Neurogenic Thoracic Outlet Syndrome

Abstract

Background

Thoracic outlet syndrome (TOS) refers to a group of disorders in which there is compression of and/or damage to the neurovascular structures at the thoracic outlet, i.e., at the transition from chest to neck. The incidence of neurogenic thoracic outlet syndrome (nTOS) is estimated to be 2–3 / 100 000 / year, with an estimated prevalence of 10 / 100 000. Patients present with upper extremity sensorimotor symptoms that are often related to movement. The aim of the present article is to highlight the clinical presentation patterns of nTOS and to provide an overview of its diagnosis and treatment.

Methods

Selective literature search for prospective observational studies and RCTs, including systematic reviews and meta-analyses.

Results

There is no multicenter randomized controlled trial available on the treatment of nTOS. Prospective observational studies with a hierarchical study design report a positive effect of physiotherapy in 27–59% of cases. After unsuccessful conservative treatment, up to 56–90% benefit from surgical management. Patients with nTOS are more severely affected compared with those with other forms of TOS and benefit less from transaxillary first rib resection. nTOS patients who underwent supraclavicular decompression without rib resection had excellent surgical outcomes in 27%, good outcomes in 36%, acceptable outcomes in 26%, and poor surgical outcomes in 11% of cases. There is no systematic comparison available of the types of surgical management involved. Also, there is currently no uniform classification available for all medical sub-disciplines. Therefore, interpretation, and comparability of the study results are limited.

Conclusion

Although nTOS is the most common form of TOS, studies on its treatment are currently limited in terms of numbers and quality. The type of surgical management varies according to the experience and preference of the surgeon, treating specialty, special anatomic features, and clinical symptoms.

cme plus

This article has been certified by the North Rhine Academy for Continuing Medical Education. Participation in the CME certification program is possible only over the internet: cme.aerzteblatt.de. The deadline for submission is 27 October 2023.

Thoracic outlet syndrome (TOS) is a heterogeneous group of disorders characterized by compression of, and/or damage to, the neurovascular structures at the thoracic outlet, i.e., the passage from the chest into the neck. One or more anatomic structures of the upper thoracic outlet may be affected (the brachial plexus, the subclavian artery [a.], and/or the subclavian vein [v.]). There are a variety of causes for compression of, and damage to, these structures (1). The classic distinction is between arterial (aTOS), venous (vTOS), and neurogenic thoracic outlet syndrome (nTOS) (2). In German-speaking countries, the literature in current journals and textbooks focuses on aTOS, as does the S2 guideline of the German Society for Vascular Surgery and Vascular Medicine (Deutsche Gesellschaft für Gefäßchirurgie und Gefäßmedizin e. V., DGG) (an update was due in 2010, but did not appear; no update is now planned, according to a reply from the DGG to an inquiry on May 23, 2022) (3, 4). Yet the more recent international literature, based on the uniform classification of the Society for Vascular Surgery (in the USA), reveals a trend toward recognition of primary nTOS as the most common type of TOS (2). In large case series from the USA, for example, in a prospective analysis of outpatient cases at the University of South Florida, the percentage of nTOS was 82%. (5) 82–85% of patients who underwent TOS surgery and whose TOS was classified by the uniform standards of the Society for Vascular Surgery had nTOS (6, 7). The percentage of women among nTOS patients ranged from 59% to 95% (6, 8, 9). The accurate determination of the incidence and prevalence of nTOS presents a methodological challenge. An analysis in the United States in 2021 yielded an estimated incidence of 2–3 cases and an estimated prevalence of approximately 10 cases per 100 000 persons per year (5, 10). The numbers are thought to be much higher in athletes, particularly in sports involving intense use of the upper limbs, such as swimming, rowing, or volleyball (11, 12). Some authors also describe a further type called “disputed” thoracic outlet syndrome (dTOS), which is characterized by inconsistent symptoms (1). The Society for Vascular Surgery, when it proposed the adoption of the uniform classifying standard in 2016, explicitly advised against the use of the term dTOS (2). In everyday clinical practice, there is much uncertainty about the presentation, proper diagnostic evaluation, characterization, and treatment of nTOS. The road to correct diagnosis and appropriate treatment is often long. Rochkind et al. described a group of patients with pronounced motor deficits for whom there were delays of 1.3 to 15 years before diagnosis and surgical treatment (13, 14). As described vividly by Dubuisson et al., patients with TOS are often misdiagnosed and subjected to unnecessary operations and therapies. In the cited study, three of seven patients were initially treated incorrectly. One of them underwent two unhelpful surgical procedures—cervical discectomy and ulnar nerve decompression at the elbow—before the correct diagnosis of nTOS was made (15).

Anatomic particularities in the individual can be a risk factor, especially an accessory rib, a prominent C7 transverse process, additional ligaments and muscles such as the costotransverse ligament, Sibson‘s fascia or muscle between the C7 transverse process and the first rib, or a short costoclavicular distance (13, 14, 16, 17). There can also be acquired factors such as trauma, high-performance sports, a job demanding intense use of the upper limb(s), and the normal descent of the shoulder muscles between age 30 and 50. Musicians, for example, suffer disproportionately from nTOS, as do persons whose jobs demand a great deal of work on a computer or overhead (18– 21).

In this article, we discuss the current state of the evidence on nTOS in order to help physicians identify patients with this condition more easily in clinical practice, while providing an overview of the diagnostic evaluation and of the options for treatment.

Methods

Two independent reviewers (MTP, NFD) carried out a selective literature search in Medline via PubMed, employing the search terms „thoracic outlet syndrome“ and „neurogenic thoracic outlet syndrome“ for the period 1982–2022. This yielded 2979 and 392 hits, respectively (date of search, 28 February 2022). Only articles in German or English were considered.

