Other patients describe persistent leg pain that does not change significantly with assuming a flexed posture. They may not obtain relief by lying supine in bed. These are patients with compression associated with neural foraminal or lateral recess stenosis.
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Explore This IssueAugust 2007
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Patients with spinal stenosis may have no physical abnormalities when examined in the seated position, and abnormalities may appear only after the patient is stressed by walking until leg pain appears.7 Sciatica caused by lumbar spinal stenosis is distinct from radiculopathy associated with an intervertebral disc herniation. Objective neurologic findings – including asymmetric reflexes, sensory loss, or motor weakness – are found in a minority of stenosis patients.8
In many circumstances, I complete the physical examination to be sure that no other findings indicate an alternate diagnosis. For example, an essential portion of the examination is internal and external rotation of the hips. On more than one occasion, I’ve diagnosed severe hip osteoarthritis in someone with leg pain with lumbar roentgenograms and MR scan demonstrating minimal narrowing with a presumptive diagnosis of lumbar spinal stenosis. I also palpate the feet for the presence of dorsalis pedis and posterior tibial pulses to eliminate the possibility of vascular claudication.
Many radiographic techniques are available to evaluate the spinal stenosis patient.9 The least sensitive but most available is a set of plain roentgenograms of the lumbar spine. I order anteroposterior and lateral views as my initial test in most individuals. I may order oblique views if I am concerned about facet joint osteophytes and foraminal stenosis. I obtain flexion and extension views to observe abnormal motion if I am concerned about instability of the spine. This method is helpful in identifying potential candidates with significant lumbar spondylosis, foraminal narrowing, short pedicles, facet joint arthritis, or degenerative spondylolisthesis. Remember that these features are common findings among asymptomatic individuals of a similar age. Roentgenographic abnormalities are compatible, but not diagnostic, of spinal stenosis.
MR is the next radiographic test I order when further delineation of the osseous and soft tissue elements in both the sagittal and axial planes of the lumbar spine is necessary. This technique can visualize the areas of neural compression in the central canal, the lateral recess, and the neural foramen without X-ray exposure. I look for abnormalities at levels of the lumbar spine that correlate with the patient’s clinical symptoms. However, it is rare that just one level of the lumbar spine is stenotic with only mild spondylosis at other levels. Not uncommonly, more than one level has some degree of stenosis with the greatest narrowing on the opposite side to the one that is most symptomatic. MR abnormalities are compatible with, but not diagnostic of, spinal stenosis. (See Figure 1)