Peripheral Nerve Injuries
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Talk delivered to the residents at the SSHS annual hand review course on 26 Feb 2015.
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Peripheral Nerve Injuries
- 1. Peripheral Nerve Injuries Chye Yew Ng MBChB(Hons) FRCS(Tr&Orth) British Diploma in Hand Surgery European Board of Hand Surgery Diploma Consultant Hand & Orthopaedic Surgeon Fellowship Director, Upper Limb Fellowship Wrightington Hospital
- 2. www.wrightington.com Overview Basic science Classification of nerve injuries Principles of nerve surgery What (I think) you may be asked
- 3. www.wrightington.com Please draw the cross section of a nerve Axon Fascicle Nerve Endoneuriu m Epineurium Perineurium EpiPEn = Epi â Peri â Endo A&E Extrinsic & Intrinsic vascular supply Longitudinal â Segmental - Interconnected
- 4. www.wrightington.com Degeneration & Regeneration Lee & Wolfe. Peripheral nerve injury & repair. JAAOS 2000
- 5. www.wrightington.com Central Neuronal Death & Neuroprotection Neuronal death after peripheral nerve injury Acetyl-L-carnitine Arrests sensory neuronal death Speeds up regeneration N-acetyl-cysteine Provides sensory and motor neuronal protection Hart et al. Neurological Research 2008
- 6. www.wrightington.com Nerve Injury & Recovery Motor Proprioception Touch Temperature Pain Sympathetic Recovery Injury Lee & Wolfe. Peripheral nerve injury & repair. JAAOS 2000
- 8. www.wrightington.com Mechanoreceptors Characteristics Meissnerâs corpuscles â˘Rapidly adapting â˘Sensitive to light touch Merkelâs discs â˘Slowly adapting â˘Pressure, texture â˘Low frequency vibration â˘Static 2PD Pacinian corpuscles â˘Rapidly adapting â˘High frequency vibration â˘Rapid indentations of skin â˘Ovoid, 1mm in length Ruffini terminals â˘Slowly adapting â˘Skin stretch SubcutaneousCutaneous
- 9. www.wrightington.com Slowly Adapting Rapidly Adapting Low frequency vibration Merkel Meissner High frequency vibration Ruffini Pacinian
- 10. www.wrightington.com Mechanisms of Injuries Crush / compression Stretch / traction Laceration / transection Metabolic disturbance Ischaemia Radiation Electrical injury Thermal injury
- 11. www.wrightington.com Classification of Nerve Injuries Seddon BMJ 1942 Neurapraxia (Transient Block) Axonotmesis (Lesion in Continuity) Neurotmesis (Division of a nerve) Brain 1943 ⢠Localised degeneration of the myelin sheaths ⢠Complete interruption of axons ⢠Preservation of supporting structures (Schwann tubes, endoneurium, perineurium) ⢠All essential parts destroyed ⢠Interruption can occur without apparent loss of continuity
- 12. www.wrightington.com Classification of Nerve Injuries Neurapraxia Axonotmesis Neurotmesis Motor - - - Sensory +/- - - Autonomic +/- - - NCS Conduction block at the site Distal conduction preserved Loss of conduction both at and distal to the lesion Loss of conduction both at and distal to the lesion EMG No fibrillation Fibrillation ++ Fibrillation ++ Recovery Days to weeks provided the cause is removed Months provided the cause is removed No recovery unless repaired
- 13. www.wrightington.com Classification of Nerve Injuries Sunderland 1951 I II III IV V Focal conduction block NO Wallerian degeneration Axonal Disruption Axon + Endoneurium Disruption Axon + Endoneurium + Perineurium Disruption Axon + Endoneurium + Perineurium + Epineurium Disruption Cross-innervation
- 14. www.wrightington.com Sunderlandâs Classification Grabb & Smithâs Plastic Surgery 6th edition. Chapter 9
- 15. www.wrightington.com Physiological Conduction Block Type A Intraneural circulatory arrest Metabolic block with no nerve fibre pathology Immediately reversible Type B Intraneural oedema Increased endoneurial fluid pressure Reversible within days or weeks