Results

Clinical features

Patients with nTOS typically present with movement-dependent pain, especially upon abduction and retroversion of the arm, with or without a neurologic deficit (motor: paresis; sensory: hypesthesia) and/or a tingling paresthesia in the dermatomes and muscles supplied by the inferior trunk (C8/Th1), along with local tenderness at the thoracic outlet (etable 1) (1, 22– 26). In rarer cases, structures innervated by the superior and middle trunks may also be affected. Pronounced damage is indicated by the presence of a Gilliatt-Sumner hand, i.e., combined atrophy of the thenar, hypothenar, and intrinsic hand muscles, which are supplied by the median and ulnar nerves (27). There may be simultaneous compression of the vascular structures of the thoracic outlet, with corresponding symptoms (22). The criteria for the presence of nTOS proposed by the Society for Vascular Surgery and the nTOS classification proposed by the European Society of Neurosurgical Specialists are reproduced in eTable 2 (2, 28).

eTable 1. Clinical manifestations of neurogenic thoracic outlet syndrome and their frequency of appearance (1, 23– 26).

Manifestation	Frequency in various studies
Pain	73–90%
Paresthesia	32–98%
Numbness	42–80%
Site of sensory symptoms: hand or finger arm shoulder neck or head	92–100% 85–92% 55–88% 37–50%
Subjective muscle weakness	68–85%
Muscle atrophy in ADM, APB, and interossei	65%
Positive Hoffman-Tinel sign	65–75%
Positive elevated arm stress test	81–100%
Positive upper limb tension test	85–100%
Positive anterior/middle scalene muscle pressure test	60%
Sleep disturbance	49%

ADM, adductor digiti minimi muslce (m.); APB, abductor pollicis brevis (m.)

Diagnostic evaluation: history, clinical examination, provocative tests, imaging, and neurophysiology

When the history is taken, particular attention should be paid to previous trauma to the clavicle and thoracic outlet. The intensity, severity, duration, and motion dependence of the current symptoms should be documented. At this point, the distinction between nTOS, aTOS, and vTOS can already be made. If there is swelling of the arm associated with pain, vTOS (also called Paget-von-Schroetter syndrome) can be tentatively diagnosed. Typical features of aTOS include cold fingers, livid or pale coloration of the hand, individual fingers, or fingertips, a faint or absent pulse at the wrist, arm weakness during use, and/or throbbing pain in the arm (1, 2). If a diagnosis of vTOS or aTOS is suspected, further vascular tests are indicated (Doppler ultrasonography, CT angiography, digital subtraction angiography [DSA], MR angiography).

If nTOS is suspected, the clinical neurological examination is very important, with special attention to motor, sensory, and autonomic function, particularly the identification of signs of muscle weakness (1, 27). Studies have shown that provocative maneuvers such as the Adson test, elevated arm stress test (EAST), supraclavicular pressure test, and costoclavicular maneuver are generally of moderate sensitivity (72%) and low specificity (53%). The low specificity (corresponding to a high false positive rate) is shown in detail in Table 1 and needs to be borne in mind when these tests are used (29– 31). The most informative finding in the experience of many clinicians is a positive Hoffmann-Tinel sign on deep supraclavicular palpation, with a comparison of the two sides (18).

In a review paper, the American College of Radiology recommends that patients with nTOS should have a chest x-ray to rule out a bony anomaly. Magnetic resonance imaging (MRI) of the cervicobrachial plexus and the chest can be used to rule out a local neoplasm or infectious/inflammatory process (2). Advances in magnetic MR neurography now enable high-resolution imaging of neural structures and the visualization of compression sites (32, 33). MRI of the cervical spine is recommended to rule out common differential diagnoses including cervical disc herniation, cervical spinal canal stenosis, and cervical neuroforaminal stenosis (28, 34). Other potential differential diagnoses and their characteristics, and differential-diagnostic techniques, are listed in the Box (35– 40, e1).

High-resolution nerve ultrasound (HNUS) is increasingly used in clinical practice. HNUS enables simultaneous visualization of the arterial, venous, and neural elements of the thoracic outlet in dynamic positions, with direct visualization of any compressing structures. Its disadvantages are that it is examiner-dependent and has a shallow penetration (e2, e3). A typical neurosonographic finding is the wedge-sickle sign, i.e., crescentic elongation of the inferior trunk because of compressing structures.

Neurophysiological diagnostic testing in nTOS serves to exclude common differential diagnoses such as carpal tunnel syndrome, cubital tunnel syndrome, Loge-de-Guyon syndrome, and cervical radiculopathy (e4). The utility of sensory nerve action potentials (SNAP) of the medial cutaneous antebrachial nerve for the diagnosis of nTOS has been shown in multiple studies (ebox) (e4, e5).

eBOX. Ancillary diagnostic testing.

(2, 28, 32–33, 2–5)

• clinical electrophysiology

  electroneurography with sensory nerve action potentials (SNAP) of the medial antebrachial cutaneous nerve; exclusion of C8 radiculopathy, ulnar nerve syndrome, Loge-de-Guyon syndrome, carpal tunnel syndrome

• x-ray of the thoracic outlet

  detection of bony anomalies (cervical rib, elongated C7, post-traumatic callus formation)

• magnetic resonance imaging of the cervical spine

  exclusion of cervical neuroforaminal stenosis, myelopathy, syringomyelia

• magnetic resonance imaging of the brachial plexus

  exclusion of a mass (schwannoma, Pancoast tumor)

• laboratory testing and cerebrospinal fluid analysis

  exclusion of Lyme disease, diabetic radiculoplexitis, idiopathic brachial plexus neuritis

• neurosonography

  dynamic visualization of anatomic structures (subclavian artery, subclavian vein, brachial plexus) and structures compressing them, duplex subclavian artery, wedge-sickle sign

Local anesthetic infiltration may be helpful; botulinum toxin and steroids, too, can be injected as trial therapy. These interventions are used as diagnostic aids, but sometimes also as treatment (2, e6).

