Wright Test

Wright Test, also known as the Hyperabduction Test, is a key diagnostic procedure used in the assessment of thoracic outlet syndrome (TOS).

The Wright Test evaluates potential neurovascular compression within the thoracic outlet – the anatomical space bordered by the first thoracic rib, the clavicle, and the superior border of the scapula. This region contains critical neurovascular structures supplying the upper extremity.

The compression typically occurs in the subpectoral space, between the coracoid process, the pectoralis minor muscle, and the chest wall. Both the brachial plexus and the axillary artery traverse the area between the pectoralis minor muscle and the thorax, making them susceptible to compression as they enter the axilla.

The Wright Test specifically evaluates radial artery pulsation, which serves as an indicator of axillary artery patency since the radial artery arises directly from the axillary artery (which itself branches from the subclavian artery).

In 1945, Irving S. Wright first described the diminution of the radial pulse in 93% of 150 asymptomatic individuals when their arm was hyperabducted to an overhead position with the elbow flexed to 90°. He attributed this finding to axillary artery compression beneath the pectoralis minor tendon within the subcoracoid space. This observation laid the foundation for what would become a standard assessment tool for thoracic outlet syndrome.

Additional research by Raaf, Gilroy, Meyer, and others subsequently found similar positive results in up to 70% of asymptomatic volunteers. Rayan and Jensen later suggested that positive symptoms might also result from ulnar nerve compression behind the medial epicondyle, noting that original Wright test description involved elbow flexion.

See Also Brachial Plexus Anatomy

How do you perform the Wright Test?

• The patient is sitting or standing with arms hanging down loosely.
• The examiner palpates the patient’s radial pulse.
• The examiner first tests the affected side by passively abducting the arm to 180° while checking the radial pulse and noting the angle at which the radial pulse weakens or disappears.
• Then he or she checks the other arm and compares the results.

Some examiners have modified the technique over time. A common variation of the Wright test involves flexing the patient’s elbow to 90° while horizontally extending and laterally rotating the shoulder. The patient then rotates their head away from the test side while the examiner monitors the radial pulse. This modified approach is sometimes referred to as the Allen maneuver.

See Also: Adson Test

What does a positive Wright Test mean?

• The wright test is positive if there is an obvious weakening of the radial pulse and/ or neurologic symptoms in the tested arm within a short time.
• These symptoms include paresthesia and the hand “falling asleep” and possibly even Raynaud’s phenomenon, as occurs when sleeping on one’s stomach with the arms over the head.

Sensitivity & Specificity

No diagnostic accuracy studies have been performed to determine the sensitivity and specificity of the Wright Test.

However, is important to note that a number of studies have found that arm elevation induces radial pulse obliteration in 60–69% of normal subjects.

Notes

• The compression occurs in the subpectoral space, between the coracoid process, the pectoralis minor, and the chest wall.
• The compression can be evaluated at the radial artery, because it arises directly from the axillary artery, which in turn arises from the subclavian artery.
• Both the brachial plexus and the axillary artery run through the area between the pectoralis minor muscle and the thorax.
• They usually become compressed between the coracoid process and the pectoralis minor muscle shortly before entering the axilla.

The following should be considered in the differential diagnosis of the positive Wright test:

1. An infiltrative tumor (such as a Pancoast tumor) growing into the plexus.
2. A tardive radiation-induced palsy.
3. A neuroma within the brachial plexus.

Thoracic Outlet Syndrome

• The thoracic outlet is the anatomic space bordered by the first thoracic rib, the clavicle, and the superior border of the scapula, through which the great vessels and nerves of the upper extremity pass.
• Thoracic Outlet Syndrome TOS is a syndrome characterized by symptoms attributable to compression of the neural or vascular anatomic structures that pass through the thoracic outlet.
• The other names used for TOS are based on descriptions of the potential sources for its compression. These names include cervical rib syndrome, scalenus anticus syndrome, hyperabduction syndrome, costoclavicular syndrome, pectoralis minor syndrome, and first thoracic rib syndrome.

The bony boundaries of the outlet include:

1. The clavicle.
2. The first rib.
3. The scapula.

The outlet passage is further defined by the interscalene interval, a triangle with its apex directed superiorly. This triangle is bordered anteriorly by the anterior scalene muscle, posteriorly by the middle scalene muscle, and inferiorly by the first rib.

The lowest trunk of the brachial plexus, which is made up of rami from the C8 and T1 nerve roots, is the most commonly compressed neural structure in TOS

TOS was first noted in 1743 when an association was made between the cervical rib and TOS, although it was not until 1818, that the medical management of TOS was discussed. In the early twentieth century, Adson stressed the role of the scalene muscles in neurovascular compromise, and Wright showed that shoulder hyperabduction could produce thoracic outlet obstruction.

Reference

1. Gilroy J, Meyer JS: Compression of the subclavian artery as a cause of ischaemic brachial neuropathy. Brain 86:733 746, 1963.
2. Raaf J: Surgery for cervical rib and scalenus anticus syndrome. J Am Med Assoc 157:219–25, 1955
3. Wright IS: The neurovascular syndrome produced by hyperabduction of the arms. Am Heart J 29:1–19, 1945.
4. Sadeghi-Azandaryani M, Bürklein D, Ozimek A, Geiger C, Mendl N, Steckmeier B, Heyn J. Thoracic outlet syndrome: do we have clinical tests as predictors for the outcome after surgery? Eur J Med Res. 2009 Sep 28;14(10):443-6. doi: 10.1186/2047-783x-14-10-443. PMID: 19748851; PMCID: PMC3352227.
5. Gilroy J, Meyer JS. Compression of the subclavian artery: a cause of ischaemic brachial neuropathy. Brain. 1963;86:733–46.
6. Rayan GM, Jensen C. Thoracic outlet syndrome: provocative examination maneuvers in a typical population. J Shoulder Elbow Surg. 1995;4(2):113–7.
7. Clinical Tests for the Musculoskeletal System 3rd Ed. Book.
8. Dutton’s Orthopaedic Examination, Evaluation, And Intervention 3rd Edition.
9. Morton, DA, Foreman KB, Albertine KH: The Big Picture: Gross Anatomy, McGraw-Hill, 2011.)