Dr. David Moss

1. Peripheral Nerve Repair
David Moss, MD

3. Indications
• Preserve or restore function
– Innervation of skin, muscle, other target
organs
• After transection, direct repair or graft
offers only chance of recovery
• Irreparable proximal stump → nerve
transfers
• Irreparable distal stump → muscular
neurotization (implant into muscle)

4. • Quicker reconnection of nerve → better
result
– > 18 months → permanent end organ failure
(muscle cell death)
• Isolated nerve laceration repair timing:
– Within 1-2 weeks to avoid retraction and
scarring

5. Anatomy

6. • Epineurium
– Nourish and protect
fascicles
• Perineurium
– Major contributor to
nerve tensile strength
• Endoneurium
– Nourish axons

7. Fascicular arrangement
• Median nerve motor branch
– Volar-radial
• Ulnar nerve motor branch
– Dorsal-ulnar

9. Classification

11. Seddon
• Neuropraxia
– Local myelin change
– Usually due to
compression or
traction
– Axons in continuity
– No distal degeneration
– Good prognosis
• Axonotmesis
– Loss of axon continuity
– Connective tissue
intact
– Variable prognosis
• Neurotmesis
– Disruption of entire
nerve
– Usually transection

14. Order of functional failure
and recovery
• Failure
– Motor
– Proprioception
– Touch
– Temperature
– Pain
– Sympathetics
• Recovery
– Sympathetics
– Pain
– Temperature
– Touch
– Proprioception
– Motor

15. Physiology of nerve degeneration
• Laceration
– Cell body swells and becomes eosinophilic
– Cell nucleus displaced peripherally
– Proximal stump degeneration to proximal
node of ranvier

16. Wallerian degeneration
• Nerve breakdown distal to site of injury
• Begins 48-96 hours after transection
• Myelin deteriorates
• Schwann cells proliferate
– Phagocytose myelin and debris

17. Diagnosis of nerve injury
• Sympathetic paralysis
– Skin in distribution red and dry
• Tinel sign
• Neuro exam

18. • Martin-Gruber anastomosis
– Median to ulnar nerve crossover in forearm
– “overly median innervated hand”
– AIN to ulnar nerve
– Motor only
• Riche-Cannieu anastomosis
– Median to ulnar nerve crossover in hand
– May be median to ulnar or reverse

19. EMG
• Fibrillations
– Appear as muscles are denervated
– Onset 10-14 days after injury

20. Nerve repair

21. • Freshen ends to healthy nerve
• Suture epineurium only
– No advantage to intra-fascicular repair
• Use as few sutures as possible to re-
approximate nerve ends
• Tension-free
• 8-0 suture for the digital nerves
• Microscope often helpful

22. Fibrin glue
• No definitive evidence yet
• Gaining popularity
• Faster than suture
• Useful for multiple repairs
– Cable graft
• Can be used to augment suture repair to
prevent gapping

24. Nerve graft
• If direct, tension-free repair not possible
• Sural nerve
• MABCN

25. Nerve tubes
• Up to 3 cm gap
– Tubes equivalent to nerve graft
• PLA and collagen superior to PGA