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Sacral Sparing

- See: neurological exam:

- Discussion:
    - sacral segments must be carefully examined for sensation & motor power;
    - scaral sparing is evidenced by perianal sensation, rectal motor function, and great toe flexor activity;
    - in patient w/ an apparent complete neurologic injury, any sensory awareness distally or scant evidence of motor activity must be 
    - preservation of sacral function might be the only finding to indicate an incomplete cord lesion (which has the potential for recovery);
          - if patient has immediatae paralysis and no signs of sacral sparing, he is considered to have a complete cord lesion;
    - as soon as spinal shock is over (i.e, return of bulbocavernosus returns) a definite diagnosis of complete lesion can be made;
    - while patient will not recover functional motor power in extremities, there may be progressive return of cervical nerve root function 
          w/ recovery of wrist and hand muscle function;
          - this should not be confused w/ regeneration or recovery of cord function;
    - in the acute situation, sparing of sensation to pin prick in a motor segment w/ grade 0 power indicates an 85% chance of motor recovery 
          to at least grade 3;
          - pin prick sensation (spinothalamic tract) is more prognostic than posterior column function due to the proximity of the spinothalamic 
                  tract to the corticospinal tract;
          - ref: Sparing of sensation to pin prick predicts recovery of a motor segment after injury to the spinal cord.
- Absence of Sacral Neurologic Function:
    - may be the only neurologic deficit on examination;
    - exam that fails to include testing of perianal sensation, rectal tone, and great toe flexion can be misinterpreted as normal;
    - injury just to the conus will allow the pt to move both extremities & pain of injury can prevent detection of perianal sensory loss