The Human Disharmony Loop: The Central and Villainous Roles of the Scapula and the Pectoralis Minor in Chronic Pain

The Human Disharmony Loop: The Central and Villainous Roles of the Scapula and the Pectoralis Minor in Chronic Pain | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article The Human Disharmony Loop: The Central and Villainous Roles of the Scapula and the Pectoralis Minor in Chronic Pain Ketan Sharma, James Friedman This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8569667/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Many patients suffer from chronic pain of the shoulder, neck, upper back, and/or arm. They may be diagnosed with fibromyalgia, complex regional pain syndrome, myofascial pain, thoracic outlet, subacromial pain, cervical radiculopathy, cervicogenic headaches, post-mastectomy pain, occupational shoulder disorder. These remain mysterious and challenging. The pectoralis minor (PM) is the only muscle of the scapula innervated by the lower trunk, potentially a sequela of the evolution from quadrupeds to bipeds. The Human Disharmony Loop (HDL) is a clinical model where this neurologic asymmetry renders the scapula prone to protraction, which pathologizes the full upper limb girdle and generates headaches and neck stiffness, upper back tightness, shoulder weakness, and hand numbness/tingling. We hypothesize some of the above diagnoses are manifestations of the HDL. 318 patients with the above who met HDL diagnostic criteria underwent PM tenotomy with brachial plexus neurolysis (PM + ICN). At 12 months, average pain decreased from 7.3/10 to 2.1/10, average shoulder abduction increased from 96 to 170 degrees, occipital headaches decreased from 77% to 2%. In summary, humans may be plagued by chronic pain because our scapula tends to protract, its ancestral quadrupedal state. Certain intractable patients may benefit substantially from PM + ICN. Health sciences/Diseases Health sciences/Medical research Health sciences/Neurology Biological sciences/Neuroscience Health sciences/Signs and symptoms Chronic pain upper limb scapula pectoralis minor Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Humans are plagued by chronic pain. The most common disability worldwide consumes over $ 650 billion in annual costs. 1 One-fifth of Americans suffer from chronic pain at any given time, of which two-thirds persist longer than a year. 2 Upper back and neck pain alone constitutes the fourth leading cause of disability. 3 Despite its ubiquity, chronic pain afflicting the upper limb girdle – neck, upper back, shoulder, and arm – continues to bewilder. An array of syndromes remains intractable, including thoracic outlet (TOS), scapular dyskinesis (SD), myofascial pain (MPS), fibromyalgia, complex regional pain syndrome (CRPS), work-related musculoskeletal disorder (WRMD), post-mastectomy pain syndrome (PMPS), cervical radiculopathy, subacromial pain (SAPS), and cervicogenic headaches. These feature some manifestation of pain – headaches, stiffness, tightness, weakness, numbness, and/or coolness – from the neck to the fingertips. They also share contentious diagnostic criteria, convoluted pathophysiology, and ineffectual treatments. 4 – 11 Chronic pain regrettably remains a disease with end goals of treatment and not cure. 12 The key to the upper limb is the scapula. 13 The scapula dynamically connects the body (thorax) to the arm (humerus), coordinating mobility and stability. To enable the full arc of overhead reach, the scapula glides along the thorax to perform two critical functions: optimizing excursion of the deltoid and rotator cuff and maintaining articular congruity to prevent impingement. The peri-scapular chain, comprised of the dorsal trapezius, levator scapulae, rhomboids, lateral serratus anterior, and ventral pectoralis minor (PM), controls this motion. Given its central role, abnormal scapulothoracic motion or SD can generate a wide array of dysfunction 14 , but continues to perplex, with numerous proposed causes that are likely associations instead. 15 Previously, we described the Human Disharmony Loop (HDL), a clinical model of upper limb dysfunction. 15 – 17 (Fig. 1 ) A neurologic asymmetry surrounds the scapula that may be a sequelae of our evolution from quadrupeds to bipeds: the dorsal peri-scapular chain is controlled by the upper C4-6 roots while the ventral PM carries lower C8-T1 innervation. 15 This renders the scapula prone to protraction, the direction of pull by the PM. Protraction deforms the scapula’s numerous connections and produces occipital headaches and neck stiffness, upper back tightness, shoulder weakness, and hand numbness/tingling. 16 (Fig. 2 ) Treatment consists of PM tenotomy with infraclavicular plexus neurolysis (PM + ICN), with secondary neurolysis if needed, to normalize scapular mechanics and reharmonize the limb girdle. Theoretically, the HDL anatomically incorporates the above chronic pain disorders (Fig. 3 ) and explains their symptoms via clear pathways (Fig. 4 ). Hence, we hypothesize some of these may be pathoanatomic sequelae of the PM warping scapular mechanics. In this paper, we report the outcomes of PM + ICN to treat chronic upper limb pain in patients who meet HDL criteria. Materials and Methods This is a retrospective case series of consecutive patients treated by a single fellowship-trained board-certified hand surgeon. Inclusion criteria included: age > 13 years and meeting HDL diagnostic criteria. Exclusion criteria included: follow-up < 12 months. Patients with any of the following diagnosed by the referring provider were included: TOS, SICK scapula/SD, MPS, fibromyalgia, CRPS, WRMD, SAPS, cervical radiculopathy, cervicogenic headaches, PMPS, Burner/Stinger. All patients trialed at least 6 weeks of therapy before surgery. Patients were evaluated pre-operatively and at 2, 6, 12, 24, and 52 weeks post-operatively. At each visit, patients completed a self-reported pain questionnaire. The scratch collapse test (SCT) identified neuropathic lesions at the thoracic outlet, PM, suprascapular notch, quadrilateral space, radial, cubital, and carpal tunnels. 18 Shoulder abduction range of motion (ROM) values were measured. Scapula dyskinesis on exam was classified as none (no protraction), dynamic (protraction with overhead reach only), or static (protraction at rest). 17 Each patient underwent PM + ICN, followed by physical therapy emphasizing anterior chain stretching and posterior chain strengthening. 15 , 17 At 12 weeks post-operatively, patients were offered secondary neurolysis for lingering pain or weakness. Outcomes included self-reported visual analogue scale pain scores out of 10, occipital headaches, neuropathic lesions, shoulder ROM, need for secondary neurolysis. Treatment response was qualitatively categorized via relative pain reductions as poor ( 50%). 19 Institutional Review Board (IRB) approval was obtained by the St. Luke’s Health System IRB, and need for consent was waived as the data was anonymous and posed minimal risk to patients. Student’s t -test and chi-squared analysis compared continuous and categorical variables of interest, respectively; two-tailed \(\:\alpha\:\) =0.05 was used for all tests. Statistical analysis was performed using STATA v14.0. Results N = 318 patients were included. Average age was 51. Sex was 68% female. Patients had a history of: TOS 17%, fibromyalgia 23%, CRPS 14%, WRMD 19%, MPS 33%, cervical radiculopathy 32%, Burner/Stinger syndrome 4%, SAPS 84%, SD 4%, PMPS 4%, cervicogenic headaches 69%. (Table 1 ) Following PM + ICN, average pain decreased from 7.3/10 to 2.1/10, headaches decreased from 77% to 2%, average shoulder abduction increased from 96 to 170 degrees. Scapular dyskinesis normalized from 99% static and 1% dynamic to 93% none, 6% dynamic and 1% static. Prevalence of clinical neuropathy decreased as follows: thoracic outlet 55% to 2%, suprascapular notch 58% to 2%, quadrilateral space 81% to 16%, radial tunnel 70% to 20%, cubital tunnel 21% to 20%, and carpal tunnel 42% to 16%. (All p < 0.01) Overall, 17% of patients required secondary neurolysis, most commonly of the radial (10%), ulnar (10%), and axillary (9%) nerves. Overall treatment response was 78% substantial, 18% important, and 4% poor. Average follow-up was 22 months. (Table 2 ) Table 1 Patient Characteristics & Clinical Presentation N = 318 patients Age 1 51.0 (49.2, 52.9) BMI 1 29.8 (29.0, 30.5) Gender Male 101 (32%) Female 217 (68%) Chronic Pain Syndromes Thoracic Outlet Syndrome 53 (17%) Fibromyalgia 73 (23%) Complex regional pain syndrome 45 (14%) Work-related musculoskeletal disorder 60 (19%) Myofascial pain syndrome 106 (33%) Cervical radiculopathy 104 (32%) Burner/Stinger 9 (3%) Subacromial pain syndrome 266 (84%) Scapular dyskinesis 13 (4%) Post-mastectomy pain syndrome 11 (4%) Cervicogenic headaches 220 (69%) Laterality Right 186 (59%) Left 132 (42%) Prior Surgery Subacromial decompression + adjunct 2 89 (28%) Total shoulder arthroplasty 27 (8%) 1st rib resection 5 (2%) Cervical fusion 53 (17%) Distal neurolysis 3 90 (28%) 1 Average (95% CI) 2 Adjunct procedures include rotator cuff repair, biceps tenodesis, distal clavicle excision, labrum repair 3 Includes carpal, cubital, radial tunnel release Table 2 Clinical Outcomes Pre-Operative Post-Operative P-Value Pain 1 7.3 (7.1, 7.5) 2.1 (1.3, 3) < 0.01 Concomitant Neuropathy Thoracic Outlet 174 (55%) Suprascapular 183 (58%) Axillary 259 (81%) Radial 223 (70%) Cubital 68 (21%) Carpal 133 (42%) Thoracic Outlet 7 (2%) Suprascapular 5 (2%) Axillary 51 (16%) Radial 65 (20%) Cubital 64 (20%) Carpal 51 (16%) < 0.01 Headaches 244 (77%) 5 (2%) < 0.01 ROM 2 97 degrees (93, 100) 171 degrees (169, 174) < 0.01 Scapular Dyskinesis 3 None 0 (0%) Dynamic 4 (1%) Static 314 (99%) None 294 (93%) Dynamic 18 (6%) Static 4 (1%) < 0.01 Secondary Neurolysis 4 N/A Overall 17% Thoracic Outlet 4 (1%) Suprascapular 2 (1%) Axillary 30 (9%) Radial 31 (10%) Cubital 33 (10%) Carpal 18 (6%) N/A Treatment Response 5 N/A Substantial 248 (78%) Important 58 (18%) Poor 12 (4%) N/A 1 Average (95% CI) 2 Average pain-free range of motion (ROM) value for shoulder abduction (95% CI) 3 Scapular dyskinesis on exam was classified as: none (no protraction), dynamic (protraction with overhead reach), static (protraction at rest) 4 Patients were offered secondary neurolysis for provocative neuropathic lesions on exam causing lingering pain at 3 months postoperatively 5 Treatment response was categorized via relative pain reductions as poor ( 50%) Discussion In this study, refractory patients suffering from chronic pain of the upper limb who met HDL criteria underwent PM + ICN. Diagnoses included TOS, SD, MPS, fibromyalgia, CRPS, WRMD, SAPS, PMPS, cervical radiculopathy, and cervicogenic headaches. Despite exhaustive efforts, these remain mysterious and intractable. 