| ABSTRACT: |
An animal model of cauda equina syndrome was
developed. Neurologic recovery was analyzed following immediate, early,
and delayed decompression. Five experimental groups, each containing six
dogs, were studied. Compression of the cauda equina was performed in all
30 dogs following an L6-7 laminectomy. The cauda equina was constricted
by 75% in each group. The first group was constricted and immediately decompressed.
The remaining groups were constricted for 1 hour, 6 hours, 24 hours, and
1 week, respectively, before being decompressed. Somatosensory evoked potentials
were performed before and after surgery, before and immediately after decompression,
and 6 weeks following decompression. Daily neurologic exams using the Tarlov
grading scale were performed. At 6 weeks postdecompression, all dogs were
killed, and the neural elements analyzed histologically. Following compression,
all 30 dogs had significant lower extremity weakness, tail paralysis, and
urinary incontinence. All dogs recovered significant motor function 6 weeks
following decompression. The dogs with immediate decompression generally
recovered neurologic function within 2-5 days. The dogs receiving 1-hour
and 6-hour compression recovered within 5-7 days. The dogs receiving 24-hour
compression remained paraparetic 5-7 days, with bladder dysfunction for
7-10 days and tail dysfunction persisting for 4 weeks. The dogs with compression
for 1 week were paraparetic (Tarlov Grade 2 or 3) and incontinent during
the duration of cauda equina compression. They recovered to walking by 1
week and Tarlov Grade 5 with bladder and tail control at the time of euthanasia.
Immediately after compression, all five groups demonstrated at least 50%
deterioration of the posterior tibial nerve evoked potential amplitudes.(ABSTRACT
TRUNCATED AT 250 WORDS) |