Types of nerve damage

• Neurapraxia

• Axonotmesis

• Neurotmesis

• Traumatic neuroma

• Compression injury causing temporary disruption of nerve conduction

• The whole nerve remains structurally intact.

• Good prognosis with complete recovery of nerve function

The axon is damaged but the perineurium and epineurium remain intact

• Leads to central chromatolysis

• Results in Wallerian degeneration

• Definition: the reaction of a neuronal cell body in response to an axonal injury

• Function: increase in protein synthesis to help restore the integrity of the damaged axon

• Characteristics

  • Swelling of the neuronal body

  • Dispersion of the Nissl bodies

  • Displacement of the nucleus to the periphery

• Definition: an active neuronal degeneration process in response to axonal injury

• Function

  • To clear axonal debris and prevent scarring

  • Facilitate targeted reinnervation and functional recovery of tissues previously innervated by that axon before injury

• Characteristics

  • Initially retained electrical excitability of axonal membrane distal to the injury, lasting up to 36 hours

  • Progressive degeneration of distal segment cytoskeleton with dissolution of axonal membrane

  • Degradation of residual myelin sheath by macrophages and Schwann cells

  • The proximal stump either stays in place or retracts slightly

  • Ultimately, the cell body will sprout regenerative nerve fibers that, ideally, reinnervate the distal tissues.

  • Regeneration is significantly more efficient in the peripheral nervous system than in the central nervous system.

  • Good chance of at least partial recovery

• Complete nerve transection

• Connective sheath damage

• The chances of recovery are very poor without surgical repair.

Benign, painful nodular thickening caused by nerve regeneration at the site of different forms of nerve injury