Update on Spinal Stenosis in SeniorsThe most common cause of back pain in adults 65 and older is spinal stenosis. Stenosis is a narrowing of the spinal canal or openings for the spinal nerve roots. Changes associated with aging cause the spinal nerves to increase in size while the space around these structures gets smaller.
In this report, orthopedic surgeons review the signs and symptoms and differential diagnosis for spinal stenosis. Differential diagnosis means the surgeon first sorts out whether the low back pain (LBP) is mechanical, nonmechanical, or visceral. Then the diagnosis is narrowed down more specifically.
With mechanical LBP there is usually no known cause for the symptoms. All imaging studies are within normal limits. Nerve and muscle testing are considered normal. Degenerative disc disease, disc herniations, and fractures can cause mechanical LBP. But these are easily identified with X-rays, MRIs, or CT scans.
Infections and tumors pressing on the nerve structures create nonmechanical LBP. And conditions such as kidney infections, pelvic disease, peptic ulcers, and aortic aneurysms are visceral problems that can refer pain to the low back region.
MRIs may be the best tool for identifying spinal stenosis as the cause of the patient's LBP. Multiplanar views can be taken showing details of the nerves, fat, discs, ligaments, and spaces. Electrodiagnostic tests of nerve and muscle function add information about level and severity of the affected nerve root.
Usually with stenosis there are multiple nerve roots involved. This helps separate stenosis from radiculopathy, which is more likely to affect a single nerve at a time. Radiculopathy refers to any process affecting the nerve(s). This could be a nerve that is inflamed, pinched, or has a lack of blood flow.
The differential diagnosis becomes more difficult when the patient has both stenosis and radiculopathy. And patients with diabetes can develop painful neuropathies affecting multiple nerves. The clinical picture looks a lot like spinal stenosis. That's when electrodiagnostic tests help with the diagnosis.
Treatment is divided into conservative (nonoperative) care and surgical management. Unless the symptoms are severe or the patient is rapidly getting worse, conservative care is always advised first. Anti-inflammatory drugs, physical therapy, and steroid injections into the epidural space around the spinal cord may be tried.
If improvement doesn't occur with conservative care, then decompressive surgery to take pressure off the neural structures is next. This is usually done by removing some or all of the bone around the nerve roots. Laminectomy to remove the lamina from around the spinal cord is still the number one surgical choice. The lamina is a column of bone that forms an arch around the spinal cord. Any bone spurs around the nerve are also scraped away. Any disc fragments are removed.
Other surgical procedures used to treat stenosis include fenestration and distraction laminoplasty. Fenestration is the drilling of holds in the lamina. Less bone is removed this way, which helps save spinal stability. This method is best used when only one opening around a single nerve root is affected.
Distraction laminoplasty describes a procedure in which the ligaments between two vertebra are removed. A special tool is used to distract (pull apart) the spinous processes of two vertebral bodies. The spinous process is the bump you feel along the back of the spine. It is really a projection of bone away from the vertebral body. Once the bones are distracted, the surgeon removes part of the facet (spinal) joint. The inner one-third of the lamina is also scraped away to make more room inside the spinal canal.
A newer technique is to place a spacer between two spinous processes. This is called an interspinous process spacer. Putting a spacer between two of these bony knobs holds the vertebrae in proper alignment and relieves the pressure from around the neural structures. The soft tissue structures are preserved with this technique. Local anesthesia can be used. Only a small incision is needed.
More and more surgeons are performing these surgeries endoscopically. This is called a minimally invasive procedure. Special training is required to achieve this level of surgical expertise. Serious complications can occur otherwise. The outcomes of these various surgical techniques continue to be investigated.
Some studies show no difference between patients who were treated surgically and those who received conservative care. Other long-term studies such as the Maine Lumbar Spine Study report significantly greater improvement after surgery compared to nonoperative care.
The differences in outcomes fade over time, though. By the end of 10 years, the results are fairly equal between the groups. And although surgery for spinal stenosis provides greater relief faster than nonoperative care, over time, the condition (and the painful symptoms) come back. These findings were supported by the results of another study: the Spine Patient Outcomes Research Trial (SPORT).
By looking at the long-term results of treatment, it appears that outcomes are improving as patient selection becomes more specific. Laminectomy is still the most commonly used procedure. Some of the less invasive techniques don't remove enough bone and the surgery ends up a failure.
Research has been able to identify factors that predict which patients can improve the most with different types of surgical treatment. For example, patients with diabetes don't do as well. They are more likely to develop infections after the operation and less likely to be satisfied with the results. And patients who don't have severe stenosis (as seen on imaging studies) have a lower rate of improvement in back and leg pain.
Surgeons expect to see more and more cases of spinal stenosis in years to come. With the aging of America and more people developing stenosis, treatment results will continue to improve.
Ra'Kerry K. Rahman, et al. Thoracolumbar Spine. Lumbar Spinal Stenosis. In Current Orthopaedic Practice. July/August 2008. Vol. 19. No. 4. Pp. 351-356.
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