Introduction
Spinal stenosis refers to narrowing of the spinal canal, nerve root canals, or intervertebral foramina due to spondylosis and degenerative disk disease. This process usually occurs in the cervical and lumbar spine; it seldom occurs in the thoracic spine.
Frequency
Approximately 250,000-500,000 US residents have symptoms of spinal stenosis. This represents about 5 of every 1000 Americans older than 50 years. Current estimates indicate that 70 million Americans are older than 50 years. This number is estimated to grow by 18 million in the next decade alone, suggesting that the prevalence of spinal stenosis will increase.
Etiology
Spinal stenosis is part of the aging process, and it is not possible to predict who will be affected. No clear correlation exists between the symptoms of stenosis and race, occupation, sex, or body type. The degenerative process can be managed, but it cannot be prevented by diet, exercise, or lifestyle.
The 2 forms of spinal stenosis are described as follows:
- Primary stenosis is congenital and relatively uncommon. The condition is diagnosed more easily because patients are younger and usually lack other complicating medical problems such as diabetes or vascular insufficiency.
- Acquired stenosis is a degenerative condition. Patients generally become symptomatic at age 50 years or older. Degenerative changes of the spine can include osteophyte formation, facet hypertrophy, bulging disks, and hypertrophy of the ligamentum flavum. Any of these processes can result in canal or foraminal narrowing. Degenerative spondylolisthesis can further compromise the canal.
Pathophysiology
The spine responds to physiological stresses with bone growth at the superior and inferior margins of the vertebral body (osteophytes). Osteophytes can form anteriorly or posteriorly. Posterior osteophytes narrow the intraspinal diameter and also cause lateral recess stenosis. This results in spinal cord or nerve root impingement. Furthermore, arthritic degeneration causes formation of synovial cysts and hypertrophy of the facet joints, which further compromise the patency of the spinal canal and the neural foramina.
During aging, the disks dehydrate and can compress and bulge. This process can cause tilting, slippage, or rotation of vertebral bodies. The ligamentum flavum also ossifies and becomes hypertrophic. The compressed disks result in shortening of the spinal column, which causes the ligamentum flavum to buckle inward and compress the spinal sac and nerve roots.
Presentation
Usually, spinal stenosis occurs at the cervical and lumbar segments, resulting in 2 different clinical presentations.
- Patients with cervical stenosis usually present with cervical radiculopathy, with or without myelopathy. Typically, the condition involves the lower cervical spine. Patients frequently complain of radiating arm pain with numbness and paresthesia in the involved dermatomes. Occasionally, associated weakness occurs in the muscles supplied by that nerve root. If the stenosis is severe enough, or if it is positioned centrally in the spine, patients may present with signs and symptoms of myelopathy (spinal cord dysfunction). Typically, these patients complain of finger numbness, clumsiness, and difficulty walking due to spasticity and loss of position sense. In more severe cases, the patients can have bowel and bladder control dysfunction. Upon examination, these patients have "long-tract signs" such as hyperreflexia and clonus.
- Patients with lumbar stenosis usually present with a constellation of symptoms that include lower back pain, radiating leg pain (unilateral or bilateral), and possible bladder and bowel difficulties. The classic presentation is radiating leg pain associated with walking that is relieved by rest (neurogenic claudication). When patients bend forward, the pain diminishes. Rarely, patients with lumbar stenosis present with cauda equina syndrome (bilateral leg weakness, urinary retention due to atonic bladder).
Patients often endure spinal stenosis for years because they mistakenly accept their symptoms as an inevitable part of aging. Early treatment is important for a better outcome.
Indications
When a patient presents with signs and symptoms of myelopathy or cauda equina syndrome, urgent surgical decompression of the spinal cord or nerve roots is indicated. Significant muscle weakness due to nerve root impingement is also a strong indication for surgical intervention. If the patient has already developed muscle atrophy, a full return of muscle strength would not be expected even after surgical decompression.
Radicular pain is the most common symptom of spinal stenosis, and thus the most common indication for surgery. Pain is a totally subjective complaint, and no reliable, objective means measures pain severity. Therefore, it is up to the surgeon and the patient to decide if surgery is desirable. Usually, if the patient's quality of life is compromised because of pain and there are no effective or acceptable nonsurgical treatments, it is reasonable to recommend surgery.
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 Overview: Spinal Stenosis |
| Workup: Spinal Stenosis |
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| Follow-up: Spinal Stenosis |
| References |
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References
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Further Reading
Keywords
spinal stenosis, lumbar stenosis, narrowing of the spinal canal, narrowing of the nerve root canals, narrowing of the intervertebral foramina, spondylosis, degenerative disk disease, cervical spine, lumbar spine, thoracic spine, primary stenosis, congenital stenosis, acquired stenosis, osteophytes, bone spurs, facet hypertrophy, bulging disks, hypertrophy of the ligamentum flavum, canal narrowing, foraminal narrowing, degenerative spondylolisthesis, cauda equina syndrome
