Normal and pathological anatomy of the lumbar spinal nerve root canals.

4 In the 1 970s there were two outstanding changes which influenced the management of spinal disorders. First, significant advances occurred in investigative methods: safer water-soluble contrast agents became available, leading to improved myelography; computerised tomography heralded a revolution in non-invasive imaging of the spinal canal; ultrasonic measuring techniques were applied to the spine; and epidural venography attained some popularity. Secondly, there was a growing interest in the clinical problems attributed to spinal stenosis, with an emerging awareness of differences in symptoms and signs produced by stenosis of the central canal and of the so-called lateral canal. In this area of spinal disorders the use of terminology has remained vague, lacking in precision particularly when applied to descriptions of operative techniques. The purpose of this paper is to describe the anatomy of the nerve root canals of the lumbar spine, to outline a number of common pathological conditions which may lead to deformity of these canals and of the related intervertebral foramina, and to describe the essential surgical manoeuvres required to decompress them. A series of line drawings, constructed from anatomical specimens and from observations made at operation, illustrate the normal and pathological anatomy and demonstrate the extent of operations to decompress the spinal nerve root canals and intervertebral foramina.