What is the treatment for injuries to the thoracodorsal and long thoracic nerves?

Treatment of Thoracodorsal and Long Thoracic Nerve Injuries

For isolated long thoracic nerve palsy causing scapular winging, initial conservative management with physiotherapy for 6 months is recommended, followed by surgical nerve transfer (thoracodorsal to long thoracic nerve) if no recovery occurs and EMG shows increased distal latencies. 1

Initial Assessment and Conservative Management

Clinical Presentation

• Long thoracic nerve injury presents with scapular winging due to serratus anterior muscle palsy, causing upper-limb pain, fatigability, and weakness 1
• Thoracodorsal nerve injury affects the latissimus dorsi muscle, resulting in weakness of shoulder adduction and internal rotation 2
• Injuries typically result from violent upper-limb stretching, compression by the anterior branch of thoracodorsal artery at the "crow's foot landmark," trauma, Parsonage-Turner syndrome, or iatrogenic causes during shoulder surgery 1, 3

Diagnostic Workup

• Electromyography (EMG) should be performed to assess denervation patterns and motor unit potentials, though preoperative EMG correlates poorly with intraoperative nerve stimulation in 72% of cases 3
• Intraoperative nerve stimulation is the gold standard for surgical decision-making, not preoperative EMG 3

Conservative Treatment Period

• Physiotherapy for 6 months is the initial management approach for all nerve injuries 1
• If functional recovery fails within this timeframe and EMG shows increased distal latencies, surgical intervention should be considered 1

Surgical Management

Nerve Transfer Technique

The thoracodorsal to long thoracic nerve transfer is the primary surgical intervention for long thoracic nerve palsy with excellent functional outcomes 4, 5

Anatomic Considerations

• The lateral branch of the thoracodorsal nerve is optimal for transfer, containing an average of 1843 axons compared to 1135 axons in the long thoracic nerve 2
• The distance between the lateral thoracodorsal branch and long thoracic nerve averages 33.4 mm, making direct coaptation feasible 2
• The mean length of thoracodorsal nerve from apex of posterior axillary line to bifurcation is 31.5 mm 2

Surgical Outcomes

• Complete resolution of scapular winging occurs in most patients, with no winging in some cases and only mild winging in others at 24-33 months follow-up 5
• Return of full forward flexion of the shoulder occurs at an average of 2.5 months post-operatively 3
• Mean shoulder abduction arc improves to 134 degrees and external rotation to 124 degrees 5
• Long-term follow-up at 6.5 years demonstrates sustained full range of motion with no functional restrictions 4

Neurolysis as Alternative

• Open neurolysis of the thoracic portion of the long thoracic nerve is indicated when compression is confirmed on EMG 1
• At 6 months post-neurolysis, patients show no continuing scapular winging, significant reduction in distal latency on EMG, improved Constant scores, and considerably reduced pain 1
• Neurolysis is considered first-line surgical treatment when compression is the primary pathology 1

Surgical Decision Algorithm

Intraoperative Decision-Making

1. Perform intraoperative nerve stimulation of the long thoracic nerve 3
2. If nerve stimulates with muscle contraction: Consider neurolysis if compression is identified 1
3. If nerve does not stimulate: Proceed with nerve transfer using lateral branch of thoracodorsal nerve to long thoracic nerve 3
4. For combined brachial plexus injuries (C5-C6 root avulsions): Simultaneous nerve transfers can be performed using spinal accessory nerve to suprascapular nerve and nerve to long head of triceps to axillary nerve 5

Preservation During Axillary Surgery

Surgical Technique Considerations

The thoracodorsal and long thoracic nerves should be preserved during axillary dissection for breast cancer surgery 6

• During Level I and Level II axillary node dissection, meticulous identification and preservation of these nerves is mandatory 6
• The medial pectoral nerve should also be preserved 6
• Circumferential stripping of the axillary vein is unnecessary and increases edema risk 6

Common Pitfalls

• Do not rely solely on preoperative EMG for surgical planning, as it correlates poorly with actual nerve function in 72% of cases 3
• Avoid premature surgical intervention before completing 6 months of conservative therapy, as spontaneous recovery may occur 1
• Do not perform palliative procedures (muscle transfer, scapula-thoracic arthrodesis) as first-line treatment when nerve transfer or neurolysis options exist 1
• Ensure adequate follow-up as functional recovery from nerve transfer takes an average of 2.5 months, with continued improvement up to 33 months 5, 3