Recognising and managing thoracic outlet syndrome in primary care

Thoracic outlet syndrome (TOS) remains a diagnostic enigma in general practice. Although it is an uncommon cause of upper limb symptoms, its potential to cause chronic pain and disability means it should be considered when more common conditions do not fit the clinical picture. In primary care, management should be optimised to limit specialist referrals to those who truly need them. TOS has three subtypes: neurogenic (nTOS); venous (vTOS); and arterial (aTOS). Over 90% of cases are neurogenic (brachial plexus compression), ¹ whereas the vascular subtypes are far rarer but can present acutely and require urgent management. Vascular cases are typically referred directly to vascular surgery, whereas nTOS often follows an insidious course with symptoms that are subtle, non-specific, and easily misattributed to other conditions. ²

When to suspect thoracic outlet syndrome

Patients with nTOS often present with arm numbness, a sense of heaviness or fatigue, diffuse arm ache, and tingling in the hand. Symptoms are usually worse with elevation of the arms or sustained overhead activity. This picture is easily mistaken for cervical radiculopathy, carpal tunnel syndrome, or shoulder pathology. However, nTOS symptoms do not conform to a single dermatome or nerve distribution, and they may fluctuate with changes in posture. ³ Recognising this atypical pattern is key to considering TOS as a diagnosis when more common explanations have been ruled out.

Making a diagnosis of TOS in primary care is challenging. There are no universally accepted diagnostic criteria, ⁴ so it is largely a diagnosis of exclusion. ‘Couch-side’ provocation manoeuvres such as the Roos test (elevated arm stress test) or Adson’s test can reproduce the patient’s symptoms and support the clinical impression, but these tests have a high false-positive rate and are not definitive. ⁵ Many other clinical tests are described, which are of varying sensitivity and specificity (Table 1). Results should be interpreted with caution in the context of the overall clinical picture. On examination, true neurological deficits, such as objective weakness, muscle atrophy, or sensory loss, are usually absent in nTOS. It is still essential to look for any focal neurological signs that might suggest an alternative cause, for example, a cervical nerve root lesion. Special tests for other conditions, such as Spurling’s test for cervical radiculopathy or Tinel’s test and Phalen’s test at the wrist for carpal tunnel syndrome, can help identify those diagnoses. GPs should also be vigilant for vascular signs (for example, markedly reduced pulses, arm swelling, or colour change), which would point to a vascular cause rather than nTOS.

Table 1. Key provocative tests in thoracic outlet syndrome.

