Thoracic Outlet Compression (TOC), commonly referred to as Thoracic Outlet Syndrome (TOS), is a complex condition involving compression of neurovascular structures in the thoracic outlet—the narrow passageway between the collarbone (clavicle) and first rib. As a general practitioner in Australia, I frequently encounter patients presenting with symptoms that align with TOS, though diagnosis and management require careful clinical evaluation due to overlapping features with other musculoskeletal and neurological disorders.
What is Thoracic Outlet Compression?
TOC occurs when nerves (brachial plexus), arteries (subclavian artery), or veins (subclavian vein) become compressed in the thoracic outlet. It is classified into three subtypes:
- Neurogenic TOS (nTOS): Accounts for 90–95% of cases, involving brachial plexus compression.
- Venous TOS: Caused by subclavian vein compression, leading to swelling, discolouration, or thrombosis.
- Arterial TOS: Rare but serious, involving subclavian artery compression, which may cause ischemia or aneurysm.
In Australia, neurogenic TOS is most frequently diagnosed, particularly in young adults and middle-aged women.
Causes & Risk Factors
The etiology of TOC is multifactorial, often arising from anatomical, traumatic, or functional factors:
- Anatomical variations: Cervical ribs (present in 0.5–1% of the population) or fibrous bands.
- Trauma: Whiplash injuries, clavicle fractures, or repetitive strain (e.g., overhead athletes, manual labourers).
- Postural dysfunction: Prolonged poor posture (e.g., forward head position, rounded shoulders) causes muscle imbalance.
- Muscular hypertrophy: Enlargement of the scalene or pectoral muscles, often due to repetitive activity.
Women aged 20–50 are disproportionately affected, likely due to smaller thoracic outlet dimensions and hormonal influences on ligamentous laxity.
Symptoms
Symptoms vary by subtype but often overlap:
- Neurogenic TOS:
- Pain or aching in the neck, shoulder, or arm, exacerbated by arm elevation.
- Paresthesia (tingling/numbness) in the ulnar nerve distribution (fourth and fifth fingers).
- Weakness or muscle wasting in severe cases (Gilliatt-Sumner hand).
- Venous TOS:
- Swelling, heaviness, or bluish discolouration of the arm.
- Arterial TOS:
- Cold, pale extremities, diminished pulse, or sudden ischemia.
Red flags include unilateral arm swelling, ischemic changes, or sudden weakness, warranting urgent referral to exclude vascular complications.
Diagnosis
Diagnosing TOC is challenging due to the lack of definitive tests. A thorough clinical history and physical examination are paramount:
- Provocative tests:
- Adson’s test: Diminished radial pulse with neck rotation and inhalation.
- Roos test: Reproduction of symptoms with sustained arm elevation.
- Imaging:
- X-ray or MRI to detect cervical ribs or bony anomalies.
- Doppler ultrasound or angiography for vascular assessment.
- Differential diagnosis: Exclude cervical radiculopathy, carpal tunnel syndrome, or rotator cuff pathology.
In Australia, GPs often collaborate with physiotherapists and specialists to confirm diagnosis, particularly when symptoms persist despite conservative management.
Treatment
Management focuses on relieving compression and addressing underlying causes:
- Conservative Therapies (First-Line):
- Physical therapy:
- Postural correction to reduce scapular depression and forward head posture.
- Stretching tight scalene and pectoralis minor muscles.
- Strengthening scapular stabilisers (e.g., trapezius, serratus anterior).
- Medication: NSAIDs for pain/inflammation, neuromodulators (e.g., gabapentin) for neuropathic pain.
- Activity modification: Avoiding overhead activities or repetitive movements that exacerbate symptoms.
- Interventional Procedures:
- Botulinum toxin injections: Temporarily relax hypertrophic scalene muscles in refractory neurogenic TOS.
- Venous/arterial thrombolysis: For acute thrombosis in vascular TOS.
- Surgical Referral:
Indicated for severe or progressive cases:
- Scalenectomy: Resection of the anterior scalene muscle.
- First rib resection: To decompress the thoracic outlet.
- Cervical rib excision: If present.
In Australia, surgery is typically performed by vascular or thoracic surgeons, with postoperative rehabilitation essential to restore function.
Prognosis and Follow-Up
Most patients improve with conservative care, particularly if diagnosed early. However, chronic neurogenic TOS may lead to permanent nerve damage if untreated. Regular follow-up is crucial to monitor progress and adjust management.
Conclusion
Thoracic Outlet Compression is a nuanced condition requiring a high index of suspicion and multidisciplinary collaboration. As GPs, our role involves recognising subtle symptoms, initiating conservative therapies, and facilitating timely referrals when needed. With appropriate management, many patients achieve significant symptom relief and return to daily activities.
By maintaining awareness of TOC’s varied presentations and leveraging Australia’s robust healthcare networks, we can mitigate the long-term impacts of this often-overlooked syndrome.
Thoracic Outlet Compression & Dr Clem Bonney
Dr Clem Bonney is a dual-qualified General Practitioner and Occupational & Environmental Physician with a special interest in musculoskeletal injuries and complex regional pain syndromes, including Thoracic Outlet Compression (TOC). Thoracic Outlet Compression, a condition often misunderstood or misdiagnosed in occupational settings. Dr Bonney utilises a multidisciplinary approach to assessment and rehabilitation, incorporating physical medicine, diagnostic imaging, functional assessments, and interventional strategies to restore movement and reduce neurovascular impingement.
He is committed to early identification, accurate diagnosis, and targeted rehabilitation to optimise recovery and workforce re-engagement in patients suffering from TOC and similar musculoskeletal conditions.