The Journal of Bone and Joint Surgery, Vol 77, Issue 1 32-38, Copyright © 1995 by Journal of Bone and Joint Surgery, Inc
Lumbar foraminal stenosis: critical heights of the intervertebral discs and foramina. A cryomicrotome study in cadavera
T Hasegawa, HS An, VM Haughton and BH Nowicki
Department of Orthopaedic Surgery, Medical College of Wisconsin, Milwaukee.
One hundred lumbar intervertebral foramina from eighteen spines of fresh
cadavera were studied to assess the relationship between compression of the
nerve root and the height of the intervertebral disc and the morphological
characteristics of the intervertebral foramen as determined on
cryomicrotome sections. The critical posterior disc height and the critical
foraminal height that were associated with entrapment and compression of
the nerve root were determined. Significant positive correlations were
demonstrated between compression of the nerve root and the posterior disc
height, the foraminal height, and the foraminal cross-sectional area for
the four intervertebral levels between the second lumbar and first sacral
vertebrae. Nerve-root compression was evident in twenty-one of the 100
foramina, in eight of the ten foramina in which the posterior disc height
was four millimeters or less, and in four of the five foramina in which the
foraminal height was fifteen millimeters or less. These critical dimensions
may be indicators of foraminal stenosis in the lumbar spine. However,
compression of a spinal nerve root does not always cause sciatica, and the
clinical findings must always be taken into account when a diagnosis of
stenosis is considered.