Experimental studies on the pathomechanism of symptoms caused by the lumber canal stenosis

点击翻译按钮获取中文摘要

To understand the pathomechanism of intermittent claudication caused by the lumbar canal stenosis, animal experimental studies using monkey which has similar cauda equina with human being were carried out.A specially designed implantable device made from titanium was fabricated to apply sustained and quantitatively controlled compression to the lumber dural tube. Single turn of the screw advanced 0.75mm of round plastic made plate which was attached at the end of the screw. Increment of the compression was carried out increasing 1mm at 1 week interval. Myelography was performed at every 2 weeks to observe the shape of the cauda equina. 4 monkeys underwent the implantation of the device and were followed up for 4 month to 1 year and 3 months, although, prominent thickening and redundancy of the cauda equina has not been revealed by myelography. Cauda equina evoked potentials recorded after stimulating the nerve trunk of lower extremities showed temporal dispersion according to the increment of the compression. We could not find any effect of intravenous injection of prostaglandin on the wave configuration of the cauda equina evoked potentials in the animal with approximately 65% compression to the dural tube.One monkey was sacrificed to observe change of the cauda equina by naked eye and histologically. Although caudae equina were squeezed in to the space which was about 1/3 of the original dural tube, prominent redundancy was not observed. Histologically, destruction of the myelin sheath, axonal degeneration and vaculation were found in the cauda equina. Nerve fibers with large diameter were dominantly damaged and decreased in number. The duration of sustained compression was regarded to be insufficient, therefore, it is deemed necessity to continue further observation of animals with myelography and evoked potentials.