What is the pathophysiology of cervical spondylosis?

Updated: Apr 23, 2020
  • Author: Hassan Ahmad Hassan Al-Shatoury, MD, PhD, MHPE; Chief Editor: Dean H Hommer, MD  more...
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Answer

Intervertebral disks lose hydration and elasticity with age, and these losses lead to cracks and fissures. The surrounding ligaments also lose their elastic properties and develop traction spurs. The disk subsequently collapses as a result of biomechanical incompetence, causing the annulus to bulge outward. As the disk space narrows, the annulus bulges, and the facets override. This change, in turn, increases motion at that spinal segment and further hastens the damage to the disk. Annulus fissures and herniation may occur. Acute disk herniation may complicate chronic spondylotic changes.

As the annulus bulges, the cross-sectional area of the canal is narrowed. This effect may be accentuated by hypertrophy of the facet joints (posteriorly) and of the ligamentum flavum, which becomes thick with age. Neck extension causes the ligaments to fold inward, reducing the anteroposterior (AP) diameter of the spinal canal.

As disk degeneration occurs, the uncinate process overrides and hypertrophies, compromising the ventrolateral portion of the foramen. Likewise, facet hypertrophy decreases the dorsolateral aspect of the foramen. This change contributes to the radiculopathy that is associated with cervical spondylosis. Marginal osteophytes begin to develop. Additional stresses, such as trauma or long-term heavy use, may exacerbate this process. These osteophytes stabilize the vertebral bodies adjacent to the level of the degenerating disk and increase the weight-bearing surface of the vertebral endplates. (See images below) The result is decreased effective force on each of these structures.

A cervical myelogram shows advanced spondylotic ch A cervical myelogram shows advanced spondylotic changes and multiple compression of the spinal cord by osteophytes.
A 59-year-old woman presented with a spastic gait A 59-year-old woman presented with a spastic gait and weakness in her upper extremities. A T2-weighted sagittal magnetic resonance imaging scan shows cord compression from cervical spondylosis, which caused central spondylotic myelopathy. Note the signal changes in the cord at C4-C5, the ventral osteophytosis, buckling of the ligamentum flavum at C3-C4, and the prominent loss of disk height between C2 and C5.
A 48-year-old man presented with neck pain and pre A 48-year-old man presented with neck pain and predominantly left-sided radicular symptoms in the arm. The patient's symptoms resolved with conservative therapy. An axial, gradient-echo magnetic resonance imaging scan shows moderate anteroposterior narrowing of the cord space due to a ventral osteophyte at the C4 level, with bilateral narrowing of the neural foramina (more prominently on the left side).
A 48-year-old man presented with neck pain and pre A 48-year-old man presented with neck pain and predominantly left-sided radicular symptoms in the arm. The patient's symptoms resolved with conservative therapy. A T2-weighted sagittal magnetic resonance imaging scan shows ventral osteophytosis, most prominent between C4 and C7, with reduction of the ventral cerebrospinal fluid sleeve.

Degeneration of the joint surfaces and ligaments decreases motion and can act as a limiting mechanism against further deterioration. Thickening and ossification of the posterior longitudinal ligament (OPLL) also decreases the diameter of the canal. [4, 5, 6]

The blood supply of the spinal cord is an important anatomic factor in the pathophysiology. Radicular arteries in the dural sleeves tolerate compression and repetitive minor trauma poorly. The spinal cord and canal size also are factors. A congenitally narrow canal does not necessarily predispose a person to myelopathy, but symptomatic disease rarely develops in individuals with a canal that is larger than 13 mm.


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