4 – 11 However, decoupling the PM from the coracoid normalized scapular mechanics and produced profound clinical improvement, suggesting some forms of these pathologies are subsets of the HDL. (Fig. 3 ) The PM pathologizes the full upper limb girdle by deforming the scapula’s numerous connections. First, PM tightness produces medial coracoid tenderness. Second, brachial plexus traction generates secondary neuropathy via double crush. 20 Third, scapula displacement stretches the upper trapezius and rhomboids. 21 Fourth, upper trapezius stretch irritates the occipital nerves to the scalp. 22 – 24 Fifth, narrowing of the subacromial and costoclavicular spaces compresses the neurovascular bundle and impinges the rotator cuff. 25 (Visually, the shoulder assumes the ubiquitous hunched posture.) Thus, a single anatomic source spawns an expansive yet reproducible distribution of pain: occipital headaches and neck stiffness, upper back tightness, shoulder weakness, and hand numbness/tingling. (Fig. 2 ) To date, a variety of specialists have treated these symptoms separately, with mixed results. 4 – 11 In contrast, the HDL offers a unifying framework with clear anatomic pathways that accounts for all symptoms and explains many observations. (Table 3 ) For instance, MPS occurs when the anterior PM pull stretches the dorsal trapezius and rhomboids, as excessive muscle tension creates trigger points. 26 In WRMD, clerical workers repeatedly protract their scapula which triggers loop entry and generates paracervical, parascapular, and glenohumeral pain and cuff tendonitis. 27 , 28 In cervical radiculopathy, degenerative disc disease weakens the dorsal peri-scapular chain which relatively strengthens the PM and produces the constellation of cervicogenic headaches, shoulder weakness and arm pain 29 , and radiating neuropathy. 30 Notably, neither injections, decompression, nor fusion provide long-term pain relief, suggesting compression within the spine is not the principal pain generator. 5 , 31 SAPS encompasses shoulder pain and weakness with overhead reach, with findings of subacromial bursitis and cuff tendinopathy, but the true etiology remains contentious. 32 Current surgeries, despite being common, demonstrate no clinical benefit. 6 , 33 , 34 But within the HDL, SAPS is the subset of the acromion lowering and impinging the subacromial structures. This explains both the repeated intra-operative findings and the inefficacy of current surgeries, as the degraded subacromial structures are secondary. 17 Table 3 HDL Anatomic Explanations for Clinical Observations Seen in Chronic Pain Syndromes of the Upper Limb 1 Clinical Observation Syndrome(s) HDL Anatomic Explanation Higher prevalence in women CRPS, fibromyalgia, TOS Weight of breast tissue tightens the PM Persistent and widespread pain not isolated to single nerve distribution disproportionate to any inciting event CRPS, fibromyalgia Deformation of the scapula’s connections pathologizes the full girdle from the neck to fingers Abnormal distal hand sensory, motor, vasomotor, and trophic changes CRPS, fibromyalgia, TOS Brachial plexus stretch and costoclavicular compression Overall poor response to treatment CRPS, fibromyalgia, TOS, SAPS, MPS, cervical radiculopathy Positive feedback nature of central loop, and current treatments targeting pathoanatomic sequelae Trigger or tenderness points of neck, upper back (peri-scapular), anterior shoulder CRPS, fibromyalgia, MPS, SAPS Pathological stretch of dorsal scapular muscles, and medial coracoid tenderness Presence of occipital headaches Fibromyalgia, TOS, MPS, WRMD, cervicogenic headaches, cervical radiculopathy, PMPS Occipital neuritis from upper trapezius stretch Development of trigger points after computer use, piano playing, carrying a backpack, and association of trigger points with cervical spine pathology MPS, cervical radiculopathy, WRMD Repeated scapula protraction and/or cervical spine pathology triggers loop entry Association of neck pain, occipital headaches, and radiating neuropathy Cervical radiculopathy, cervicogenic headaches Stenosis of cervical roots triggers loop entry producing upper trapezius stretch, costoclavicular compression and brachial plexus stretch, and occipital neuritis Scapula protraction SD, TOS, SICK scapula PM pulls the scapula in its direction of protraction due its unique C8-T1 innervation 1. HDL = Human disharmony loop, CRPS = complex regional pain syndrome, TOS = thoracic outlet syndrome, SAPS = subacromial pain, PMPS = post-mastectomy pain syndrome, SD = scapular dyskinesis, MPS = myofascial pain syndrome, WRMD = work-related musculoskeletal disorder TOS remains controversial due to vague presentation, unreproducible diagnostic criteria, and ineffective treatments. 4 , 35 – 39 Many questions remain, including presence of occipital headaches and scapular protraction 40 , inefficacy of surgical decompression and scalene chemodenervation 4 , 29 , and higher prevalence in women. 29 But interpreted as the HDL subset of costoclavicular space narrowing, these uncertainties are answered: scapula protraction is the cause, headaches are a separate loop sequela, and the overlying breast in women tightens the PM. SD is similarly baffling with many purported bony, articular, and neurologic causes. Revealingly, regardless of alleged cause, the scapula protracts. 8 The HDL answers why: protraction is the vector of pull by the true culprit, the PM. One form of dyskinesis, SICK Scapula, is theorized to result from the geometry of the scapula gliding “up and over” the ellipsoid thorax, with the PM tightening secondarily. 41 The HDL reverses the causality: PM tightness tugs the scapula into dyskinesis, an imbalance of muscular forces and not bony shapes. PMPS is attributed to neuralgia of the intercostobrachial nerve, but also features neck, upper back, and shoulder pain and radiating neuropathy 7 , all HDL sequelae resulting from plexus neuritis. Both CRPS and fibromyalgia include widespread pain, hand sensorimotor abnormalities, and peri-scapular and peri-occipital trigger points, with no clear cause. 42 However, the HDL produces these symptoms and tenderness/trigger points in the same distribution, but supplies anatomic reasoning. (Fig. 5 ) Moreover, the HDL provides an evolutionary rationale for the ubiquity of chronic upper limb pain. 1 – 3 Humans are the only obligate bipedal mammal, but our upper limb descends from the quadrupedal forelimb. For quadrupeds, optimal leaping and sprinting requires coordination between the forepaw and the ventral scapula stabilizer, so the lower trunk synchronizes both. Protraction is the default scapula position in quadrupeds 43 , but pathological in humans. 8 , 15 Due to an evolutionary idiosyncrasy, our scapula is prone to reverting to its quadrupedal state. Chronic pain may be the price of our shoulder motion, the most of any joint in the mammal kingdom. 13 , 44 As acute pain is a signal of tissue damage carrying survival value 12 , chronic pain should also harbor an anatomic foundation. Our findings suggest the HDL may be this missing basis. The uniform response to PM + ICN across a wide range of heterogenous disorders – reducing pain in fibromyalgia, eliminating headaches in cervical radiculopathy, and restoring motion in SAPS, etc. – suggests these may stem from a common anatomic source. The HDL may constitute a unifying syndrome of chronic upper limb pain with an evolutionary foundation and most importantly an effective remedy. Our study has important limitations. As a retrospective study limited to one practice, unknown confounders and/or the placebo effect could account for the results. The physical examination and patient outcomes were recorded subjectively, and future studies should utilize validated instruments. For instance, neuropathy was diagnosed via the SCT which has its limitations 45 , although no gold standard exists. 46 Our principal outcome of pain is subjective, but no objective measurement exists, and self-reported reductions nonetheless remain meaningful. 47 We did not employ standardized patient-reported outcomes (PROs), but these are simply numerical aggregates of subjective responses, can be harder for patients to interpret, and may convey differences that are statistically significant but not clinically meaningful. 48 , 49 To prove our assertions, future studies must compare HDL treatment versus standard of care in large, randomized interventions. Our ~ 2-year average follow-up does not prove permanence. Crucially, our findings only apply to those ‘in the loop’. The terminal symptoms of the HDL can certainly occur independently. 17% of patients required secondary neurolysis, emphasizing the prevalence of double-crush. Surgeons should follow explicit diagnostic criteria (Fig. 2 ), exhaust conservative options first, and closely survey patients after treatment. Breaking the loop via PM + ICN is the first step in a longitudinal and multi-disciplinary process to pain relief. Of note, 4% of patients exhibited poor response. While low, this highlights the complex nature of chronic pain. These failures could represent diagnostic error, nociplastic process, and/or central sensitization, and collaboration with pain management and other specialties remains critical. In conclusion, some forms of upper limb chronic pain may be manifestations of the Human Disharmony Loop, the tendency of the human scapula to protract due to the ventral chain’s lower trunk innervation. Certain intractable patients may benefit substantially from PM + ICN but should be counseled that 17% require secondary neurolysis and 4% respond poorly. Declarations Author Contribution KS and JF contributed equally to this work. KS conceptualized the study, developed the methodology, performed the experiments, analyzed the data, and wrote the original draft. JF contributed to methodology development, validated the results, performed formal data analysis, reviewed and edited the manuscript, and supervised the project. Both authors read and approved the final manuscript. Data Availability All data has been de-identified and can be accessed at: https://doi.org/10.6084/m9.figshare.30994186. Funding Declaration No funding was required for this study. References Donnelly, J. M. & Simons, D. G. Travell, Simons & Simons' myofascial pain and dysfunction: the trigger point manual . Third edition. ednWolters Kluwer Health, (2019). Nahin, R. L., Feinberg, T., Kapos, F. P. & Terman, G. W. Estimated Rates of Incident and Persistent Chronic Pain Among US Adults, 2019–2020. JAMA Netw. Open. 6 , e2313563. https://doi.org/10.1001/jamanetworkopen.2023.13563 (2023). DALYs, G. B. D. et al. Global, regional, and national disability-adjusted life years (DALYs) for 306 diseases and injuries and healthy life expectancy (HALE) for 188 countries, 1990–2013: quantifying the epidemiological transition. Lancet 386 , 2145–2191. https://doi.org/10.1016/S0140-6736(15)61340-X (2015). Povlsen, B., Hansson, T. & Povlsen, S. D. Treatment for thoracic outlet syndrome. Cochrane Database Syst Rev CD007218 (2014). (2014). https://doi.org/10.1002/14651858.CD007218.pub3 Nikolaidis, I., Fouyas, I. P., Sandercock, P. A. & Statham, P. F. Surgery for cervical radiculopathy or myelopathy. Cochrane Database Syst Rev CD001466 (2010). (2010). https://doi.org/10.1002/14651858.CD001466.pub3 Karjalainen, T. V. et al. Subacromial decompression surgery for rotator cuff disease. Cochrane Database Syst Rev 1, CD005619 (2019). https://doi.org/10.1002/14651858.CD005619.pub3 Chang, P. J., Asher, A. & Smith, S. R. A Targeted Approach to Post-Mastectomy Pain and Persistent Pain following Breast Cancer Treatment. Cancers (Basel) . 