Redundant nerve roots of the cauda equina: clinical aspects and consideration of pathogenesis

In order to investigate the clinical significance of redundant nerve roots of the cauda equina (RNR) and their pathogenesis, the following studies were performed: 1) examination of 1,256 myelograms of patients with lumbar disease; 2) clinical analysis of 55 patients with RNR and 75 without RNR; 3) electrophysiological examination of 9 patients with RNR; and 4) anatomical and histopathological examination of 6 autopsy cases. RNR were found in 42% of patients with severely constricted spinal canals. In comparing patients with RNR and those without RNR, RNR were found in older patients, these patients exhibited a longer period from the onset of the symptoms to the time of myelographic manifestation, and they caused more severe signs and symptoms. The spatial distribution of redundant nerve roots and the extent of degeneration of nerve fibers in redundant nerve roots indicated the close causal relationship between RNR and constriction of the spinal canal. As the pathogenesis of RNR, the authors suggest a squeezing force from the constricted spinal canal acting on the nerve roots.