Test	How to perform (clinical technique)	Associated TOS subtype(s)	Sensitivity	Specificity
Adson’s test	Patient seated, arm slightly abducted and extended. Examiner palpates radial pulse; patient takes a deep breath, extends neck, and turns head towards the affected side. A positive test is indicated by a marked decrease or disappearance of the radial pulse. (Indicates compression of the subclavian artery by a tight anterior scalene or cervical rib)	Primarily arterial TOS (compression of subclavian artery at scalene triangle); not very sensitive for pure neurogenic TOS	79–92%	≈76%
Roos test (EAST)	Patient’s arms abducted 90° and externally rotated at shoulders, elbows flexed 90°. Patient opens and closes the hands slowly for 3 minutes. Test is positive if it reproduces the patient’s typical symptoms (gradual onset of neck/shoulder pain radiating down the arm with paraesthesias) or if the patient cannot maintain the position because of distress. Note: If arterial flow is compromised, the elevated arm may turn pale; if venous outflow is compressed, the arm may become cyanotic or swollen	Mainly neurogenic TOS (provokes brachial plexus symptoms by prolonged overhead position); can also reveal arterial TOS (arm pallor) or venous TOS (cyanosis, swelling) during the manoeuvre	≈84%	≈30%
Wright’s test (hyperabduction)	Patient seated; examiner palpates the radial pulse while passively hyperabducting the arm (>90° abduction with external rotation) and holding it overhead for up to 1 minute. The patient’s head is turned away from the test side. A positive test is indicated by a significant diminution of the radial pulse and/or reproduction of arm symptoms (pain or tingling)	Neurogenic or arterial TOS (compression of the neurovascular bundle under the pectoralis minor, in the subcoracoid space). Loss of pulse suggests vascular TOS (note: ~7% of people without TOS also have a positive pulse change), whereas reproduction of neurologic symptoms suggests brachial plexus involvement	70–90%	29–53%
Eden’s test (costoclavicular manoeuvre)	Examiner palpates the radial pulse and draws the patient’s shoulders down and back (chest lifted in an ‘at attention’ military posture). The patient can also actively assume this position. A positive test is a notable decrease in the pulse vigour or onset of numbness/tingling in the arm. (This manoeuvre narrows the space between the clavicle and first rib)	Costoclavicular compression of the subclavian vessels and/or brachial plexus (between first rib and clavicle). Often associated with venous TOS (patients report arm heaviness or swelling when carrying heavy packs) but can provoke arterial or neurogenic symptoms as well (because of general neurovascular bundle compression)	Up to ~92%	Variable
Supraclavicular pressure test	Patient seated with arms relaxed. Examiner applies firm pressure to the supraclavicular fossa (over the upper trapezius and anterior scalene region) for ~30 seconds. The test is positive if it reproduces the patient’s usual pain or paraesthesias in the arm/hand (due to brachial plexus provocation)	Neurogenic TOS (directly compresses the brachial plexus at the interscalene triangle). (This test specifically targets nerve elements and is not used for vascular TOS)	— (Not well established)	85–98%
Cyriax release test	Patient seated; examiner stands behind and grasps the patient’s forearms with elbows bent. The examiner lifts the shoulder girdle upward (passively elevating the shoulders/scapulae) and holds for 1–3 minutes. A positive test is delayed reproduction of the patient’s usual neurogenic symptoms (pain or tingling in the hand/arm) during the elevation hold	Neurogenic TOS (provokes brachial plexus irritation by relieving downward traction). A positive Cyriax release suggests nerve compression pathology; it helps distinguish true neurogenic TOS from other causes of symptoms	— (Not reported in literature)	77–97%

EAST = elevated arm stress test. TOS = thoracic outlet syndrome.

Initial investigations should be minimal and targeted. A plain chest X-ray including the cervicothoracic junction can reveal structural abnormalities such as a cervical rib or an apical lung mass. If vTOS is suspected, such as if a patient describes a swollen, discoloured arm after vigorous activity, an urgent Doppler ultrasound is warranted to check for subclavian vein thrombosis. ⁶ For neurogenic presentations, advanced imaging is often not needed at the primary care stage. A cervical spine MRI or nerve conduction study might be reserved for cases where a cervical disc prolapse or distal nerve entrapment is strongly suspected, ideally after specialist advice. In the absence of red flags, a trial of conservative management with observation is reasonable before pursuing more invasive investigations.

Managing thoracic outlet syndrome in primary care

Not every patient with suspected TOS needs immediate referral to a tertiary specialist unit. Most patients with nTOS can be managed initially through local musculoskeletal (MSK) services, orthopaedic clinics, or neurology clinics. ⁷ This approach helps avoid overwhelming the limited specialist centres. Tertiary thoracic outlet or brachial plexus surgical services should be reserved for patients with clear, refractory symptoms and definitive surgical indications that have not responded to conservative measures.

Conservative management is the cornerstone of therapy for nTOS. Structured physiotherapy focusing on posture correction, scapular stabilisation, stretching of the scalene and pectoralis minor muscles, and neural mobilisation exercises is the recommended first-line approach. ⁸ Specialist physiotherapy may not always be readily available, but even a basic home exercise programme, combined with patient education, reassurance and regular follow-up, can be beneficial. Symptom improvement often takes months and requires persistence. GPs should counsel patients on maintaining realistic expectations and adherence to therapy.

