What is Lumbar Spinal Stenosis and How is It Diagnosed?
Lumbar spinal stenosis occurs when the spinal canal narrows in the lower back (known as the lumbar region) due to either hardening of the soft tissues of the spine or an overgrowth of bone or tissue. This narrowing compresses the spinal canal and irritates the nerves of the spinal cord, resulting in pain, weakness or numbness in the lower half of the body. There are three types of lumbar spinal stenosis:
- Lateral stenosis – the most common type; occurs when a nerve root leaves the spinal canal and is compressed by either a bulging disc, herniated disc or some other type of bone growth.
- Central stenosis – develops when the central canal in the lower back is constricted, resulting in the compression of the cauda equina nerve roots at the bottom of the spinal cord.
- Foraminal stenosis – occurs when a nerve root in the lower back is compressed by a bone spur right before it leaves the spinal canal.
Accurate identification of the exact type of lumbar spinal stenosis is critical to proper treatment. A definitive diagnosis cannot be done by physical examination alone. Once a patient presents with the characteristic symptoms of lumbar spinal stenosis (which are discussed below), a physician will perform imaging tests such as a MRI or CT scan. Also, it is important for the physician to differentiate lumbar spinal stenosis from other lower back conditions that present with similar symptoms, such as musculoskeletal low back pain, spinal disc disease or peripheral vascular disease.
Causes and Symptoms of Lumbar Spinal Stenosis
By the age of 50, approximately 95% of people have some type of deterioration of the spine. Lumbar spinal stenosis happens most frequently in patients over age 60 and generally affects men and women equally, although women tend to require treatment more often for their symptoms. Younger people can also develop lumbar spinal stenosis if they have some type of genetic curvature and/or narrowing of the spinal canal or sustain a spinal injury.
The most common cause of lumbar spinal stenosis is osteoarthritis. As people age, discs in the back degenerate, losing their water content and start to dry out and weaken, causing settling of the discs and loss of space between the discs. This increased pressure causes the joints to disintegrate and the cartilage protecting the joints starts to wear away. Once the cartilage wears away entirely, bone begins rubbing on bone and the body compensates by growing new bone (known as spurs) to help support the vertebrae, which in turn, narrows the spinal canal.
Symptoms of lumbar spinal stenosis occur when the spinal cord or the spinal nerve endings are compacted. The typical symptoms include:
- Lower back pain.
- More pain while standing or stretching and less pain when sitting or leaning forward.
- Sciatica or burning pain beginning in the buttocks and radiating down the legs.
- Numbness, cramping or tingling in the buttocks or legs.
- Stiffness in the legs and thighs.
- Weakness in the legs or "foot drop" (sufferers feel like their foot slaps the ground while walking).
- Loss of bladder and/bowel control in severe cases.
Lumbar spinal stenosis symptoms begin moderately and worsen over a long period of time. Similar to arthritis, patients with this type of spinal stenosis will experience flares in symptoms. Also, symptoms can become so severe that daily activities can become limited and impact quality of life.
Prevention and Treatment
Since lumbar spinal stenosis is caused by changes to the spinal canal due to age, not much can be done to prevent its onset. However, practicing good spinal health through regular exercise focusing on flexibility, maintaining a healthy weight and keeping good posture can help reduce the severity of symptoms if the condition occurs. Also, smoking should be avoided – studies have shown that smoking reduces bone density, magnifies the risk of fractures and bone deterioration, and inhibits healing after surgery. Other preventative measures are limiting the use of alcohol and/or sedatives to avoid dizziness or drowsiness and removing household obstacles to minimize falling accidents.
There are various nonsurgical and surgical treatment methods available for relieving the symptoms of lumbar spinal stenosis. Nonsurgical methods are used to restore movement and relieve pain only and do not correct the narrowing of the spinal canal. Nonsurgical methods include anti-inflammatory medications, steroid injections, physical therapy, lumbar traction and acupuncture. Chiropractic care can help relieve pain, but is not recommended for patients with osteoporosis or herniated discs.
Laminectomy and spinal fusion are the two main surgical options for those patients whose mobility has been greatly impaired due to lumbar spinal stenosis with excellent results for relieving pain. A laminectomy is a procedure that removes the bone, bone spurs and/or ligaments that are compacting the nerves. Spinal fusion involves the "welding" of two or more vertebrae, forming one smooth bone, to eliminate movement and slippage between the vertebrae and alleviate pain. Regardless of the surgery used, rehabilitation is required to help regain strength and flexibility in the spine.
American Academy of Family Physicians website, "Point-of-Care Guides – Diagnosing Lumbar Spinal Stenosis", https://www.aafp.org/afp/2009/1115/p1145.html
American Academy of Orthopaedic Surgeons website, https://orthoinfo.aaos.org/topic.cfm?topic=A00329
Ullrich, Jr., MD, Peter F., "Lumbar Spinal Stenosis: A Definitive Guide", https://www.spine-health.com/conditions/spinal-stenosis/lumbar-spinal-stenosis-a-definitive-guide
WebMD.com website, https://www.webmd.com/back-pain/tc/lumbar-spinal-stenosis-topic-overview