Neurogenic intermittent claudication in lumbar spinal canal stenosis: the clinical relationship between the local pressure of the intervertebral foramen and the clinical findings in lumbar spinal canal stenosis.

STUDY DESIGN The clinical relationship between the local pressure of the intervertebral foramen and the clinical findings in lumbar spinal canal stenosis were evaluated. OBJECTIVE To investigate the pathogenesis of neurogenic intermittent claudication in lumbar spinal canal stenosis. SUMMARY OF BACKGROUND DATA The genesis of neurogenic intermittent claudication is generally considered to result from nerve root ischemia; however, the exact pathogenesis of neurogenic intermittent claudication remains uncertain. METHODS From a total of 20 lumbar spinal canal stenosis patients, 29 L5/S1 vertebral foramens were studied. All patients showed neurogenic intermittent claudication, and also showed neurologic abnormalities in L5 area. Intraoperatively, the local pressure of the intervertebral foramen was continuously measured using a micro-tip catheter transducer whereas the lumbar spine postures were changed under passive movement, and the relationships between the local pressure and the preoperative clinical findings in lumbar spinal canal stenosis were analyzed. RESULTS The local pressure of the intervertebral foramen significantly increased during lumbar spine extension (P<0.001). The patients who demonstrated large changes in the local pressure between flexion and extension showed a significantly poor walking ability (P=0.003). Moreover, the patients who had 2-level lumbar spinal canal stenosis showed significantly smaller changes in the local pressure between flexion and extension than 1-level lumbar spinal canal stenosis patients (P=0.01). CONCLUSIONS The present study suggests that the genesis of neurogenic intermittent claudication in lumbar spinal canal stenosis may be greatly affected by the variation of the dynamic mechanical stress on the spinal nerve roots of the lumbar spine, rather than the static mechanical stress on the spinal nerve roots with each posture. Moreover, 2-level lumbar spinal canal stenosis patients demonstrated radicular symptoms with relatively less external stress on their spinal nerve roots in the vertebral foramen than that observed in 1-level lumbar spinal canal stenosis patients.