Treatment: conservative treatment and the timing and type of surgery

In a prospective observational study, the conservative treatment of nTOS with physical therapy satisfactorily improved symptoms in 27% of cases (e7). Other studies of conservative therapy were not conducted or evaluated specifically for nTOS. The injection of botulinum toxin into the anterior and middle scalene muscles reduced pain but had no effect on functional scores (SF-36, Disability of the Arm, Shoulder, and Hand [DASH] questionnaire, paresthesia). Kinesiology tapes lessened pain and improved DASH scores compared to placebo tapes. In the DASH, a commonly used questionnaire for assessing the severity of TOS symptoms, functional restrictions of the upper limb with respect to 30 different activities are rated on a scale (e8). A randomized trial with a cross-over design demonstrated that steroid injections alleviated pain (as measured by the VAS) to a greater extent than scalene muscle stretching exercises (e6, e9, e10).

Primary conservative therapy is indicated in the absence of motor manifestations (28, e11). Appropriate surgical treatment should be performed promptly (within a few weeks at most) if there is weakness, hypotrophy, or atrophy of the upper limb muscles (nTOS 1).

There is no consensus on when surgery is indicated in patients without motor weakness. Proper patient selection and surgical timing are essential to lessen the suffering of those who can benefit from surgery while avoiding needless operations in those who cannot. In the authors’ view, surgery should be offered to patients with typical motion-dependent symptoms, severe distress, and an anatomical abnormality (nTOS 2). It may also be proposed to patients who have no anatomic abnormality, yet display typical radicular symptoms, after differential diagnoses have been excluded (nTOS 3a), if they have not benefited from 8–12 weeks of conservative treatment and their quality of life and everyday activities are markedly impaired (28).

For patients with diffuse symptoms or purely cervicoscapular symptoms and without an anatomical anomaly (nTOS 3b and nTOS 3c), the authors consider that surgery is only rarely indicated. Other differential diagnoses should be meticulously excluded. In such cases, intensified conservative treatment, interdisciplinary pain therapy, and a psychosomatic evaluation (where indicated) are advisable, so that needless operations and their complications can be avoided (e12).

A variety of surgical treatments are carried out by specialists in different surgical disciplines. A transaxillary approach with removal of the first rib or an accessory cervical rib may be complicated by injury to the brachial plexus (in 1–3% of cases), the subclavian vein or the thoracic duct, by pneumothorax (3% to 26% of cases), or by an injury of the sympathetic chain resulting in Horner syndrome (6, 25, e13, e14). Neurosurgeons often prefer a microsurgical approach from above the clavicle, with the aid of intraoperative neuromonitoring to protect the brachial plexus (see Figure, modified from [e15]). This approach is considered less traumatic and thus less likely to cause scarring. It enables good circumferential exposure of the compressed (nerve, artery, vein) and compressing structures (scalene muscles, ligaments, C7 transverse process, an accessory rib if present, and the first rib if necessary). In recent years, some plastic surgeons and vascular surgeons have also turned to the supraclavicular approach, with or without standard resection of the first rib (e16, e17). The posterior subscapular approach is now rarely used, generally only for recurrences.

Summary of the state of the evidence

There has been only one single-center randomized controlled trial (RCT) of surgery for a form of TOS that should probably be classified as dTOS or nTOS 3b or nTOS 3c. In this study, transaxillary rib resection was compared with supraclavicular “neuroplasty” without rib resection. In the group with rib resection, good to excellent results were obtained in 75% of cases, after a median follow-up interval of 37 months; the corresponding figure in the group without rib resection was only 48% (p = 0.05) (e18). This study has also been included in the current Cochrane analyses despite weaknesses in study design with respect to randomization and inclusion criteria (e19, e20). The second RCT in the updated 2014 Cochrane analysis concerned the effect of botulinum toxin injections in TOS patients, but without any specific evaluation in patients with nTOS; we have, therefore, not included this RCT in our tabular review (e6). No other RCTs on nTOS can be found in the literature. Three prospective observational studies, in which patients first underwent standardized physiotherapy and were operated on only if they did not benefit from it, showed a benefit from physiotherapy in 27–59% of cases. Two of these studies were designed specifically for nTOS, while the third contained an nTOS-specific analysis. Moreover, it was found that many (ca. 90%) of the patients who underwent surgery after unsuccessful physiotherapy benefited from it, with 75% returning to work within five months after surgery (e7, e13, e21). Patients with nTOS are more severely affected than those with other types of TOS, benefit less from transaxillary rib resection, and need secondary treatment more often than vTOS patients (e13). In nTOS patients who underwent supraclavicular decompression without rib resection, the surgical outcome was excellent in 27% of cases, good in 36%, acceptable in 26%, and poor in 11% (Table 2, eTable 3) (25, e7, e13, e19-e28). In a systematic review of ten single-center trials with heterogeneous inclusion criteria and treatment methods, there was an nTOS-specific pooled analysis of four trials, but no conclusions could be drawn regarding the efficacy of surgical therapies because variations in trial design did not enable a valid comparison (e23). The published case series of robot-assisted first rib resection are single-center studies with low case numbers and do not yet enable a systematic, nTOS-specific evaluation (e29, e30).

Table 2. The state of the evidence on neurogenic thoracic outlet syndrome (short version).

