Peripheral Nerve Injury: Classification, Diagnosis, and Treatment

Peripheral Nerve Injury

Classifiation of peripheral nerve injuries with methods of treatment of cut injured nerve.

Answer.

Classifiation of Peripheral Nerve Injuries

• Seddon’s Classifiation
  • Neurapraxia: It is a temporary physiological paralysis of nerve conduction. Here recovery is complete.
  • Axonotmesis: Division of nerve fiers or axons with intact nerve sheath. Reaction of degeneration is distally with near complete recovery.
  • Neurotmesis: Here complete division of nerve fiers with sheath occurs. Degeneration occurs proximally up to the fist node of Ranvier as well as distal to the injury. Recovery is incomplete even after nerve suturing. There is complete loss of motor and sensory functions with loss of reflxes. lf the nerve is mixed type other than pure motor or sensory recovery is still poorer.
  • Neuromas:
    • True neuroma or false neuroma
    • End neuroma or side neuroma.
• Sunderland’s classifiation
• Conduction block: Temporary neuronal block
• Axonotmesis but endoneurium is preserved.
• Axonotmesis with disruption of endoneurium, but perineurium is preserved
• Here disruption of endo and perineurium has occurred but endoneurium is intact.
• Neurotmesis with disruption of endoneurium,perineurium and epineurium has occurred.

Treatment of Cut injured nerve

Usually, microscope or loup is used for nerve suturing.

• Epineurorrhaphy: Only epineurium is sutured using interrupted sutures.
• Epi-perineurorrhaphy: Initially, perineural sheath and then epineurium is sutured.
  • If nerve is lacerated marker stitches are placed at cut end site to identify the nerve for suturing at later period.
  • If nerve suturing fails or it cannot be done, tendon transfer is done at later period after 4 to 6 months.

Nerve suturing can be:

• Primary repair:
  • It is done immediately after injury.
  • Nerve ends are minimally trimmed very close using a blade.
  • Fascicles of the nerve are oriented correctly.
  • Two stay sutures are placed to keep the orientation properly.
  • Usually, epineural suturing is done using 8 zero polypropylene interrupted sutures.
  • 6-8 sutures are placed for large peripheral nerve like median or ulnar nerve.
  • For or small nerve like digital nerve, only 2-3 sutures are placed.
• Secondary repair:
  • It is done at a later period.
  • It is in a pre-existing scar tissue.
  • Here fist nerve ends, but proximal and distal are identifid, carefully dissects; adequately.
  • Proximal neuroma and distal glioma trimmed for l cm to expose the normal fascicles of nerve ends.
  • Often guide sutures of silk may be present which were placed earlier during exploration of trauma.
  • Once nerve ends are clean, it is sutured alike primary suturing with stay sutures, with proper alignment of fascicles, followed by epineural suturing.
  • Here as epineurium is thicker, suturing is easier.