Abstract:
Anatomical narrowing of the lumbar vertebral canal and intervertebral foramina
has been reported as a cause of compression of the cauda equina and the emerging
nerve roots (Sarpyener, 1945; Schlesinger & Taveras, 1953; Verbiest, 1954; Crock,
1981; Venner & Crock, 1981). The compression is associated with neurological
complications, notably pain in the back and lower limbs on walking, weakness
and paraesthesiae along the distribution of the affected nerve roots. Classically,
the symptoms are relieved by reversing the lumbar lordosis either by bending or
crouching. Verbiest (1954, 1955, 1977) called this 'the lumbar spinal stenosis
syndrome', and suggested that it could result from congenital or developmental
narrowing of the canal. Morphometric studies by Epstein, Epstein & Lavine
(1962), Hinck, Hopkins & Clark (1965), Hinck, Clark & Hopkins (1966) and Eisenstein
(1977) have established that the abnormality may involve the transverse,
sagittal or both diameters of the canal. In a recent review, however, Verbiest (1977)
has made it clear that in developmental stenosis, the transverse diameters (interpedicular
distances) are normal whereas the sagittal diameters are reduced because
of thickened laminae and articular processes, and in some cases also, because of
short pedicles. Recognition of the two types of stenosis thus depends, in part, on
proof of involvement of the transverse and sagittal diameters. Clearly it is necessary
to have baseline values for use in diagnostic work. Tables giving normal values of
the sagittal diameter have been compiled by Huizinga, Heiden & Vinken (1951),
Hinck et al. (1965), Sand (1970), Eisenstein (1977) and by Larsen & Smith (1981)
for groups of Caucasian and South African subjects. Age, racial and ethnic variations
in the shape and dimensions of the canal are reported, although Eisenstein (1977)
cautions that the racial differences are subtle and probably insignificant.
