This clinical state must be differentiated from cervical disc disease, spondylosis, and tumor. The main aids in diagnosis are the CSF findings (minor pleocytosis and oligoclonal IgG abnormalities), present in 70 to 90 percent of cases, the demonstration by MRI of other unsuspected white matter lesions in the spinal cord and brain.
Cervical Spondylosis With Myelopathy (Spondylitic Myelopathy) (See Also Chap. 10)
It has been stated, correctly in our opinion, that this is the most frequently observed myelopathy in general practice. It is a degenerative disease of the spine involving the lower and midcervical vertebrae that narrows the spinal canal and intervertebral foramina and causes progressive injury of the spinal cord, roots, or both.
Historical note Key, in 1838, probably gave the first description of a spondylotic bar, or ossified protrusion into the spinal canal. In 2 cases of compressive myelopathy with paraplegia, he found “a projection of the inter-vertebral substance and posterior ligament of the spine, which was thickened and presented as a firm ridge that had lessened the diameter of the canal by nearly a third.” The ligament, where it passes over the posterior surface of the intervertebral substance, was found to be “ossified.” In 1892, Horsley performed a cervical laminectomy on such a patient, removing a “transverse ridge of bone” compressing the spinal cord at the level of the sixth cervical vertebra. Thereafter, operations were performed in many cases of this sort, and the tissues removed at operation were repeatedly misidentified as benign cartilaginous tumors or “chondromata.” In 1928, Stookey described the pathologic effects upon the spinal cord and roots of these “ventral extradural chondromas.” Peet and Echols, in 1934, were probably the first to suggest that the so-called chondromata represented protrusions of disc material. But this idea never gained wide credence until the publication, in the same year, of the classic article on the ruptured intervertebral disc by Mixter and Barr. Although their names are associated with the lumbar disc syndrome, 4 of their original 19 cases were instances of cervical disc disease. It was C.S. Kubik who identified the extruded material as nucleus pulposus from surgical specimens obtained by Mixter and Barr at operation.
Also of importance is Gowers’ account, in 1892, of vertebral exostoses, in which he described osteophytes that protrude from the posterior surfaces of the vertebral bodies and encroach upon the spinal canal, causing slow compression of the cord as well as bony overgrowth in the intervertebral foramina, giving rise to radicular pain. Gowers correctly predicted that these lesions would offer a more promising field for the surgeon than would other kinds of vertebral tumors.
For some reason, there was little awareness of the frequency and importance of spondylotic myelopathy for many years after these early observations had been made. All the interest was in the acute ruptured disc. Finally, it was Russell Brain who, in 1948, put cervical spondylosis on the neurologic map, so to speak. He drew a distinction between acute rupture and protrusion of the cervical disc (often traumatic and more likely to compress the nerve roots than the spinal cord) and chronic spinal cord and root compression consequent to disc degeneration and associated osteophytic outgrowths (hard disc), as well as changes in the surrounding joints and ligaments. In 1957, Payne and Spillane documented the importance of a developmentally smaller-than-normal spinal canal in the genesis of myelopathy in patients with cervical spondylosis. These reports were followed by a spate of articles on the subject (see Wilkinson). Rowland’s review of the natural history of cervical spondylosis and the results of surgical therapy is a useful modern reference, as is that by Uttley and Monro.