Degenerative disc disease (DDD) is part of the natural process of growing older. Unfortunately, as we age, our intervertebral discs lose their flexibility, elasticity, and shock absorbing characteristics. The ligaments that surround the disc, called the annulus fibrosis, become brittle and they are more easily torn. At the same time, the soft gel-like center of the disc, called the nucleus pulposus, starts to dry out and shrink. Degenerative disc disease is as certain as death and taxes, and to a certain degree this process happens to everyone. However, not everyone who has degenerative changes in their cervical spine has pain. Many people who have "normal" necks have MRI's that show disc herniations, degenerative changes, and narrowed spinal canals. Every patient is different, and it is important to realize that not everyone develops symptoms as a result of degenerative disc disease.
There are soft-tissue discs between the bony vertebral bodies in your cervical spine that are called intervertebral discs. These discs are composed of a soft gel-like center called the nucleus pulposus, and a tough outer lining that surrounds the disc called the annulus fibrosis. The intervertebral disc creates a joint between each of the vertebral bodies that allows them to flex and extend, rotate slightly, and move with respect to one another. When the outer lining that surrounds the disc tears, the soft center squeezes out through the opening, creating a "herniated", "slipped", or "ruptured disc". Each of these terms describes the same process.
Myelopathy is a term that means that there is something wrong with the spinal cord itself. This is usually a later stage of cervical spine disease, and is often first detected as difficulty walking due to generalized weakness or problems with balance and coordination. This type of process occurs most commonly in the elderly, who can have many reasons for having trouble walking or problems with gait and balance. However, one of the more worrisome reasons that these symptoms are occurring is that bone spurs and other degenerative changes in the cervical spine are squeezing the spinal cord. Myelopathy affects the entire spinal cord, and is very different from isolated points of pressure on the individual nerve roots.
Doctors use the term radiculopathy to specifically describe pain, and other symptoms like numbness, tingling, and weakness in your arms or legs that are caused by a problem with your nerve roots. The nerve roots are branches of the spinal cord that carry signals out the rest of the body at each level along the spine. This term comes from a combination of the Latin word radix, which means the roots of a tree, and the Latin word pathos, which means a disease. This disease is often caused by direct pressure from a herniated disc or degenerative changes in the cervical spine that cause irritation and inflammation of the nerve roots.
Cervical spondylolysis is a disorder that narrows the spinal canal in the neck compressing the spinal cord or spinal nerve roots. It's a fracture or defect in the pars anticulars (a portion of the bone between each of the joints of the back), allowing one vertebral body to slide forward on the next. Spondylolyosis is sometimes referred to as pars interarticularis defect. It may be unilateral or bilateral and is usually due to a developmental defect but may be secondary to a fracture. Spondylolysis affects the area of the vertebra called the pedicle. The pedicle is part of the bony ring that protects the spinal nerves, and is the portion that connects the vertebral body to the facet joints. It's a disease that often times affects middle-aged and older adults who have degenerative discs and vertebrae in their neck. When a spondylolysis is present, the back part of the vertebra and the facet joints simply are not connected to the body, except by soft tissue.
Stenosis is a term used to describe a narrowing of various parts of the body. Cervical stenosis is a degenerative disease where the spinal canal and neural foramina narrow and compress the spinal cord and nerve roots. Stenosis occurs when pressure increases inflaming the facet joints. The facet joints are overlapping arches that form the spinal canal. These joints are covered with cartilage and a membrane. Degenerative changes and wear and tear can cause the facet joints to inflame. This disorder is most common in people over 50 years of age. However, genetics and congenital factors may predispose a person for stenosis.