Wallerian Degeneration

Original Editor - Anthonia Abraham
Top Contributors - Anthonia Abraham, Kim Jackson, Cindy John-Chu and Lucinda hampton

Clinically Relevant Anatomy

Wallerian degeneration is an active process of retrograde degeneration of an axon that is a result of a nerve lesion.

Within a nerve, each axon is surrounded by a layer of connective tissue called the endoneurium. The axons are bundled together into groups called fascicles, and each fascicle is wrapped in a layer of connective tissue called the perineurium. Finally, the entire nerve is wrapped in a layer of connective tissue called the epineurium.

Mechanism of Injury

The pathological process of Wallerian degeneration is in 4 stages;

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 of the transected membranes are sealed until degeneration. This is marked by the formation of axonal sprouts. this occurs in less than a day and allows for nerve reservation and regeneration

Mylien Clearance

Usually, the rate of clearance is slower in the Central Nervous System than the peripheral Nervous system due to the clearance rate of myelin. Another reason for the different rate is the change in permeability of the blood-tissue barrier in the two systems. In PNS, the permeability increases throughout the distal stump, but the barrier disruption in CNS is limited to just the site of injury. In the CNS, olingodendrocites inhibit regeneration.

If soma/ cell body is damaged neuron can not generate, However if the injury is at the end of the axon, 1mm per day. distal segment undergoes granular disintegration over several days to weeks. by the 7th day macrophages clears axonal and myelin debris. schwann cells multiply to fill are previously occupied by former segment completed by mutubles leaving endometrial tube and swancells.

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Clinical Presentation

Most patients have presentations of nerve damage.

These presentations may include[2]

• Paralysis of associated structures to denervated nerves
• Gradual onset of numbness, prickling, or tingling in your feet or hands, which can spread upward into your legs and arms
• Sharp, jabbing, throbbing, freezing, or burning pain
• Extreme sensitivity to touch
• Lack of coordination and falling
• Muscle weakness or paralysis if motor nerves are affected
• Neuromatous or causalgia pain

Diagnostic Procedures

Electromyography

Nerve Conduction Studies

Pain assessment

Sensation deficit and skin condition

Muscle strength/loss

Functional deficits

Outcome Measures

Depends on various criteria including pain and psychosocial skills but could include:

• Oxford scale
• Visual analogue scale
• Short form McGill pain questionnaire

(see Outcome Measures Database)

Management / Interventions

Wallerian Degeneration is a nerve repair mechanism. Managing nerve damage can include the use Cryotherapy, Exercise,

Resources

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