Lumbar stenosis means narrowing of the central spinal canal. Standing normally causes a narrowing of the lumbar spinal canal, and sitting somewhat enlarges the spinal canal. In patients with lumbar stenosis, the spinal canal is compromised, and upright activities such as standing and walking cause more canal compromise with associated symptoms.
Lumbar stenosis is a natural progression of lumbar degenerative disc disease. Some patients will give a history in which they have developed repeated attacks of pain over a period of many years, only to have the pattern of pain change. Other patients will have been relatively asymptomatic throughout most of their life until they begin to develop symptoms of lumbar stenosis.
The patient who is symptomatic from lumbar stenosis develops rather classic situational pain. Such a patient is comfortable sitting and is generally comfortable on first standing. However, with standing for a period of several minutes or with walking anywhere from half a block to many blocks, the patient develops increasing symptoms of low back pain. The back pain can become sufficiently severe that the patient must stop walking. Typically, the patient will either flex forward or sit down, obtaining almost immediate pain relief because these postures open up the spinal canal. Resumption of walking leads to recurrence of symptoms. Many patients relate how they can walk in a grocery store for a long period of time because they hold onto the grocery cart and can flex their trunk forward, thereby opening up the spinal canal.
Sometimes the patient will develop situational pain with standing and walking, but the pain will be referred down one or both legs. Flexing the trunk forward or sitting down will similarly alleviate symptoms almost immediately. The patient generally is comfortable lying down and generally does not awaken from pain in the middle of the night. If lumbar stenosis becomes more critical, the patient can develop associated leg numbness or weakness. If the spinal canal becomes quite compromised, then motor weakness and even bowel and bladder symptoms can develop, although this is unusual in lumbar stenosis.
As opposed to those patients who have arterial insufficiency in their legs, spinal stenosis patients can ride a bicycle or climb stairs without much difficulty. Arterial insufficiency, also known as claudication , means that the blood flow to the legs is diminished because of a blockage, usually from atherosclerosis, which is a fatty build-up within the artery. In arterial insufficiency, exercise involving the legs becomes impaired as the muscles, which demand more blood flow during exercise, become starved for oxygen since increased blood flow is unavailable.
Because riding a bicycle or climbing stairs involves flexing the trunk forward and opening the spinal canal, the patient with pure lumbar stenosis can tolerate these activities because his narrow spinal canal becomes more opened. The patient with arterial insufficiency develops symptoms based solely on whether the legs are demanding more blood flow because of an increase in muscle use from activity. Because both lumbar stenosis and arterial insufficiency tend to be medical conditions that develop in older patients, and therefore commonly coexist, it is important to make the distinction between these two conditions.
Cause of Lumbar Stenosis
Lumbar stenosis is a natural extension of progressive lumbar degenerative disc disease. As the discs degenerate, bridging osteophytes may develop, and the facet joints may become hypertrophic. As noted in this article, degeneration of the discs brings the vertebrae closer together. The osteophytes are a type of calcium deposit that develops in response to the vertebrae approaching one another. As joints undergo hypertrophic changes, they become larger than normal; this increase in size is similarly a result of a calcium build-up that develops as a response to the facets approaching one another. The osteophytes and hypertrophic facet changes are a type of overgrowth phenomenon that narrows the spinal canal. As degeneration continues, the ligaments also can become hardened and thickened, producing further overgrowth changes. The end result is that a progressive encroachment occurs on the central spinal canal (Image 1).
The pain associated with lumbar stenosis may be from compromise of a lumbar nerve root, regional spinal blood flow, or both. Classic spinal stenosis pain develops in an upright posture, especially with walking, because blood flow in the spinal region increases. Because a competition for space in the spinal canal occurs, compromise of regional blood flow or nerve root develops; thus, assuming a more flexed-forward posture alleviates the symptoms.
Patients with lumbar stenosis usually have a flattening of the normal lumbar spine curvature. They are often pitched slightly forward when standing. Forward bending is usually without restriction, but backward extension usually is limited, either by pain or because the spine cannot move in such a manner because of the advanced degenerative changes. Usually, no palpable tenderness is present in the spine. In patients who have pain only, without numbness or weakness, the neurologic examination is normal. Otherwise, there may be subtle changes in reflexes, muscle strength testing, or sensory perception. Walking may be limited by pain, and patients often tend to pitch forward somewhat with more prolonged walking.
Imaging and Diagnostic Studies
Plain radiographs of the lumbar spine reveal evidence of degenerative changes, with disc space narrowing and osteophytes. Magnetic resonance imaging (MRI) is a more definitive study for lumbar stenosis. The health of the disc, the size of the spinal canal, and the relative location of the nerve roots can best be appreciated with an MRI study. A computed tomography (CT) scan of the lumbar spine may afford more accurate bony measurements, but provides less detail regarding the spinal canal and nerve roots.
