Peripheral Nerve Repair

Peripheral Nerve Repair

David Moss, MD

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)

• 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

Anatomy

• Epineurium – Nourish and protect

fascicles

• Perineurium – Major contributor to

nerve tensile strength

• Endoneurium– Nourish axons

Fascicular arrangement

• Median nerve motor branch – Volar-radial

• Ulnar nerve motor branch– Dorsal-ulnar

Classification

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

Order of functional failureand recovery

• Failure – Motor– Proprioception– Touch

– Temperature

– Pain

– Sympathetics

• Recovery– Sympathetics– Pain– Temperature

– Touch

– Proprioception

– Motor

Physiology of nerve degeneration

• Laceration– Cell body swells and becomes eosinophilic– Cell nucleus displaced peripherally– Proximal stump degeneration to proximal

node of ranvier

Wallerian degeneration

• Nerve breakdown distal to site of injury

• Begins 48-96 hours after transection

• Myelin deteriorates

• Schwann cells proliferate– Phagocytose myelin and debris

Diagnosis of nerve injury

• Sympathetic paralysis– Skin in distribution red and dry

• Tinel sign

• Neuro exam

• 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

EMG

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

Nerve repair

• 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

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

Nerve graft

• If direct, tension-free repair not possible

• Sural nerve

• MABCN

Nerve tubes

• Up to 3 cm gap – Tubes equivalent to nerve graft

• PLA and collagen superior to PGA