Your spine is made up of bones called vertebrae. Each bone has two parts: the body, which is flat and roughly round, and the vertebral arch, which is the spiny-looking part on the back. When you look at a vertebra from the top (Figure 1, left), you can see that there's a space between the vertebral body and the vertebral arch. In your spine, these round openings in the vertebrae line up, forming a protective tunnel around the spinal cord (Figure 1, right). This bony tunnel is called the spinal canal. At each vertebral level, small openings in the bone allow nerves, vessels, and supporting ligaments to exit the spinal canal. These small openings are called foramina (the singular form of foramina is foramen, from the Latin word forare, meaning "to bore or pierce"). Spinal stenosis is a painful, sometimes disabling condition. It's typically caused by degenerative changes associated with osteoarthritis, such as overgrowth of bone and soft tissue. The space within the canal narrows, putting pressure on the spinal cord. In foraminal spinal stenosis, a variant of the condition, the foramina (fuh-RAM-in-uh) become narrowed, impinging on nerves that pass through these openings.
What is spinal stenosis?
The spinal canal contains the spinal cord, an amazing two-lane superhighway carrying signals that control movement and sensation. One lane conducts motor impulses from the brain to your body. This pathway governs all voluntary movement-everything from driving to the sports stadium to munching a hot dog and leaping to your feet when your team scores.
The other lane sends sensory information from your body to your brain. Signals arriving from this lane tell your brain all too clearly that-Argh!-that trek from the parking lot to the stadium was painful, and your cushy box seat feels pretty good right now.
Normally, signals flow freely in both directions. But what if space inside the tunnel gets tight, narrowing the roadway? That’s what happens in patients with spinal stenosis.
Acquired spinal stenosis
Spinal stenosis that develops over time or as a result of injury is known as acquired spinal stenosis. It’s also associated with certain endocrine system and metabolic disorders, and with certain autoimmune disease. Even infectious disease can sometimes lead to spinal stenosis. Any spinal cord dysfunction associated with acquired spinal stenosis is called myelopathy.
Congenital spinal stenosis
People born with a narrow spinal canal have a form of the disease called congenital spinal stenosis.
What are the symptoms of spinal stenosis?
The cardinal symptom of spinal stenosis is pain aggravated by walking or standing and eased by sitting, flexing the back (such as hunching over a shopping cart), or lying down. (Doctors call this intermittent neurologic claudication.) A stooped posture relieves pressure on the spinal cord, alleviating pain. Thus gait disorders (walking difficulties) are common among those with spinal stenosis.
When the condition affects the lumbar spine, it can cause aching pain in the buttocks, thighs, or knees, a sensation of warmth in the legs, sciatic pain, or back pain. Patients report having trouble standing for long periods. Spinal stenosis of the cervical spine can cause pain, weakness, or numbness in the arms or hands. Most patients have pain on both sides of the body.
What causes spinal stenosis?
A variety of conditions can narrow the spinal canal:
Degenerative disc disease
Calcification of spinal ligaments
Aging can calcify the ligaments that pass through the spinal foramina. They become hardened and thickened, a condition called hypertrophy (hy-PER-troe-fee). The thickened ligment can compress the spinal cord.
Bone spurs, which doctors call osteophytes (OSS-tee-oh-fytes) can form within the spinal canal, impinging on the spinal cord.
Spondylolisthesis (spahn-dih-low-LISS-thuh-siss) occurs when a vertebra shifts forward or backward, out of alignment with the vertebra above it. A misaligned vertebra can crowd the spinal cord.
Facet joint syndrome
Facet (fuh-SETT) joints can become arthritic, constricting the neural foramina.
How common is spinal stenosis?
Spinal stenosis is most common in men and women over age 60. Cervical spinal stenosis affects one of every 100,000 people. Lumbar stenosis affects 5 of every 100,000 people. To put it another way, of those over age 60, about 20% have spinal stenosis that can be seen on MRI. In fact, among people over age 65, spinal stenosis is the most common reason for having surgery on the lumbar spine. Fortunately, though, most people with the condition have no associated pain or other symptoms.
How is spinal stenosis diagnosed?
Spinal stenosis is diagnosed on the basis of your symptoms, the physician’s physical examination, and the results of imaging studies, such as CT and MRI scans. The physician will assess your range of motion and ask you to rate your pain. He or she will also ask about your general health and activity level, past injuries, and symptoms. Your symptoms are especially important in diagnosing spinal stenosis because patients with this condition present a classic clinical picture: pain on standing or walking with relief on sitting, lying down, or flexing the back (see Symptoms above).
How is spinal stenosis treated?
As with all spinal disorders, unless the condition is disabling, your physician will recommend that you make some simple lifestyle adjustments before considering prescription medications, surgery, or other options. Your doctor might, for instance, recommend that you get more exercise and improve your posture. He or she might want you to complete a few sessions with a physical therapist or begin taking an over-the-counter nonsteroidal anti-inflammatory drug (NSAID) such as naproxen (Aleve) or ibuprofen (Advil). If those measures are ineffective, you and your doctor can consider the following options:
An NSAID such as indomethacin (Indocin) can reduce inflammation within the spinal canal. Anticonvulsant and antidepressant medications, such as gabapentin (Neurontin) and pregabalin (Lyrica), can interrupt the transmission of pain signals from the spinal cord to the brain.
To relieve pain caused by spinal cord compression, the doctor can inject an anesthetic agent and a long-acting steroid medication into the epidural space (the space between the membranes protecting the spinal cord and the walls of the spinal canal).
Performing specific exercises can help you maintain spinal motion, strengthen your back and abdominal muscles, and build endurance. These efforts stabilize the spine. A licensed therapist can also apply pain-relief interventions, such as electrical stimulation, massage, ultrasound therapy, and heat/cold therapy.
Surgical treatment of spinal stenosis is aimed at relieving pressure on the spinal cord and keeping the disease from progressing. Your surgeon’s operative approach depends on which portion of your spinal cord is compressed.
Surgery typically involves an open procedure known as a laminectomy. Although that approach often works well, half of patients end up with lingering back pain and stiffness. An alternative approach perfected by Inspired Spine is called oblique lateral lumbar interbody fusion (OLLIF). Using this minimally invasive keyhole procedure, patients recover quickly and many return to life as they knew it before back pain began to steal the show.
Visit our OLLIF page for details on the procedure.