Searching term based on article type (author, year)	Findings	Quality criteria—critical discussion
Systematic review (Dessureault-Dober et al. 2018; e25)	● Results of the 4 included studies are reported again ● Venous compression on MRI in abduction is common in normal subjects as well (low validity of MRI in these cases) ● Provocation MRI in arm abduction more informative in TOS patients, especially in aTOS ● The maximum diagnostic accuracy of clinical tests cannot be ascertained because of a lack of comparison to the gold standard	● study design not nTOS-specific, but partly with specific analysis concerning nTOS
Systematic review (Peek et al. 2017; e23)	● surgical treatment of nTOS resulted in a DASH improvement of 28.3 points ● 56–89% of nTOS patients had improved symptoms after surgery	● part of the review is nTOS-specific
Systematic review (Yin et al. 2019; e24)	● best therapeutic success (80%) in the supraclavicular decompression group with 1st rib left intact ● complications most common in supraclavicular scalenectomy and rib resection group compared to transaxillary rib resection and supraclavicular decompression groups (25.9% vs. 22.5% vs. 12.6%) ● for nTOS: best results for surgical success and complete pain-free rate for supraclavicular decompression with 1st rib left intact	● no nTOS-specific design, but partly nTOS-specific analysis (4 studies with nTOS)
Systematic review (Doneddu et al. 2017; e26)	● narrative review of diagnosis and treatment without quantification of outcomes	● nTOS-specific
Systematic review (Povlsen et al. 2010; e19)	● transaxillary rib resection alleviates pain more than supraclavicular decompression ● analysis complicated by lack of standard diagnostic criteria	● no nTOS-specific design, but primary reference to a study on the nTOS subtype
Systematic review (Povlsen et al. 2014 – updated; e20)	● analysis complicated by lack of standard diagnostic criteria ● the diagnoses were assigned exclusively by the physicians conducting the study	● no nTOS-specific design, but primary reference to a study on the nTOS subtype
Observational study (Baldermann et al. 2017; e22)	● pain at the base of the neck, paresthesia, worse pain on arm elevation, and a pressure sensation at the scalene triangle or pectoralis minor m. predicted nTOS	● nTOS-specific
Observational study (Pesser et al. 2021; 25)	● 39.1% were satisfied with physiotherapy (not nTOS-specific) ● 60.9% had surgery; the outcome was excellent in 30.3% of surgical cases, good in 41.6%, fair in 15.7%, and poor in 12.4% (not nTOS-specific) ● 10.4% of nTOS patients had no improvement, or recurrence, of symptoms after surgery	● partially nTOS-specific
Observational study (Baldermann et al. 2019; e7)	● 27% satisfied with physiotherapy alone ● surgery in 60% of the cases studied ● surgical outcome excellent in 27%, good in 36%, fair in 26%, and poor in 11% of cases	● nTOS-specific
Observational study (Jordan et al. 2020; e27)	● worse pain in 3 patients (1 CRPS, 2 TOS) for a few days after the intervention ● no permanent complications ● 61% of the TOS patients were clinically improved at 3 moths, 22% at 6 months	● study design not nTOS-specific, results partially reported in nTOS-related fashion
Observational study (Fouasson-Chailloux et al. 2021; e28)	● QuickDASH in nTOS 58.8 ± 13.4 ● 30% less strength in nTOS hands than in patients’ unaffected limbs ● 19% less strength in nTOS hands than in hands of normal controls ● 19.5% less strength in key grip in patients’ nTOS hands compared with unaffected side ● no difference in strength between nTOS hands and normal controls	● nTOS-specific
Observational study (Chandra et al. 2011; e21)	● surgery was offered to 24 (41%) of the patients and performed in 21 ● there were relevant differences between groups regarding age and past history (prior trauma, sports exposure) ● 90% of the patients who underwent surgery benefited at 1 year, with lowering of the QuickDASH impairment score to 20.5	● nTOS-specific
Observational study (Chang et al. 2009; e13)	● 50% of nTOS patients and 77% of vTOS patients returned to work during the study period ● baseline characteristics (SF-12, DASH) of nTOS patients significantly worse than those of vTOS patients ● gradual improvement month by month in DASH, SF-12, and mental component scores in both patient groups	● no nTOS-specific design, but specific analysis of nTOS cases

Study aspects that were given a positive quality rating are marked with a (+), those that were given a negative quality rating with (-). Information concerning nTOS-specific analyses in each study is found in the column headed “Quality criteria - critical discussion.”

The search for “neurogenic thoracic outlet syndrome” combined with “systematic review“ yielded 6 hits; the search for “neurogenic thoracic outlet syndrome” combined with “meta-analysis” yielded 2 hits, one duplicate, and one publication that was not nTOS-specific. The search for “neurogenic thoracic outlet syndrome” combined with “randomized controlled trial” yielded 5 hits, 3 of which had already been retrieved by the previous searches and 2 of which contained no specific evaluation for nTOS. The search for “neurogenic thoracic outlet syndrome” combined with “observational study” yielded 7 hits, but an nTOS-specific analysis was carried out only for a small number of aspects.

aTOS, arterial TOS; BMI, body-mass index; BPI, Brief Pain Inventory; CBSQ, Cervical Brachial Symptom Questionnaire; CRPS, complex regional pain syndrome; CT, computerized tomography; DASH, Disabilities of the Arm, Shoulder, and Hand; DLV, Dutch Language Version; EAST, elevated arm stress test; EQ 5D, 5-Dimensional European Quality of Life Questionnaire; McGill, McGill Pain Questionnaire; MRI, magnetic resonance imaging; nTOS, neurogenic TOS; PCS, Pain Catastrophizing Scale; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses; PROM, patient-reported outcome measure; QOL, quality of life; QUADAS-2, Quality Assessment of Diagnostic Accuracy Studies; SDS, Simple Descriptive Scale; SF-12, Short Form Health Survey (with 12 items); TOS, thoracic outlet syndrome; VAS, Visual Analog Scale; vTOS, venous TOS.

The information displayed here is derived from References 25, e7, and e18–e28.

eTable 3. The definition of neurogenic thoracic outlet syndrome (nTOS) according to the Society for Vascular Surgery (USA) and the nTOS subclassification according to the Peripheral Nerve Section of the European Association of Neurosurgical Societies (EANS) (2, 28).

