What are the typical presentation and treatment options for a young to middle-aged adult with thoracic outlet syndrome, presenting with neck and shoulder pain, numbness, and weakness in the affected limb?

Thoracic Outlet Syndrome: Clinical Presentation

Thoracic outlet syndrome presents with upper extremity pain, paresthesias, numbness, and weakness that worsens with arm elevation or abduction, caused by compression of neurovascular structures at the superior thoracic outlet. 1

Classification and Anatomical Basis

TOS is divided into three distinct variants based on the compressed structure 2, 1:

• Neurogenic TOS (95% of cases): Compression of the brachial plexus, most commonly in the costoclavicular space, with rare compression in the pectoralis minor space 1, 3, 4
• Venous TOS (4-5% of cases): Compression of the subclavian vein 1, 4
• Arterial TOS (1% of cases): Compression of the subclavian artery 1, 4

Compression occurs in three anatomical spaces 1:

• Interscalene triangle
• Costoclavicular triangle (formed by clavicle superiorly, anterior scalene muscle posteriorly, first rib inferiorly)
• Pectoralis minor space (subpectoral tunnel)

Clinical Presentation by Type

Neurogenic TOS

• Pain in shoulder and proximal upper extremity radiating to neck 5
• Paresthesias and numbness in forearm and hand, particularly in ulnar distribution 3, 5
• Arm weakness and fatigue 3
• Symptoms exacerbated by overhead activities, arm abduction, or postural changes 1, 6
• Painless wasting of intrinsic hand muscles in severe cases 7

Venous TOS

• Arm swelling and discoloration 3
• Venous engorgement visible on examination 4
• May present acutely with subclavian vein thrombosis (Paget-Schroetter syndrome) 1
• Repetitive stress leads to vein wall thickening, fibrosis, and thrombogenic surface 1

Arterial TOS

• Arm fatigue and claudication with activity 3
• Hand discoloration and coolness 3
• Digital ischemia or gangrene in severe cases from distal emboli 1
• Fixed or dynamic stenosis, aneurysm formation, mural thrombus 1

Underlying Etiologies

Common causes include 1, 3:

• Congenital bone variations (36%): cervical ribs, first rib anomalies 1
• Congenital fibromuscular anomalies (11%): fibrous bands, scalene muscle variations 1, 3
• Positional compression (53%): muscular hypertrophy, postural abnormalities 1
• Trauma: neck injury causing scalene muscle scarring 3
• Repetitive overhead motions or work stress 3, 6

Diagnostic Approach

Initial Evaluation

Start with chest radiography to identify osseous abnormalities such as cervical ribs or first rib anomalies 1. This is the appropriate first imaging study 1.

Type-Specific Imaging

For Neurogenic TOS 1:

• MRI without IV contrast is sufficient to diagnose neurogenic TOS, showing compression of neurovascular bundles in costoclavicular, interscalene, and pectoralis minor spaces 1
• High-resolution T1 and T2-weighted sequences in sagittal and axial planes delineate brachial plexus, muscular attachments, and compression sites 1
• Imaging must be performed in both neutral and stressed (arm abducted) positions to demonstrate dynamic compression 1
• T1-weighted imaging identifies causative lesions including cervical ribs, congenital fibromuscular anomalies, and muscular hypertrophy 1

For Venous TOS 1:

• US duplex Doppler is excellent for initial evaluation, showing venous compression during arm abduction 1
• CTV obtained 120-180 seconds after IV contrast demonstrates venous obstruction 1
• Contrast injection should be performed in the contralateral arm to avoid artifact 1

For Arterial TOS 1:

• CTA with IV contrast, MRA, or US duplex Doppler are appropriate 1
• Studies demonstrate fixed or dynamic stenosis, aneurysm, mural thrombus, or distal emboli 1

Critical Imaging Pitfalls to Avoid

• Do not use CT or ultrasound alone for neurogenic TOS, as these modalities lack resolution of neural structures 1
• Avoid noncontrast time-of-flight MRA techniques as they suffer from flow artifacts causing false-positive stenosis or thrombosis 1
• Venous compression during arm abduction is commonly seen in both asymptomatic and symptomatic individuals, making clinical correlation essential 1, 8
• Do not overlook concomitant cervical spine pathology that may mimic or exacerbate TOS symptoms 1, 8

Ancillary Testing

• Electromyography and nerve conduction studies provide helpful diagnostic information 7, 5
• Physical examination maneuvers (Adson, Wright, Roos tests) help establish diagnosis 3, 7

Treatment Algorithm

Conservative Management (First-Line)

All patients should undergo conservative management for 3-6 months before considering surgery, unless presenting with acute vascular complications 1, 8. Conservative treatment includes 3, 7:

• Supervised physical therapy and strengthening exercises 3, 5
• Postural modification training 8, 6
• Anti-inflammatory medication 3
• Weight loss if indicated 3
• Botulinum toxin injections for muscle spasm 3

Surgical Indications

Surgery should only be considered when 1, 8:

• Conservative management fails after adequate 3-6 month trial 1, 8
• True neurogenic TOS with progressive symptoms and significant functional compromise 1
• Vascular TOS with thrombosis or vascular complications 1, 4
• High-risk occupations where recurrence prevention is critical 1
• Imaging confirmation of specific anatomical abnormality causing compression (cervical rib, first rib anomaly, fibrous band) 8

Surgical Approaches

The most common surgical treatments include 3, 7:

• First rib resection through transaxillary approach 7, 5
• Anterior scalenectomy 9, 8
• Brachial plexus neurolysis 3
• Cervical rib resection when present 5
• Supraclavicular exposure or combined approaches for complex cases 7

For venous TOS with thrombosis, surgical decompression must follow initial endovascular thrombolysis to address underlying anatomical compression 1. Vascular exploration with direct visualization of the subclavian vein is often required to assess for residual stenosis or webs 1.

The complexity of first rib resection, including proximity to critical neurovascular structures (brachial plexus, subclavian artery and vein), necessitates inpatient level of care for close postoperative monitoring 9.

Postoperative Management

• Begin passive/assisted shoulder mobilization immediately postoperatively 3
• Progress to resistance strength training by 8 weeks 3

Surgical Complications

Major complications include 3, 7:

• Subclavian vessel injury potentially leading to exsanguination and death 3
• Brachial plexus injury 3
• Pneumothorax 3, 5
• Hemothorax 3
• Temporary brachial paralysis 5

Outcomes

With careful patient selection, surgical intervention yields satisfactory results 7, 5:

• Complete symptom relief in 82.6% of appropriately selected patients 5
• Partial relief in remaining patients 5
• Success depends on proper identification of anatomical abnormality and adequate conservative management trial 8, 7