Allen Test for TOS

The Allen Test (also called the Allen Maneuver) is a physical examination procedure used to assess for Thoracic Outlet Syndrome (TOS). It tests for neurovascular compression by placing the arm in a position of mechanical stress and monitoring for pulse obliteration or symptom reproduction.

Additional tests for Thoracic Outlet Syndrome: Roos Test | Adson’s Maneuver

Important: Do not confuse this with Allen’s Test for wrist circulation (radial and ulnar artery patency). These are completely different procedures.

Thoracic Outlet Syndrome: A Brief Overview

Thoracic Outlet Syndrome refers to compression of neurovascular structures as they pass through the thoracic outlet. Three potential compression sites exist:

1. Interscalene triangle: between the anterior and middle scalene muscles and the first rib
2. Costoclavicular space: between the clavicle and first rib
3. Subcoracoid/pectoralis minor space: beneath the pectoralis minor and coracoid process

Structures at risk:

• Brachial plexus (compression produces neurogenic TOS, the most common type, approximately 95% of cases)
• Subclavian/axillary artery (arterial TOS)
• Subclavian vein (venous TOS)

Common contributing factors include a cervical rib, hypertrophied anterior scalene, poor posture, overhead work demands, and prior clavicle or first rib trauma.

How to Perform the Allen Test

Patient position: Seated, relaxed.

Starting arm position:

• Shoulder abducted to 90°
• Shoulder fully externally rotated
• Elbow flexed to 90°

Examiner: Palpate the radial pulse throughout the test.

Test movement: Ask the patient to rotate their head away from the tested arm (contralateral rotation).

Positive finding: Radial pulse becomes diminished or absent following head rotation.

Interpreting the Result

Pulse obliteration alone is not sufficient to call a test positive in a clinically meaningful way.

Multiple studies have found that a significant proportion of asymptomatic individuals show pulse obliteration in the abducted, externally rotated position. Rayan and Jensen (1995) found this in over 50% of healthy, pain-free subjects. A false positive rate that high makes the test poorly specific when used in isolation.

A clinically meaningful positive result requires both:

• Pulse obliteration
• Reproduction of the patient’s familiar symptoms (paresthesias, arm heaviness, pain, or color change)

If the pulse drops but the patient feels nothing, interpret with caution. If the pulse drops and the patient says “that’s exactly what I feel at work,” that’s a meaningful positive.

Diagnostic Accuracy

Property	Notes
Sensitivity	Variable; limited high-quality data available
Specificity	Poor when pulse obliteration is the sole criterion
Clinical utility	Improves significantly when symptom reproduction is required

The Allen Test should not be used in isolation. It is most useful as part of a multi-test TOS battery, where clustering positive findings increases diagnostic confidence.

TOS Screening Battery

No single test reliably confirms or excludes TOS. The following are commonly used together:

• Allen Test (this test): subcoracoid neurovascular tension, pulse monitoring
• Adson’s Test: anterior scalene compression; head extension and ipsilateral rotation
• Roos Test (EAST): sustained overhead position with repeated hand opening and closing; positive if symptoms reproduced within 3 minutes
• Costoclavicular Test: military brace posture, testing costoclavicular compression

The Roos Test is generally considered the most sensitive of the group for neurogenic TOS.

Differential Diagnosis

Before committing to a TOS diagnosis, rule out:

• Cervical radiculopathy (C5-T1)
• Carpal tunnel syndrome
• Cubital tunnel syndrome
• Rotator cuff pathology
• Double crush syndrome
• Raynaud’s phenomenon (for vascular or color change presentations)

Cervical radiculopathy is the most important differential. Both conditions can present with arm pain, numbness, and tingling. A thorough cervical spine screen should precede or accompany TOS testing.

References

• Rayan GM, Jensen C. Thoracic outlet syndrome: provocative examination maneuvers in a typical population. J Shoulder Elbow Surg. 1995;4(2):113-117.
• Hooper TL, Denton J, McGalliard MK, Brismée JM, Sizer PS. Thoracic outlet syndrome: a controversial clinical condition. Part 1: anatomy, and clinical examination/diagnosis. J Man Manip Ther. 2010;18(2):74-83.
• Sanders RJ, Hammond SL, Rao NM. Diagnosis of thoracic outlet syndrome. J Vasc Surg. 2007;46(3):601-604.
• Magee DJ. Orthopedic Physical Assessment. 6th ed. St. Louis: Saunders/Elsevier; 2014.

Video Demonstration

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