CaseReportJamie Philp , Won Jae Jeong , Paul Paily 1. Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston, USACorresponding author: Jamie Philp, jamie.philp@bcm.eduAbstractThoracic outlet syndrome (TOS) results from compression of the neurovascular bundle in the thoracic outlet.Several etiologies can contribute to the development of thoracic outlet syndrome, including both congenitaland acquired causes. Historically, trapezius pathology has not been considered a cause of TOS; however,here we report a patient with neurogenic TOS plus ipsilateral trapezius hypertonicity and hypertrophy whohad significant symptomatic improvement following botulinum toxin injections to trapezius.Categories: Physical Medicine & RehabilitationKeywords: trapezius hypertrophy, botulinum toxin injection, trapezius tightness, thoracic outlet syndrome,neurogenic thoracic outlet syndromeIntroductionThoracic outlet syndrome (TOS) represents a group of disorders that arise due to compression of theneurovascular structures in the thoracic outlet. TOS can be classified as a neurogenic, arterial, or venoussubtype depending on the compressed structure [1,2]. The etiologies of TOS are variable and can includecongenital or acquired anatomic abnormalities, scalene or pectoralis muscle hypertrophy, and regionalfibrosis due to trauma or repetitive arm motion [3].Treatment of TOS typically involves a multidisciplinary approach tailored to the subtype and severity ofsymptoms. Conservative measures such as physical therapy focusing on posture correction, stretching, andstrengthening exercises are often first-line [4,5]. In cases refractory to conservative management, surgicaldecompression may be considered. Although several studies show the benefit of surgical interventions intreating TOS, other studies support conservative management over surgical treatment due to its adverseeffects or limited efficacy [6-11]. Alternatively, botulinum toxin injections to scalene, pectoralis minor, andsubclavius have also been performed; this less invasive approach has shown promise in alleviating thesymptoms of TOS, as temporary weakening of these muscles can help decompress the affected structures inthe thoracic outlet [12-14].Pathology of the trapezius muscle has not traditionally been considered as a cause of TOS as the trapeziusdoes not directly border the thoracic outlet; however, the superior fibers of the trapezius attach to the distalclavicle, a recognized border of the thoracic outlet. We hypothesize that hypertonicity and hypertrophy ofthe trapezius contribute to the development of TOS through its attachment to the distal clavicle.Overactivity of the trapezius, particularly the superior fibers, can pull the distal clavicle superiorly andposteriorly, narrowing the costoclavicular space of the thoracic outlet. Here, we report a patient withneurogenic TOS plus ipsilateral trapezius hypertonicity and hypertrophy who had significant symptomaticimprovement following botulinum toxin injections to trapezius. This supports the hypothesis that trapeziusoveractivity can contribute to the narrowing of the thoracic outlet and subsequent compression of thestructures within.Case PresentationA 36-year-old female professional golf player with a history of multiple left shoulder labral repairs about adecade ago presented with three years of persistent left shoulder pain and reduced range of motion, and oneyear of numbness, tingling, and coldness in the first, fourth, and fifth digits of the left hand. Physicalexamination showed a reduced passive and active range of motion in her left shoulder, and an attempt atoverhead activity resulted in pain in the trapezius, scalene, latissimus dorsi, and pectoral region. Given thepossible comorbidity of adhesive capsulitis, the patient underwent several weeks of physical therapy, whichsignificantly improved her shoulder range of motion. However, the patient continued to experiencenumbness, tingling, and coldness in her left digits, indicating a deeper underlying issue.Upon further physical examination, the patient was noted to have significant hypertrophy and tightness ofthe transverse trapezius, tenderness in the scalene and pectoral areas, and decreased grip strength on theleft side. Wright's test and Roos's test were positive, prompting suspicion of neurogenic thoracic outlet1 1 1 Open Access CaseReport  DOI: 10.7759/cureus.63825How to cite this articlePhilp J, Jeong W, Paily P (July 04, 2024) An Uncommon Culprit: Trapezius Dystonia as a Cause of Thoracic Outlet Syndrome: A Case Report.Cureus 16(7): e63825. DOI 10.7759/cureus.63825syndrome (NTOS). To exclude other possible diagnoses such as shoulder, cervical spine, or brachial plexuspathologies, various imaging, and interventions were performed: MRIs of the cervical spine and brachialplexus were unremarkable, and an intra-articular corticosteroid injection at the left shoulder provided norelief, suggesting a low likelihood of cervical spine, brachial plexus, or shoulder pathology and furthersupporting the diagnosis of NTOS. As a conservative therapeutic measure for NTOS, oral methocarbamolwas prescribed, and the patient reported a mild but not dramatic improvement in her symptoms.Given her history of professional golfing and the exam finding of tightness and hypertrophy of the lefttrapezius, we theorized that these trapezius abnormalities could be the culprits causing her NTOS. Althoughshe also had tenderness in the