The lumbar spine or low back is the third major region of the spine. Most people have five bone blocks or vertebrae in the lumbar spine, although it is not unusual to have four or six. Each vertebra is stacked on top of the other and between each vertebra is a gel-like cushion called a disc (intervertebral disc). The vertebrae and discs are held together by groups of ligaments with small joints that help to make the spine flexible.
In the centre of the spinal column is a vertical canal that contains the spinal cord. Nerves emerge from the spinal cord through the spaces between the vertebrae. The spinal cord and the nerves form a communicating pathway between the brain and muscles by transmission of ‘electrical signals’.
A common cause of low back pain is lumbar spinal stenosis. It occurs when the space around the spinal cord in the lower back narrows.
Symptoms
You may experience some of the following:
- Low back pain.
- Burning pain, numbness or tingling (a “pins-and-needles” sensation) in buttocks.
- Numbness, tingling or shooting pain down legs.
- Sensation of heaviness on walking or prolonged standing.
- Weakness in the legs or ‘foot drop’.
- Less pain with leaning forward or sitting. This is because bending forward increases the space in the canal.
- Pain becomes progressively worse with walking.
In most cases, symptoms will gradually worsen with time. People often complain of gradually increasing difficulty with walking for long periods of time.
Causes
The most common cause of spinal canal narrowing is arthritis. Arthritis is a common ageing process that occurs with most joints in the body due to daily wear and tear. In the spine, arthritis can present in a few ways:
- There are small joints called facet joints between the bones of your spine that enhance movement. With long-term use, the surfaces of the joints begin to lose their protective covering and rub against one another. New bone that continues to form will slowly grow sideways leading to spurs called osteophytes that jut into the canal space and pinch the nerves running through it.
- The discs gradually lose their water content as people get older and may eventually collapse. This reduction in disc space height can pinch against the nerves that run out of the spaces between the vertebrae.
- The ligaments holding the bones of the spine together thicken or harden with age further narrowing the canal space.
Tumour, infection and metabolic bone disorders can cause narrowing of the spinal canal but these causes are much less common than degenerative arthritis.
Risk Factors
Age. Everyone will have a certain degree of degenerative changes in the spine by age 50.
Lumbar spinal stenosis most often occurs in adults over 60 years old, with equal chances in men and women. However, not everyone will have symptoms. Due to the ‘wear and tear’ nature of this problem, there is little that can be done to prevent lumbar spinal stenosis.
Inherited conditions. A small proportion of people can have back problems that start earlier in age (30–50 years old) due to congenital narrowing of the spinal canal.
Investigations
What tests are used to diagnose spinal canal stenosis?
After discussing your symptoms and examining your back, the doctor will confirm the diagnosis with a few tests such as:
- Spinal X-rays
- Magnetic resonance imaging (MRI)
- Additional tests may include computed tomography (CT) scans
Treatment
Treatment of lumbar spinal stenosis mainly focuses on restoring function and relieving pain. This involves a range of non-surgical approaches. Surgery is generally only reserved for managing severe symptoms that reduce quality of life due to pain and weakness.
Non-surgical approaches to treatment
Although these non-surgical methods do not reverse the process of narrowing of the spinal canal, they help relieve pain and improve functioning.
- Physical therapy. The physiotherapist will teach you a few stretching exercises to strengthen the abdominal and back muscles and this can often help to manage symptoms.
- Anti-inflammatory medications (NSAIDs). These are similar to painkillers with the added effect of aiding in reducing swelling around the nerve. Because stenosis pain is caused by pressure on a spinal nerve, reducing inflammation (swelling) around the nerve may relieve pain. They are prescribed for long-term use to be effective. Note: These medicines must be used carefully as they can lead to gastritis or stomach ulcers. Always use them in conjunction with a doctor’s advice. If you develop acid reflux or stomach pains while taking an anti-inflammatory, be sure to talk with your doctor.
- Steroid injections. If the approaches above do not seem to have much effect, the next step will be to try steroid injections around the nerves of the back. Cortisone (steroid) is a powerful anti-inflammatory. Cortisone injections around the nerves or in the “epidural space” can decrease swelling, as well as pain. It is not recommended to receive these, however, more than 3 times per year. These injections are more likely to decrease pain and numbness but not weakness of the legs. They do not always work for everyone but sometimes its effectiveness will only be apparent on the second attempt.