Society for Vascular Surgery (USA)

EANS Peripheral Nerve Section

● Fulfillment of 3 of the following 4 criteria: 1) pain or tenderness of the thoracic outlet 2) distal neurological abnormalities 3) absence of other pathology 4) symptom alleviation after injection of a local anesthetic into the scalene muscles

● nTOS 1 – hypotrophic nTOS: patients presenting with muscle weakness, hypotrophy, or atrophy in the upper limbs (usually distally) ● nTOS 2 – irritative nTOS with anatomical anomaly: patients without motor involvement presenting with pain or sensory symptoms in conjunction with an anatomical particularity or anomaly ● nTOS 3 – irritatives nTOS without anatomical anomaly: patients without motor involvement presenting with pain or sensory symptoms, not in conjunction with any anatomical particularity or anomaly nTOS 3a – radicular nTOS 3b – cervicoscapular nTOS 3c – diffuse

EANS, European Association of Neurosurgical Societies; nTOS, neurogenic thoracic outlet syndrome

Overview

The available evidence on the treatment of nTOS is limited in both quality and quantity. The available nTOS-specific evidence does, however, permit the conclusion that conservative treatment should be tried first in patients who have no motor deficit. If surgery is needed, there is a strong case for supraclavicular decompression without rib resection. The single available RCT on rib resection versus supraclavicular neuroplasty must be viewed critically from the methodological point of view; its results cannot be generalized to patients with motor deficits (nTOS 1) or anatomical anomalies (nTOS 2). The choice of treatment depends, at present, on the experience and expertise of the treating physicians. A consensus document recently issued by experienced European neurosurgeons contains a recommendation for the anterior and supraclavicular microsurgical approach, with the aid of intraoperative neuromonitoring.

Table 1. Descriptions and false-positive rates of clinical functional tests for thoracic outlet syndrome (29, 31).

Test	Description	A) in normal subjects	B) in patients with carpal tunnel syndrome / normal subjects
Supraclavicular pressure (SCP) test	Pain induced by pressure on the plexal elements in the triangle between the sternocleidomastoid m., the scalene mm., and the clavicle, as well as beneath it (compared to the asymptomatic side).	● pulse change in 21% ● pain in 2% ● paresthesia in 15%	● 61% / 30%
Elevated arm stress test (EAST)	Both arms in 90° abduction and external rotation with elbows in the plane of the chest wall; opening and closing hands for 3 minutes.	● pulse change in 6 % ● pain in 21% ● paresthesia in 36%	● 77% / 47%
Upper limb tension test (ULTT)	Head turn away from the symptomatic side and arm elevation with extended wrists.
Costoclavicular maneuver (CCM)	Pulling the shoulders backwards and donwnwards for 30 seconds.	● pulse change in 11% ● pain in 0% ● paresthesia in 15%	● 48% / 16 %
Adson test	330° abduction and extension with palpation of the radial pulse, which weakens or disappears when the neck is extended and tthe head is turned toward the symptomatic side.	● pulse change in 11% ● pain in 0% ● paresthesia in 11%	● 42% / 9%

In two prospective studies, the false-positive rates of the functional tests were studied A) in normal subjects and B) in patients with carpal tunnel syndrome as well as in normal subjects (29, 31). In the study by Nord et al. (31), two different Adson tests were performed; the description here (in the “Description” column) is confined to one of these two, for the sake of comparability.

BOX. The major differential diagnoses of thoracic outlet syndrome with their individual features and differential-diagnostic modalities (35– 40, e1).

• C8 radiculopathy

  • usually without clearly movement-dependent symptoms, unlike nTOS; sensorimotor deficits similar to those of nTOS

  • for differential diagnosis (D/Dx): cervical spine MRI and neurophysiologic examination with electromyography (EMG)

• cervical myelopathy

  • often, the posterior columns are the most severely affected, with distal sensory disturbances of the upper and lower limbs in cervical spinal stenosis; no motion dependence of the symptoms

  • for D/Dx: cervical spine MRI, neurophysiological studies

• lower brachial plexus neuritis

  • severe pain that begins acutely and usually persists for about one week; after a delay, weakness and sensory deficits in places

  • for D/Dx: typical dynamics of the clinical manifestations

• other mechanisms of brachial plexus paresis

  • e.g., due to a mass (Pancoast tumor, nerve sheath tumor); the clinical examination and electrophysiological studies do not enable the definitive diagnosis in such cases

  • for D/Dx: brachial plexus MRI

• nerve compression syndromes of the median and ulnar nn. (ulnar neuropathy at the cubital tunnel and Loge-de-Guyon syndrome)

  • tingling paresthesia in the distribution of the nerve, motor weakness and atrophy

  • for D/Dx: neurophysiological studies, with neurography (inching, if indicated) and EMG if indicated

• borreliosis (Lyme disease)

  • peripheral-radicular root damage in stage II Lyme borreliosis; history of a tick bite, erythema migrans, and/or other symptoms such as headache, fatigue, paresthesia, and sleep disturbance; no motion dependence of the symptoms

  • for D/Dx: CSF examination (lymphocytic pleocytosis, detection of Borrelia burgdorferi by enzyme-linked immunosorbent assay [ELISA] and Western blot

• fibromyalgia

  • chronic pain in multiple body regions, sleep disturbance, fatigability, tenderness at 11/18 specific pressure points, exclusion of a somatic disease that adequately explains the symptoms

  • For D/Dx: e.g., a fibromyalgia symptom questionnaire

• amyotrophic lateral sclerosis (ALS)

  • no movement dependence of symptoms, predominantly distal mainly involving the small muscles of the hand and the plantar flexors, fasciculations and muscle spasms, rapid progression, respiratory insufficiency in further course, bulbar symptoms, spasticity (often of the legs), ALS-plus symptoms: dementia, autonomic dysfunction

  • for D/Dx: clinical features, laboratory tests

Figure.

