Trauma: Peripheral Nerve Injury

Types of Injury

• Neurapraxia
  • Injury: Focal Demyelination
    • No Damage to Axon or Connective Tissue
  • Reversible
• Axonotmesis
  • Injury: Axon Damaged
    • Connective Tissue (Epineurium, Perineurium & Endoneurium) Preserved
  • Reversible
• Neurotmesis
  • Injury: Total Transection of Axon & Connective Tissue
  • Non-Reversible

Regeneration

• Regeneration Rate: 1-2 mm/Day
• Wallerian Degeneration: Degeneration of Distal Axon to Create Microenvironment Conductive for Regeneration & Reinnervation
  • Primarily Mediated by Schwann Cells

Brachial Plexus Injury (BPI)

• Law of 70’s:
  • 70% Due to Traffic Accidents
  • 70% of Those Involve Motorcycles or Bicycles
  • 70% Sustain Multiple Injuries
  • 70% Sustain a Lesion of the Supraclavicular Plexus
  • 70% of These Have ≥ 1 Plexus Root Avulsion
  • 70% Also Sustain Root Avulsions of the Lower Plexus
  • 70% of Lower Root Avulsions Experience Chronic Pain

Burner Syndrome

• Also Known as a “Stinger” Injury
• Cause: Trauma to the Base of the Neck/Shoulder
• Most Common in Collision Sports (Football, Hockey, Wrestling)
• Pathophysiology: Stretching of the Spinal Roots
  • Most Common in Upper Roots (C5/C6)
• Presentation:
  • Sustained Paresthesia
  • Burning Sensation Down the Lateral Arm
• Usually Transient – Sensory Function Returns Before Motor Function
  • Lasts Minutes-Days
• Diagnosis: History & Physical Exam
  • Consider Electromyography (EMG) if Symptoms Persist Longer than 3 Weeks
• Treatment: Observation

Treatment

• Closed Injury
  • Neurapraxia: Conservative Management
  • Axonotmesis vs Neurotmesis: Electrodiagnostic Studies After 3-6 Months
    • Axonal Recovery (Axonotmesis): Conservative Management
    • No Axonal Recovery: Surgery & Monitor for Action Potentials Across Lesion
      • Action Potentials Recorded (Axonotmesis) – Conservative Treatment
      • No Action Potentials Recorded (Neurotmesis) – Surgical Repair
• Open Injury
  • Lesion in Continuity: Conservative Management
  • Lesion in Discontinuity:
    • Laceration: Immediate Repair
    • Blunt Transection: Early Repair (2-4 Weeks)
      • Allow Decreased Inflammation
    • *May Require Radial/Sural Nerve Graft if Contracted