- 16. www.wrightington.com Classification of Nerve Injuries Lundborg 1988 Physiological conduction block Myelin damage Axonal damage Axon + Endo damage Axon + Endo + Peri damage Axon + Endoneuriu m + Perineurium + Epineurium damage Type A Type B Sunder land 1951 I II III IV V Seddon 1942 Neurapraxia (Transient Block) Axonotmesis (Lesion in Continuity) Neurotmesis (Division of a nerve)
- 17. www.wrightington.com Classification of Nerve Injuries Lundborg 1988 Physiological conduction block Myelin damage Axonal disruption Axon + Endo Axon + Endo + Peri Axon + Endoneuriu m + Perineurium + Epineurium Type A Type B Sunder land 1951 I II III IV V Seddon 1942 Neurapraxia (Transient Block) Axonotmesis (Lesion in Continuity) Neurotmesis (Division of a nerve) Non- degenerative Degenerative
- 18. www.wrightington.com Classification of Nerve Injuries Lundborg 1988 Physiological conduction block Myelin damage Axonal disruption Axon + Endo Axon + Endo + Peri Axon + Endoneuriu m + Perineurium + Epineurium Type A Type B Sunder land 1951 I II III IV V Seddon 1942 Neurapraxia (Transient Block) Axonotmesis (Lesion in Continuity) Neurotmesis (Division of a nerve)
- 19. www.wrightington.com Sunderland âVIâ Grabb & Smithâs Plastic Surgery 6th edition. Chapter 9
- 20. www.wrightington.com Nerve in Danger! Pain, Pain, Pain ⢠Burning ⢠Severe Autonomic dysfunction ⢠Absence of sweating ⢠Smoothness & dryness of skin Tinelâs sign ⢠Distal to Proximal ⢠Regenerating touch fibres
- 21. www.wrightington.com In clinical practice, how do you distinguish? Axonotmesis versus Neurotmesis Nature of injury Serial observations Exploration Seddon BMJ 1942 (Imaging)
- 23. www.wrightington.com Nerve Surgery Neurolysis Nerve repair Nerve grafting Nerve transfer
- 26. www.wrightington.com Prerequisites for Nerve Repair Skeletal stability Healthy tissue bed Healthy nerve ends No undue tension Adequate soft tissue coverage
- 27. www.wrightington.com Epineurial versus Group Fascicular Repairs Epineurial Less exact Simple Group Fascicular Better alignment More dissection (scarring) The functional results of group fascicular repair has not been shown to be more superior than that of epineurial repair. Lee & Wolfe. Peripheral nerve injury & repair. JAAOS 2000
- 28. www.wrightington.com Which of the following is false regarding fibrin glue? a) Fibrin glue is nontoxic and does not block axon regeneration b) It may be used in combination with suture repair c) The outcome of fibrin glue repair is inferior to that of suture repair d) The common components of fibrin sealants include fibrinogen, thrombin and calcium chloride e) It has low tensile strength Tse & Ko. Nerve glue for upper extremity reconstruction. Hand Clinics 2012
- 29. www.wrightington.com Prognostic Factors of Outcomes â˘AgePatient factor ⢠Level of injury (distal vs proximal) ⢠Type of nerve (pure vs mixed functions) ⢠Condition of nerve ends Injury factors ⢠Delay to repair ⢠Length of gap Surgical factors
- 30. www.wrightington.com Nerve Grafts/Conduits Autologous Source Nerve autograft Vein (+/- muscle) Off-the-shelf Type I collagen Caprolactone Polyglycolic acid (PGA) Processed nerve allograft Lin et al. Nerve Allografts & Conduits in Peripheral Nerve Repair. Hand Clinics 2013 Kaushik & Hammert. Options for Digital Nerve Gap. JHSAm 2015
- 31. www.wrightington.com A 35 year-old male presented with numbness along the radial border of his right index finger 9 months after he sustained a cut in his first web. After surgical exploration and debridement, there is a 3.5cm nerve defect in the radial digital nerve. What is the most appropriate surgical reconstructive option? a) Flexion of digit to achieve primary repair before gradual distraction b) Type I collagen nerve conduit c) Autologous vein graft d) Posterior interosseous nerve graft e) Polyglycolic acid (PGA) conduit
- 32. www.wrightington.com Principles of Motor Nerve Transfers Donor nerve near target motor end plates Expendable donor nerve Pure motor donor nerve Donor-recipient size match Donor function synergy with recipient function Motor re-education improves function Mackinnon SE, Novak CB. Hand Clin 1999