Can tight latissimus dorsi (lats) muscles lead to thoracic outlet syndrome?

Can Tight Latissimus Dorsi Muscles Lead to Thoracic Outlet Syndrome?

Tight latissimus dorsi muscles can contribute to thoracic outlet syndrome by altering shoulder biomechanics and posture, which may compress neurovascular structures at the thoracic outlet. 1, 2

Anatomical Basis and Mechanism

Thoracic outlet syndrome (TOS) results from compression of neurovascular structures (brachial plexus, subclavian artery, and/or subclavian vein) as they pass through three potential spaces:

1. Costoclavicular triangle: Between clavicle, anterior scalene muscle, and first rib
2. Interscalene triangle: Between anterior scalene, middle scalene, and first rib
3. Pectoralis minor space: Between pectoralis minor muscle and chest wall 3

Tight latissimus dorsi muscles can contribute to TOS through:

• Altered shoulder biomechanics: The latissimus dorsi attaches to the humerus and when tight, can pull the shoulder into internal rotation and depression
• Postural changes: Creates rounded shoulders and forward head posture
• Muscular imbalance: Leads to compensatory patterns that narrow the thoracic outlet spaces
• Repetitive stress: Activities requiring repetitive upper extremity movements can exacerbate compression when lats are tight 2

Clinical Presentation

TOS presents with varying symptoms depending on which structures are compressed:

• Neurogenic TOS (nTOS): Upper extremity pain, numbness, tingling, weakness (most common form, ~90% of cases) 4
• Venous TOS (vTOS): Swelling, discoloration, heaviness of the arm
• Arterial TOS (aTOS): Claudication, coldness, pallor, decreased pulses 5

Diagnostic Approach

For suspected TOS related to tight lats:

1. Physical examination:

   • Assess for diminished radial pulse with provocative maneuvers (Adson's Test, Wright's Test)
   • Look for systolic blood pressure difference >25 mmHg between arms 1
   • Evaluate for muscle imbalances and postural abnormalities

2. Imaging:

   • Chest radiography: First-line to identify osseous abnormalities 1
   • MRI of brachial plexus: Gold standard for neurogenic TOS, should include neutral and arms-abducted positions 1
   • Ultrasound duplex Doppler: For evaluating vascular compression 1

Management Approach

For TOS related to tight latissimus dorsi:

1. Conservative management (first-line approach):

   • Targeted physical therapy: Focus on latissimus dorsi stretching and release
   • Postural correction: Address forward head and rounded shoulder posture
   • Strengthening of antagonist muscles: Strengthen external rotators and scapular stabilizers
   • Activity modification: Reduce repetitive overhead movements 6

2. Surgical intervention (if conservative management fails):

   • First rib resection
   • Scalenectomy
   • Cervical rib resection (if present)
   • Vascular reconstruction (for vTOS or aTOS with complications) 1

Important Clinical Considerations

• TOS is often a diagnosis of exclusion with poor accuracy of clinical testing 6
• Bilateral TOS is rare but possible, especially with postural or anatomical predispositions 7
• Rehabilitation is vital for neurogenic TOS and post-surgical recovery in all TOS types 6
• The prevalence of symptomatic TOS is estimated at 10 per 100,000 people 3

Pitfalls to Avoid

• Misdiagnosis: TOS symptoms can mimic other conditions like cervical radiculopathy or peripheral nerve entrapment
• Delayed treatment: Prolonged compression can lead to permanent neurological damage
• Inadequate rehabilitation: Addressing only the latissimus dorsi without correcting overall biomechanics and posture may lead to treatment failure
• Overlooking contributing factors: Cervical ribs, congenital fibromuscular anomalies, and muscular hypertrophy can all contribute to TOS 1