Thoracic Outlet Syndrome: The Misdiagnosed Cause of Arm Pain and Numbness

What Is Thoracic Outlet Syndrome?

Thoracic outlet syndrome (TOS) is compression of the nerves, arteries, or veins in the thoracic outlet — the space between the collarbone and first rib through which the brachial plexus, subclavian artery, and subclavian vein pass on their way to the arm. TOS is significantly underdiagnosed because its symptoms overlap with many other conditions — and because many clinicians are unfamiliar with its specific clinical presentation.

The Three Types of TOS

Neurogenic TOS (95% of Cases)

Compression of the brachial plexus causes arm and hand pain, numbness and tingling (especially ring and little fingers), weakness, and aching in the neck, shoulder, and arm. This is the most common form and most amenable to conservative chiropractic and PT care.

Venous TOS (~4%)

Subclavian vein compression causing arm swelling, heaviness, and cyanosis. Requires vascular surgical consultation.

Arterial TOS (~1%)

Subclavian artery compression causing arm pallor, coldness, and claudication. Requires surgical consultation.

What Causes TOS

• Cervical rib — an extra rib from C7, present in 0.5–1% of the population
• Tight scalene muscles — narrow the scalene triangle through which the brachial plexus passes
• Forward head posture and rounded shoulders — the most common contributing factor; narrows the costoclavicular space
• First rib elevation — from tight scalenes or rib joint restriction
• Pectoralis minor tightness — compresses the neurovascular bundle at the subcoracoid space

How We Treat TOS at Pittsburgh Physical Medicine

Postural Correction

Scapular retraction, thoracic extension, and deep cervical flexor activation mechanically open the thoracic outlet. This is the cornerstone of conservative TOS management.

Scalene and Pectoralis Minor Release

Graston technique and targeted soft tissue work release the primary muscular contributors to outlet narrowing — one of the most impactful interventions for symptomatic relief.

First Rib Mobilization

A restricted or elevated first rib is a consistent TOS finding. Chiropractic mobilization of the first rib directly opens the thoracic outlet and often produces immediate improvement.

Neural Mobilization

Brachial plexus neural gliding exercises reduce nerve sensitivity and restore normal nerve mobility throughout the outlet.

We treat TOS for desk workers, overhead athletes, and tradespeople from Shadyside, Lawrenceville, Bloomfield, Squirrel Hill, Oakland, Highland Park, Point Breeze, and Regent Square.