Clinical recording of pressure on the spinal cord and cauda equina. Part 2: position changes in pressure on the cauda equina in central lumbar spinal stenosis.

To define the site, degree, and dynamics of mechanical compression of the spinal nerve roots, pressure was measured in 42 patients with clinical symptoms and myelographic findings indicating central lumbar spinal stenosis. Pathological pressure on the cauda equina was found in 67% of the patients. The pressure in the region of the spinal block was high during standing and walking, and in several patients exceeded mean arterial blood pressure. The block pressure was the main mechanical factor in the central part of the spinal canal causing pain and paresis. Elevated fluid pressure caudal to the block was an additional but usually subordinate factor. In 33% of the patients, normal pressure on the cauda equina was found, and lateral compression of multiple nerve roots seemed to be the only mechanical symptom-causing factor. Clinically, these patients could not be distinguished from patients with central compression. After laminectomy with decompression of the cauda equina, the field should be inspected for lateral narrowing which, if present, should be treated.