Foundational Rehab
← Back to Blog
Pain2026-03-06•7 min read

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

What Is Thoracic Outlet Syndrome?

Thoracic outlet syndrome (TOS) is compression of nerves and/or blood vessels in the space between your collarbone and first rib (the thoracic outlet). This causes pain, numbness, tingling, or weakness in the arm and hand.

TOS is often missed or misdiagnosed because symptoms overlap with many other conditions—carpal tunnel, cervical radiculopathy, rotator cuff problems.

Types of TOS

Neurogenic TOS (95%)

Compression of the brachial plexus (nerve bundle):

  • Most common type by far
  • Causes pain, numbness, weakness
  • Affects arm and hand

    • Venous TOS (3-5%)

    Compression of the subclavian vein:

  • Arm swelling
  • Bluish discoloration
  • Feeling of heaviness
  • May lead to blood clots

    • Arterial TOS (1%)

    Compression of the subclavian artery:

  • Coldness, pallor in arm
  • Weak or absent pulse
  • Risk of blood clots
  • Medical emergency if acute

    • What Causes TOS?

    Anatomical Variations

  • Cervical rib (extra rib)
  • Abnormal muscle bands
  • Enlarged scalene muscles
  • Abnormal first rib

    • Posture

  • Forward head posture
  • Rounded shoulders
  • Drooping shoulders
  • Prolonged poor posture

    • Repetitive Movements

  • Overhead work
  • Typing
  • Assembly line work
  • Throwing athletes

    • Trauma

  • Whiplash injury
  • Clavicle fracture
  • Repetitive strain

    • Symptoms

    Neurogenic TOS Symptoms

    Pain:

  • Neck, shoulder, arm, hand
  • Often vague and diffuse
  • May be worse at night

    • Numbness/tingling:

  • Usually in ring and pinky fingers (ulnar distribution)
  • May affect entire hand
  • Worse with arm elevation

    • Weakness:

  • Grip weakness
  • Difficulty with fine motor tasks
  • Dropping things

    • Aggravating factors:

  • Arms overhead
  • Carrying heavy bags
  • Working at computer
  • Sleeping

    • Vascular TOS Symptoms

    Venous:

  • Arm swelling
  • Blue discoloration
  • Visible veins on chest

    • Arterial:

  • Cold, pale arm
  • Weak pulse
  • Fatigue with arm use

    • Diagnosis

    Why It's Tricky

  • Symptoms overlap with many conditions
  • No single definitive test
  • Often a diagnosis of exclusion

    • Physical Exam Tests

    Adson's test:

  • Turn head toward affected arm
  • Extend neck, take deep breath
  • Positive if pulse decreases or symptoms occur

    • Roos test (EAST):

  • Arms up in "stick-up" position
  • Open and close fists for 3 minutes
  • Positive if reproduces symptoms or can't complete

    • Wright's test:

  • Arm overhead and externally rotated
  • Positive if pulse decreases or symptoms occur

    • Imaging

  • X-ray (cervical rib, first rib abnormality)
  • MRI (rule out disc herniation, see soft tissues)
  • MRA/venography (if vascular type suspected)

    • Nerve Testing

  • EMG/NCS often normal in neurogenic TOS
  • May help rule out carpal tunnel, cervical radiculopathy

    • Conservative Treatment

    Posture Correction (Essential)

    Goals:

  • Reduce forward head posture
  • Lift and retract shoulders
  • Open up thoracic outlet space

    • Key changes:

  • Chin tucks throughout day
  • Shoulder blade squeezes
  • Avoid forward slouching
  • Ergonomic workstation

    • Physical Therapy

    First-line treatment:

  • 70-80% improve with PT
  • Requires consistency (3-6 months)

    • Focus areas:

  • Posture correction
  • Stretching tight structures
  • Strengthening stabilizers
  • Nerve gliding

    • Stretching

    Scalene stretch:

  • Sit, hold onto seat with one hand
  • Tilt head away and slightly back
  • Hold 30 seconds
  • 3 reps each side

    • Pec stretch (doorway):

  • Forearm against doorframe
  • Step through doorway
  • Hold 30 seconds
  • Vary elbow height

    • First rib mobilization:

  • Can be done by PT
  • Self-technique: reach over head, side bend away, take deep breath

    • Strengthening

    Middle and lower trapezius:

  • Prone Y raises
  • Prone T raises
  • Rows with scapular retraction

    • Serratus anterior:

  • Push-up plus
  • Wall slides

    • Deep neck flexors:

  • Chin tucks
  • Head lift from supine

    • Nerve Gliding

    Ulnar nerve glide:

  • Arm at side
  • Bend wrist back
  • Bend elbow, then straighten
  • Gentle tension only
  • 10 reps

    • Activity Modification

  • Avoid prolonged overhead work
  • Take breaks from computer
  • Don't carry heavy bags on shoulder
  • Use good posture always

    • Exercises

    Corner Stretch

  • Stand in corner
  • Forearms on walls, elbows at 90°
  • Lean in
  • Hold 30 seconds
  • Opens chest, stretches pecs

    • Chin Tucks

  • Pull chin straight back
  • Create double chin
  • Hold 5 seconds
  • 10 reps, multiple times daily

    • Scapular Squeezes

  • Squeeze shoulder blades together and down
  • Hold 5 seconds
  • 15 reps

    • Shoulder Shrugs with Relaxation

  • Shrug shoulders to ears
  • Hold 3 seconds
  • Drop and relax
  • Feel difference between tension and relaxation
  • 10 reps

    • When Surgery Is Needed

    Indications

  • Failed 3-6 months conservative treatment
  • Vascular TOS with clot or significant compression
  • Severe, disabling symptoms
  • Objective muscle wasting

    • Surgical Options

  • First rib resection
  • Scalenectomy
  • Cervical rib removal (if present)

    • Outcomes

  • Variable depending on type
  • Vascular TOS: surgery often urgent and effective
  • Neurogenic TOS: surgery more controversial, outcomes mixed

    • Prognosis

    With Conservative Treatment

    Most neurogenic TOS improves with:

  • Consistent posture work
  • Stretching and strengthening
  • Lifestyle modifications
  • Time (3-6 months)

    • Key to Success

    Consistency is everything:

  • Daily stretching
  • Postural awareness all day
  • Ergonomic changes
  • Patient commitment

    • TOS is frustrating because it's often missed and takes time to improve. But most people get better with dedicated conservative treatment—posture correction, stretching, strengthening. If you've had vague arm symptoms that don't fit other diagnoses, TOS might be the answer. Give physical therapy a solid 3-6 months before considering surgery.

    Ready to Start Your Recovery?

    Get personalized rehab programs powered by AI guidance and evidence-based protocols.

    Try the App Free