13. https://doi.org/10.3390/cancers13205191 (2021). Roche, S. J., Funk, L., Sciascia, A. & Kibler, W. B. Scapular dyskinesis: the surgeon's perspective. Shoulder Elb. 7 , 289–297. https://doi.org/10.1177/1758573215595949 (2015). Haldeman, S. & Dagenais, S. Cervicogenic headaches: a critical review. Spine J. 1 , 31–46. https://doi.org/10.1016/s1529-9430(01)00024-9 (2001). Sommer, C. [Fibromyalgia syndrome]. Inn Med (Heidelb) (2025). https://doi.org/10.1007/s00108-025-01994-2 Shekarsarai, C., McQuibban, N. A. & Gullick, N. The Analgesic Efficacy of Therapies Used for Complex Regional Pain Syndrome: A Systematic Review. Cureus 17 , e91697. https://doi.org/10.7759/cureus.91697 (2025). Cohen, S. P., Vase, L. & Hooten, W. M. Chronic pain: an update on burden, best practices, and new advances. Lancet 397 , 2082–2097. https://doi.org/10.1016/S0140-6736(21)00393-7 (2021). Rockwood, C. A. Rockwood and Matsen's the shoulder . Fifth edition. ednElsevier, (2017). Ben Kibler, W., Lockhart, J. W., Cromwell, R. & Sciascia, A. Managing Scapular Dyskinesis. Phys. Med. Rehabil Clin. N Am. 34 , 427–451. https://doi.org/10.1016/j.pmr.2022.12.008 (2023). Sharma, K. & Friedman, J. M. The Human Disharmony Loop: A Case Series Proposing the Unique Role of the Pectoralis Minor in a Unifying Syndrome of Chronic Pain, Neuropathy, and Weakness. J. Clin. Med. 14 https://doi.org/10.3390/jcm14051769 (2025). Friedman, J. M., Iyengar, J. & Sharma, K. Validation of the human disharmony loop: Pectoralis minor tenotomy significantly reduces pain and improves function in historically challenging patients who meet reproducible and explicit diagnostic criteria. PLoS One . 20 , e0326815. https://doi.org/10.1371/journal.pone.0326815 (2025). Sharma, K., Iyengar, J. & Friedman, J. The Human Disharmony Loop: The Anatomic Source Behind Subacromial Impingement and Pain. J. Clin. Med. 14 https://doi.org/10.3390/jcm14165650 (2025). Cheng, C. J., Mackinnon-Patterson, B., Beck, J. L. & Mackinnon, S. E. Scratch collapse test for evaluation of carpal and cubital tunnel syndrome. J. Hand Surg. Am. 33 , 1518–1524. https://doi.org/10.1016/j.jhsa.2008.05.022 (2008). Smith, S. M. et al. Interpretation of chronic pain clinical trial outcomes: IMMPACT recommended considerations. Pain 161 , 2446–2461. https://doi.org/10.1097/j.pain.0000000000001952 (2020). Osterman, A. L. The double crush syndrome. Orthop. Clin. North. Am. 19 , 147–155 (1988). Provencher, M. T. et al. Surgical Release of the Pectoralis Minor Tendon for Scapular Dyskinesia and Shoulder Pain. Am. J. Sports Med. 45 , 173–178. https://doi.org/10.1177/0363546516664720 (2017). Leone, M., D'Amico, D., Grazzi, L., Attanasio, A. & Bussone, G. Cervicogenic headache: a critical review of the current diagnostic criteria. Pain 78 , 1–5. https://doi.org/10.1016/S0304-3959(98)00116-X (1998). Bovim, G. et al. Topographic variations in the peripheral course of the greater occipital nerve. Autopsy study with clinical correlations. Spine (Phila Pa. 1976) . 16 , 475–478. https://doi.org/10.1097/00007632-199104000-00017 (1991). Gfrerer, L. et al. Muscle Fascia Changes in Patients with Occipital Neuralgia, Headache, or Migraine. Plast. Reconstr. Surg. 147 , 176–180. https://doi.org/10.1097/PRS.0000000000007484 (2021). Garving, C., Jakob, S., Bauer, I., Nadjar, R. & Brunner, U. H. Impingement Syndrome of the Shoulder. Dtsch. Arztebl Int. 114 , 765–776. https://doi.org/10.3238/arztebl.2017.0765 (2017). Gerwin, R. D., Dommerholt, J. & Shah, J. P. An expansion of Simons' integrated hypothesis of trigger point formation. Curr. Pain Headache Rep. 8 , 468–475. https://doi.org/10.1007/s11916-004-0069-x (2004). Rockwood, C. A. The shoulder 4th edn (Saunders/Elsevier, 2009). (!!! INVALID CITATION !!! (20)). Ballantyne, J., Fishman, S. & Rathmell, J. P. Bonica's management of pain . Fifth edition. ednWolters Kluwer Health, (2019). Woods, B. I. & Hilibrand, A. S. Cervical radiculopathy: epidemiology, etiology, diagnosis, and treatment. J. Spinal Disord Tech. 28 , E251–259. https://doi.org/10.1097/BSD.0000000000000284 (2015). Wang, X. et al. Common interventional procedures for chronic non-cancer spine pain: a systematic review and network meta-analysis of randomised trials. BMJ 388 , e079971. https://doi.org/10.1136/bmj-2024-079971 (2025). Consigliere, P., Haddo, O., Levy, O. & Sforza, G. Subacromial impingement syndrome: management challenges. Orthop. Res. Rev. 10 , 83–91. https://doi.org/10.2147/ORR.S157864 (2018). Rossi, L. A. & Ranalletta, M. Subacromial Decompression Is Not Beneficial for the Management of Rotator Cuff Disease. JBJS Rev. 8 , e0045. https://doi.org/10.2106/JBJS.RVW.19.00045 (2020). Diercks, R. et al. Guideline for diagnosis and treatment of subacromial pain syndrome: a multidisciplinary review by the Dutch Orthopaedic Association. Acta Orthop. 85 , 314–322. https://doi.org/10.3109/17453674.2014.920991 (2014). Kuhn, J. E., Lebus, V. G. & Bible, J. E. Thoracic outlet syndrome. J. Am. Acad. Orthop. Surg. 23 , 222–232. https://doi.org/10.5435/JAAOS-D-13-00215 (2015). Mackinnon, S. E. & Novak, C. B. Thoracic outlet syndrome. Curr. Probl. Surg. 39 , 1070–1145. https://doi.org/10.1067/msg.2002.127926 (2002). Qvarfordt, P. G., Ehrenfeld, W. K. & Stoney, R. J. Supraclavicular radical scalenectomy and transaxillary first rib resection for the thoracic outlet syndrome. A combined approach. Am. J. Surg. 148 , 111–116. https://doi.org/10.1016/0002-9610(84)90297-6 (1984). Urschel, H. C. Jr. Anatomy of the thoracic outlet. Thorac. Surg. Clin. 17 , 511–520. https://doi.org/10.1016/j.thorsurg.2006.12.004 (2007). Urschel, H. C. Jr. & Razzuk, M. A. Neurovascular compression in the thoracic outlet: changing management over 50 years. Ann. Surg. 228 , 609–617. https://doi.org/10.1097/00000658-199810000-00017 (1998). Raskin, N. H., Howard, M. W. & Ehrenfeld, W. K. Headache as the leading symptom of the thoracic outlet syndrome. Headache 25 , 208–210. https://doi.org/10.1111/j.1526-4610.1985.hed2504208.x (1985). Burkhart, S. S., Morgan, C. D. & Kibler, W. B. The disabled throwing shoulder: spectrum of pathology Part III: The SICK scapula, scapular dyskinesis, the kinetic chain, and rehabilitation. Arthroscopy 19 , 641–661. https://doi.org/10.1016/s0749-8063(03)00389-x (2003). Sarzi-Puttini, P., Giorgi, V., Marotto, D. & Atzeni, F. Fibromyalgia: an update on clinical characteristics, aetiopathogenesis and treatment. Nat. Rev. Rheumatol. 16 , 645–660. https://doi.org/10.1038/s41584-020-00506-w (2020). Dunn, R. H. et al. Muscular anatomy of the forelimb of tiger (Panthera tigris). J. Anat. 241 , 119–144. https://doi.org/10.1111/joa.13636 (2022). Sager, M. et al. The anatomy of the glenoid labrum: a comparison between human and dog. Comp. Med. 59 , 465–475 (2009). Faszholz, A. M. & Cheng, J. Updates to the Physiologic Mechanism, Anatomical Sites, and Diagnostic Utility of the Scratch Collapse Test: A Systematic Review. Plast. Reconstr. Surg. Glob Open. 12 , e5998. https://doi.org/10.1097/GOX.0000000000005998 (2024). Gabriel, D. C., Demetri, L. & Zhang, D. The Role of Confirmatory Testing in Carpal Tunnel Syndrome: Electrodiagnostic Study, Ultrasound and CTS-6. J. Hand Surg. Asian Pac. Vol . 30 , 3–9. https://doi.org/10.1142/S2424835525400016 (2025). Rowbotham, M. C. What is a clinically meaningful. Reduct. pain? Pain . 94 , 131–132. https://doi.org/10.1016/S0304-3959(01)00371-2 (2001). Campbell, R., Ju, A., King, M. T. & Rutherford, C. Perceived benefits and limitations of using patient-reported outcome measures in clinical practice with individual patients: a systematic review of qualitative studies. Qual. Life Res. 31 , 1597–1620. https://doi.org/10.1007/s11136-021-03003-z (2022). Zini, M. L. L., Banfi, G. A. & Narrative Literature Review of Bias in Collecting Patient Reported Outcomes Measures (PROMs). Int. J. Environ. Res. Public. Health . 18 https://doi.org/10.3390/ijerph182312445 (2021). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8569667","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":573361104,"identity":"787e50f6-398c-488a-87eb-edf75c43e3a8","order_by":0,"name":"Ketan Sharma","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAklEQVRIiWNgGAWjYBACgwNgCkIe/lEBJJmZG/BqMWxghmthfMxwBqSFEb8WYwaEFmZjxjawVvxazNj7D34u+HNH3nza4WfShfNqo/nbgVp+VGzDqcWG5zCz9My2Z4ZzbqeZSc/cdjx3xmHGBsaeM7dxa5FIZpDmbTjMOEM6wUyCd9uxXCC7gZmxDbcWM/nHzL95/hy2nyGd/k2Cd86x3PmEtBhLMLNJ87AdTpwhnWNszNtQk7uBkBbDnmQza962w8lALYUPZxw7kLsRqOUgPr8YHD/4+DbQYbZAh2048KGmLnfe+cMHH/yowK0FHRwGkweIVg8EdaQoHgWjYBSMghECAIJNXtUw4P3wAAAAAElFTkSuQmCC","orcid":"","institution":"St. Luke's Hospital","correspondingAuthor":true,"prefix":"","firstName":"Ketan","middleName":"","lastName":"Sharma","suffix":""},{"id":573361105,"identity":"f8a40d3c-e857-4da7-914b-528c3e092987","order_by":1,"name":"James Friedman","email":"","orcid":"","institution":"Sutter Medical Center","correspondingAuthor":false,"prefix":"","firstName":"James","middleName":"","lastName":"Friedman","suffix":""}],"badges":[],"createdAt":"2026-01-10 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07:56:35","extension":"html","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":117097,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8569667/v1/d0ffeff653abafbe603c7ebd.html"},{"id":100133872,"identity":"4e5a8bc1-68c9-41d9-9a1f-da49b0721c6a","added_by":"auto","created_at":"2026-01-13 10:29:32","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":256440,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe Human Disharmony Loop.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe central loop has three elements. Diverse patients can enter via each element \u003cem\u003e(green)\u003c/em\u003e. The pathoanatomic sequelae produce four groups of symptoms \u003cem\u003e(bottom row, red)\u003c/em\u003e. The positive feedback nature produces the intractable pain of the human upper limb. Pectoralis minor tenotomy with infraclavicular neurolysis breaks the cycle, reharmonizing the anatomy and obliterating the sequelae.