The Herniated Disc
The disc has already been described as a hydraulic structure that contains a flexible collection of tissues. This collection of tissues sometimes gives way when movement such as walking or standing occurs, resulting in shock to the spine. When we were young, this tissue was fluid and gel-like. With age, it becomes harder and white. If this gel-like substance works its way through the fibers of the disc, it often directly causes pressure or irritates the nerve behind the spine. This is the underlying cause for sciatica.
The nerves have a common distribution, going to the same area of the body for each individual. For example, the fifth lumbar nerve supplies the power which raises the big toe. When a pattern of pain is seen in this area, it is possible to know which nerve is likely to be involved. All the nerves exiting from the spine have a characteristic pattern of innervation (the nerve supply to a body part) and although there is some variation from patient to patient, consistency is present. The physician can usually reach conclusions about the likely causes of pain by observing the patterns of discomfort.
With this understanding of how nerves function, let us then discuss the herniated disc itself. The extruded disc fragment may press against the nerve and later move or be re-absorbed. For these reasons, herniated discs can get better; therefore, conservative treatment is the general rule. However, there are rare exceptions, such as if the patient has tremendous or disabling pain or if there is likely to be a permanent loss of bowel or bladder function.
The Degenerative Disc
The degenerative disc is different from a herniated disc. With a herniated disc, the center of the disc comes out and pushes against a nerve; however, with a degenerative disc, the disc simply “dries up.” Once the disc “dries up”, or rather loses normal hydration, the two vertebrae start to settle toward each other. This results in a change in alignment. Sometimes this change occurs so gradually that the patient does not notice any symptoms, but the low back “wear and tear” changes are evident on the x-ray films. The opposite can occur as well. A patient may present with normal x-rays and be in excruciating pain. A subtle but significant shift in the disc may be felt but not seen, presenting a problem for the treating physician. The first case with severe degenerative changes may require an abdominal examination to find the real cause of the problem. The second case with a normal x-ray may fool us into thinking that the problem is the abdomen or the extremity when the problem is actually in the back. Only a careful evaluation will likely discern between the two.
This word literally means “lysis” or“dissolution of the spine.” Spondylolysis is a stress fracture, which is a hairline crack of the small hook that latches the vertebra above onto the vertebra below. This hook keeps the vertebra above from sliding forward. With frequent motion, heavy use, or bad genetics, this hook may break. The hook does not shatter or break like a tibia or femur, but it submits to a subtle crack called a stress fracture. This is very small at first and can barely be seen but eventually, large cracks form and the fracture is completed.
Stress fractures will heal with proper rest and protection. Some stress fractures do not heal and a permanent disruption of the hook can occur. Fortunately, the spine depends on other elements such as the ligaments, muscles, and abdomen for stability. When these disruptions occur, they are usually without symptoms, though some patients will have an immediate pain. This pain may come from the now abnormal joint, from the disc, from something unrelated all together such as the abdomen or chest, or from muscle strain.
Spondylolysis is treated in order for the patient to regain comfort. If it is not caught very early on, there is unfortunately not much hope in re-establishing a bony union. However, in a young person or in a well-defined situation, a surgical procedure to restore proper anatomy is a definite possibility.
Myoligamentous Strain and Syndromes
Myoligamentous means “muscle and ligament.” This term is applied to patients who complain of localized back pain without supportive neurologic findings. The muscles and ligaments of the back can strain and tear just like the muscles and ligaments elsewhere in the body, though it is difficult to determine where such sprains and strains occur. The term should be applied only when other treatable causes of the spine have been considered such as relaxing the muscles through the use of medication and physical therapy. Generally, treatment for a “muscular-ligamentous strain” consists of rest, controlled activity, and prevention of re-injury.
Facet Joint Arthritis
The facet joints are the small joints of the spine that provide the interface between the vertebrae above and below. It is a joint subject to wear and tear and other joint diseases such as rheumatoid arthritis. Changes without pain or pain without visible change can occur, thus causing confusion in the diagnosis of facet problems.
The diagnosis of facet joint arthritis is made based on the location of pain, which is often on one side (unilateral), and also on aggravation by torsional movements of the waist. Anesthetizing the facet joint with an injection may help to confirm or disprove the diagnosis.
The treatment for facet joint disease is to initially rest the joint and to reduce the irritiation or inflammation by the use of oral anti-inflammatory medications. Sometimes an injection of cortisone into the facet joint is helpful. In the most extreme form where the facet arthritis is severe and conservative treatment is not effective, some suggest that the nerves of the facet joint be destroyed by a somewhat controversial technique where a needle is placed under x-ray control down to the area of the nerve and is then coagulated with high frequency radio waves.
Narrowing of the Canal —Central Spinal Stenosis
There are nerves which pass near the back of the spine. This spinal canal passes adjacent to the disc and the facet joint. There may be encroachment upon the canal from the disc, the facet joint, or a combination of the two. An individual nerve or the entire canal and all the enclosed nerves may be affected. Patients with a small canal are especially susceptible to such change. The narrowing of the canal results in impairment of the blood supply to the nerves passing through the area.
Spinal stenosis does not cause the same lancinating pain as that of a herniated disc. It usually causes weakness, fatigue, and aching pain in the lower extremities. These symptoms are made worse by attempts at walking or other physical activities. Treatment for central spinal stenosis centers upon relieving the pressure on the nerves. Rest is the first and safest means of relief. If nothing seems to relieve the pressure on the nerve, surgery will be required.
Narrowing of the Canal —Lateral Recess Stenosis
The lateral recess is a pocket to the side of the spinal canal. Most patients have a rounded or triangular-shaped spinal canal. Some patients, however, have a canal that is shaped like a three-cornered hat. The nerves are okay as long as they travel down the center of the canal. When a nerve leaves the center of the canal, it is pulled into the clothespin-like recess and gets pinched there. Early in the course of spinal surgery, the diagnosis of “lateral recess stenosis” was difficult. However, with the technology of the CT scan and the MRI, our ability to detect and diagnose lateral recess stenosis has improved.