- Discussion:
    - most severe nerve injury;
    - complete disruption of axons, endoneurium, perineurium, & epineurium;
    - Wallerian degeneration occurs;
    - recovery requires operative repair and the prognosis is variable, ranging from complete recovery to no recovery;
    - factors that influence the degree of recovery;
           - the age of the patient
           - type of injury
           - degree of injury
           - level of injury
                   - if an injury causes division of the nerve close to the cell body, cell death occurs;
           - presence of associated injury
           - composition of the severed nerve trunk
           - if axonal regeneration into the empty endoneural sheaths is delayed, these sheaths undergo shrinkage that becomes more severe with 
                   time;
    - nerve injury results in changes within the cell body, the axon proximal & distal to site of injury, and the functional unit innervated;
    - more proximal the injury, the greater the cell body damage, as evidenced by changes in the size and internal organization;
    - after injury, the cell body progressively enlarges for approx 20 days and remains enlarged until axon regeneration is complete;
    - proximal nerve stump swells in response to the accumulation of gel like, amorphous substance containing large quantities of acid 
           mucopolysaccaride;
    - schwan cells begin proliferating 48 to 72 hours after injuries and assume a phagocytic role (Wallerian degeneration)