Can Trauma Injure the Long Thoracic Nerve?
Yes, trauma can definitively injure the long thoracic nerve through multiple mechanisms including closed trauma, compression, stretching, traction, direct extrinsic force, and penetrating injury.
Mechanisms of Traumatic Injury
The long thoracic nerve is particularly vulnerable to traumatic injury due to its anatomical course and length. Specific traumatic mechanisms include:
- Closed trauma through compression, stretching, traction, or direct extrinsic force 1
- Penetrating injuries to the chest wall or shoulder region 1
- Acute trauma from direct impact or sudden biomechanical forces 2
- Repetitive or sudden external biomechanical forces that exert compression or place extraordinary traction along the nerve distribution 3
The nerve's long course along the chest wall makes it particularly prone to compression injury 2. In the context of major blunt trauma, nerve damage in anatomic regions like the chest and proximal extremities can result in permanent disability 4.
Common Traumatic Scenarios
Documented traumatic causes of long thoracic nerve injury include:
- Heavy weight-lifting (most common cause in one series of 50 cases) 1
- Repetitive throwing activities 1
- Motor vehicle accidents 1
- Direct trauma to the shoulder or chest wall 1
- Sports-related injuries including tennis, hockey, bowling, soccer, gymnastics, and weight lifting 3
- Work-related traction injuries (such as flight line work involving repetitive overhead movements) 3
Anatomical Vulnerability
The nerve's susceptibility to trauma stems from a "bow-stringing" phenomenon where progressive abduction and external rotation causes the nerve to stretch across a tight fascial band arising from the inferior brachial plexus 5. Nerves tolerate only a 10% increase in resting length before stretch-induced neuropraxia develops 5. This anatomical relationship explains why both sudden forceful movements and repetitive overhead activities can cause injury.
Clinical Presentation
Traumatic long thoracic nerve injury manifests as:
- Scapular winging (the hallmark finding) 3, 1
- Weakness of arm elevation 2
- Pain (present in 86% of surgical cases) 1
- Shoulder instability (affects approximately 42% of patients) 1
Prognosis and Recovery
Most cases resolve spontaneously within 9 months with conservative management 3. However, the traditional view of universal spontaneous recovery within 2 years is overly optimistic—a significant percentage of patients exhibit residual winging, muscle weakness, and fatigability 6. At least some improvement occurs in 98% of cases less than 10 years old when treated surgically 1.
Management Approach
Initial treatment should focus on:
- Refraining from strenuous use of the involved extremity 3
- Avoidance of the precipitating activity 3
- Physical therapy focusing on maintaining range of motion and strengthening associated muscles 3
- Special attention to scapulothoracic muscle stabilization to address the underlying biomechanical dysfunction 5
For cases failing conservative management beyond 12 months, surgical decompression and microneurolysis produce "good" or "excellent" results in 92% of cases, with improvement in 98% of procedures 1. Surgical decompression through supraclavicular, thoracic, or combined approaches can yield satisfactory results even when performed beyond the traditional 2-year waiting period 6.
Critical Pitfall
The most important pitfall is assuming all cases will spontaneously resolve. While conservative management should be the initial approach, patients with persistent symptoms beyond 12 months should be evaluated for surgical decompression rather than continuing indefinite observation 6, 1.