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8569667/v1/8cf389cac6d467f45b59b49b.png"},{"id":100366718,"identity":"27705610-0384-4a58-9ab5-8d2833f06f2a","added_by":"auto","created_at":"2026-01-16 07:56:30","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":2124036,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eHuman Disharmony Loop Clinical Presentation\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8569667/v1/2d9e8846ba357668abb8a51e.png"},{"id":100133879,"identity":"c2bffc7d-4e93-4aa7-8b07-80fdb65c6b3e","added_by":"auto","created_at":"2026-01-13 10:29:32","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":2988830,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eHuman Disharmony Loop Pathoanatomy Producing Chronic Pain Syndromes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA single anatomic source the PM \u003cem\u003e(orange) \u003c/em\u003eprotracts the scapula and deforms its ventral and dorsal connections, producing the myriad of upper limb chronic pain syndromes.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8569667/v1/cfecb0e7f73084d83e553706.png"},{"id":100367568,"identity":"bacd09fa-f6b1-4492-82ba-cc98c6d552e4","added_by":"auto","created_at":"2026-01-16 07:57:07","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":409470,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eHuman Disharmony Loop Incorporation of Chronic Pain Syndromes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSome of the chronic pain syndromes of the upper limb girdle are anatomic manifestations of the HDL.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8569667/v1/2f88c87879fe5b4662a13200.png"},{"id":100133875,"identity":"f001b5eb-ee38-4137-a7a7-b661a31db990","added_by":"auto","created_at":"2026-01-13 10:29:32","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":676400,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eComparison of HDL to Tenderness Points in Fibromyalgia and Trigger Points in Myofascial Pain Syndrome\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBoth MPS \u003cem\u003e(right)\u003c/em\u003e and fibromyalgia \u003cem\u003e(center) \u003c/em\u003efeature trigger and tenderness points located at the base of the neck, around the scapula, anterior shoulder, and lateral forearm. This closely matches the HDL \u003cem\u003e(left)\u003c/em\u003e, which anatomically explains the distribution.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8569667/v1/d9481a3419ccf3799e92b749.png"},{"id":101448620,"identity":"8d72dd05-7fa2-440d-85bc-817449548c58","added_by":"auto","created_at":"2026-01-29 19:24:59","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":7328481,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8569667/v1/7087e225-db73-4a47-b99c-78545f025ba7.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The Human Disharmony Loop: The Central and Villainous Roles of the Scapula and the Pectoralis Minor in Chronic Pain","fulltext":[{"header":"Introduction","content":"\u003cp\u003eHumans are plagued by chronic pain. The most common disability worldwide consumes over \u003cspan\u003e$\u003c/span\u003e650\u0026nbsp;billion in annual costs.\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e One-fifth of Americans suffer from chronic pain at any given time, of which two-thirds persist longer than a year.\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e Upper back and neck pain alone constitutes the fourth leading cause of disability.\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e Despite its ubiquity, chronic pain afflicting the upper limb girdle \u0026ndash; neck, upper back, shoulder, and arm \u0026ndash; continues to bewilder. An array of syndromes remains intractable, including thoracic outlet (TOS), scapular dyskinesis (SD), myofascial pain (MPS), fibromyalgia, complex regional pain syndrome (CRPS), work-related musculoskeletal disorder (WRMD), post-mastectomy pain syndrome (PMPS), cervical radiculopathy, subacromial pain (SAPS), and cervicogenic headaches. These feature some manifestation of pain \u0026ndash; headaches, stiffness, tightness, weakness, numbness, and/or coolness \u0026ndash; from the neck to the fingertips. They also share contentious diagnostic criteria, convoluted pathophysiology, and ineffectual treatments.\u003csup\u003e\u003cspan additionalcitationids=\"CR5 CR6 CR7 CR8 CR9 CR10\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e Chronic pain regrettably remains a disease with end goals of treatment and not cure.\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eThe key to the upper limb is the scapula.\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e The scapula dynamically connects the body (thorax) to the arm (humerus), coordinating mobility and stability. To enable the full arc of overhead reach, the scapula glides along the thorax to perform two critical functions: optimizing excursion of the deltoid and rotator cuff and maintaining articular congruity to prevent impingement. The peri-scapular chain, comprised of the dorsal trapezius, levator scapulae, rhomboids, lateral serratus anterior, and ventral pectoralis minor (PM), controls this motion. Given its central role, abnormal scapulothoracic motion or SD can generate a wide array of dysfunction\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e, but continues to perplex, with numerous proposed causes that are likely associations instead.\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003ePreviously, we described the Human Disharmony Loop (HDL), a clinical model of upper limb dysfunction.\u003csup\u003e\u003cspan additionalcitationids=\"CR16\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) A neurologic asymmetry surrounds the scapula that may be a sequelae of our evolution from quadrupeds to bipeds: the dorsal peri-scapular chain is controlled by the upper C4-6 roots while the ventral PM carries lower C8-T1 innervation.\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e This renders the scapula prone to protraction, the direction of pull by the PM. Protraction deforms the scapula\u0026rsquo;s numerous connections and produces occipital headaches and neck stiffness, upper back tightness, shoulder weakness, and hand numbness/tingling.\u003csup\u003e16\u003c/sup\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) Treatment consists of PM tenotomy with infraclavicular plexus neurolysis (PM\u0026thinsp;+\u0026thinsp;ICN), with secondary neurolysis if needed, to normalize scapular mechanics and reharmonize the limb girdle. Theoretically, the HDL anatomically incorporates the above chronic pain disorders (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) and explains their symptoms via clear pathways (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Hence, we hypothesize some of these may be pathoanatomic sequelae of the PM warping scapular mechanics. In this paper, we report the outcomes of PM\u0026thinsp;+\u0026thinsp;ICN to treat chronic upper limb pain in patients who meet HDL criteria.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eThis is a retrospective case series of consecutive patients treated by a single fellowship-trained board-certified hand surgeon. Inclusion criteria included: age\u0026thinsp;\u0026gt;\u0026thinsp;13 years and meeting HDL diagnostic criteria. Exclusion criteria included: follow-up \u0026lt;\u0026thinsp;12 months. Patients with any of the following diagnosed by the referring provider were included: TOS, SICK scapula/SD, MPS, fibromyalgia, CRPS, WRMD, SAPS, cervical radiculopathy, cervicogenic headaches, PMPS, Burner/Stinger. All patients trialed at least 6 weeks of therapy before surgery. Patients were evaluated pre-operatively and at 2, 6, 12, 24, and 52 weeks post-operatively. At each visit, patients completed a self-reported pain questionnaire. The scratch collapse test (SCT) identified neuropathic lesions at the thoracic outlet, PM, suprascapular notch, quadrilateral space, radial, cubital, and carpal tunnels.\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e Shoulder abduction range of motion (ROM) values were measured. Scapula dyskinesis on exam was classified as none (no protraction), dynamic (protraction with overhead reach only), or static (protraction at rest).\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e Each patient underwent PM\u0026thinsp;+\u0026thinsp;ICN, followed by physical therapy emphasizing anterior chain stretching and posterior chain strengthening.\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e At 12 weeks post-operatively, patients were offered secondary neurolysis for lingering pain or weakness. Outcomes included self-reported visual analogue scale pain scores out of 10, occipital headaches, neuropathic lesions, shoulder ROM, need for secondary neurolysis. Treatment response was qualitatively categorized via relative pain reductions as poor (\u0026lt;\u0026thinsp;20%), important (20\u0026ndash;50%), substantial (\u0026gt;\u0026thinsp;50%).\u003csup\u003e19\u003c/sup\u003e Institutional Review Board (IRB) approval was obtained by the St. Luke\u0026rsquo;s Health System IRB, and need for consent was waived as the data was anonymous and posed minimal risk to patients. Student\u0026rsquo;s \u003cem\u003et\u003c/em\u003e-test and chi-squared analysis compared continuous and categorical variables of interest, respectively; two-tailed \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\alpha\\:\\)\u003c/span\u003e\u003c/span\u003e=0.05 was used for all tests. Statistical analysis was performed using STATA v14.0.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e \u003cem\u003eN\u003c/em\u003e\u0026thinsp;=\u0026thinsp;318 patients were included. Average age was 51. Sex was 68% female. Patients had a history of: TOS 17%, fibromyalgia 23%, CRPS 14%, WRMD 19%, MPS 33%, cervical radiculopathy 32%, Burner/Stinger syndrome 4%, SAPS 84%, SD 4%, PMPS 4%, cervicogenic headaches 69%. (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) Following PM\u0026thinsp;+\u0026thinsp;ICN, average pain decreased from 7.3/10 to 2.1/10, headaches decreased from 77% to 2%, average shoulder abduction increased from 96 to 170 degrees. Scapular dyskinesis normalized from 99% static and 1% dynamic to 93% none, 6% dynamic and 1% static. Prevalence of clinical neuropathy decreased as follows: thoracic outlet 55% to 2%, suprascapular notch 58% to 2%, quadrilateral space 81% to 16%, radial tunnel 70% to 20%, cubital tunnel 21% to 20%, and carpal tunnel 42% to 16%. (All \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.01) Overall, 17% of patients required secondary neurolysis, most commonly of the radial (10%), ulnar (10%), and axillary (9%) nerves. Overall treatment response was 78% substantial, 18% important, and 4% poor. Average follow-up was 22 months. (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePatient Characteristics \u0026amp; Clinical Presentation\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eN\u003c/em\u003e\u0026thinsp;=\u0026thinsp;318 patients\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e51.0 (49.2, 52.9)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e29.8 (29.0, 30.