What are the symptoms of Thoracic Outlet Syndrome (TOS)?

Symptoms of Thoracic Outlet Syndrome (TOS)

Thoracic outlet syndrome presents with varying symptoms depending on which structures are compressed, including upper extremity pain, numbness, tingling, weakness, swelling, discoloration, heaviness of the arm, claudication, coldness, pallor, and decreased pulses. 1

Types of TOS and Their Specific Symptoms

TOS can be classified into three main types based on the compressed structure:

1. Neurogenic TOS (NTOS)

• Most common type (>90% of all TOS cases) 2
• Symptoms include:
  • Extremity paresthesia
  • Pain in the arm
  • Weakness of the affected limb
  • Neck pain
  • Occipital headache 2

2. Venous TOS (vTOS)

• Presents with:
  • Arm swelling
  • Cyanosis (bluish discoloration)
  • Pain due to subclavian vein obstruction
  • Visible collateral circulation in chronic cases 3, 2
  • Heaviness of the arm 1

3. Arterial TOS (aTOS)

• Least common type (≤1% of cases) 2
• Symptoms include:
  • Pallor
  • Arm claudication
  • Cool/cold extremity
  • Acute limb-threatening ischemia in cases of thrombosis 4
  • Decreased pulses 1

Physical Examination Findings

Physical examination may reveal:

• Diminished radial pulse with provocative maneuvers (although the Adson Test alone has been shown to have poor diagnostic value) 1, 2
• Muscle imbalances and postural abnormalities 1
• Positive responses to multiple provocative tests:
  • Wright's Test
  • Eden's Test
  • Upper limb tension test
  • Arm abduction to 90 degrees in external rotation (symptoms typically appear within 60 seconds) 2
  • Neck rotation and head tilting eliciting symptoms in the contralateral extremity 2

Important Clinical Considerations

• A systolic blood pressure difference of more than 25 mmHg between arms is considered significant for arterial compression 1
• Symptoms may be exacerbated by certain postures or repetitive motions such as throwing, weightlifting, and manual labor 5
• Bilateral TOS is rare but can occur, presenting with symptoms in both arms 6
• In venous TOS, complete occlusion may lead to thrombus formation and more severe symptoms 3

Diagnostic Challenges

• TOS is not a diagnosis of exclusion, and there should be evidence for a physical anomaly that can be corrected 7
• Clinical testing has poor accuracy, including sensitivity and specificity 1, 5
• Imaging findings must be correlated with clinical symptoms, as venous compression can be found in asymptomatic individuals 3
• Evaluation in both neutral and arms-abducted positions is necessary to demonstrate dynamic compression 1

Common Pitfalls in Diagnosis

• Relying solely on the Adson Test, which can be positive in many control volunteers and normal in most patients with NTOS 2
• Misdiagnosing patients as having "vascular" TOS when they actually have neurogenic TOS 2
• Relying solely on axial imaging slices, which can lead to misrepresentation of stenosis severity 1
• Failing to evaluate patients in both neutral and provocative positions during imaging studies 3, 1
• Delayed diagnosis beyond 14 days can significantly worsen outcomes 1

Understanding the specific symptom pattern is crucial for proper classification of TOS type and subsequent management decisions.