The supraclavicular approach to the neurovascular bundle of the thoracic outlet

a) The skin is incised parallel to the clavicle lateral to the sternocleidomastoid m. The omohyoid m. is then exposed and lateralized (and ligated and divided if necessary) and the anterior scalene m. is dissected with careful sparing of the phrenic n. The brachial plexus can now be gently dissected free between the anterior and middle scalene mm.

b) The division and, if necessary, partial resection of the anterior scalene m. decompresses the neural structures. The brachial plexus is circumferentially exposed under the operating microscope, and its course is followed under the clavicle. This enables the exposure and, if necessary, resection of other potentially compressing structures (middle scalene m. from the dorsal side, accessory muscles, Sibson‘s fascia, bony elements, etc.). A final check by palpation is recommended, including a check with the arm in the position that triggers the symptoms (abduction and retroversion).

Modified from König et al. (e15)

Questions on the article in issue 43/2022:

Neurogenic Thoracic Outlet Syndrome

The submission deadline is 27 October 2023. Only one answer is possible per question. Please select the answer that is most appropriate.

Question 1

According to an American study, what is the incidence of neurogenic thoracic outlet syndrome per year?

1. 2–3 per 100 000

2. 20–30 per 100 000

3. 100–150 per 100 000

4. 300–500 per 100 000

5. 1 000–2 000 per 100 000

Question 2

In the abbreviation dTOS, what does “d” stand for?

1. distributed

2. disputed

3. demarcated

4. double

5. diminished

Question 3

What clinical functional test is carried out by pulling the shoulders backwards and downwards for 30 seconds?

1. the supraclavicular pressure test

2. the Adson test

3. the upper limb tension test

4. the costoclavicular maneuver

5. the elevated arm stress test

Question 4

An anomaly in the morphology of what anatomical structure can contribute to the pathophysiology of neurogenic thoracic outlet syndrome?

1. the mediastinal pleura

2. the cardinal ligament

3. the antebrachial fascia

4. Sibson’s fascia

5. the sacrospinal fascia

Question 5

Which of the following is a typical manifestation of neurogenic thoracic outlet syndrome?

1. Dupuytren’s contracture

2. buttonhole deformity

3. shoemaker’s thumb

4. swan-neck deformity

5. Gilliatt-Sumner hand

Question 6

Which of the following is a typical manifestation of arterial thoracic outlet syndrome?

1. cold fingers

2. fasciculations in the muscles of the upper limb

3. cardiac arrhythmia

4. high blood pressure

5. hand weakness

Question 7

According to an observational study, what percentage of patients with neurogenic thoracic outlet syndrome obtained satisfactory relief of symptoms through physiotherapy?

1. 0.7%

2. 5%

3. 15%

4. 27%

5. 42%

Question 8

Which of the following makes an initial trial of conservative treatment inadvisable in a patient with neurogenic thoracic outlet syndrome?

1. pain

2. a sensory deficit

3. hand involvement

4. a motor deficit

5. local tenderness at the thoracic outlet

Question 9

What surgical approach for the treatment of neurogenic thoracic outlet syndrome is recommended by experienced neurosurgeons?

1. the microsurgical subscapular approach

2. the microsurgical transaxillary approach

3. the microsurgical supraclavicular approach

4. the microsurgical transscapular approach

5. the microsurgical peristernal approach

Question 10

What differential diagnosis of thoracic outlet syndrome can be made on the basis of the typical dynamics of the symptoms and signs, with pain of acute onset for ca. one week followed by the delayed onset of weakness and sensory deficits in places?

1. cervical myelopathy

2. Lyme disease

3. amyotrophic lateral sclerosis

4. C8 radiculopathy

5. lower brachial plexus neuritis

eTable 2. The state of the evidence on neurogenic thoracic outlet syndrome.