The following treatments are tried by some patients to varying effects:
- Lumbar traction. Traction has very limited results. There is no scientific evidence of its effectiveness.
- Acupuncture. Acupuncture can be helpful in treating some of the pain for less severe cases of lumbar stenosis. Although it can be very safe, long-term success with this treatment has not been proven scientifically.
- Chiropractic manipulation.
Surgical treatment
Surgery is considered when leg pain and walking limitation persist despite non-surgical treatment, and are interfering with daily life. It is an option rather than an obligation — stenosis is not dangerous to leave alone, and the decision rests on how much the symptoms are costing you.
- Decompression (laminectomy) — the most common operation. Bone and thickened ligament are trimmed away from the back of the spinal canal to give the nerves more room. See disc surgery.
- Decompression with fusion — if one vertebra has slipped forward on another, or the spine is unstable, the decompression may be combined with a lumbar spine fusion to stop the segment moving.
Surgery is generally better at relieving leg pain and walking distance than it is at relieving back pain. This is worth understanding before you decide, because back pain is often what people most want fixed.
Most people stay in hospital a few days and are walking from the first day. Full recovery, including building strength back up, usually takes a few months.
Complications
Lumbar spinal stenosis is not dangerous in itself, and many people live with it for years. Where it does cause problems:
- Walking distance gradually reducing, so that you stop before you want to
- Loss of fitness and muscle strength from doing less, which then makes the symptoms worse
- Falls, from numbness or weakness in the legs and from unsteadiness
- Pain that disturbs sleep and affects mood
- Numbness or weakness in a leg that does not fully recover
- Rarely, severe compression at the bottom of the spinal canal causing cauda equina syndrome — numbness around the back passage or genitals, difficulty passing or controlling urine, or sudden weakness in both legs. This is a medical emergency. Go to your nearest emergency department.
Seeking Advice
Your Family Doctor (GP)
Your Family Doctor will be able to diagnose and help treat your problem. He or she will be able to
- tell you about your problem
- advise you of the best treatment methods
- prescribe you medications
- and if necessary, refer you to Specialists (Consultants) for further treatment
Prevention
The narrowing itself comes from age-related change in the spine and cannot be prevented. What you can influence is how much it limits you:
- Stay active. Loss of fitness makes stenosis symptoms considerably worse, and activity is the single most useful thing.
- Cycling and swimming are often better tolerated than walking, because the spine is bent slightly forward rather than upright.
- Keep the abdominal and back muscles strong — a physiotherapist can set this up for you.
- Carrying less weight reduces the load through the lower back.
- If you smoke, stopping helps. Smoking is associated with more back pain and with poorer healing after any spinal surgery.
- Get help early rather than waiting until walking is severely limited, when the deconditioning is harder to reverse.
F.A.Q. | Frequently Asked Questions
Why is it easier to walk leaning on a shopping trolley?
Leaning forward opens up the spinal canal slightly and takes pressure off the nerves. Most people with stenosis find they can walk considerably further pushing a trolley, or going uphill, than they can walking upright or downhill. It is such a consistent pattern that doctors ask about it when making the diagnosis.
Will it keep getting worse?
Not necessarily, and not steadily. Symptoms often plateau for long periods, and some people improve. The narrowing does not usually progress quickly.
Do I have to have surgery?
No. Stenosis is not dangerous to leave alone, and the operation is done to improve quality of life rather than to prevent something serious. Plenty of people manage well without it. The exception is the emergency situation described under Complications.
Should I stop walking if it hurts?
No. Walking within your limits, resting, then walking again is better than avoiding it. Prolonged inactivity weakens the muscles that support the spine and tends to make things worse.
Do I need a scan?
An MRI is usually arranged if surgery is being considered, or if there are signs of nerve compression. Scans in people over 50 very often show narrowing that causes no symptoms at all, so the scan is interpreted alongside your symptoms rather than on its own.
Is this the same as sciatica?
They overlap but are not the same. Sciatica is usually one nerve irritated by a herniated disc, often affecting one leg. Stenosis is narrowing of the whole canal, usually affects both legs, and is brought on by walking and relieved by sitting.