Spinal Stenosis: What is it?

by Christina Lasich, MD Health Professional

Damage to the spinal cord, an information superhighway that originates in the brain, is a very devastating injury that can lead to paralysis. Most people have heard of traumatic spinal cord injuries because the sudden tragedies grab headlines from time to time. But, few people have heard of spinal stenosis, a narrowing of the tube which shelters the spinal cord called the spinal canal (See Spine Anatomy 101). As the space tightens like a noose, this slow strangulation of the nerves in the spine can disrupt anyone's life.

Sara turned 68 years old last month. She has enjoyed good health and has been an avid golfer. But, lately she has noticed an aching pain in her legs that occurs when she is walking or standing. This new problem has really slowed her golf game down and has made it difficult for her to even do her own grocery shopping. The only way she can make it up and down the aisles is by leaning on the shopping cart because that eases her pain. Frustrated, she calls to make an appointment with her doctor.

Spinal stenosis usually becomes noticeable in the 5th or 6th decade of life. Sara's story typifies the usual first symptoms of aching pain in one or both legs. How can a healthy woman acquire spinal stenosis? The key word is "acquire" because Sara was not born with narrow spinal canal. Although, changes to her spine have accumulated as she has gotten older. As the discs degenerate, an avalanche of problems effect the surrounding structures particularly the spinal facet joints. These joints, like finger joints, will start to swell and grow (hypertrophy) as they deteriorate. Large knuckle joints in the fingers are not such a big deal. However, big facet joints are a big deal because of the confined, small space within the spine. Any unusual growth, swelling, buckling or bulging can crowd the spinal cord as the walls close in around it in a noose-like fashion. Other parts of the spine, besides facet joints, can cause spinal stenosis. Abnormal discs, ligaments and bones can all lead to a pinched, crowded, and confined spinal cord. Sometimes people are born with deformed spinal structures (congenital spinal stenosis) and others, like Sara, develop abnormal narrowing over time (acquired spinal stenosis). But eventually, both roads lead towards the same result: very unhappy nerves that are being strangled.

Sara was not too happy when her doctor confirmed the diagnosis of spinal stenosis. Her MRI clearly shows the very narrow spinal canal at multiple levels. Her doctor was very careful to do a thorough nerve exam and check her pulses. Although she occasionally will experience numbness and tingling in her legs, today her nerves are working fine with no areas of numbness. Her pulses are strong. On his way out the door, her doctor said something about "neurogenic claudication" and told her to come back in 3 months.

That's right, neurogenic claudication is caused by spinal stenosis. Quite simply, spinal stenosis causes a limping-type pain in the legs because the pinched nerves are unhealthy and unhappy. This similar aching pain in the legs can also be caused by clogged blood vessel--"vascular claudication". The distinction between nerve and vascular problems is an important distinction to make because it affects the treatment. In this case, leaning forward on a shopping cart eased Sara's pain; therefore, she most likely has neurogenic claudication. Her doctor knows about the "shopping cart sign" and confirmed the health of her blood vessels by checking her pulses. Still, poor Sara cannot walk around with a shopping cart all day. She needs a real solution to her spinal stenosis which seems to be getting worse every day.

The progressive nature of spinal stenosis has pushed researchers to develop innovative surgical and rehabilitation techniques. Fortunately, many types of treatment can ease the pain (See Spinal Stenosis: How Is It Treated?). Unfortunately, many areas of the spine can become abnormally narrow: the cervical spine, the thoracic spine, and the lumbar spine. Within each region of the spine, multiple levels can be affected. For example, lumbar spinal stenosis typically is found at L4/5 and L3/4. Pinpointing the exact level of the nerve damage is best done with an electrodiagnostic test (a special nerve test). This test is important because finding the right location helps to focus the treatment to one spot. Even with the best technology, the chances of successful treatment are complicated by the progressive, wide spread nature of spinal stenosis. Thankfully, the future holds promise for all types of spinal cord injuries, headline grabbing or not.

Christina Lasich, MD
Meet Our Writer
Christina Lasich, MD

Christina Lasich, M.D., wrote about chronic pain and osteoarthritis for HealthCentral. She is physiatrist in Grass Valley, California. She specializes in pain management and spine rehabilitation.