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Wallerian Degeneration



- Discussion:
    - arises from severe nerve injury (axonotmesis or neurotmesis)
    - characterized by axonal enlargement into an amorphorous mass, breakdown of the axons, and schwann cell ingestion of fragmented 
            myelin to provide clean endoneural tubes for advancement of regenerating axons;
            - axonal sprouting begins within 96 hours;
            - if axonal regeneration is delayed, tubes undergo shrinkage that becomes more severe with time;

- Pathologic Findings:
    - cell body:
           - increases in size;
           - migration of nucleus to the cell periphery;
    - proximal nerve segment:
           - degeneration occurs proportionate to severity of injury;
           - degeneration extends proximally to the next node of Ranvier;
    - distal nerve segment:
           - Schwann cell proliferation;
           - collapse of endoneurial tubes;
           - distally the entire axonal material is phagocytosed from the site of injury to the endplates