Although symptoms may arise from narrowing of the spinal canal, not all patients with narrowing develop symptoms. In general, the natural history of most forms of spinal stenosis is the insidious development of symptoms. Occasionally, there can be an acute onset of symptoms precipitated by trauma or heavy activity. Many patients have significant radiographic findings with minimal complaints or physical findings. 50% of patients treated nonoperatively reported improved back and leg pain after 8 to 10 years.
Pain relief was noted after 3 months in most patients regardless of treatment, but took 12 months in a few patients. Results in conservatively treated patients deteriorated over time, however, and at 4 years were excellent or fair in 50% of patients treated nonoperatively; 80% of patients treated operatively still had good results. Results were not worse if surgery was done 3 years after failed conservative treatment, and significant deterioration did not occur during the 6 years of follow-up in any of the three groups of patients. Predictors of poor outcomes could not be identified. These authors concluded that conservative treatment is appropriate for patients with moderate pain, 50% of whom have pain relief in less than 3 months, but operative treatment probably is indicated for patients with severe pain and patients in whom conservative treatment fails.
Reported studies suggest that for most patients with spinal stenosis, a stable course can be predicted, with 15% to 50% showing some improvement with nonoperative treatment. Worsening of symptoms despite adequate conservative treatment is an indication for operative treatment.
back pain and sciatica is present in 95% and claudication present in 91% of patients. Sensory disturbance in the legs was present in 70%, motor weakness was present in 33%, and voiding disturbance was present in only 12% of patients. Despite the coexistent symptoms, back pain had been present for a median duration of 14 years and sciatica for a median duration of 2 years before presentation. Bilateral leg complaints were present in 42%, and unilateral leg symptoms were present in the other 58%. Distribution of symptoms was L5 in 91%, S1 in 63%, L1-4 in 28%, and S2-5 in 5%. 47% had symptoms specific for two nerve roots, and 35% had monoradiculopathy. Three-level and four-level radicular complaints were recorded in 17% and 1%, respectively. In patients with central spinal stenosis, symptoms usually are bilateral and involve the buttocks and posterior thighs in a nondermatomal distribution. With lateral recess stenosis, symptoms usually are dermatomal because they are related to a specific nerve being compressed. Patients with lateral recess stenosis may have more pain during rest and at night, but more walking tolerance than patients with central stenosis.
Vascular symptoms typically are felt in the upper calf, are relieved after a short rest (5 minutes) while still standing, do not require sitting or bending, and worsen despite walking uphill or riding a stationary bicycle. Neurogenic claudication improves with trunk flexion, stooping, or lying, but may require 20 minutes to improve. Patients often report better endurance walking uphill or up steps and tolerate riding a bicycle better than walking on a treadmill because of the flexed posture that occurs. Pushing a grocery cart also allows spinal flexion, which enhances endurance in most patients with neurogenic claudication.
The gait and posture after walking may reveal a positive “stoop test.” This test is done by asking the patient to walk briskly. As the pain intensifies, the patient may complain of sensory symptoms followed by motor symptoms. If the patient is asked to continue to walk, he or she may assume a stooped posture, and the symptoms may be eased, or if the patient sits in a chair bent forward, the same resolution of symptoms occurs.
Magnetic Resonance Imaging
Investigators have found abnormal findings in 67% of asymptomatic patients evaluated by MRI. In patients older than 60 years, 57% of MRI scans were abnormal, including 36% of patients with herniated nucleus pulposus and 21% with spinal stenosis. MRI is helpful in identifying other disease processes, such as tumors and infections, and is a good noninvasive study for patients with persistent lower extremity complaints after radiographic screening evaluation. MRI should be confirmatory in patients with a consistent history of neurogenic claudication or radiculopathy, but it should not be used as a screening examination because of the high rate of asymptomatic disease. Sagittal T2-weighted images are a good starting point because they give a myelogram-like image. Sagittal T1-weighted images are evaluated with particular attention focused on the foramen. An absence of normal fat around the root indicates foraminal stenosis. Axial images provide a good view of the central spinal canal and its contents on T1- and T2-weighted images. Far-lateral disc protrusions are identified on axial T1-weighted images by obliteration of the normal interval of fat between the disc and nerve root . The foraminal zone is better evaluated with sagittal T1-weighted sequences, which confirm the presence of fat around the nerve root. Spinal deformity, including scoliosis and significant spondylolisthesis, can result in suboptimal imaging by MRI. This is secondary to the curvature of the spine in and out of the plane of the scanner on sagittal sequences and difficulty obtaining true axial cuts. Another disadvantage of MRI is the cost; nonetheless, MRI has become a useful, noninvasive diagnostic tool for the evaluation of patients with extremity complaints.
