As we age, the spine changes, often leading to a degeneration of the vertebrae (bones), discs, muscles and ligaments (connective tissues) that together make up the spinal column. These changes may lead to spinal stenosis.
The term “stenosis” comes from the Greek word meaning “choking” and is often the result of degenerative conditions such as osteoarthritis (See Figure 1). and/or degenerative spondylolisthesis. When the spinal nerves in the lower back are choked, lumbar spinal stenosis occurs and most often leads to leg pain and other symptoms, as described in more detail below.
Lumbar Spinal Stenosis Symptoms
The typical symptom is increased pain in the legs with walking (pseudoclaudication), which can markedly diminish one's activity level. Patients with lumbar spinal stenosis are typically comfortable at rest but cannot walk far without developing leg pain. Pain relief is achieved, sometimes almost immediately, when they sit down again.
For most people, symptoms of lumbar stenosis will typically fluctuate, with some periods of more severe symptoms and some with fewer or none, but symptoms are not always progressive over time. For each person, the severity and duration of lumbar stenosis symptoms is different and often dictates whether conservative (non-surgical) treatment or lumbar spinal stenosis surgery is more suitable.
The symptoms of lumbar stenosis generally develop slowly over time (most patients are over 50) and symptoms may come and go. Lumbar stenosis symptoms may include:
- Leg pain (sciatica)
- Leg pain with walking (claudication)
- Tingling, weakness or numbness that radiates from the lower back into the buttocks and legs.
As lumbar spinal stenosis symptoms worsen, they may become quite debilitating. It is estimated that 400,000 Americans suffer from leg pain and/or low back pain from lumbar spinal stenosis.
Lumbar Spinal Stenosis Causes
The cause of spinal stenosis in the lumbar spine is commonly associated with aging. The facet joints (small stabilizing joints located between and behind vertebrae) tend to get larger as they degenerate and can compress the spinal nerve roots in the lower back, often producing lumbar stenosis symptoms of pain, especially with activity.
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While rare, it is also possible for degenerative lumbar stenosis to develop in younger people who have a curvature of the spinal canal or suffer a spinal injury.
Generally, patients with lumbar spine stenosis are comfortable sitting, but standing upright further decreases the space available for the nerve roots and can block the outflow of blood from around the nerve. Congested blood then irritates the nerve, causing pain. It is important to note that lumbar stenosis that causes severe nerve damage is rare and that surgery is almost always the patient’s decision.
Lumbar Spinal Stenosis Diagnosis
When a patient presents with the typical symptoms of lumbar spinal stenosis (leg pain, with or without back pain, which is aggravated by walking), a conclusive diagnosis is made using imaging studies from an MRI scan or a CT scan with myelogram (using an x-ray dye in the spinal sack fluid). Physical examination alone does not yield a conclusive lumbar stenosis diagnosis.
There are three major types of stenosis and accurate identification is vital to stenosis treatment:
- Lateral stenosis. The most common type of spinal stenosis, lateral stenosis occurs when a nerve root that has left the spinal canal is compressed by either a bulging disc, herniated disc or bone protrusion beyond the foramen (a bony, hollow archway through which all spinal nerve roots run).
- Central stenosis. Occurring when the central canal in the lower back is choked, central stenosis may lead to compression of the cauda equina nerve roots (the bundle of roots that branch off at the bottom of the spinal cord like a horse's tail).
- Foraminal stenosis. When a nerve root in the lower back is pressed on and trapped by a bone spur in the foramen, or the opening where the nerve root leaves the spinal canal.