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMale 101 (32%)\u003c/p\u003e \u003cp\u003eFemale 217 (68%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChronic Pain Syndromes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eThoracic Outlet Syndrome 53 (17%)\u003c/p\u003e \u003cp\u003eFibromyalgia 73 (23%)\u003c/p\u003e \u003cp\u003eComplex regional pain syndrome 45 (14%)\u003c/p\u003e \u003cp\u003eWork-related musculoskeletal disorder 60 (19%)\u003c/p\u003e \u003cp\u003eMyofascial pain syndrome 106 (33%)\u003c/p\u003e \u003cp\u003eCervical radiculopathy 104 (32%)\u003c/p\u003e \u003cp\u003eBurner/Stinger 9 (3%)\u003c/p\u003e \u003cp\u003eSubacromial pain syndrome 266 (84%)\u003c/p\u003e \u003cp\u003eScapular dyskinesis 13 (4%)\u003c/p\u003e \u003cp\u003ePost-mastectomy pain syndrome 11 (4%)\u003c/p\u003e \u003cp\u003eCervicogenic headaches 220 (69%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLaterality\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight 186 (59%)\u003c/p\u003e \u003cp\u003eLeft 132 (42%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePrior Surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSubacromial decompression\u0026thinsp;+\u0026thinsp;adjunct\u003csup\u003e2\u003c/sup\u003e 89 (28%)\u003c/p\u003e \u003cp\u003eTotal shoulder arthroplasty 27 (8%)\u003c/p\u003e \u003cp\u003e1st rib resection 5 (2%)\u003c/p\u003e \u003cp\u003eCervical fusion 53 (17%)\u003c/p\u003e \u003cp\u003eDistal neurolysis\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e 90 (28%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003e\u003csup\u003e1\u003c/sup\u003e Average (95% CI)\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003e\u003csup\u003e2\u003c/sup\u003e Adjunct procedures include rotator cuff repair, biceps tenodesis, distal clavicle excision, labrum repair\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003e\u003csup\u003e3\u003c/sup\u003e Includes carpal, cubital, radial tunnel release\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eClinical Outcomes\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003ePre-Operative\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003ePost-Operative\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eP-Value\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePain\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.3 (7.1, 7.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.1 (1.3, 3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eConcomitant Neuropathy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eThoracic Outlet 174 (55%)\u003c/p\u003e \u003cp\u003eSuprascapular 183 (58%)\u003c/p\u003e \u003cp\u003eAxillary 259 (81%)\u003c/p\u003e \u003cp\u003eRadial 223 (70%)\u003c/p\u003e \u003cp\u003eCubital 68 (21%)\u003c/p\u003e \u003cp\u003eCarpal 133 (42%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThoracic Outlet 7 (2%)\u003c/p\u003e \u003cp\u003eSuprascapular 5 (2%)\u003c/p\u003e \u003cp\u003eAxillary 51 (16%)\u003c/p\u003e \u003cp\u003eRadial 65 (20%)\u003c/p\u003e \u003cp\u003eCubital 64 (20%)\u003c/p\u003e \u003cp\u003eCarpal 51 (16%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeadaches\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e244 (77%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eROM\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e97 degrees (93, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e171 degrees (169, 174)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eScapular Dyskinesis\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNone 0 (0%)\u003c/p\u003e \u003cp\u003eDynamic 4 (1%)\u003c/p\u003e \u003cp\u003eStatic 314 (99%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNone 294 (93%)\u003c/p\u003e \u003cp\u003eDynamic 18 (6%)\u003c/p\u003e \u003cp\u003eStatic 4 (1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSecondary Neurolysis\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOverall 17%\u003c/p\u003e \u003cp\u003eThoracic Outlet 4 (1%)\u003c/p\u003e \u003cp\u003eSuprascapular 2 (1%)\u003c/p\u003e \u003cp\u003eAxillary 30 (9%)\u003c/p\u003e \u003cp\u003eRadial 31 (10%)\u003c/p\u003e \u003cp\u003eCubital 33 (10%)\u003c/p\u003e \u003cp\u003eCarpal 18 (6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTreatment Response\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSubstantial 248 (78%)\u003c/p\u003e \u003cp\u003eImportant 58 (18%)\u003c/p\u003e \u003cp\u003ePoor 12 (4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e\u003csup\u003e1\u003c/sup\u003e Average (95% CI)\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e\u003csup\u003e2\u003c/sup\u003e Average pain-free range of motion (ROM) value for shoulder abduction (95% CI)\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e\u003csup\u003e3\u003c/sup\u003e Scapular dyskinesis on exam was classified as: none (no protraction), dynamic (protraction with overhead reach), static (protraction at rest)\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e\u003csup\u003e4\u003c/sup\u003e Patients were offered secondary neurolysis for provocative neuropathic lesions on exam causing lingering pain at 3 months postoperatively\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e\u003csup\u003e5\u003c/sup\u003e Treatment response was categorized via relative pain reductions as poor (\u0026lt;\u0026thinsp;20%), important (20\u0026ndash;50%), substantial (\u0026gt;\u0026thinsp;50%)\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this study, refractory patients suffering from chronic pain of the upper limb who met HDL criteria underwent PM\u0026thinsp;+\u0026thinsp;ICN. Diagnoses included TOS, SD, MPS, fibromyalgia, CRPS, WRMD, SAPS, PMPS, cervical radiculopathy, and cervicogenic headaches. Despite exhaustive efforts, these remain mysterious and intractable.\u003csup\u003e\u003cspan additionalcitationids=\"CR5 CR6 CR7 CR8 CR9 CR10\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e However, decoupling the PM from the coracoid normalized scapular mechanics and produced profound clinical improvement, suggesting some forms of these pathologies are subsets of the HDL. (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eThe PM pathologizes the full upper limb girdle by deforming the scapula\u0026rsquo;s numerous connections. First, PM tightness produces medial coracoid tenderness. Second, brachial plexus traction generates secondary neuropathy via double crush.\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e Third, scapula displacement stretches the upper trapezius and rhomboids.\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e Fourth, upper trapezius stretch irritates the occipital nerves to the scalp.\u003csup\u003e\u003cspan additionalcitationids=\"CR23\" citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e Fifth, narrowing of the subacromial and costoclavicular spaces compresses the neurovascular bundle and impinges the rotator cuff.\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e (Visually, the shoulder assumes the ubiquitous hunched posture.) Thus, a single anatomic source spawns an expansive yet reproducible distribution of pain: occipital headaches and neck stiffness, upper back tightness, shoulder weakness, and hand numbness/tingling. (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eTo date, a variety of specialists have treated these symptoms separately, with mixed results.\u003csup\u003e\u003cspan additionalcitationids=\"CR5 CR6 CR7 CR8 CR9 CR10\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e In contrast, the HDL offers a unifying framework with clear anatomic pathways that accounts for all symptoms and explains many observations. (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) For instance, MPS occurs when the anterior PM pull stretches the dorsal trapezius and rhomboids, as excessive muscle tension creates trigger points.\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e In WRMD, clerical workers repeatedly protract their scapula which triggers loop entry and generates paracervical, parascapular, and glenohumeral pain and cuff tendonitis.\u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e,\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e In cervical radiculopathy, degenerative disc disease weakens the dorsal peri-scapular chain which relatively strengthens the PM and produces the constellation of cervicogenic headaches, shoulder weakness and arm pain\u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e, and radiating neuropathy.\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e Notably, neither injections, decompression, nor fusion provide long-term pain relief, suggesting compression within the spine is not the principal pain generator.\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e SAPS encompasses shoulder pain and weakness with overhead reach, with findings of subacromial bursitis and cuff tendinopathy, but the true etiology remains contentious.\u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e Current surgeries, despite being common, demonstrate no clinical benefit.\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e,\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e But within the HDL, SAPS is the subset of the acromion lowering and impinging the subacromial structures. This explains both the repeated intra-operative findings and the inefficacy of current surgeries, as the degraded subacromial structures are secondary.