Symptoms of spinal stenosis usually respond favorably to nonoperative management. Despite symptoms of back pain, radiculopathy, or neurogenic claudication, conservative management is successful in most patients. Conservative measures should include rest not exceeding 2 days, pain management with antiinflammatory medications or acetaminophen, and participation in a trunk-stabilization exercise program, along with good aerobic fitness. Other methods should be reserved for patients who are limited by pain and should be used to maximize participation in the exercise program. Traction has no proven benefit in the adult lumbar spine. For a patient with unremitting symptoms of radiculopathy or neurogenic claudication, epidural steroid injections may be useful in alleviating symptoms to allow better participation in physical therapy. Epidural steroids can give significant symptomatic relief, although no scientific study has documented long-term efficacy. If spinal stenosis is present with coexistent degenerative arthritis in the hips or knees, some permanent limitation in activity may be necessary regardless of treatment.
All had spinal stenosis documented by CT or MRI and symptoms of disabling back, buttock, or leg pain. Except for a few patients with acute neurological changes who initially were prescribed 1 to 2 weeks of bed rest, patients were given one course of oral corticosteroids on a 7-day tapered schedule. An epidural steroid injection was given if symptoms persisted, with a repeat injection given if necessary by the transforaminal route at the point of most severe constriction. A third injection was administered only at the treating physician's discretion, usually for flare-ups during follow-up. For less severe symptoms, nonsteroidal antiinflammatory medications were used for 4 to 6 weeks, and this occasionally was repeated. All patients participated in physical therapy that included postural exercises, gentle lumbopelvic mobilization exercises, and a daily flexion lumbar stabilization program. Sustained improvement was reported in 24% and mild improvement in 28%, with 13% definitely worse. Regarding walking, 40% reported improvement, 35% reported no change, and 25% reported worsening at final follow-up.
Epidural Steroid Injection
Spinal stenosis and the resultant mechanical compression of neural elements can cause structural and chemical injury to the nerve roots. Edema and venous congestion of the nerve roots can lead to further compression and ischemic neuritis. This may result in the leakage of neurotoxins, such as phospholipase and leukotriene B, which can lead to increased inflammation and edema. Corticosteroids are potent antiinflammatory medications and result in a decrease in leukocyte migration, the inhibition of cytokines, and membrane stabilization. These actions coupled with their ability to reduce edema provide the rationale for the use of epidural steroid injections in spinal stenosis. Although epidural steroid injections have been used in the treatment of spinal stenosis for many years, no scientifically validated long-term outcomes have been reported to substantiate their use, and most prospective reports show no statistically significant benefit. A meta-analysis showed that epidural steroids have little short-term advantage over placebo for the treatment of leg pain. Studies also are divided on the long-term results and the avoidance of surgery.
Accurate placement of translaminar injections seems to be equally difficult, with successful placement reported in 70%. Complications are infrequent but can occur and include hypercorticism, epidural hematoma, temporary paralysis, retinal hemorrhage, epidural abscess, chemical meningitis, and intracranial air.
The ideal candidate for epidural steroid injection seems to be a patient who has acute radicular symptoms or neurogenic claudication unresponsive to traditional analgesics and rest, with significant impairment in activities of daily living. We have used this technique successfully in our treatment algorithm for neurogenic claudication and radiculopathy.
The primary indication for surgery in patients with spinal stenosis is increasing pain that is resistant to conservative measures. Because the primary complaint often is back pain and some leg pain, pain relief after surgery may not be complete. Most series report a 64% to 91% rate of improvement, with 42% in patients with diabetes, but most patients still have some minor complaints, usually referable to the preexisting degenerative arthritis of the spine. Neurological findings, if present, improve inconsistently after surgery. normally 30% had complete improvement in motor symptoms after laminectomy, with 58% regaining grade 4 strength or better at a mean follow-up of 3 years. Reoperation rates vary from 6% to 23%. Prognostic factors include better results with a disc herniation, stenosis at a single level, weakness of less than 6 weeks' duration, monoradiculopathy, and age younger than 65 years. Reversal of neurological consequences of spinal stenosis seems to be a relative indication for surgery unless the symptoms are acute.
A patient's inability to tolerate the restricted lifestyle necessitated by the disease and the failure of a good conservative treatment regimen should be the primary determining factors for surgery in a well-informed patient. The patient should understand the potential for the operation to fail to relieve pain or to worsen it, especially in regard to the axial component of the symptoms. In addition to the general risks of spinal surgery, the severity of symptoms and lifestyle modifications should be considered. Lumbar spinal stenosis does not result in paralysis, only decreased ambulatory capacity, and conservative management is warranted indefinitely in a patient with good function and manageable symptoms. Cervical and thoracic spinal stenoses are associated with painless paralysis in the form of cervical and thoracic myelopathy and require closer attention and follow-up.
Surgical options include:
- Over the roof decompression