Cervical degenerative disc disease
Cervical degenerative disc disease is generally discussed in terms of cervical spondylosis, a term which is sometimes used synonymously with cervical spinal stenosis.
Spondylosis usually implies a more widespread age-related degenerative condition of the cervical spine including various combinations of the following:
1. Congenital cervical spinal stenosis (the shallow cervical canal 1))
2. Degeneration of the cervical intervertebral disc producing a focal stenosis due to a cervical bar which is usually a combination of:
a. Osteophytic spurs (hard disc in neurosurgical jargon)
b. And/or protusion of the intervertebral disc material (soft disc)
3. Hypertrophy of any of the following (which also contribute to canal stenosis):
a. Lamina
b. Dura
c. Articular facets
d. Ligaments, including
Increased stenosis in extension is more common than flexion (based on MRI studies 2) and cadaver studies), largely due to posterior inbuckling of ligamentum flavum 3).
Posterior longitudinal ligament: may include ossification of the posterior longitudinal ligament 4). May be segmental or diffuse. Often adherent to dura.
Ossification of the ligamentum flavum 5) (yellow ligament).
4. Cervical subluxation: due to disc and facet joint degeneration.
5. Altered mobility: severely spondylotic levels may be fused and are usually stable, however there is often hypermobility at adjacent or other segments.
6. Telescoping of the spine due to loss of height of vertebral bodys.Shingling of laminae.
7. Alteration of the normal lordotic curvature 6) (NB: the amount of abnormal curvature did not correlate with the degree of myelopathy)
a. reduction of lordosis including:
Straightening
Reversal of the curvature (kyphosis): may cause bowstringing of the spinal cord across ostophytes
b. exaggerated lordosis (hyperlordosis): the least common variant (may also cause bowstringing).
Although the majority of individuals > 50 yrs old have radiologic evidence of significant degenerative disease of the cervical spine, only a small percentage will experience neurologic symptoms 7).