\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eHDL Anatomic Explanations for Clinical Observations Seen in Chronic Pain Syndromes of the Upper Limb\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eClinical Observation\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eSyndrome(s)\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eHDL Anatomic Explanation\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHigher prevalence in women\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCRPS, fibromyalgia, TOS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWeight of breast tissue tightens the PM\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePersistent and widespread pain not isolated to single nerve distribution disproportionate to any inciting event\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCRPS, fibromyalgia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDeformation of the scapula\u0026rsquo;s connections pathologizes the full girdle from the neck to fingers\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAbnormal distal hand sensory, motor, vasomotor, and trophic changes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCRPS, fibromyalgia, TOS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBrachial plexus stretch and costoclavicular compression\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOverall poor response to treatment\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCRPS, fibromyalgia, TOS, SAPS, MPS, cervical radiculopathy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePositive feedback nature of central loop, and current treatments targeting pathoanatomic sequelae\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTrigger or tenderness points of neck, upper back (peri-scapular), anterior shoulder\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCRPS, fibromyalgia, MPS, SAPS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePathological stretch of dorsal scapular muscles, and medial coracoid tenderness\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePresence of occipital headaches\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFibromyalgia, TOS, MPS, WRMD, cervicogenic headaches, cervical radiculopathy, PMPS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOccipital neuritis from upper trapezius stretch\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDevelopment of trigger points after computer use, piano playing, carrying a backpack, and association of trigger points with cervical spine pathology\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMPS, cervical radiculopathy, WRMD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRepeated scapula protraction and/or cervical spine pathology triggers loop entry\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAssociation of neck pain, occipital headaches, and radiating neuropathy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCervical radiculopathy, cervicogenic headaches\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eStenosis of cervical roots triggers loop entry producing upper trapezius stretch, costoclavicular compression and brachial plexus stretch, and occipital neuritis\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eScapula protraction\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSD, TOS, SICK scapula\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePM pulls the scapula in its direction of protraction due its unique C8-T1 innervation\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003e1. HDL\u0026thinsp;=\u0026thinsp;Human disharmony loop, CRPS\u0026thinsp;=\u0026thinsp;complex regional pain syndrome, TOS\u0026thinsp;=\u0026thinsp;thoracic outlet syndrome, SAPS\u0026thinsp;=\u0026thinsp;subacromial pain, PMPS\u0026thinsp;=\u0026thinsp;post-mastectomy pain syndrome, SD\u0026thinsp;=\u0026thinsp;scapular dyskinesis, MPS\u0026thinsp;=\u0026thinsp;myofascial pain syndrome, WRMD\u0026thinsp;=\u0026thinsp;work-related musculoskeletal disorder\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTOS remains controversial due to vague presentation, unreproducible diagnostic criteria, and ineffective treatments.\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan additionalcitationids=\"CR36 CR37 CR38\" citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e Many questions remain, including presence of occipital headaches and scapular protraction\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e, inefficacy of surgical decompression and scalene chemodenervation\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e, and higher prevalence in women.\u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e But interpreted as the HDL subset of costoclavicular space narrowing, these uncertainties are answered: scapula protraction is the cause, headaches are a separate loop sequela, and the overlying breast in women tightens the PM. SD is similarly baffling with many purported bony, articular, and neurologic causes. Revealingly, regardless of alleged cause, the scapula protracts.\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e The HDL answers why: protraction is the vector of pull by the true culprit, the PM. One form of dyskinesis, SICK Scapula, is theorized to result from the geometry of the scapula gliding \u0026ldquo;up and over\u0026rdquo; the ellipsoid thorax, with the PM tightening secondarily.\u003csup\u003e\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e The HDL reverses the causality: PM tightness tugs the scapula into dyskinesis, an imbalance of muscular forces and not bony shapes. PMPS is attributed to neuralgia of the intercostobrachial nerve, but also features neck, upper back, and shoulder pain and radiating neuropathy\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e, all HDL sequelae resulting from plexus neuritis. Both CRPS and fibromyalgia include widespread pain, hand sensorimotor abnormalities, and peri-scapular and peri-occipital trigger points, with no clear cause.\u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e However, the HDL produces these symptoms and tenderness/trigger points in the same distribution, but supplies anatomic reasoning. (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eMoreover, the HDL provides an evolutionary rationale for the ubiquity of chronic upper limb pain.\u003csup\u003e\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e Humans are the only obligate bipedal mammal, but our upper limb descends from the quadrupedal forelimb. For quadrupeds, optimal leaping and sprinting requires coordination between the forepaw and the ventral scapula stabilizer, so the lower trunk synchronizes both. Protraction is the default scapula position in quadrupeds\u003csup\u003e\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e, but pathological in humans.\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e Due to an evolutionary idiosyncrasy, our scapula is prone to reverting to its quadrupedal state. Chronic pain may be the price of our shoulder motion, the most of any joint in the mammal kingdom.\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e As acute pain is a signal of tissue damage carrying survival value\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e, chronic pain should also harbor an anatomic foundation. Our findings suggest the HDL may be this missing basis. The uniform response to PM\u0026thinsp;+\u0026thinsp;ICN across a wide range of heterogenous disorders \u0026ndash; reducing pain in fibromyalgia, eliminating headaches in cervical radiculopathy, and restoring motion in SAPS, etc. \u0026ndash; suggests these may stem from a common anatomic source. The HDL may constitute a unifying syndrome of chronic upper limb pain with an evolutionary foundation and most importantly an effective remedy.\u003c/p\u003e \u003cp\u003eOur study has important limitations. As a retrospective study limited to one practice, unknown confounders and/or the placebo effect could account for the results. The physical examination and patient outcomes were recorded subjectively, and future studies should utilize validated instruments. For instance, neuropathy was diagnosed via the SCT which has its limitations\u003csup\u003e\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e\u003c/sup\u003e, although no gold standard exists.\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e Our principal outcome of pain is subjective, but no objective measurement exists, and self-reported reductions nonetheless remain meaningful.\u003csup\u003e\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e We did not employ standardized patient-reported outcomes (PROs), but these are simply numerical aggregates of subjective responses, can be harder for patients to interpret, and may convey differences that are statistically significant but not clinically meaningful.\u003csup\u003e\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e,\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e To prove our assertions, future studies must compare HDL treatment versus standard of care in large, randomized interventions. Our\u0026thinsp;~\u0026thinsp;2-year average follow-up does not prove permanence. Crucially, our findings only apply to those \u0026lsquo;in the loop\u0026rsquo;. The terminal symptoms of the HDL can certainly occur independently. 17% of patients required secondary neurolysis, emphasizing the prevalence of double-crush. Surgeons should follow explicit diagnostic criteria (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), exhaust conservative options first, and closely survey patients after treatment. Breaking the loop via PM\u0026thinsp;+\u0026thinsp;ICN is the first step in a longitudinal and multi-disciplinary process to pain relief. Of note, 4% of patients exhibited poor response. While low, this highlights the complex nature of chronic pain. These failures could represent diagnostic error, nociplastic process, and/or central sensitization, and collaboration with pain management and other specialties remains critical.\u003c/p\u003e \u003cp\u003eIn conclusion, some forms of upper limb chronic pain may be manifestations of the Human Disharmony Loop, the tendency of the human scapula to protract due to the ventral chain\u0026rsquo;s lower trunk innervation. Certain intractable patients may benefit substantially from PM\u0026thinsp;+\u0026thinsp;ICN but should be counseled that 17% require secondary neurolysis and 4% respond poorly.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eKS and JF contributed equally to this work. KS conceptualized the study, developed the methodology, performed the experiments, analyzed the data, and wrote the original draft. JF contributed to methodology development, validated the results, performed formal data analysis, reviewed and edited the manuscript, and supervised the project. Both authors read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eAll data has been de-identified and can be accessed at: https://doi.org/10.6084/m9.figshare.30994186.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cu\u003eFunding Declaration\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funding was required for this study.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDonnelly, J. M. \u0026amp; Simons, D. G. \u003cem\u003eTravell, Simons \u0026amp; Simons' myofascial pain and dysfunction: the trigger point manual\u003c/em\u003e. Third edition. ednWolters Kluwer Health, (2019).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNahin, R. L., Feinberg, T., Kapos, F. P. \u0026amp; Terman, G. W. Estimated Rates of Incident and Persistent Chronic Pain Among US Adults, 2019\u0026ndash;2020. \u003cem\u003eJAMA Netw. Open.\u003c/em\u003e \u003cb\u003e6\u003c/b\u003e, e2313563. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1001/jamanetworkopen.2023.13563\u003c/span\u003e\u003cspan address=\"10.1001/jamanetworkopen.2023.13563\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2023).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDALYs, G. B. D. et al. Global, regional, and national disability-adjusted life years (DALYs) for 306 diseases and injuries and healthy life expectancy (HALE) for 188 countries, 1990\u0026ndash;2013: quantifying the epidemiological transition. \u003cem\u003eLancet\u003c/em\u003e \u003cb\u003e386\u003c/b\u003e, 2145\u0026ndash;2191. