Symptoms of Thoracic Outlet Syndrome
Thoracic outlet syndrome presents with distinct symptom patterns depending on which neurovascular structure is compressed—neurogenic TOS (95% of cases) causes pain, paresthesias, and weakness in the shoulder and upper extremity, while venous TOS (4-5%) presents with arm swelling and venous obstruction, and arterial TOS (1%) manifests as arterial insufficiency symptoms. 1
Neurogenic TOS Symptoms (Most Common)
Pain is the predominant symptom, typically localized to the shoulder and proximal upper extremity with radiation to the neck 2:
- Paresthesias and numbness in the forearm and hand, often following specific nerve distribution patterns 2, 3
- Weakness in the affected upper extremity 3
- Painless wasting of intrinsic hand muscles in true neurogenic TOS cases 4
- Symptoms are exacerbated by postural changes with arm elevation or abduction, which narrows the anatomical compression spaces 5
The symptoms typically develop gradually, with patients experiencing complaints for months to years (mean 2.6 years in one surgical series) before definitive diagnosis 2.
Venous TOS Symptoms
Venous compression of the subclavian vein produces distinct vascular symptoms 5:
- Arm swelling and heaviness 1
- Venous thrombosis (Paget-Schroetter syndrome), which often presents more urgently 1
- Visible venous distension in the upper extremity 1
- Symptoms worsen with arm use and elevation 5
Arterial TOS Symptoms
Arterial insufficiency from subclavian artery compression causes 4:
- Arterial thrombosis, typically recognized expeditiously through clinical examination 1
- Coldness and pallor of the affected extremity 4
- Claudication symptoms with arm use 4
- Digital ischemia in severe cases 1
Anatomical Context for Symptom Patterns
Compression occurs in three distinct anatomical spaces that determine symptom distribution 5:
- Interscalene triangle: Most common compression site 4
- Costoclavicular space (formed by clavicle, anterior scalene muscle, and first rib): Typically causes venous symptoms when narrowed 5
- Pectoralis minor space (subpectoral tunnel): Relevant for chest and axillary symptoms, though compression here is rare 5
Critical Diagnostic Pitfalls
Arm and hand pain, paresthesias, and weakness are common complaints, but only a small minority of patients with these symptoms actually have TOS 3. The clinician must exclude more common conditions:
- Cervical degenerative arthritis can mimic TOS symptoms and must be ruled out with cervical spine imaging 3, 5
- Carpal tunnel syndrome presents with similar hand paresthesias 3
- Brachial plexitis should be excluded with appropriate imaging 5
- Venous compression during arm abduction is commonly seen in both asymptomatic and symptomatic individuals, making clinical correlation essential 5
Treatment Algorithm Based on TOS Type
Conservative management should be attempted first for neurogenic TOS, consisting of physical therapy and postural modification for 3-6 months 5, 2. Surgery is reserved for:
- Failure of conservative treatment after adequate trial (3-6 months) 5
- True neurogenic TOS with progressive symptoms or significant functional compromise 5
- Vascular TOS (arterial or venous) with thrombosis or vascular complications 1
For venous and arterial TOS with thrombosis, immediate intervention is required 1:
- Thrombolysis to restore blood flow 1
- First rib resection and anterior scalenectomy to prevent recurrence by addressing the underlying structural compression 1
- Subclavian artery reconstruction in arterial TOS cases 1
Muscular hypertrophy or tension in scalene muscles can contribute to space narrowing during weight-bearing activities, explaining symptom exacerbation with specific movements 5.