Diagnostic Imaging of Lumbosacral Disease

Diagnostic imaging of degenerative lumbosacral stenosis (DLSS) has been challenging until the introduction of computed tomography (CT) and magnetic resonance imaging (MRI).

Former methods included survey radiography, stress radiography, myelography, epidurography, transosseous and intravenous venography, discography, scintigraphy and linear tomography.

Survey radiography gives an overview of the anatomic situation (eg. presence or absence of transitional vertebrae) and allows the evaluation of signs of degenerative disease. Its main disadvantages include poor soft tissue contrast, superimposition and positional artifacts. Stress radiography can demonstrate movement or instability, but is affected by the same limitations.

Myelography can only be used if the dural sac is reaching into the sacrum which may end anywhere between L6 and the sacral vertebrae. Furthermore it will not demonstrate compressions originating in the dorsal, lateral or foraminal compartments.

Epidurography outlines the epidural spaces at the lumbosacral junction. Sensitivity is low for lesions obstructing less than 50% of the vertebral canal.

Discography of the lumbosacral disk could help delineating the borders of the disk and demonstrate herniations. In combination with epidurography it has been proposed as a rather accurate method for demonstrating cauda equine compression2. However it is an invasive method and fails to demonstrate lateral and foraminal compressions.

Osseous and intravenous venography could be used to demonstrate space occupying lesions at the lumbosacral junction. They are rather difficult to perform and can be false positive due to incomplete venous sinus filling and variations in sinus configuration.

All these methods have in common that they were used to diagnose cauda equine compression by evaluating indirect signs such as space occupying effects or demonstration of disk herniation or spondyloarthritis. It was not possible to directly visualize the nerves of the cauda equina.  [...]