Since the mechanism of nerve-root compression by protruded intervertebral disks was described in 1934,1 it has been customary to consider pain in the low back, with sciatica, to be the probable result of disk disease. Although this is likely to be true in most cases, it was found in one study reported elsewhere in The Journal (p. 1070) that numerous situations were presented in which this axiom was extremely dangerous and led to oversight of resectable primary caudal tumors. Resultant morbidity at a later date included paraplegia, loss of sphincter control and premature death.
Primary tumors of the conus medullaris and filum terminale produce neurologic deficit of a lower-motor-neuron type, exactly as is noted with extradural nerve-root compressions by intervertebral disk protrusions or other lesions. Since the bony intraspinal canal in the lumbar region is large, these tumors may reach massive proportions if early minimal signs are not heeded.