This document provides a detailed exploration of nerve injury and repair, focusing on the various types of nerve injuries, including Neuropraxia, Axonotmesis, and Neurotmesis. It delves into the mechanisms of Wallerian Degeneration, covering the stages of Axon Degeneration, Myelin Clearance, and Re...
• NEUROPRAXIA
• Neuropraxia is the mildest form of traumatic peripheral nerve injury. It is characterized by focal
segmental demyelination at the site of injury without disruption of axon continuity and its
surrounding connective tissues. This condition results in blockage of nerve conduction and
transient weakness or paresthesia.
• Example: Saturday night palsy, crutch palsy etc.
• AXONOTMESIS
• Axonotmesis is a term that describes the range of PNIs that are more severe than a minor
insult, such as those resulting in neurapraxia, yet less severe than the transection of the
nerve, as observed in neurotmesis. Axon is not intact and there is moderate demyelination.
Recovery is spontaneous.
• Example: fracture or dislocation (closed injury- involving nerve trunk and sparing of
integuments)
• NEUROTMESIS
• Neurotmesis is a complete transection of a peripheral nerve. Neurotmesis will produce
complete sensory and motor deficits to the skin and muscles innervated by the injured
nerve. Spontaneous recovery of function is extremely suboptimal without surgical
intervention. spontaneous recovery of function is extremely suboptimal without surgical
intervention. Neurotmesis leads to the rupture of the axon, myelin sheath, and connective
tissues.
• Example: open fractures.
WALLERIAN DEGENERATION
- Wallerian degeneration is an active process of retrograde degeneration of the distal end of
an axon that is a result of a nerve lesion. It occurs between 7 to 21 days after the lesion
occurs. After the 21st day, acute nerve degeneration will show on the electromyograph.
- -The pathological process of Wallerian degeneration is in 3 stages;
1. Axon Degeneration
Within approximately 30 minutes of injury, there is a separation of the proximal and distal ends of
the nerve. After a short latency period, the transected membranes are sealed until degeneration
which is marked by the formation of axonal sprouts. This occurs in less than a day and allows for
nerve reinnervation and regeneration
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