Thoracic Outlet Syndrome

Thoracic Outlet Syndrome (TOS) results from compression of the brachial plexus, subclavian artery or subclavian vein as they pass through the thoracic outlet, causing pain, numbness and vascular symptoms in the upper limb. Its incidence varies widely, with many cases likely underdiagnosed due to overlapping symptoms with other conditions.

Common sites of compression:

• Interscalene triangle (most common)
• Costoclavicular space
• Subcoracoid space

Causes of Thoracic Outlet Syndrome

Clinical Presentation

1. Neurogenic Thoracic Outlet Syndrome (NTOS) - Most Common (~90-95%)

Often triggered by hyperextension neck trauma, such as whiplash from car accidents. Symptoms follow a lower trunk or upper trunk pattern of brachial plexus involvement.

Lower Trunk Involvement (C8-T1 fibers affected)

• Pain - neck, shoulder and arm region along the ulnar nerve distribution (medial arm, forearm and 4th & 5th fingers).
• Paresthesia - numbness and tingling in the affected areas.
• Weak grip strength and fine motor difficulty (trouble holding objects, writing).

Upper Trunk Involvement (C5-C6 fibers affected)

• Pain - neck, shoulder and face pain.
• Paresthesia - lateral arm tingling and numbness, mimicking C5-C6 radiculopathy.

Key Physical Exam Findings

• Gilliatt-Sumner hand - atrophy of thenar and hypothenar muscles due to chronic nerve compression.
• Positive provocation tests - symptoms worsen with arm elevation or provocative maneuvers (e.g., Roos test, Adson’s test).

 

2. Venous Thoracic Outlet Syndrome (VTOS) – 5% of Cases

More common in young, healthy men (2x more than women). It is caused by subclavian vein compression, leading to venous congestion.

Symptoms

• Arm swelling and heaviness, especially after activity.
• Bluish discoloration (cyanosis) due to venous stasis.
• Dilated veins over the shoulder or chest, indicating collateral circulation.
• Effort-induced pain and paresthesias due to vascular engorgement.
• 15% risk of pulmonary embolism (PE) due to clot formation (Paget-Schroetter syndrome).

Key Physical Exam Findings

• Visible venous distension in the affected arm.
• Worsening symptoms with repetitive arm use or overhead activity.

3. Arterial Thoracic Outlet Syndrome (ATOS) – Rarest but Most Severe

It is usually asymptomatic until embolization occurs (blockage due to a clot or plaque). It is caused by subclavian artery compression, leading to arterial insufficiency.

Symptoms

• Pain and paresthesias in the hand or fingers.
• Cyanosis (bluish discoloration) and coldness in the fingers due to reduced blood flow.
• Fatigue and early muscle cramping in the arm with exertion (claudication).
• Color changes (pallor, mottling or dusky fingers).
• Digital gangrene in severe cases due to chronic ischemia.

Key Physical Exam Findings

• Absent or weak distal pulses (radial artery pulse) with arm elevation.
• Delayed capillary refill in the fingers.
• Tender supraclavicular prominence or palpable pulsation, suggesting vascular compression.
• Audible supraclavicular bruit (vascular sound) when the arm is held in compression positions.

 

Exacerbating Factors

• Overhead activities - raising the arms can worsen compression and symptoms.
• Prolonged arm use - activities like carrying heavy bags or working at a computer can aggravate TOS.
• Symptoms improve when resting the arm or repositioning it to relieve compression.

 

Diagnosing Thoracic Outlet Syndrome

 

Differential Diagnosis

• Cervical Radiculopathy
• Carpal Tunnel Syndrome
• Ulnar Nerve Entrapment (Cubital Tunnel Syndrome)
• Rotator Cuff Pathology
• Pancoast Tumor
• Brachial Plexopathy
• Subacromial Impingement Syndrome
• Complex Regional Pain Syndrome (CRPS)
• Peripheral Arterial Disease (PAD)
• Raynaud’s Phenomenon
• Myofascial Pain Syndrome
• Multiple Sclerosis (MS) – if neurological symptoms are widespread

 

Physiotherapy Management of Thoracic Outlet Syndrome (TOS)

Physiotherapy plays a crucial role, especially in Neurogenic TOS (nTOS), and may serve as an adjunct to medical and surgical management in Arterial (aTOS) and Venous (vTOS) TOS.

Goals of Physiotherapy Management

1. Improve neuromuscular control and strength.
2. Enhance mobility Reduce compression on neurovascular structures.
3. Restore optimal posture and movement patterns.
4. Improve neuromuscular of the thoracic spine and upper extremity.
5. Address biomechanical dysfunctions contributing to symptoms.

