What are the clinical manifestations of thoracic outlet syndrome?

Clinical Manifestations of Thoracic Outlet Syndrome

Thoracic outlet syndrome presents with arm pain and swelling, arm fatigue, paresthesias, weakness, and hand discoloration, with specific symptom patterns determined by whether neurogenic, venous, or arterial structures are compressed. 1

Neurogenic TOS (Most Common Type)

Neurogenic symptoms dominate the clinical picture in the majority of TOS cases:

• Pain and paresthesias in the shoulder and upper extremity, typically following the distribution of the brachial plexus 1, 2
• Arm fatigue with overhead activities or repetitive arm movements 1
• Weakness affecting the upper extremity, which may progress over time 1, 2
• Painless wasting of intrinsic hand muscles in true neurogenic TOS, representing objective neurologic compromise 2
• Numbness and tingling in the arm and hand, often in an ulnar nerve distribution (C8-T1) 1, 3

The compression occurs most frequently in the costoclavicular space (53% positional, 36% from congenital bone variations, 11% from fibromuscular anomalies), with rare compression in the pectoralis minor space 4. Importantly, cervical spine pathology may mimic or exacerbate these symptoms and must be differentiated 4, 5.

Venous TOS

Venous compression produces distinct upper extremity swelling and discoloration:

• Arm swelling from subclavian vein compression and obstruction 1, 2
• Discoloration of the hand, typically cyanotic or dusky appearance 1
• Venous distention visible in the upper extremity 4
• Symptoms worsen with arm abduction at 90 degrees, which narrows the costoclavicular space 4

Repetitive stress leads to vein wall thickening, fibrosis, and intimal damage, creating a thrombogenic surface that may result in acute thrombosis (Paget-Schroetter syndrome) 4.

Arterial TOS (Rarest Type)

Arterial involvement produces ischemic symptoms in the affected extremity:

• Pallor of the arm and hand from arterial insufficiency 2, 6
• Cool arm temperature compared to the contralateral side 6
• Arm claudication with repetitive overhead motion or exercise 6
• Digital ischemia or gangrene in severe cases from distal emboli 4, 6
• Fixed or dynamic stenosis, aneurysm formation, or mural thrombus may develop from chronic arterial compression 4

Arterial TOS is particularly associated with repetitive overhead arm motion in athletes and results from intimal damage, thrombosis, and risk of distal embolization 4, 6.

Key Clinical Patterns

Symptom exacerbation occurs with specific provocative positions:

• Postural changes with arm elevation or abduction narrow the anatomical spaces (interscalene triangle, costoclavicular space, pectoralis minor space) 4
• Muscular hypertrophy or tension in scalene muscles contributes to space narrowing during weight-bearing activities 4
• Neck trauma or repeated work stress can cause scalene muscle scarring or dislodging of congenital cervical ribs, compressing the brachial plexus 1

Common Pitfalls in Recognition

Avoid misdiagnosing TOS by recognizing these critical distinctions:

• Dynamic venous compression during arm abduction is commonly seen in both asymptomatic and symptomatic individuals, making clinical correlation essential 4, 7
• Concomitant cervical spine pathology (such as C5-C6 disc space narrowing) may be the primary cause of symptoms rather than TOS 4, 5
• Bilateral symptoms suggest spinal cord pathology rather than unilateral TOS 5
• TOS is not a diagnosis of exclusion—there should be evidence for a physical anomaly that can be corrected 1