Cauda equina dysfunction. The significance of two-level pathology.

The pathophysiology of neurogenic claudication is not well understood. It is generally believed that stenosis of the central vertebral canal is significant, but some believe that it is root canal stenosis or stenosis of the foramen that is important, not pathology in the central canal. There are, however, clinical anomalies incompatible with either view. In this article, 49 patients with neurogenic claudication were examined with myelography and computed tomography, recording the frequency of multilevel central canal stenosis and the presence of coexistent root canal stenosis. Of the 49 patients, 46 had either multilevel central canal stenosis or stenosis of both central and root canals. It was concluded that neurogenic claudication is generally associated with at least two levels of stenosis. A hypothesis of two-level venous compression, with venous pooling of one or several nerve roots, explains some of the pathophysiology of neurogenic claudication. This hypothesis is compatible with clinical and experimental observations, but it has yet to be confirmed.