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0140-6736(15)61340-X\u003c/span\u003e\u003cspan address=\"10.1016/S0140-6736(15)61340-X\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2015).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePovlsen, B., Hansson, T. \u0026amp; Povlsen, S. D. Treatment for thoracic outlet syndrome. \u003cem\u003eCochrane Database Syst Rev\u003c/em\u003e CD007218 (2014). (2014). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/14651858.CD007218.pub3\u003c/span\u003e\u003cspan address=\"10.1002/14651858.CD007218.pub3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNikolaidis, I., Fouyas, I. P., Sandercock, P. A. \u0026amp; Statham, P. F. Surgery for cervical radiculopathy or myelopathy. \u003cem\u003eCochrane Database Syst Rev\u003c/em\u003e CD001466 (2010). (2010). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/14651858.CD001466.pub3\u003c/span\u003e\u003cspan address=\"10.1002/14651858.CD001466.pub3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKarjalainen, T. V. et al. Subacromial decompression surgery for rotator cuff disease. \u003cem\u003eCochrane Database Syst Rev\u003c/em\u003e 1, CD005619 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/14651858.CD005619.pub3\u003c/span\u003e\u003cspan address=\"10.1002/14651858.CD005619.pub3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChang, P. J., Asher, A. \u0026amp; Smith, S. R. A Targeted Approach to Post-Mastectomy Pain and Persistent Pain following Breast Cancer Treatment. \u003cem\u003eCancers (Basel)\u003c/em\u003e. 13. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/cancers13205191\u003c/span\u003e\u003cspan address=\"10.3390/cancers13205191\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRoche, S. J., Funk, L., Sciascia, A. \u0026amp; Kibler, W. B. Scapular dyskinesis: the surgeon's perspective. \u003cem\u003eShoulder Elb.\u003c/em\u003e \u003cb\u003e7\u003c/b\u003e, 289\u0026ndash;297. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1177/1758573215595949\u003c/span\u003e\u003cspan address=\"10.1177/1758573215595949\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2015).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHaldeman, S. \u0026amp; Dagenais, S. Cervicogenic headaches: a critical review. \u003cem\u003eSpine J.\u003c/em\u003e \u003cb\u003e1\u003c/b\u003e, 31\u0026ndash;46. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/s1529-9430(01)00024-9\u003c/span\u003e\u003cspan address=\"10.1016/s1529-9430(01)00024-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2001).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSommer, C. [Fibromyalgia syndrome]. \u003cem\u003eInn Med (Heidelb)\u003c/em\u003e (2025). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00108-025-01994-2\u003c/span\u003e\u003cspan address=\"10.1007/s00108-025-01994-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShekarsarai, C., McQuibban, N. A. \u0026amp; Gullick, N. The Analgesic Efficacy of Therapies Used for Complex Regional Pain Syndrome: A Systematic Review. \u003cem\u003eCureus\u003c/em\u003e \u003cb\u003e17\u003c/b\u003e, e91697. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.7759/cureus.91697\u003c/span\u003e\u003cspan address=\"10.7759/cureus.91697\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCohen, S. P., Vase, L. \u0026amp; Hooten, W. M. Chronic pain: an update on burden, best practices, and new advances. \u003cem\u003eLancet\u003c/em\u003e \u003cb\u003e397\u003c/b\u003e, 2082\u0026ndash;2097. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0140-6736(21)00393-7\u003c/span\u003e\u003cspan address=\"10.1016/S0140-6736(21)00393-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRockwood, C. A. \u003cem\u003eRockwood and Matsen's the shoulder\u003c/em\u003e. Fifth edition. ednElsevier, (2017).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBen Kibler, W., Lockhart, J. W., Cromwell, R. \u0026amp; Sciascia, A. Managing Scapular Dyskinesis. \u003cem\u003ePhys. Med. Rehabil Clin. N Am.\u003c/em\u003e \u003cb\u003e34\u003c/b\u003e, 427\u0026ndash;451. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.pmr.2022.12.008\u003c/span\u003e\u003cspan address=\"10.1016/j.pmr.2022.12.008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2023).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSharma, K. \u0026amp; Friedman, J. M. The Human Disharmony Loop: A Case Series Proposing the Unique Role of the Pectoralis Minor in a Unifying Syndrome of Chronic Pain, Neuropathy, and Weakness. \u003cem\u003eJ. Clin. Med.\u003c/em\u003e \u003cb\u003e14\u003c/b\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/jcm14051769\u003c/span\u003e\u003cspan address=\"10.3390/jcm14051769\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFriedman, J. M., Iyengar, J. \u0026amp; Sharma, K. Validation of the human disharmony loop: Pectoralis minor tenotomy significantly reduces pain and improves function in historically challenging patients who meet reproducible and explicit diagnostic criteria. \u003cem\u003ePLoS One\u003c/em\u003e. \u003cb\u003e20\u003c/b\u003e, e0326815. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1371/journal.pone.0326815\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0326815\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSharma, K., Iyengar, J. \u0026amp; Friedman, J. The Human Disharmony Loop: The Anatomic Source Behind Subacromial Impingement and Pain. \u003cem\u003eJ. Clin. Med.\u003c/em\u003e \u003cb\u003e14\u003c/b\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/jcm14165650\u003c/span\u003e\u003cspan address=\"10.3390/jcm14165650\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCheng, C. J., Mackinnon-Patterson, B., Beck, J. L. \u0026amp; Mackinnon, S. E. Scratch collapse test for evaluation of carpal and cubital tunnel syndrome. \u003cem\u003eJ. Hand Surg. Am.\u003c/em\u003e \u003cb\u003e33\u003c/b\u003e, 1518\u0026ndash;1524. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jhsa.2008.05.022\u003c/span\u003e\u003cspan address=\"10.1016/j.jhsa.2008.05.022\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2008).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSmith, S. M. et al. Interpretation of chronic pain clinical trial outcomes: IMMPACT recommended considerations. \u003cem\u003ePain\u003c/em\u003e \u003cb\u003e161\u003c/b\u003e, 2446\u0026ndash;2461. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/j.pain.0000000000001952\u003c/span\u003e\u003cspan address=\"10.1097/j.pain.0000000000001952\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2020).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOsterman, A. L. The double crush syndrome. \u003cem\u003eOrthop. Clin. North. Am.\u003c/em\u003e \u003cb\u003e19\u003c/b\u003e, 147\u0026ndash;155 (1988).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eProvencher, M. T. et al. Surgical Release of the Pectoralis Minor Tendon for Scapular Dyskinesia and Shoulder Pain. \u003cem\u003eAm. J. Sports Med.\u003c/em\u003e \u003cb\u003e45\u003c/b\u003e, 173\u0026ndash;178. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1177/0363546516664720\u003c/span\u003e\u003cspan address=\"10.1177/0363546516664720\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2017).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLeone, M., D'Amico, D., Grazzi, L., Attanasio, A. \u0026amp; Bussone, G. Cervicogenic headache: a critical review of the current diagnostic criteria. \u003cem\u003ePain\u003c/em\u003e \u003cb\u003e78\u003c/b\u003e, 1\u0026ndash;5. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0304-3959(98)00116-X\u003c/span\u003e\u003cspan address=\"10.1016/S0304-3959(98)00116-X\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (1998).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBovim, G. et al. Topographic variations in the peripheral course of the greater occipital nerve. Autopsy study with clinical correlations. \u003cem\u003eSpine (Phila Pa. 1976)\u003c/em\u003e. \u003cb\u003e16\u003c/b\u003e, 475\u0026ndash;478. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/00007632-199104000-00017\u003c/span\u003e\u003cspan address=\"10.1097/00007632-199104000-00017\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (1991).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGfrerer, L. et al. Muscle Fascia Changes in Patients with Occipital Neuralgia, Headache, or Migraine. \u003cem\u003ePlast. Reconstr. Surg.\u003c/em\u003e \u003cb\u003e147\u003c/b\u003e, 176\u0026ndash;180. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/PRS.0000000000007484\u003c/span\u003e\u003cspan address=\"10.1097/PRS.0000000000007484\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGarving, C., Jakob, S., Bauer, I., Nadjar, R. \u0026amp; Brunner, U. H. Impingement Syndrome of the Shoulder. \u003cem\u003eDtsch. Arztebl Int.\u003c/em\u003e \u003cb\u003e114\u003c/b\u003e, 765\u0026ndash;776. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3238/arztebl.2017.0765\u003c/span\u003e\u003cspan address=\"10.3238/arztebl.2017.0765\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2017).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGerwin, R. D., Dommerholt, J. \u0026amp; Shah, J. P. An expansion of Simons' integrated hypothesis of trigger point formation. \u003cem\u003eCurr. Pain Headache Rep.\u003c/em\u003e \u003cb\u003e8\u003c/b\u003e, 468\u0026ndash;475. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11916-004-0069-x\u003c/span\u003e\u003cspan address=\"10.1007/s11916-004-0069-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2004).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRockwood, C. A. \u003cem\u003eThe shoulder\u003c/em\u003e 4th edn (Saunders/Elsevier, 2009).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003e(!!! INVALID CITATION !!! (20)).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBallantyne, J., Fishman, S. \u0026amp; Rathmell, J. P. \u003cem\u003eBonica's management of pain\u003c/em\u003e. Fifth edition. ednWolters Kluwer Health, (2019).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWoods, B. I. \u0026amp; Hilibrand, A. S. Cervical radiculopathy: epidemiology, etiology, diagnosis, and treatment. \u003cem\u003eJ. Spinal Disord Tech.\u003c/em\u003e \u003cb\u003e28\u003c/b\u003e, E251\u0026ndash;259. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/BSD.0000000000000284\u003c/span\u003e\u003cspan address=\"10.1097/BSD.0000000000000284\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2015).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang, X. et al. Common interventional procedures for chronic non-cancer spine pain: a systematic review and network meta-analysis of randomised trials. \u003cem\u003eBMJ\u003c/em\u003e \u003cb\u003e388\u003c/b\u003e, e079971. