A normal vertebra is shown on the left. On the right, a small spinal canal, which causes spinal stenosis.
Spinal stenosis is a narrowing of the spinal canal, the opening created by the small hole found in each of the vertebrae that make up the human spinal column.
Normally, the spinal canal is large enough to hold the spinal cord, a thick bundle of nerves that transmits signals between the brain and the arms, legs and torso. In spinal stenosis, the spinal canal is narrowed, which can in turn compress the spinal cord's nerves, causing pain, numbness and other symptoms.
The two most common types of spinal stenosis are lumbar spinal stenosis (occurring in the five large lumbar vertebrae in the lower back), and cervical spinal stenosis (occurring in the seven smaller vertebrae in the neck region).
Causes of spinal stenosis
In most cases, spinal stenosis is caused by age-related osteoarthritis and associated conditions, such as the development of bone spurs (osteophytes), degenerative disc disease (spondylosis), herniated discs or the thickening of spinal ligaments.
Spinal stenosis can also be caused by scoliosis — a curvature of the spine — or by achondroplasia, an inherited bone condition that reduces the diameter of the spinal canal, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS).
In other cases, spinal stenosis can be caused by the growth of tumors in or near the spine, spinal injuries or Paget's disease, an uncommon condition that causes the rapid development of soft bony tissue.
Spinal stenosis is most common among people over the age of 50; it's more frequently seen among women than men, and among people with a history of spinal injury or surgery.
Symptoms of spinal stenosis
Many people can have spinal stenosis without any symptoms. If the spinal canal narrows until it places pressure on the spinal cord, however, symptoms usually begin to develop over time.
These symptoms can include back pain, numbness, weakness, cramping or general pain in the arms or legs. Pain, numbness or tingling is commonly felt radiating from the buttocks down the outside of the leg when the sciatic nerve is affected.
In more severe cases of spinal stenosis, foot disorders such as "foot drop" (when a foot slaps on the floor while walking), incontinence, sexual dysfunction and partial or complete leg paralysis can result.
A health care professional can diagnose spinal stenosis through a physical examination and by examining X-rays, computed tomography (CT) scans, magnetic resonance imaging (MRI) scans or an electromyogram (EMG).
Treatment of spinal stenosis
For most mild cases of spinal stenosis, treatments can include pain medications including non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil) or naproxen (Aleve), or other other-the-counter pain medication such as acetaminophen (Tylenol).
More severe cases may require prescription painkillers such as the anti-seizure drugs gabapentin(Neurontin) and pregabalin (Lyrica), or opiates such as oxycodone (Oxycontin, Percocet) and hydrocodone (Vicodin). Some physicians also recommend antidepressants or muscle relaxants to treat spinal stenosis.
Injections of corticosteroids may help to alleviate the inflammation around a compressed nerve. But because these injections can weaken nearby bone and connective tissue, only a few injections a year are usually recommended, according to the Mayo Clinic.
Physical therapy, acupuncture, massage, chiropractic therapy, exercise and other treatments can help alleviate the pain and other symptoms of spinal stenosis.
Surgery for spinal stenosis
In severe cases, where more conservative treatments have failed to achieve results, surgery may be recommended. A laminectomy removes the tissue — ligaments, bone or bone spurs — that are compressing the spinal cord.
A laminectomy (sometimes referred to as a "decompression") may be performed alone or in conjunction with spinal fusion. In a spinal fusion, two or more vertebrae are permanently fused together using a bone graft taken from the pelvis or hipbone, according to the American Academy of Orthopaedic Surgeons.
The National Institutes of Health (NIH) and other organizations are supporting research into the prevention and treatment of spinal stenosis. For example, researchers affiliated with NIAMS have published results from their Spine Patient Outcomes Research Trial (SPORT), the largest trial ever to compare surgical and non-surgical treatments for spinal stenosis.
An early report from the study — published in the New England Journal of Medicine in 2008 — found that surgery was more effective than non-surgical treatment in relieving symptoms associated with spinal stenosis, though patients who received non-surgical therapies also experienced some benefit during the study period. Other studies, including a follow-up SPORT study published in the journal Spine in 2010, confirmed these results.