 

1. Patient Education & Activity Modification

Proper education helps in reducing symptom exacerbation and promoting self-management.

Postural Awareness

• Avoid forward head posture and rounded shoulders, which can narrow the thoracic outlet.
• Use posture correction cues such as chin tuck, scapular retraction and thoracic extension.

Ergonomic Advice

• Adjust desk height, chair support and keyboard position to prevent excessive shoulder elevation or depression.
• Use armrests to avoid prolonged static positioning.

Avoiding Aggravating Activities

• Limit repetitive overhead tasks that stress the thoracic outlet (e.g., painting, hairstyling).
• Avoid carrying heavy objects over the affected shoulder.

Sleeping Posture

• A neutral neck position with supportive pillows prevents excessive compression overnight.

 

2. Pain Management & Symptom Relief

Pain relief techniques improve function and tolerance for corrective exercises.

Manual Therapy

• Soft tissue release for tight scalenes, pectoralis minor and upper trapezius to relieve tension.
• Myofascial release techniques to reduce fascial restrictions.
• Joint mobilizations for the cervical and thoracic spine to restore movement.

Neural Mobilization (For Neurogenic TOS)

• Ulnar nerve glides (especially if symptoms radiate to the 4th and 5th fingers).
• Median and radial nerve mobilizations if nerve tension signs are present.

Electrotherapy (if needed)

• TENS or Therapeutic Ultrasound to reduce pain and muscle tightness (especially in chronic cases).
• Heat therapy to promote blood flow and relaxation.

 

3. Postural & Biomechanical Correction

Correcting postural imbalances is key for long-term improvement (94% improvement reported in one study).

Strengthening Exercises

Scapular stabilization exercises

• Serratus anterior activation: Wall slides, push-up plus.
• Lower trapezius strengthening: Prone Y raises.

Deep neck flexor strengthening to reduce forward head posture:

• Chin tuck exercises (cervical retraction).

Thoracic extension exercises to counteract kyphosis:

• Foam roller thoracic extensions.

Stretching Exercises

It includes stretching of pectoralis minor & major (doorway stretch or foam roller release). Scalene stretch can also be performed (gentle lateral neck flexion stretch).

 

4. Mobility & Nerve Decompression

Restricted thoracic spine mobility and elevated first rib are common contributors to shoulder dysfunction and neurovascular compression seen in conditions like Thoracic Outlet Syndrome (TOS).

Thoracic Spine Mobilization

• Foam roller thoracic extension.
• Seated thoracic rotations.

First Rib Mobilization

• Manual therapist-assisted first rib mobilization.
• Self-mobilization with a strap or towel under the first rib.

Breathing Retraining

• Diaphragmatic breathing to reduce scalene overactivity.
• Avoid excessive upper chest breathing, which can increase thoracic outlet compression.

5. Functional Strength & Return to Activity

A gradual return to activity is essential in preventing re-injury and ensuring proper recovery. Strengthening the muscles that support the glenohumeral joint and scapular stabilizers enhances joint control and reduces strain on passive structures like ligaments and the joint capsule.

Progressive Resistance Training

• Rotator cuff strengthening to support the glenohumeral joint.
• Rows with resistance bands.
• Shoulder external rotation exercises.

Closed Kinetic Chain Exercises

• Wall slides to activate the serratus anterior.
• Push-up plus to improve scapular protraction control.

Proprioceptive & Neuromuscular Retraining

• Band exercises and use of unstable surfaces to improve dynamic control of the shoulder girdle.
• Gradual reintroduction of overhead activities and sports/work tasks.

6. Monitoring & Referral (If Needed)

If vascular symptoms persist (swelling, cyanosis, weak pulse), refer to a vascular specialist and if neurological deficits worsen (muscle atrophy, severe weakness), refer to a neurologist.

Surgical Considerations & Physiotherapy Role

For patients undergoing surgery (e.g., first rib resection, anterior scalenectomy), physiotherapy plays a critical role in rehabilitation.

Preoperative Physiotherapy

• Strengthen postural muscles to improve recovery.
• Neural mobility drills to prevent postoperative nerve irritation.

Postoperative Physiotherapy

• Early motion exercises to prevent scar tissue adhesions.
• Progressive strengthening to restore function (return to sports ~3.5 months).
• Manual therapy to optimize mobility of the shoulder, cervical spine, and thoracic spine.