What is Spinal Stenosis?
"Central stenosis" or "spinal stenosis" refers to a narrowing of the spinal canal (central passage for spinal cord and nerves). Many spinal conditions, including spinal instability, herniated disc, or advanced arthritis can lead to a decrease in the amount of space for the spinal cord or spinal roots in the spinal canal. "Foraminal stenosis" refers to a narrowing of the space for a single nerve root as it exits a "foramen." This educational section is about central spinal stenosis. Stenosis may occur anywhere in the spinal canal, but this section will discuss the most common form: "lumbar spinal stenosis."
Lumbar spinal stenosis most commonly occurs in people over 50 years old. There are a number of causes of lumbar spinal stenosis. Each patient may have a different reason, or several reasons for stenosis. These are the most common:
Congenital stenosis: Some people are born with less room in the spinal canal, a condition called "congenital stenosis." These individuals are at a higher risk for stenosis.
Degenerative disc disease: As we age, our intervertebral discs wear out and may push into the spinal canal. This is the most common cause of spinal stenosis. For more information, see Degenerative Disc Disease.
Spinal instability: In advanced degenerative disease or a "pars fracture," the spine may become unstable. When the vertebrae move in an unstable spine, they may pinch off the nerves in the spinal canal.
Lumbar spinal stenosis is nearly always worse with standing, and "spinal extension" or leaning back. This is because there is more pressure on the intervertebral discs, which are compressed when standing upright or leaning back. The legs will become tired, heavy, and painful after walking for a certain distance. These symptoms will improve after sitting or leaning forward.
The most important part of the diagnosis is a proper evaluation by a specialist.
History: Your medical provider should appreciate that your medical history may contribute to your symptoms, which may or may not be related to your symptoms. It is also important to understand the timeframe for your symptoms, and what makes the symptoms worse or better. Your provider will also learn all previous treatments you have had, and if they have provided any relief.
Physical Examination: In addition to a good medical history, a thorough physical examination is the most important part of the diagnosis for any spine-related problem. During the physical examination, your provider may try to reproduce your symptoms, and will assess any long-term nerve damage that may have been caused.
X-rays: X-rays are often the first step for imaging. Even if other images have been taken, x-rays provide unique information that is not available from other studies.
MRI: An MRI scanner uses a magnetic field and radio waves that are not harmful to visualize the body in 3D. In most circumstances, it is the best way to see the soft tissues of the body, including nerves, intervertebral discs, and other parts of the spine other than the bones. An MRI or a CT scan is necessary to diagnose lumbar spinal stenosis.
CT: A CT scan uses many x-rays to produce a 3D image of the body. It is often the best way to visualize the spinal bones or bone spurs.
Injections: Spinal injections may be used to help diagnose the cause of a patient's symptoms. In addition to providing relief, they also provide useful information for your provider to pinpoint the cause of symptoms. If you have an injection, it is important to document how the injection affected your symptoms.
MRI showing severe spinal stenosis
For many people, lumbar spinal stenosis can significantly decrease quality of life. For those patients who do not improve with spinal injections and nonsurgical methods, an operation called a "decompression" may be recommended. Often, a minimally invasive procedure can relieve symptoms with a short recovery and only a few restrictions. For patients with severe spinal stenosis that involves many levels of the spine, an "open" procedure may be recommended. For more information, see Lumbar Decompression. For some patients, a Lumbar Fusion may be beneficial.