The sagittal diameter of the lumbar vertebral canal in normal adult Nigerians

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. There appears to be no information on the sagittal diameter of the lumbar vertebral canal of Nigerians. The aim of the present study is primarily, to determine the normal ranges of the sagittal diameters of the lumbar vertebral canal in the Nigerian population, and to find out whether they differ from those of other populations.