Conventional spin-echo T1-weighted parasagittal magnetic resonance
images of fifteen consecutive patients who had spondylolytic
spondylolisthesis were evaluated for evidence of impingement of a nerve
root, which was indicated by the loss of perineural fat within the foramen.
Seventeen of a possible thirty nerve roots appeared to be impinged on at
the level of the spondylolisthesis. Thirteen of these seventeen nerve roots
were associated with clinical evidence of radiculopathy on the side of the
root with impingement. None of the thirteen nerve roots that did not appear
to have impingement were associated with clinical evidence of
radiculopathy. The association between the impingement of a nerve root as
seen on magnetic resonance images and clinical symptoms was significant (p
< 0.001). Impingement of the nerve root within the neural foramen
appeared to be the cause of the radiculopathy in these patients who had
spondylolytic spondylolisthesis, and magnetic resonance imaging was a good
method for discrimination between nerve roots that were associated with a
radiculopathy and those that were not.