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1136/bmj-2024-079971\u003c/span\u003e\u003cspan address=\"10.1136/bmj-2024-079971\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eConsigliere, P., Haddo, O., Levy, O. \u0026amp; Sforza, G. Subacromial impingement syndrome: management challenges. \u003cem\u003eOrthop. Res. Rev.\u003c/em\u003e \u003cb\u003e10\u003c/b\u003e, 83\u0026ndash;91. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2147/ORR.S157864\u003c/span\u003e\u003cspan address=\"10.2147/ORR.S157864\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2018).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRossi, L. A. \u0026amp; Ranalletta, M. Subacromial Decompression Is Not Beneficial for the Management of Rotator Cuff Disease. \u003cem\u003eJBJS Rev.\u003c/em\u003e \u003cb\u003e8\u003c/b\u003e, e0045. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2106/JBJS.RVW.19.00045\u003c/span\u003e\u003cspan address=\"10.2106/JBJS.RVW.19.00045\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2020).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDiercks, R. et al. Guideline for diagnosis and treatment of subacromial pain syndrome: a multidisciplinary review by the Dutch Orthopaedic Association. \u003cem\u003eActa Orthop.\u003c/em\u003e \u003cb\u003e85\u003c/b\u003e, 314\u0026ndash;322. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3109/17453674.2014.920991\u003c/span\u003e\u003cspan address=\"10.3109/17453674.2014.920991\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2014).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKuhn, J. E., Lebus, V. G. \u0026amp; Bible, J. E. Thoracic outlet syndrome. \u003cem\u003eJ. Am. Acad. Orthop. Surg.\u003c/em\u003e \u003cb\u003e23\u003c/b\u003e, 222\u0026ndash;232. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.5435/JAAOS-D-13-00215\u003c/span\u003e\u003cspan address=\"10.5435/JAAOS-D-13-00215\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2015).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMackinnon, S. E. \u0026amp; Novak, C. B. Thoracic outlet syndrome. \u003cem\u003eCurr. Probl. Surg.\u003c/em\u003e \u003cb\u003e39\u003c/b\u003e, 1070\u0026ndash;1145. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1067/msg.2002.127926\u003c/span\u003e\u003cspan address=\"10.1067/msg.2002.127926\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2002).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eQvarfordt, P. G., Ehrenfeld, W. K. \u0026amp; Stoney, R. J. Supraclavicular radical scalenectomy and transaxillary first rib resection for the thoracic outlet syndrome. A combined approach. \u003cem\u003eAm. J. Surg.\u003c/em\u003e \u003cb\u003e148\u003c/b\u003e, 111\u0026ndash;116. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0002-9610(84)90297-6\u003c/span\u003e\u003cspan address=\"10.1016/0002-9610(84)90297-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (1984).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUrschel, H. C. Jr. Anatomy of the thoracic outlet. \u003cem\u003eThorac. Surg. Clin.\u003c/em\u003e \u003cb\u003e17\u003c/b\u003e, 511\u0026ndash;520. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.thorsurg.2006.12.004\u003c/span\u003e\u003cspan address=\"10.1016/j.thorsurg.2006.12.004\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2007).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUrschel, H. C. Jr. \u0026amp; Razzuk, M. A. Neurovascular compression in the thoracic outlet: changing management over 50 years. \u003cem\u003eAnn. Surg.\u003c/em\u003e \u003cb\u003e228\u003c/b\u003e, 609\u0026ndash;617. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/00000658-199810000-00017\u003c/span\u003e\u003cspan address=\"10.1097/00000658-199810000-00017\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (1998).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRaskin, N. H., Howard, M. W. \u0026amp; Ehrenfeld, W. K. Headache as the leading symptom of the thoracic outlet syndrome. \u003cem\u003eHeadache\u003c/em\u003e \u003cb\u003e25\u003c/b\u003e, 208\u0026ndash;210. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1526-4610.1985.hed2504208.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1526-4610.1985.hed2504208.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (1985).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBurkhart, S. S., Morgan, C. D. \u0026amp; Kibler, W. B. The disabled throwing shoulder: spectrum of pathology Part III: The SICK scapula, scapular dyskinesis, the kinetic chain, and rehabilitation. \u003cem\u003eArthroscopy\u003c/em\u003e \u003cb\u003e19\u003c/b\u003e, 641\u0026ndash;661. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/s0749-8063(03)00389-x\u003c/span\u003e\u003cspan address=\"10.1016/s0749-8063(03)00389-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2003).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSarzi-Puttini, P., Giorgi, V., Marotto, D. \u0026amp; Atzeni, F. Fibromyalgia: an update on clinical characteristics, aetiopathogenesis and treatment. \u003cem\u003eNat. Rev. Rheumatol.\u003c/em\u003e \u003cb\u003e16\u003c/b\u003e, 645\u0026ndash;660. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/s41584-020-00506-w\u003c/span\u003e\u003cspan address=\"10.1038/s41584-020-00506-w\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2020).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDunn, R. H. et al. Muscular anatomy of the forelimb of tiger (Panthera tigris). \u003cem\u003eJ. Anat.\u003c/em\u003e \u003cb\u003e241\u003c/b\u003e, 119\u0026ndash;144. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/joa.13636\u003c/span\u003e\u003cspan address=\"10.1111/joa.13636\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSager, M. et al. The anatomy of the glenoid labrum: a comparison between human and dog. \u003cem\u003eComp. Med.\u003c/em\u003e \u003cb\u003e59\u003c/b\u003e, 465\u0026ndash;475 (2009).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFaszholz, A. M. \u0026amp; Cheng, J. Updates to the Physiologic Mechanism, Anatomical Sites, and Diagnostic Utility of the Scratch Collapse Test: A Systematic Review. \u003cem\u003ePlast. Reconstr. Surg. Glob Open.\u003c/em\u003e \u003cb\u003e12\u003c/b\u003e, e5998. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/GOX.0000000000005998\u003c/span\u003e\u003cspan address=\"10.1097/GOX.0000000000005998\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2024).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGabriel, D. C., Demetri, L. \u0026amp; Zhang, D. The Role of Confirmatory Testing in Carpal Tunnel Syndrome: Electrodiagnostic Study, Ultrasound and CTS-6. \u003cem\u003eJ. Hand Surg. Asian Pac. Vol\u003c/em\u003e. \u003cb\u003e30\u003c/b\u003e, 3\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1142/S2424835525400016\u003c/span\u003e\u003cspan address=\"10.1142/S2424835525400016\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRowbotham, M. C. What is a clinically meaningful. \u003cem\u003eReduct. pain? Pain\u003c/em\u003e. \u003cb\u003e94\u003c/b\u003e, 131\u0026ndash;132. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0304-3959(01)00371-2\u003c/span\u003e\u003cspan address=\"10.1016/S0304-3959(01)00371-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2001).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCampbell, R., Ju, A., King, M. T. \u0026amp; Rutherford, C. Perceived benefits and limitations of using patient-reported outcome measures in clinical practice with individual patients: a systematic review of qualitative studies. \u003cem\u003eQual. Life Res.\u003c/em\u003e \u003cb\u003e31\u003c/b\u003e, 1597\u0026ndash;1620. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11136-021-03003-z\u003c/span\u003e\u003cspan address=\"10.1007/s11136-021-03003-z\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZini, M. L. L., Banfi, G. A. \u0026amp; Narrative Literature Review of Bias in Collecting Patient Reported Outcomes Measures (PROMs). \u003cem\u003eInt. J. Environ. Res. Public. Health\u003c/em\u003e. \u003cb\u003e18\u003c/b\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/ijerph182312445\u003c/span\u003e\u003cspan address=\"10.3390/ijerph182312445\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Chronic pain, upper limb, scapula, pectoralis minor","lastPublishedDoi":"10.21203/rs.3.rs-8569667/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8569667/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMany patients suffer from chronic pain of the shoulder, neck, upper back, and/or arm. They may be diagnosed with fibromyalgia, complex regional pain syndrome, myofascial pain, thoracic outlet, subacromial pain, cervical radiculopathy, cervicogenic headaches, post-mastectomy pain, occupational shoulder disorder. These remain mysterious and challenging. The pectoralis minor (PM) is the only muscle of the scapula innervated by the lower trunk, potentially a sequela of the evolution from quadrupeds to bipeds. The Human Disharmony Loop (HDL) is a clinical model where this neurologic asymmetry renders the scapula prone to protraction, which pathologizes the full upper limb girdle and generates headaches and neck stiffness, upper back tightness, shoulder weakness, and hand numbness/tingling. We hypothesize some of the above diagnoses are manifestations of the HDL. 318 patients with the above who met HDL diagnostic criteria underwent PM tenotomy with brachial plexus neurolysis (PM\u0026thinsp;+\u0026thinsp;ICN). At 12 months, average pain decreased from 7.3/10 to 2.1/10, average shoulder abduction increased from 96 to 170 degrees, occipital headaches decreased from 77% to 2%. In summary, humans may be plagued by chronic pain because our scapula tends to protract, its ancestral quadrupedal state. Certain intractable patients may benefit substantially from PM\u0026thinsp;+\u0026thinsp;ICN.\u003c/p\u003e","manuscriptTitle":"The Human Disharmony Loop: The Central and Villainous Roles of the Scapula and the Pectoralis Minor in Chronic Pain","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-13 10:29:28","doi":"10.21203/rs.3.rs-8569667/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"6212a9bb-520c-454f-9af9-6b4c827c3627","owner":[],"postedDate":"January 13th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":61006408,"name":"Health sciences/Diseases"},{"id":61006409,"name":"Health sciences/Medical research"},{"id":61006410,"name":"Health sciences/Neurology"},{"id":61006411,"name":"Biological sciences/Neuroscience"},{"id":61006412,"name":"Health sciences/Signs and symptoms"}],"tags":[],"updatedAt":"2026-01-29T19:24:16+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-13 10:29:28","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8569667","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8569667","identity":"rs-8569667","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}