How should thoracic outlet syndrome be diagnosed and treated?

Diagnosis and Treatment of Thoracic Outlet Syndrome

Initial Diagnostic Approach

Begin with chest radiography to identify osseous abnormalities such as cervical ribs or first rib anomalies, which account for 36% of cases, then proceed to type-specific imaging based on clinical presentation. 1

Classification and Clinical Presentation

TOS manifests in three distinct forms based on the compressed structure:

• Neurogenic TOS (95% of cases): Presents with arm/hand pain, paresthesias, and weakness from brachial plexus compression 2, 3
• Venous TOS (4-5%): Causes arm swelling, venous thrombosis (Paget-Schroetter syndrome), and discoloration 2, 4
• Arterial TOS (1%): Results in arm claudication, digital ischemia, or gangrene from subclavian artery compression 1, 3

Compression occurs in three anatomical spaces: the interscalene triangle, costoclavicular space, and pectoralis minor space, with the costoclavicular space being most commonly affected. 1

Type-Specific Diagnostic Imaging

Neurogenic TOS Diagnosis

MRI of the chest without IV contrast is the primary imaging modality for neurogenic TOS, as it directly visualizes the brachial plexus and demonstrates compression in all three anatomical spaces. 5

• Perform high-resolution T1-weighted and T2-weighted sequences in sagittal and axial planes to delineate the brachial plexus, muscular attachments, and compression sites 5
• Image in both neutral and arms-abducted positions to demonstrate effacement of fat adjacent to brachial plexus roots, trunks, or cords 1
• T1-weighted imaging identifies causative lesions including cervical ribs, congenital fibromuscular anomalies, and muscular hypertrophy 1
• Do not rely on CT or ultrasound alone for neurogenic TOS, as these modalities lack adequate resolution of neural structures 5

Venous TOS Diagnosis

• 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
• Perform imaging in both neutral and stressed (arm abducted) positions to demonstrate dynamic compression 1
• Contrast injection should be performed in the contralateral arm to avoid artifact 1

Arterial TOS Diagnosis

Use CTA with IV contrast, MRA, or US duplex Doppler to identify fixed or dynamic stenosis, aneurysm, mural thrombus, or distal emboli. 1

• Contrast-enhanced 3D MRA/MRV can be performed at 1.5T or 3T with breath-hold arterial and equilibrium phase imaging 1
• Avoid noncontrast time-of-flight techniques as they suffer from flow artifacts causing false-positive stenosis or thrombosis 1

Critical Diagnostic Pitfalls to Avoid

• Venous compression during arm abduction is commonly seen in both asymptomatic and symptomatic individuals, making clinical correlation essential 1
• Do not overlook concomitant cervical spine pathology that may mimic or exacerbate TOS symptoms 1, 5
• Imaging confirmation of a specific etiology (bony tubercle, clavicle fracture, congenital cervical rib, or first rib abnormality) is necessary to establish medical necessity for surgical intervention 1
• Dynamic compression of vessels during provocative maneuvers is common and may not necessarily indicate pathology requiring surgical intervention 1

Treatment Algorithm

Conservative Management (First-Line for Neurogenic TOS)

All neurogenic TOS patients should undergo conservative management for 3-6 months before considering surgery, unless they have progressive symptoms, significant functional compromise, or work in high-risk occupations. 1

Conservative treatment includes:

• Physical therapy and strengthening exercises 2
• Anti-inflammatory medication 2
• Weight loss 2
• Botulinum toxin injections 2

Surgical Intervention Indications

Surgical decompression is indicated when conservative management fails after 3-6 months, or immediately when patients have true neurogenic or vascular TOS with progressive symptoms, significant functional compromise, or vascular complications. 1

Venous TOS Surgical Approach

• Urgent thrombolysis and anticoagulation for acute thrombosis 4
• Surgical decompression following initial endovascular treatment is mandatory to address the underlying anatomical compression and prevent recurrence 1
• First rib resection and anterior scalenectomy, plus resection of any cervical ribs 3
• Vascular exploration with direct visualization of the subclavian vein to assess for residual stenosis, webs, or intrinsic venous pathology 1

Arterial TOS Surgical Approach

• Restoration of arterial blood flow (thrombolysis if needed) 4
• First rib resection and anterior scalenectomy 3
• Subclavian artery reconstruction is often required 3

Neurogenic TOS Surgical Approach

• Brachial plexus decompression and neurolysis 2
• Scalenotomy with or without first rib resection 2
• Transaxillary approach allows the greatest field of view for first rib excision 6
• Supraclavicular approach is favored for scalenotomies when the anterior scalene muscle impinges on surrounding structures 6

Postoperative Management

• Begin passive/assisted mobilization of the shoulder immediately postoperatively 2
• By 8 weeks postoperatively, patients can begin resistance strength training 2
• MRI without IV contrast may be performed postoperatively to evaluate adequate decompression 5

Surgical Complications

Serious complications include injury to the subclavian vessels potentially leading to exsanguination and death, brachial plexus injury, hemothorax, and pneumothorax. 2