How should I perform a physical examination for suspected thoracic outlet syndrome?

Physical Examination for Thoracic Outlet Syndrome

Begin by classifying the suspected TOS subtype through targeted history and provocative maneuvers, as neurogenic TOS (>90% of cases), venous TOS, and arterial TOS each require distinct examination approaches and have different physical findings that guide all subsequent management decisions. 1, 2

Initial Assessment and Inspection

• Palpate for anatomical abnormalities including cervical ribs, prior clavicular or rib fractures, and assess for scalene muscle hypertrophy, particularly in patients with overhead activity or repetitive upper extremity use 1
• Inspect for visible signs of venous TOS: arm swelling, cyanosis, prominent collateral veins over the chest wall or neck 1, 2
• Examine for arterial TOS findings: arm pallor, coolness, color changes, or signs of distal ischemia 1
• Document neck trauma history, especially whiplash injuries, which commonly cause scalene muscle scarring leading to neurogenic TOS 2

Provocative Maneuvers for Neurogenic TOS

The most diagnostically valuable tests reproduce symptoms through position and compression, not pulse changes—the Adson test (radial pulse deficit) has been definitively shown to have no clinical value and should be abandoned. 2

High-Yield Provocative Tests (94% positive in confirmed cases):

• Neck rotation and head tilting: Rotate and tilt the head, which should elicit paresthesias in the contralateral extremity if neurogenic TOS is present 2, 3
• Upper Limb Tension Test (ULTT): Comparable to straight leg raising for the upper extremity; systematically stresses the brachial plexus 2, 3
• Elevated Arm Stress Test (EAST): Abduct both arms to 90 degrees in external rotation and have the patient open and close their fists—symptoms typically develop within 60 seconds in neurogenic TOS 2, 3
• Compression testing: Direct compression over the scalene triangle or supraclavicular fossa reproduces symptoms in 94% of neurogenic TOS cases 3

Test Interpretation Nuances:

• Using multiple provocative tests in combination significantly improves specificity (individual tests have mean sensitivity 72%, specificity 53%) 4
• The hyperabduction test (positive predictive value 92%) and Wright test are particularly useful when positive 4
• Symptoms must be reproduced during testing—isolated findings without symptom reproduction are not diagnostic 3, 4

Examination for Venous TOS

• Measure arm circumference bilaterally to quantify swelling 2
• Assess for venous distention and collateral vein patterns over the anterior chest wall and neck 1
• Perform provocative arm positioning (abduction, overhead) while palpating for increased venous engorgement 4
• Critical pitfall: Venous compression with arm abduction occurs in asymptomatic individuals—diagnosis requires documented thrombosis or collateral formation, not compression alone 1

Examination for Arterial TOS

• Palpate radial, ulnar, and brachial pulses bilaterally at rest and with provocative positioning 2
• Assess capillary refill and temperature differences between extremities 2
• Examine digits for signs of embolic phenomena (splinter hemorrhages, digital ischemia, gangrene) 1
• Auscultate the supraclavicular fossa for bruits suggesting arterial stenosis or aneurysm 4

Sensory Testing

• Two-point discrimination is normal in 98% of TOS cases—abnormal findings suggest alternative diagnoses 3
• Baseline vibration thresholds may be normal, but measuring changes during provocative maneuvers can be useful 3
• Light touch and pinprick testing in C8-T1 distribution (medial forearm and hand) for neurogenic TOS 2

Motor Examination

• Assess for painless wasting of intrinsic hand muscles, which indicates true neurogenic TOS with objective findings 5
• Test grip strength bilaterally and document weakness patterns 2
• Evaluate shoulder girdle muscle strength, particularly in overhead positions 6

Key Diagnostic Pitfalls to Avoid

• Do not rely on pulse deficits during Adson or other vascular maneuvers—these are positive in many asymptomatic controls and normal in most neurogenic TOS patients 2
• Do not diagnose TOS by exclusion—there must be evidence of a physical anomaly (anatomical narrowing, compression during examination) that can be corrected 6
• Recognize that electromyography and nerve conduction studies are normal in the vast majority (only 1-2% positive at brachial plexus level), so negative electrodiagnostic studies do not exclude TOS 3, 5
• Overlap syndromes with combined neurogenic, venous, and arterial features occur and require assessment for all three subtypes 1
• Severe cervical spondylosis contributes to symptoms in 14% of cases and must be distinguished from or recognized as coexisting with TOS 7

Documentation

• Record which specific provocative tests were positive and the latency to symptom reproduction 3
• Document bilateral findings even if symptoms are unilateral, as this aids in establishing abnormality 4
• Note any anatomical abnormalities detected on palpation 1
• Quantify functional impairment with side-specific assessment of dynamic tasks 8