Because lumbar stenosis is situational pain, medication management is often unsuccessful. In essence, patients feel well when they are sitting and lying supine and only have pain while standing and walking. Because this is not an inflammatory condition, nonsteroidal anti-inflammatory drugs (NSAIDs) do not provide significant relief. However, subgroups of patients may improve. Narcotic analgesics are not indicated, because they generally do not help the situational pain while standing and walking and may leave patients feeling groggy otherwise.
Spinal manipulation is not indicated for lumbar stenosis, although gentle spine mobilization techniques may be helpful. Acupuncture may be helpful if maladaptive muscular responses contribute to symptomatology (See here for details). Similarly, physical therapy and spine stabilization programs may be helpful if associated maladaptive responses cause symptoms.
Therapeutic injections by way of lumbar epidural corticosteroid injections may ameliorate symptoms, and sometimes this relief lasts for months. Occasionally, lumbar stenosis pain is associated with facet jamming, and a combination of epidural injections and facet injections may be indicated. If pain relief is sustained for months, patients can undergo repeat injections as needed; this treatment may be effective indefinitely. Sometimes, patients respond beneficially to therapeutic injections, become more active, and experience prolonged pain relief.
In some patients, epidural injections lead to considerable pain relief, but the pain recurs within weeks. Unfortunately, epidural injections should not be provided more often than 3 injections every 4 months and, in such cases, nonsurgical treatment options become limited. If patients have unilateral leg symptoms, selective nerve root injections may be more effective than lumbar epidural corticosteroid injections.
Surgical indications for lumbar stenosis are somewhat similar to those for surgical indications for lumbar disc herniation (see here for details). If the stenosis is critical and associated with bowel or bladder function or progressive motor loss, then emergency surgery is indicated, assuming the patient can tolerate such surgery medically. The difficulty with lumbar stenosis is that it is usually a disease of the elderly, similar to osteoarthritis of the hip and knees. Thus, this surgery may entail more serious medical risks.
A relative surgical indication for lumbar stenosis is that the patient has ongoing pain that has not responded to good conservative management. The classic patient who will generally do well with surgery is the patient who has responded quite beneficially to epidural corticosteroid injections, who has little medical risk, and who develops recurring pain weeks to months following the epidural injections. If spinal stenosis is limited to one or two spinal segments, then a decompressive laminectomy can be performed (Image 2-3). In patients with more severe degenerative disc changes, or with evidence of spine instability, lumbar fusion is required in addition to decompressive laminectomy.
Some patients have severe, situational back or leg pain, but are not candidates for lumbar spine surgery. In select cases, a spinal cord stimulator may be a viable alternative. The spinal cord stimulator may override the pain of the lumbar stenosis and, as long as the patient remains intact neurologically, such treatment may improve the quality of life considerably.
Lumbar stenosis is a result of a progressive lumbar degenerative disc disease. However, once patients develop lumbar stenosis, they do not necessarily develop progressive symptoms over time. Indeed, some patients develop worsening of spinal canal narrowing, but their symptoms improve. This latter consideration leads one to believe that other factors may be involved in the pain of spinal stenosis. In part, the body may develop adaptive changes.
Another possibility is that physiologic changes have occurred, and the pain threshold has changed. For example, there are occasions when the patient’s perception of pain with lumbar stenosis can change according to the patient’s underlying emotional sense of wellbeing. This is not universally the case, but the unexplained fluctuations of pain in patients who have lumbar stenosis suggest that physiologic pathways sometimes play a primary role in mediating pain. With this in mind, patients should be encouraged to engage in mindful activities, and issues that cause a sense of inner conflict should be addressed and resolved, if it all possible.
Many times, patients become increasingly discouraged when they develop progressive symptoms of lumbar stenosis, and they essentially lose their sense of hope. They become more chairbound, homebound, and socialize less and less, all out of fear of pain. This is a cycle that can lead to even more progressive maladaptive changes, both physically and psychologically. In addition to considering all other treatment options, patients should be encouraged either to work with a physical therapist or to perform some type of group exercise. Psychological counseling may be indicated. In essence, it is important to prevent a further cascade of symptoms, which can lead to a considerable loss of hope and associated depression in such patients.
- Lumbar stenosis is a degenerative condition of the spine that results in narrowing of the spinal canal.
- Lumbar stenosis causes pain when a patient is standing or walking, and pain is usually relieved when sitting down.
- Surgery is indicated for lumbar stenosis when bowel or bladder incontinence or severe leg weakness results from the stenosis. Surgery also may be performed when pain persists despite good nonsurgical management.
- Lumbar epidural corticosteroid injections sometimes provide relief for many months in patients with lumbar stenosis. If the relief is more short-lived, surgery may be necessary.
- It is important to consider secondary depression in elderly patients who feel a sense of hopelessness because of quality-of-life limitations secondary to symptoms of lumbar stenosis.