Thoracic Outlet Syndrome: Arm Fatigue, Numbness, and the Breathing Fix
Quick answer: Thoracic outlet syndrome (TOS) is compression of the nerves and/or vessels that pass between the neck, first rib, and collarbone on their way to the arm. Most cases are neurogenic (nerve compression - around 90%), and most neurogenic cases respond well to physiotherapy focused on posture, breathing, and first-rib mobility without surgery.
What it feels like
- Arm heaviness or fatigue with overhead activity (lifting, washing hair, hanging laundry)
- Numbness or tingling - often the inner forearm and little/ring fingers (lower brachial plexus)
- Discomfort in the front of the shoulder or inner upper arm
- Cold, pale, or discoloured hand in a minority of cases (vascular TOS)
- Symptoms reproducible by raising both arms overhead for a minute or two
The three subtypes
Neurogenic TOS (~90%)
Brachial plexus irritation. Often no specific imaging finding - diagnosis is clinical, supported by provocation tests (Roos, Wright's, Adson's) and sometimes nerve conduction studies.
Venous TOS (~5%)
Subclavian vein compression, sometimes with thrombosis (Paget-Schroetter). Usually presents with arm swelling and discoloration. Vascular emergency if acute thrombosis - ER, not physio.
Arterial TOS (~1-3%)
Subclavian artery compression, often associated with a cervical rib. Rare; needs vascular surgery assessment.
Why posture and breathing matter
The thoracic outlet is a triangle formed by the first rib, scalene muscles, and clavicle. Three things narrow it:
- Forward head posture shortens the scalenes and lifts the first rib. The space gets tighter.
- Upper-chest (apical) breathing - overusing the scalenes as accessory breathing muscles. The first rib is constantly being hiked.
- Rounded shoulders and a poor-functioning lower trapezius - the clavicle and shoulder girdle drop forward and down onto the neurovascular bundle.
Fix all three and the outlet opens.
Physiotherapy approach
Diaphragmatic breathing retraining - the single highest-value intervention. Takes the scalenes out of the breathing loop and calms the first rib. Daily practice for 6-8 weeks changes habits built over years.
Scalene and pec minor release - soft-tissue work to the overactive muscles. Self-release is taught for home.
First-rib mobilisation - manual techniques and self-mobilisation with a belt or towel.
Scapular retraining - lower trap and serratus anterior strengthening. Opens up the costoclavicular space.
Nerve gliding - gentle brachial plexus and ulnar nerve glides once irritability is lower.
Workstation and sleep position review - side-sleeping with a heavy pillow often aggravates TOS; workstation height matters.
What doesn't help
- Aggressive stretching of the scalenes in the acute phase - often flares symptoms
- Cervical traction alone - may be added, not a standalone fix
- Scalenectomy as a first step - surgery is for people who have genuinely failed 3-6 months of well-delivered physiotherapy
Surgery (when it's warranted)
Vascular TOS (venous with thrombosis, or arterial) is surgical. Neurogenic TOS that has failed thorough conservative care for 3-6 months and has objective findings may also be considered. Outcomes are mixed - TOS surgery has a higher complication rate than most elective shoulder surgery.
In Ipoh
TOS physiotherapy needs a clinician familiar with the provocation tests and able to differentiate TOS from cervical radiculopathy, shoulder impingement, and peripheral nerve entrapments - they overlap. Expect RM80-150 per session, typically 8-12 sessions over 8-12 weeks. Daily home programme is essential.