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 spaces between each 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 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 surface of the joints begin to lose their protective covering and rub against one another. New bone that continue to form will slowly grow sideways leading to spurs called osteophytes that jutt 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 focus 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 pain killers 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 it’s effectiveness will only be apparent on 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.
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