Lumbar Spondylolisthesis

Lumbar spondylolisthesis is a condition in which one vertebral body becomes progressively out of alignment with another in a front-to-rear orientation. Typically, the problematic vertebral body is a certain degree forward of the body below it. Different magnitudes of displacement are described as the "grade", such as, grade 2 which is worse than grade 1. There are relatively common forms of spondylolisthesis which can occur along with degenerative arthritis and Lumbar Spinal Stenosis although these conditions tend not to be as structurally unstable as other forms. Instability means abnormal sliding motion and change in the alignment during spinal movements. In addition to "mechanical" spinal discomforts due to abnormal stresses on ligaments, disc and muscles, spondylolisthesis can be associated with nerve compressions due to a variety of reasons. First, the intervertebral disc which used to fit neatly between the vertebral bodies is obligated to "hang over" the edge of one body toward the front and the other body toward the rear. Often, the rear surface of the disc just bridges in a straight or slightly curved line from the bottom edge of one body to the top edge of the other. However, a Herniated Lumbar Disc can also occur at this region which can contribute to nerve compression. At other times, there is compression or irritation of nerves as they exit through the side openings ("foramina") of the spinal canal and pass underneath abnormal facet joints or abnormal portions of the lamina. Constriction (stenosis) of the entire spinal canal can occur but is most often associated with the arthritic forms of spondylolisthesis.


Cause of Lumbar Spondylolisthesis

Spondylolisthesis can be a progressively acquired spinal deformity occurring in the context of severe degenerative arthritis or it can occur as a result of a (usually hidden) birth abnormality of the spine. Both forms usually develop slowly over the course of many years and a person might not have any symptoms he considers abnormal until the process has been well established. Many people have no neurological symptoms and some even have few mechanical symptoms other than what they have come to know as "muscular pains". Degenerative spondylolisthesis can be described as a deformity of the facet joints which normally prevent forward sliding of one vertebral body on another. The bone structure slowly yields to forces producing malalignment and is remolded. Many individuals will be found to have no instability or change in alignment during spinal movement but some will be unstable. Occasionally, the upper vertebral body involved in the malalignment is displaced to the rear rather than toward the front, a condition sometimes called "retrolisthesis", which is usually not severe but can also be unstable. In the congenital form due to birth abnormality, there is malformation of the facet joints or a portion of the lamina ("pars defect") which renders the facet joints less effective in stabilizing the spine against forward and backward movements. Over the first few decades of life, the accumulated stresses progressively defeat the remaining structures which are maintaining alignment and the forward displacement of the upper body begins. Possibly, the natural degeneration of the intervertebral disc between those bodies eliminates the strongest bond and leads to progressive slippage. Occasionally, patients will notice sudden worsening of previously mild low back pains following physical exertion or an accident. At other times, low back pain develops slowly without notable incidents.

Treatment of Lumbar Spondylolisthesis

Lumbar spondylolisthesis can be managed without surgery if symptoms are relatively mild, especially if the amount of malalignment is slight and if there is no apparent change in malalignment with bending movements on X-ray. It stands to reason that, the more a person physically uses his low back, the more likely a spondylolisthesis will be symptomatic. A lumbar corset brace will provide added support during times of anticipated physical exertion and may be enough to protect someone from overly straining a structurally weakened spine. Anti-inflammatory medications can alleviate some of the symptoms following flare-ups. If there is notable instability or incapacitating mechanical pain, these remedies might prove insufficient. Neurological symptoms due to compression of exiting nerves by abnormal tissues, Herniated Lumbar Disc or Lumbar Spinal Stenosis, can also precipitate a need for surgical decompression. Surgery, when necessary, involves a spinal fusion for which there are multiple surgical techniques available, depending on the circumstances. Occasionally, the consideration for surgery is mostly neurological or mostly mechanical but both conditions are treated by the surgical strategy. If there are no neurological symptoms, fusion surgery to stabilize the area might be appropriate without nerve decompression. However, nerve decompression without fusion is considered most often in cases of stable degenerative spondylolisthesis and is still a matter of some controversy. Whether or not a person needs fusion surgery is frequently a judgement which must be made after careful review of diagnostic tests, medical history and examination by the surgeon. The prospect should never be taken lightly because spinal fusion represents a major compromise with nature, permanently altering the structure of the spine in a dramatic way. Fusion can be accomplished by bone grafts, threaded cylinders placed in the disc space, or a variety of metal devices attached to the spine (usually in combination with bone graft). Lumbar bracing after surgery is common for a period of time to allow bone grafts to heal in place.

Outcome/Restrictions of Lumbar Spondylolisthesis

The outcome of treatment for lumbar spondylolisthesis is most frequently judged by the presence or absence of low back discomfort. The success of a surgery for spinal instability is evaluated by this almost entirely subjective measure more than any other type of spinal operation. As mentioned for other conditions, low back pain can be caused by a multitude of things including muscular irritability, inflammation, and degeneration which makes it most difficult to predict total resolution of mechanical back pain with a surgery designed only to halt movement between two or maybe three spinal segments. This is why the surgeon will consider performing a fusion only when there is a conspicuous spinal abnormality or anticipated instability most likely to be a cause of substantial discomfort or nerve compression. Properly selected patients who undergo lumbar spinal fusion with or without nerve decompression and who heal solidly are generally better than they would have been without surgery. Neurological symptoms are likely to resolve, improve or, at least, stabilize as discussed in other pages. Low back pain might resolve in a nearly complete fashion or it might persist to a tolerable degree in the majority of patients. Some patients develop worsening problems as other spinal degenerations occur in time, occasionally requiring additional surgery for similar or different reasons than the first surgery. The probability of total success usually diminishes with subsequent operations, especially with respect to mechanical low back pains, and so, their necessity must be even more carefully scrutinized by an experienced spinal surgeon. Usually, a person who needs a spinal fusion will only need that one surgery unless something unforseen happens in the future. Individuals who have successful fusions must remain mindful that their spine is still more vulnerable than a normal spine and are well advised to be cautious with physical exertions as much as possible. This is even more important for individuals who have been successful without an operation.


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