The cervical spine is made up of the first seven vertebrae. Its two primary purposes are to allow us to move the head, and to protect the spinal cord that travels through it. As we age, it is normal for the disks between the bones to wear out, or degenerate. This is called degenerative disk disease, or spondylosis.
When a disk wears out, it behaves like a tire without enough air. It not only shrinks down in height, but bulges at the sides. In some people, this bulging can combine with other arthritic changes of the spine to narrow the spinal canal, where the spinal cord travels. It can get to the point where it is so tight that there is pressure being placed on the spinal cord. This narrowing is called cervical spinal stenosis.
If enough pressure is placed on the spinal cord, it can start to malfunction. This is a condition known as myelopathy. Cervical myelopathy shows up as difficulty with fine motor tasks of the hands (think trouble buttoning a shirt, worsening handwriting, difficulty picking up pills, etc.), abnormal reflexes, and balance problems. Many patients have this creep up on them over months or years. Often, it is family or friends who notice that the patient is walking unsteadily or falling more frequently. This is unrelated to dizziness or the room “spinning”. Sometimes there is worsening weakness or numbness.
The course of myelopathy is generally one of progressive decline in function unless treated surgically. Some very mild cases may be observed closely, with intervention planned if the condition worsens. However, since the primary goal of surgery is to stop the decline in function, we tend to intervene more aggressively. This is because myelopathy is a form of spinal cord injury, and even if you successfully relieve the pressure, the spinal cord does not always fully recover. That is why we try to act earlier, before severe loss of function has occurred.
Special tests such as an MRI scan are used to determine the location and degree of narrowing. Sometimes a CAT scan with dye injected in the spinal fluid is used instead, this is a CT myelogram. Occasionally testing of nerve function (an EMG) is used to try to tell the difference between myelopathy and diseases of the peripheral nerves.
When surgery is called for, there are a variety of procedures used to relieve the pressure. Some of these are performed through the front of the neck, while others are approached from the back of the neck. Some of the terms for these operations are: anterior cervical discectomy and fusion, anterior cervical corpectomy, laminectomy with fusion, or cervical laminaplasty. The choice of procedure is based on a variety of factors, including prior surgeries, the exact source of the compression, the shape of the spine, and the number of levels that are tight.