Etiology — what causes it

Compression of the neurovascular bundle (brachial plexus, subclavian artery, subclavian vein) in one of three anatomical spaces: scalene triangle, costoclavicular space, or pectoralis minor space. Contributors include cervical rib, anomalous fibrous bands, scalene hypertonicity, drooping shoulder posture, repetitive overhead loading, and trauma.

Epidemiology — who gets it

Neurogenic TOS represents over 95% of cases; vascular forms are rare. More common in women, peak age 20–50. Often associated with repetitive overhead occupations and sports.

Clinical signs

Provocation tests have modest individual diagnostic value but include Roos elevated arm stress test (EAST), Adson, Wright, and costoclavicular maneuvers. Reproduction of arm symptoms within 3 minutes of EAST is suggestive. Scapular dyskinesis and forward-head posture often present. Vascular signs (color change, pulse change) when present support vascular TOS.

Symptoms

Neurogenic — arm pain, paresthesia, weakness, often along the medial forearm and hand. Aggravated by overhead positions. Vascular — arm swelling, color change, cool sensation, or fatigue with use. Symptoms may worsen at night.

Best evidence for chiropractic treatment

Conservative care produces meaningful improvement in approximately 60–80% of neurogenic TOS cases over 6 months (Hooper et al., J Hand Ther). Treatment emphasizes scalene and pectoralis minor release, scapular and postural retraining, nerve mobilization, and graded loading. Surgery is reserved for vascular cases, true neurogenic TOS with progressive deficit, and refractory conservative care failures.

Subtypes

  • Neurogenic TOS. Most common (95%+); brachial plexus compression.
  • Venous TOS (Paget-Schroetter). Subclavian vein compression with arm swelling and discoloration.
  • Arterial TOS. Rare; often associated with cervical rib. Requires vascular referral.

When to seek emergency care

Some symptoms need urgent medical attention — not a chiropractic visit. Call 911 or go to the nearest emergency department for: progressive limb weakness, loss of bowel or bladder control, saddle anesthesia (numbness in the groin/inner thighs), severe unrelenting pain unrelieved by position, signs of fracture after significant trauma, chest pain, stroke-like symptoms (face drooping, arm weakness, speech changes), or any rapidly worsening or unusual symptom.

Bottom line

Most neurogenic thoracic outlet cases improve with structured conservative care over 3–6 months. Scapular control, postural retraining, and progressive loading are the foundation.