The rapid reversibility of leg pain with a change in posture is strong evidence for the important role of vascular obstruction as a primary component of the pathogenesis of neurogenic claudication. The longer the duration of the vascular compromise, the more persistent and total becomes the neural dysfunction. The clinical correlate would be radicular pain followed by numbness and muscular weakness. Alleviation of vascular congestion can normalize the function of the sciatic nerve and diminish leg pain. Therefore, the goal of therapy is to maximize neural blood flow and restore nerve function.
Clinical History
Neurogenic or pseudoclaudication is the most common symptom associated with spinal stenosis.6 Pain that is associated with standing or walking occurs in the buttock, thigh, or lower leg. The patterns of back and/or leg pain are as different as the patients who have the disorder. Most patients will complain of low back and leg pain. A smaller proportion will have leg pain alone. Many patients will have bilateral leg pain. The extent of the leg pain may be different in the extremities. Multiple dermatomes may be affected. The widespread distribution of symptoms makes it difficult to ascribe compression to a single nerve root lesion. In addition to pain, patients may also have numbness, paresthesias, and weakness in the lower extremities. Less commonly, similar symptoms can occur while patients are lying down and are relieved by getting out of bed. Neurogenic claudication is relieved by lying down, sitting, or flexing at the waist. Many elderly patients enjoy going to the grocery store so that they can flex over the shopping carts.
Some of my most perplexing patients have been those with spinal stenosis. One was an executive with the chief complaint of medial knee pain. He wanted me to diagnose his problem so I could save his marriage. He had knee pain for about a year that was exacerbated by standing and relieved by sitting. He had been evaluated with knee radiographs and magnetic resonance (MR) demonstrating no abnormality. Knee braces and physical therapy were of no benefit. What did this have to do with his marriage? He could sit at his desk and play racquetball three times a week without pain, but could not dance more than a few minutes with his wife before he had to sit down. She suspected he did not love her anymore, but he did.
Of course, the problem was not in his knee, but in his lumbar spine. When the man played racquetball, he was in a flexed posture. When he danced, he was in an extended posture. An MR scan of the lumbar spine revealed his spinal stenosis. He received a course of nonsteroidal anti-inflammatory drugs (NSAIDs) and epidural corticosteroid injections with an excellent response. His marriage was saved!