Stenosis is a medical term that means narrowing. There is a space in the spinal column called the central canal. When that is narrowed in the low back we call this lumbar spinal stenosis.
The bundle of nerves travel together through the spine and leave the spine to connect to the skin (sensation), muscles of the legs, as well as nerves that contribute to the bowel, bladder, and sexual function.
Nerves travel together in a bundle through the lumbar spine. When that space becomes too small the nerves become compressed.
What are the symptoms of spinal stenosis?
When the nerves become compressed people can feel a variety of different symptoms in their legs. When nerves connected to the skin are affected people experience numbness, tingling, burning, or itching feelings anywhere from their feet all the way up to their back. Aching, shooting, throbbing, or cramp like pain can be experienced in any muscle group in the leg. The most common areas are the back of the thighs (hamstrings), and calves.
A particular feature of spinal stenosis is pain with walking. When patients experience these pains in their legs mostly with walking, doctors term this “neurogenic claudication”. This pain can come on after walking for either short or long periods of time and may vary from day to day. Sometimes it’s not just tingling or pain but weakness; where a person feels like their legs are going to give out. A characteristic of this neurogenic claudication is relief of symptoms when the person sits down or leans forward. Often these pain and tingling sensations are in both legs. In some people it seems to affect one leg more than the other.
What causes spinal stenosis?
There are a few different things that can contribute to narrowing of the space in the lumbar spine:
Disc herniation: Rubbery discs sit in between each of the vertebrae (spine bones) to add cushion and allow movement. The discs have a tough outer shell and jelly-like center. The discs can break open and bulge out, causing them to press on or irritate nearby nerves. (A disc that breaks open and bulges is called a “herniated disc.”)
Lumbar spondylosis: Wear and tear changes in the spine can form bumps called bone spurs, which press on nearby nerves. Also there are ligaments that become thickened as we get older which can also lead to less space for the nerves.
Sometimes these symptoms come on suddenly after heavy lifting. Jobs or activities with repetitive spine flexion predispose to disc herniation. Sometimes there is no specific event that can be identified as causing this.
What tests will I need?
Imaging tests – like an MRI, or CT scans, create pictures of the inside of the body. These imaging tests can show problems with the spine like those described above. These tests are ordered when your doctor thinks you may benefit from injections or surgery.
Electromyography (also called “EMG”) – is a test that checks how the nerves are working. It is used to find nerve damage from lumbosacral radiculopathy as well as other nerve problems that can affect the leg. Some people with significant stenosis may have a lot of numbness and tingling in their feet. While this can happen in people with lumbar stenosis, sometimes numbness and tingling in the feet can be a sign of a nerve disease. An EMG can sometimes be helpful to determine if the nerves in general are healthy, and whether the symptoms are more likely caused by the spinal stenosis.
How is spinal stenosis treated?
Some people are able to improve their symptoms by changing how they walk. At times the pain can be improved when a person leans forward. Often this would happen if they lean over something like a shopping cart. Some people will find benefit of a 4 wheeled walker so they can lean forward when they are walking. Walkers can be purchased with a seat so that they are able to sit and take a break to let the pain ease off. Other treatment options include:
Pain medicines that you can get without a prescription like ibuprofen or acetominophen (If these do not work, stronger prescription pain medicines are available like opiate or nerve pain medicines.)
Powerful anti-inflammation drugs called corticosteroids are occasionally presribed for short periods of time to reduce nerve inflammation and give pain relief.
Physical therapy can be helpful to review spine biomechanics (movement patterns), spinal extension exercises, nerve gliding exercises, and occasionally traction. These techniques are more often effective is there is a disc herniation contributing to the stenosis. If thickened ligaments and bony changes from spondylosis are the greatest factor; these techniques are less likely to be of benefit.
Epidural steroid injections are spinal injections of powerful anti-inflammatory medicines called corticosteroids. This medicine is injected into the epidural space that connects to where the nerves are. It doesn’t move discs or bone, but takes some of the swelling and inflammation out of the nerves. This can relieve pain for 3 – 6 months at a time. These injections can be repeated.
Sometimes surgery is needed to relieve the pain and prevent further neurological damage. Surgery can be indicated for very severe pain where a person can’t function. Progressive neurological damage with weakness can indicate that surgery is necessary. Bowel/Bladder nerve involvement is a relative emergency and usually necessitates surgery.
How serious is this to my health?
Spinal stenosis is not a life threatening condition and can improve over time. Cauda Equina Syndrome however, is a serious condition that happens when the nerve roots to the bowel, bladder, genitalia are compressed.
When this happens a doctor can usually detect it by examining you. A person with cauda equina can have difficulty voiding (peeing), bladder incontinence (accidents), severe constipation, or numbness/tingling/burning around the anus, penis, vagina (the “saddle region”), and erectile dysfunction in men.
If the following symptoms occur please see your GP/ emergency urgently: Progressive weakness, very severe pain, “saddle symptoms”, or bowel/bladder changes.
What will surgery do?
Surgery will cut out part of the disc or bone so it is not pushing on the nerves. This will open up the narrowing in the spine. This is done to relieve pain in the leg, or relieve pressure from the cauda equina if it is being pinched (cauda equina syndrome). Even after successful surgery you may still be left with weakness or numbness if the nerves are already damaged.