Article (author, year)	Inclusion criteria	Exclusion criteria	Number of studies and patients; duration of follow-up	Diagnostic studies and interventions	Outcome criteria	Outcome	Quality criteria - critical discussion
Search item: systematic reviews
Dessureault-Dober et al. 2018 (e25)	● Studies on the validity of diagnostic tests in TOS. ● Articles in English and French. ● Comparisons with one diagnostic test against another primary diagnostic tool (CT, neurography, ultrasound, electrophysiology, angiography)	● marked bias according to the QUADAS-2 criteria	● 10 of 1 767 screened studies were included for assessment of the risk of bias ● 4 of the 10 studies were evaluated	● clinical tests vs. imaging studies and neurophysiologic examinations (MRI or CT or angiography or Doppler or neurography or electrophysiologic testing) vs. ● Adson test ● modified Adson test ● Allen test ● EAST test ● hyperabduction / Wright-Test ● costoclavicular test / Eden test ● Tinel sign	clinical tests: ● any compression of the neurovascular bundle with the arm in the neutral position (MRI or CT or angiography) ● Doppler ultrasonography	● Results of the 4 included studies are reported again. ● Venous compression on MRI in abduction is common in normal subjects as well (low validity of MRI in these cases) ● Provocation MRI in arm abduction more informative in TOS patients, especially in aTOS ● The maximum diagnostic accuracy of clinical tests cannot be ascertained because of a lack of comparison to the gold standard	● PRISMA, QUADAS (+) ● study design not nTOS-specific, but partly with specific analysis concerning nTOS (+) ● re-reporting of results of the 4 included studies without new pooling or the like (-) ● no quantitative overview, reproduction, or discussion of the results of the 4 selected studies (-) ● criteria for the different diagnostic modalities not clearly defined (-) ● Tinel sign and supraclavicular pressure test not distinguished from each other (-)
Peek et al. 2017 (e23)	● studies with a description of the outcome in English ● retrospective and prospective studie s	● fewer than 5 cases ● r eviews ● studies on endoscopic or robot-assisted transaxillary rib resection	● 11 of 330 screened studies ● 10 studies on nTOS with 9 to 200 patients and a median follow-up of 3–90 months ● 5 studies on vTOS ● 2 studies on aTOS	● pectoralis major tenotomy ● supraclavicular decompression (including rib resection, neurolysis, cervical rib resection) ● conservative treatment ● transaxillary rib resection	● DASH, SF-12, EQ 5D, Derkash classification, surgical complications	● surgical treatment of nTOS resulted in a DASH improvement of 28.3 points ● 56–89% of nTOS patients had improved symptoms after surgery	● PRISMA (+) ● part of the review is nTOS-specific (+) ● inclusion of retrospective and prospective studies ● the included studies are from one institution each; the outcome criteria are uniform, but the inclusion criteria, diagnostic criteria, and treatment methods are heterogeneous across studies and not standardized (-) ● only 4 papers were included in the pooled DASH score analysis, as studies without uniform outcome criteria were not considered (-)
Yin et al. 2019 (e24)	● studies including outcomes after TOS surgery	● < 10 patients ● reoperation for recurrences ● patients who were already included in other studies ● letters, comments, reviews	● 32 studies ● 17 transaxillary rib resections ● 9 supraclavicular rib resections and scalenectomy ● 14 supraclavicular decompressions without rib resection	● transaxillary rib resection vs. ● supraclavicular rib resection and scalenectomy vs. ● supraclavicular decompression without rib resection	● surgical outcome, complete relief of pain, complications	● best therapeutic success (80%) in the supraclavicular decompression group with 1st rib left intact ● complications most common in supraclavicular scalenectomy and rib resection group compared to transaxillary rib resection and supraclavicular decompression groups (25.9% vs. 22.5% vs. 12.6%) ● for nTOS: best results for surgical success and complete pain-free rate for supraclavicular decompression with 1st rib left intact	● PRISMA (+) ● no nTOS-specific design, but partly nTOS-specific analysis (4 studies with nTOS) ● heterogeneous study quality and results ● anatomical particularities not described (cervical rib, etc.) ● investigator-dependent outcome criteria, no standardized questionnaires
Doneddu et al. 2017 (e26)	● date of publication from 1 January 2006 to 30 June 2016	● this article only included vascular cases	● 4 systematic analyses ● 6 clinical studies ● 36 reviews				● nTOS-specific (+)
Povlsen et al. 2010 (e19)	● randomized, controlled trials with a diagnosis of TOS (unspecified) ● interventions with the purpose of treating TOS	● no randomization	● 1 of 33 screened studies ● 55 patients	● transaxillary rib resection vs. supraclavicular decompression (neuroplasty)	● primary: change in pain rate measured on the VAS at least 6 months after surgical treatment ● secondary: muscle strength, disability, paresthesia and numbness, complications of interventions	● transaxillary rib resection alleviates pain more than supraclavicular decompression ● analysis complicated by lack of standard diagnostic criteria	● no nTOS-specific design, but primary reference to a study on the nTOS subtype (–) ● only one study included: subject to high bias at randomization (-) ● inclusion of patients without muscular weakness, formally dTOS (-) ● small number of patients (-) ● single-center studies only (-)
Povlsen et al. 2014 (updated) (e20)	● randomized, controlled trials with a diagnosis of TOS (unspecified) ● interventions with the purpose of treating TOS	●no randomization	● 2 of 34 screened studies ● 92 patients	● botulinum toxin vs. saline injection ● transaxillary rib resection vs. supraclavicular decompression (neuroplasty)	● primary: change in pain rate measured on the VAS at least 6 months after surgical treatment ● secondary: muscle strength, disability, paresthesia and numbness, complications of interventions	● analysis complicated by lack of standard diagnostic criteria ● the diagnoses were assigned exclusively by the physicians conducting the study	● no nTOS-specific design, but primary reference to a study on the nTOS subtype (–) ● only 2 studies included (–) ● heterogeneous design of the included studies (–) ● randomization in the surgical study was subject to high bias (–) ● TOS-subclassification not uniform; typical nTOS was not considered in one of the studies, and the other contained no clear criteria for distinguishing the various types of TOS (–) ● small number of patients (-) ● single-center studies only (-)
Search item: observational studies
Balderman et al. 2016 (e22)	● nTOS	● not mentioned	● 150 patients	● retrospective analysis of prospectively collected data	● QuickDASH, CBSQ, Mc Gill, BPI, SF-12, SDS, PCS	● pain at the base of the neck, paresthesia, worse pain on arm elevation, and a pressure sensation at the scalene triangle or pectoralis minor m. predicted nTOS	● nTOS-specific ● single-center (–) ● predefined outcome criteria(+)
Pesser et al. 2021 (25)	● nTOS (according to the criteria of the Society for Vascular Surgery)	● no consent for storage of data in the institutional database	● 476 patients with nTOS (out of 856 with suspected TOS)	● prospective cohort study with multidisciplinary treatment pathway ● 186 patients were treated with physiotherapy (no nTOS-specific analysis); 274 nTOS patients / 307 arms (17 patients bilateral, 16 recurrent) were operated on (primary transaxillary decompression and rib resection in 276 cases and primary supraclavicular decompression with rib resection in 21; supraclavicular approach in patients with high BMI and in recurrences; resection of an accessory cervical rib in 34)	● telephone interview, completion of the TOS disability scale questionnaire, CBSQ, DASH-DLV and SF-12 after a mean of 16.9 ± 9.2 months	● 39.1% were satisfied with physiotherapy (not nTOS-specific) ● 60.9% had surgery; the outcome was excellent in 30.3% of surgical cases, good in 41.6%, fair in 15.7%, and poor in 12.4% (not nTOS-specific) ● 10.4% of nTOS patients had no improvement, or recurrence, of symptoms after surgery	● partially nTOS-specific (+) ● single-center (–) ● telephone interview (–) ● case and patient definition inconsistent and non-transparent (-) ● no uniform follow-up time point
Balderman et al. 2019 (e7)	● nTOS	● not mentioned	● 183 patients	● prospective, single-center observational study with hierarchical design: 6 weeks of physiotherapy ● if unsuccessful: supraclavicular decompression and resection of the 1st rib	● QuickDASH, SF-12, patient-related outcome classified as excellent, good, fair, or poor, according to PROM	● 27% satisfied with physiotherapy alone ● surgery in 60% of the cases studied ● surgical outcome excellent in 27%, good in 36%, fair in 26%, and poor in 11% of cases	● nTOS-specific (+) ● prospective (+) ● single-center (–) ● clear diagnostic criteria (+) ● more patients than in other studies; accepted and predefined outcome criteria (+)
Jordan et al. 2020 (e27)	● not mentioned	● not mentioned	● 62 patients	● single-armed observational study of the effect of plasma concentrate treatment with alpha-2-macroglobulin supplementation	● clinical improvement at 3 and 6 months	● worse pain in 3 patients (1 CRPS, 2 TOS) for a few days after the intervention ● no permanent complications ● 61% of the TOS patients were clinically improved at 3 moths, 22% at 6 months	● study design not nTOS-specific, results partially reported in nTOS-related fashion (-) ● single-center (–) ● not only nTOS patients included; 23 patients with CRPS (–) ● inclusion and exclusion criteria not clearly defined (–) ● quality-control checklists were not used (–) ● no information regarding possible examiner bias (–)
Fouasson-Chailloux et al. 2021 (e28)	● patients with unilateral or bilateral nTOS ● consent to the rehabilitation program	● other possible diagnoses	● 85 patients with nTOS vs. ● 85 normal controls	● two-armed observational study ● therapeutic intervention not specified	● QuickDASH, grip strength, key grip strength	● QuickDASH in nTOS 58.8 ± 13.4 ● 30% less strength in nTOS hands than in patients’ unaffected limbs ● 19% less strength in nTOS hands than in hands of normal controls ● 19.5% less strength in key grip in patients’ nTOS hands compared with unaffected side ● no difference in strength between nTOS hands and normal controls	● screening not mentioned (–) ● no measures against bias mentioned (e.g., blinding) (–) ● nTOS-specific (+) ● single-center (–) ● clearly defined outcome criteria (+) ● standardized inclusion and outcome criteria (+)
Chandra et al. 2011 (e21)	● upper limb symptoms suggestive of nTOS: pain, paresthesia, numbness, weakness, motor impairment	● venous or arterial TOS	● 59 patients	● prospective, single-center, hierarchical design: ● 1–4 months of physiotherapy in case of insufficient benefit: ● supraclavicular decompression with first rib resection and middle and anterior scalenectomy	● QuickDASH, QOL-scale (0–100)	● surgery was offered to 24 (41%) of the patients and performed in 21 ● there were relevant differences between groups regarding age and past history (prior trauma, sports exposure) ● 90% of the patients who underwent surgery benefited at 1 year, with lowering of the QuickDASH impairment score to 20.5	● nTOS-specific (+) ● single-center (–) ● defined outcome criteria (+) ● no randomization, no specific methods for bias reduction mentioned (-)
Chang et al. 2009 (e13)	● age > 18 years ● patients who did not benefit from physiotherapy ● consent	● not mentioned	● 70 of 105 potentially eligible patients (44 nTOS / 26 vTOS)	● transaxillary resection of the first rib	● SF-12, DASH, score concerning mental components, return to work	● 50% of nTOS patients and 77% of vTOS patients returned to work during the study period ● baseline characteristics (SF-12, DASH) of nTOS patients significantly worse than those of vTOS patients ● gradual improvement month by month in DASH, SF-12, and mental component scores in both patient groups	● no nTOS-specific design, but specific analysis of nTOS cases (–) ● single-center (–) ● defined outcome criteria (+) ● no randomization, no specific methods for bias reduction mentioned (-)