scalene and pectoral areas, these muscles were not notably hypertoniccompared to her trapezius. Therefore, we hypothesized that botulinum toxin injection to the trapezius mayconfer greater benefit than injection to the scalene or pectoralis muscles. Thus, we injected botulinum toxininto the superior fibers of her left trapezius. Following the first injection, the patient experienced a transientexacerbation of symptoms, which subsided after two weeks, later leading to improvement. A subsequentinjection administered one year later resulted in marked improvement without any adverse effects. Overall,the patient reported a significant reduction of symptoms, with most days having minimal or no symptoms.The patient was able to return to her usual activities and is scheduled for a repeat botulinum toxin injectionto her left trapezius.DiscussionThe thoracic outlet is an anatomically complex region that spans from the supraclavicular fossa to the axilla.There are three areas where structures of the neurovascular bundle may be compressed within the thoracicoutlet: the inter-scalene triangle (bordered by the anterior and middle scalene muscles and first rib), thecostoclavicular space (bordered by the subclavius muscle, clavicle, and first rib), and the retro-pectoral space(bordered by pectoralis minor and ribs) [3]. The costoclavicular space is particularly relevant to ourhypothesis because abnormal positioning of the clavicle can compress the brachial plexus in this area. Thedistal clavicle serves as the attachment point for the superior fibers of the trapezius, which originate fromvarious points in the skull and neck and are inserted at the lateral third of the clavicle. When these fiberscontract, they pull the clavicle superiorly and posteriorly, narrowing the costoclavicular space and exertingtraction on the subclavius muscle. The subclavius, attaching the clavicle inferiorly to the first rib, contractsin response to counteract the trapezius's pull. This muscle action may explain the patient's tenderness in thisregion. Anatomically, the contractions of these muscles can cause functional disruption of the brachialplexus: the superior and posterior position of the clavicle compresses the brachial plexus posteriorly, whilethe subclavius's contraction elevates the first rib against the clavicle, further narrowing the costoclavicularspace.The diagnosis of NTOS is difficult as the differential diagnosis is broad, and there is no gold-standarddiagnostic test. The differential diagnosis of NTOS includes peripheral nerve entrapments, cervicalradiculopathy, brachial plexopathies, and various musculoskeletal conditions [15]. The diagnosis is usuallysuspected based on clinical presentation and specific risk factors. For example, in our patient’s case, the riskfactors include her age, sex, history of multiple shoulder surgeries, and repetitive activity from golf. Thediagnosis may also be supported by provocative physical exam maneuvers and radiographic findings,although radiographic findings may be normal. Over 90% of TOS cases are neurogenic TOS, with the lowerbrachial plexus most commonly compromised [3]. This patient’s risk factors, presentation, lack of responseto intra-articular corticosteroid injection, and positive response to muscle relaxants supported the diagnosisof NTOS.The first-line treatment for TOS is conservative and consists of physical therapy focused on stretching,weight control, and posture, as well as non-steroidal anti-inflammatory drugs (NSAIDs) and musclerelaxants. Antidepressants and anticonvulsants are also prescribed for neuropathic pain. Refractory casesare often managed with surgical decompression via first rib resection and/or scalenectomy [3]. The role ofsurgical intervention is debatable, however, as studies report mixed evidence regarding outcomes followingsurgical versus conservative management [6-11]. For example, a retrospective cohort performed by Orlandoet al. (2015) reported over 90% rates of improvement or resolution of symptoms after first rib resection [6].However, a study performed by Landry et al. (2001) reported no significant difference in functional outcomein patients who had first rib resection compared to conservative management over a mean follow-up periodof 4.2 years [7], and Franklin et al. (2000) reported over 70% of patients who received surgery still hadsignificant functional limitations over a mean follow-up period of 4.8 years [8]. Intraoperative complicationsof surgical management include pneumothorax, transient phrenic nerve injury, hematoma formation [9],and brachial plexus injury [10]. Patients may also require surgical revision due to tissue regrowth,inadequate resection, or scar tissue formation [16]. Thus, when the risks of surgery are weighed againstpotential benefits, surgical management of TOS remains controversial, particularly in patients with no clearanatomic abnormalities.As an alternative to the surgical approach, botulinum toxin injection has shown promise as a less invasivetherapeutic option for certain cases of TOS, particularly those with symptoms due to muscleoveractivity [12-14]. By temporarily weakening the targeted muscles, botulinum toxin injection can helpexpand the space of the thoracic outlet, reducing compression of the neurovascular structures and2024 Philp et al. Cureus 16(7): e63825. DOI 10.7759/cureus.63825 2 of 4alleviating symptoms [12]. This approach may be considered when conservative