Adjunctive pain management can support patients while physiotherapy is underway. Non-steroidal anti-inflammatory medications and simple analgesics, as well as neuropathic agents such as amitriptyline or gabapentin, are commonly used. ⁹ If muscle spasm is significant, a short course of muscle relaxants may be helpful. Equally important is addressing the psychological impact of chronic pain. Patients with nTOS often become frustrated or anxious after seeing multiple providers without a clear diagnosis. ⁴

Supporting and counselling patients

GPs can best support a patient with suspected TOS by first acknowledging the diagnostic uncertainty and explaining that definitive diagnosis can be challenging. The GP should reassure the patient that this uncertainty does not invalidate their symptoms and then set realistic expectations for management. They should emphasise that initial treatment will be conservative, outlining a stepwise plan of targeted physiotherapy, activity/posture modifications, and appropriate analgesia as the first-line approach. The GP should not only explain that these measures are effective in relieving symptoms for the majority of patients but also clarify that improvement is usually gradual rather than immediate. It is important to note that surgical interventions are only considered in more severe or unresponsive cases, so the patient understands that surgery is a last resort if conservative therapy fails. To foster understanding and adherence, the GP should provide clear education about TOS and the rationale behind each recommended exercise or lifestyle change, integrating these recommendations into the patient’s daily routine. The GP should stress that consistent compliance with prescribed physiotherapy and home exercises is crucial for recovery. Throughout the conversation, maintaining a calm and empathetic tone is key, validating the patient’s frustrations and concerns, encouraging questions, and conveying optimism that with patience and persistence their function and comfort can improve over time.

A sensible referral pathway: getting patients to the right place

If a patient’s symptoms do not improve despite comprehensive conservative treatment, referral to secondary care is indicated. Depending on local resources, this might be to a musculoskeletal interface clinic, an upper limb orthopaedic surgeon, a vascular surgeon, or a neurologist. ³ A UK-wide survey found considerable variation in referral patterns and access to TOS expertise, underscoring the importance of clear local pathways. ³ Direct referral to a tertiary TOS centre, such as a specialist brachial plexus or vascular unit, is usually unnecessary as a first step. Premature referral can delay urgent treatment for those who need it and lead to unnecessary investigations and worry in others. ⁷

Surgery is reserved for the small subset of patients with severe, persistent symptoms, or significant vascular compromise, that do not resolve with conservative management. The surgical procedure typically involves decompression of the thoracic outlet, sometimes by removing the first rib, and releasing any fibrous bands or tight scalene muscles. A large UK case series reported good or excellent outcomes in 84% of patients following surgical treatment for TOS. ¹ However, results for nTOS surgery are variable, and many patients have coexistent chronic pain that can limit the benefit of surgical intervention. Careful patient selection, ideally by a multidisciplinary team, is essential before proceeding to surgery.

GPs should remain alert to the vascular forms of TOS, as these require urgent action. Venous TOS, namely, effort thrombosis or Paget–Schroetter syndrome, usually presents in a young, active individual with sudden unilateral arm swelling and cyanosis due to subclavian vein thrombosis. ¹⁰ Arterial TOS is very rare but can cause acute limb ischaemia, presenting as a cold, pale hand with weak pulses or even digital emboli. These presentations are red flags that warrant immediate vascular surgical referral. ⁶

Summary

Thoracic outlet syndrome is rare and often overlooked in primary care, but prompt recognition can prevent prolonged patient distress. In most cases of nTOS, patient education, targeted exercises, pain control, and reassurance will lead to improvement without the need for invasive treatment. ⁹ The GP’s role is to suspect TOS when appropriate, rule out serious alternative causes, initiate conservative therapy, and refer to the right specialist if needed. By maintaining a high index of suspicion and a supportive approach, GPs can navigate the uncertainty of TOS and help patients achieve meaningful improvement.

Provenance

Freely submitted; externally peer reviewed.

Competing interests

The authors have declared no competing interests.