Study aspects that were given a positive quality rating are marked with a (+), those that were given a negative quality rating with (-). Information concerning nTOS-specific analyses in each study is marked in boldface. The search for “neurogenic thoracic outlet syndrome” combined with “systematic review“ yielded 6 hits; the search for “neurogenic thoracic outlet syndrome” combined with “meta-analysis” yielded 2 hits, one duplicate, and one publication that was not nTOS-specific.

The search for “neurogenic thoracic outlet syndrome” combined with “randomized controlled trial” yielded 5 hits, 3 of which had already been retrieved by the previous searches and 2 of which contained no specific evaluation for nTOS. The search for “neurogenic thoracic outlet syndrome” combined with “observational study” yielded 7 hits, but an nTOS-specific analysis was carried out only for a small number of aspects.

aTOS, arterial TOS; BMI, body-mass index; BPI, Brief Pain Inventory; CBSQ, Cervical Brachial Symptom Questionnaire; CRPS, complex regional pain syndrome; CT, computerized tomography; DASH, Disabilities of the Arm, Shoulder, and Hand; DLV, Dutch Language Version; EAST, elevated arm stress test; EQ 5D, 5-Dimensional European Quality of Life Questionnaire; McGill, McGill Pain Questionnaire; MRI, magnetic resonance imaging; nTOS, neurogenic TOS; PCS, Pain Catastrophizing Scale; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses; PROM, patient-reported outcome measure; QOL, quality of life; QUADAS-2, Quality Assessment of Diagnostic Accuracy Studies; SDS, Simple Descriptive Scale; SF-12, Short Form Health Survey (with 12 items); TOS, thoracic outlet syndrome; VAS, Visual Analog Scale; vTOS, venous TOS.

The information displayed here is derived from References 25, e7, and e18–e28.