measures fail to provideadequate relief or in conjunction with other treatments in a comprehensive management plan for TOS. Thetarget muscles previously described in the literature for botulinum toxin injection consist of scalene,pectoralis minor, and subclavius as they surround the thoracic outlet [13,17-19]. So far, injection of thetrapezius muscle in treating TOS has never been described in literature except by Jordan et al. (2017);however, even in this study, the main targets were scalene, pectoralis minor, or subclavius muscles, andtrapezius was only additionally targeted to treat pain and dystonia [14].Although trapezius pathology has not been traditionally associated with the development of TOS, weobserved a patient whose presentation was consistent with NTOS in the context of ipsilateral trapeziushypertonicity and hypertrophy. She had significant symptomatic improvement following two injections ofbotulinum toxin to the hypertrophied trapezius, suggesting that the pathology of this muscle contributed toher symptoms. We hypothesize that trapezius hypertonicity and subsequent hypertrophy may contribute tothe development of TOS through its attachment at the distal clavicle. The superior and posterior positions ofthe clavicle, as well as the resulting activation of the subclavius elevating the first rib, together narrow thecostoclavicular space and compress the structures within. Thus, as demonstrated here, patients with TOSand concurrent trapezius hypertrophy can benefit from botulinum toxin injections to trapezius. Trapeziushypertrophy may be underdiagnosed in patients with TOS as it is not a traditional target of treatment;therefore, patients with TOS should be evaluated for trapezius hypertonicity as a potential target oftreatment. The reduction of trapezius hypertonicity (and subsequent reduction of hypertrophy) may providesymptomatic relief through physiologic decompression of this area.ConclusionsThoracic outlet syndrome results from compression of the neurovascular bundle in the thoracic outlet.Patients with symptoms refractory to physical therapy and NSAIDs have been managed with botulinumtoxin injections to the scalene and pectoralis muscles, as well as surgical decompression, with varying levelsof success. Here, we report a patient with neurogenic TOS with marked trapezius hypertonicity andhypertrophy who had significant symptomatic improvement with botulinum toxin injections to thetrapezius. Trapezius hypertrophy may contribute to the development of thoracic outlet syndrome byelevating the distal clavicle and narrowing the thoracic outlet. Botulinum toxin injection to the trapeziusmay help decompress the thoracic outlet and provide symptomatic relief as an effective nonoperativemanagement strategy for TOS.Additional InformationAuthor ContributionsAll authors have reviewed the final version to be published and agreed to be accountable for all aspects of thework.Concept and design:  Jamie Philp, Paul Paily, Won Jae JeongAcquisition, analysis, or interpretation of data:  Jamie Philp, Paul Paily, Won Jae JeongDrafting of the manuscript:  Jamie Philp, Paul Paily, Won Jae JeongCritical review of the manuscript for important intellectual content:  Jamie Philp, Paul Paily, Won JaeJeongSupervision:  Paul PailyDisclosuresHuman subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: Incompliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/servicesinfo: All authors have declared that no financial support was received from any organization for thesubmitted work. Financial relationships: All authors have declared that they have no financialrelationships at present or within the previous three years with any organizations that might have aninterest in the submitted work. Other relationships: All authors have declared that there are no otherrelationships or activities that could appear to have influenced the submitted work.References1. Huang JH, Zager EL: Thoracic outlet syndrome. Neurosurgery. 2004, 55:897-902; discussion 902-3.10.1227/01.neu.0000137333.04342.4d2. Li N, Dierks G, Vervaeke HE, et al.: Thoracic outlet syndrome: a narrative review . J Clin Med. 2021,10:10.3390/jcm100509623. Jones MR, Prabhakar A, Viswanath O, et al.: Thoracic outlet syndrome: a comprehensive review ofpathophysiology, diagnosis, and treatment. Pain Ther. 2019, 8:5-18. 10.1007/s40122-019-0124-22024 Philp et al. Cureus 16(7): e63825. DOI 10.7759/cureus.63825 3 of 44. Crosby CA, Wehbé MA: Conservative treatment for thoracic outlet syndrome. Hand Clin. 2004, 20:43-9.10.1016/s0749-0712(03)00081-75. Luu D, Seto R, Deoraj K: Exercise rehabilitation for neurogenic thoracic outlet syndrome: a scoping review . JCan Chiropr Assoc. 2022, 66:43-60.6. Orlando MS, Likes KC, Mirza S, et al.: A decade of excellent outcomes after surgical intervention in 538patients with thoracic outlet syndrome. J Am Coll Surg. 2015, 220:934-9. 10.1016/j.jamcollsurg.2014.12.0467. Landry GJ, Moneta GL, Taylor LM Jr, Edwards JM, Porter JM: Long-term functional outcome of neurogenicthoracic outlet syndrome in surgically and conservatively treated patients. 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An Uncommon Culprit: Trapezius Dystonia as a Cause of Thoracic Outlet Syndrome: A Case Report

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An Uncommon Culprit: Trapezius Dystonia as a Cause of Thoracic Outlet Syndrome: A Case Report

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