Electrophysiological studies of intermittent claudication in lumbar stenosis.

To clarify the pathophysiology of intermittent claudication in 37 patients with lumbar spinal stenosis, neural function was evaluated by examining somatosensory evoked potentials (stress-SEPs), and nerve action potentials (stress-NAPs) before and after walking stress. It was shown preoperatively that the stress-SEPs became abnormal immediately after walking in 31 of 37 patients. In seven of nine operated patients, the assessment clearly shows that SEPs had reverted to normal after surgery. The present method is noninvasive, simple in technique, painless, and safe, a procedure therefore that is useful as the initial step in the diagnosis and treatment of patients with lumbar canal stenosis. It also may help to differentiate neurogenic from vascular intermittent claudication.