Spondylolisthesis describes the forward displacement of one vertebra over another, usually of the fifth lumbar over the body of the sacrum, or of the fourth lumbar over the fifth.
Spondylolisthesis: "A Slipped Vertebra"
The term spondylolisthesis is used to describe several different spinal disease processes where one vertebra is out of its normal alignment with the adjacent vertebra. The term means "spine slip". This is clearly seen and measurable on routine x-rays. It should not be confused with the chiropractic community's concept of a vertebra being "out" (without any imaging abnormalities, including x-rays).
The typical appearance of spondylolisthesis is one vertebra slipping forward on the vertebra below. Retrolisthesis is a term used to describe when a vertebra is slipping backward on the vertebra below. Lateralolisthesis describes the vertebra that is displaced to the side of the vertebra below. Rotatory listhesis is a degenerative condition where a vertebra rotates on the vertebra below.
Routine standing spinal x-rays are the best way to diagnose vertebral malalignment such as spondylolisthesis. Flexion and Extension (patient bending forward and backward with maximum effort) x-rays of the spine are also helpful to assess whether the spine moves excessively and is unstable.
Often, spinal stenosis (pinched spinal nerves) accompanies spondylolisthesis and additional imaging studies are required to detect the presence of nerve compression within the spinal canal. A MRI scan is an excellent test to show the soft tissues of the spine in a way not possible with x-rays. A myelogram combined with a CT scan is another excellent way to evaluate nerve compression, especially when it is related to bone spurs and other arthritic processes which can narrow the spinal canal and compress nerves.
A CT scan by itself (without a myelogram) may be useful in diagnosing the type of spondylolisthesis caused by a stress fracture. This type, called "isthmic” spondylolisthesis, can usually be diagnosed on the basis of oblique x-rays. Occasionally, isthmic spondylolisthesis is diagnosed with a CT scan.
A bone scan can be helpful at identifying a recent stress fracture that could lead to spondylolisthesis. This has an important role in children who have back pain from an undiagnosed cause, and isthmic spondylolisthesis is suspected.
Causes and Types
There are five general causes for spondylolisthesis. Isthmic spondylolisthesis results from a stress fracture in the back part of the spine (a cracked vertebra, or spondylolysis), and most commonly develops between ages 5 and 8. It may or may not cause back pain. Five percent of the adult American population has it. Fifty percent of Eskimos and 10% of professional football linemen playing in the NFL have it. It is also a common source of back pain in highly competitive gymnasts, occurring in up to a third of these athletes.
The most common type of spondylolisthesis is caused by degenerative changes in the spine, particularly in the facet joints. As these joints wear out, they become lax and fail to maintain normal spinal alignment. The same arthritic process that wears out the joints in the spine can also cause bone spurs to grow which then cause nerve compression and spinal stenosis. Stenosis and degenerative spondylolisthesis occur together very often.
Rare causes of spondylolisthesis include tumors or infection that destroy the back part of the spine, and acute fractures through the back of the spine. These destructive processes disrupt spinal stability and allow the affected vertebra to slide forward on the one below it. Somewhat rare is the congenital type of spondylolisthesis that features malformed joints in the back of the spine which allow the spine to slip.
Signs and Symptoms
Back pain is the most common complaint in people who have spondylolisthesis. The pain tends to correlate with the level of physical activity, with worsening pain with activity and improvement with rest. Most people find that the back pain is worse with standing and walking, and often better with sitting.
Another common complaint is ache in the buttock region. This can be pain referred from the degenerative joints in the low back, or could be a symptom of nerve root compression. Buttock pain can accompany back pain or occur by itself.
Leg pain that descends through the buttock, back of the thigh, past the knee, and into the calf or foot is a common sign of nerve root compression. When a spinal nerve is pinched or irritated, burning, numbness, and tingling can also be present. Muscle weakness can also result.
The type of discomfort people have varies from person to person. In early stages, patients with spondylolisthesis may not have any pain. Pain may slowly increase to become intermittent, or even constant. Patients may also live their entire lives with this condition and not ever have any significant pain.
Most people with spondylolisthesis will find improvement in their back pain with conservative care. The foundation of a conservative program typically includes a short course in physical therapy leading to a daily home exercise program.
Developing a strong trunk (abdominal, oblique, and back muscles) is vital to removing stress and pain from the spine. Patients find that when they remember to do their back and abdominal exercises regularly, they have less back and buttock pain. The time commitment for exercises need not be longer than 10 minutes a day, in most cases.
Medications can play a role in pain control. Pain killers such as Percocet, Vicodin, and other narcotics are used sparingly except in times of new onset of severe pain. These narcotics are best used short term. They are very addictive. Non-steroidal anti-inflammatory medications are the medications of choice. They can be helpful at controlling back and leg pain by reducing the inflammation from arthritic joints. Muscle relaxants are rarely helpful, with the possible exception in the case of an acute muscle strain.