Experimental Study Of Mechanism Of Neurogenic Intermittent Claudication Caused By Lumbar Spinal Canal Stenosis

As the general population ages, the prevalence of lumbar spinal canal stenosis ( LSCS) increased significantly. Neurogenic intermittent claudication (NIC) is usually caused by LSCS and is viewed as one of the characteristic symptoms of LSCS. If the pathophysiology of NIC is made clear, it will be very helpful to know further the pathophysiology and treatment of LSCS. Therefore, the study of NIC has been paid close attention to.It is believed that there are two major factors that result in NIC. One is static factor, i. e. , direct compression of nerve tissue and blood vessels, which may cause changes of neural electrophysiology, blood supply and histology. The other one are dynamic factors, which are further compression of cauda equina caused by walking and posture change and increase burden to nerve tissue caused by neural activity of motor unit increase resulting from muscle contraction during walking. These dynamic factors may cause neural electrophysiology and blood flow changes to the nerve tissue which has been compressed. Previously experimental studies were mainly about changes of electrophysiologic property and histology caused by compression of cauda equina, i. e. , studies under static factor. Until present, there are very few studies about NIC under dynamic factors. High frequency stimulation ( HFS) , as a dynamic factor, had been used in cauda equina compression model to study electrophysiological changes after it.But this might not fit clinical situation well because in simple walking of a patient suffering from LSCS, epidural pressure will increase significantly just after the beginning of walking and return to initial level after stopping walking. Therefore , a proper animal model used to study NIC should include both of the two dynamic factors, increase of both epidural pressure and impulse transmission at the same time, just as increase of epidural pressure and nerve activities during walking.Prostaglandin El ( PGE1 ) has strong peripheral vasodilating activity and platelet aggregation - inhabiting activity, and its usefulness has been confirmed both for the treatment of chronic arterial obstruction and other ischemic disease. Though it has been conformed useful in the treatment of LSCS in some clinical studies, the mechanism of it is not clear yet.The laboratory rat is one of the most commonly used experimental animals, offering as it does the best functionally characterized mammalian model system. It offers a number of unique advantages for modeling human disease. In addition , genetical homogenization, economy and easiness of handling are its advantages over porcine and dog. But because of the small size of spinal canal and rapid deflation of arterial embolectomy balloon catheter, to use balloon or nylon band in rat is practically difficult though they had been used to cause compression of cauda equina in pig or dog at certain pressure or percentage in previous experiments. Using silicon sheet to cause certain rate of compression in rat is reasonable, but the previous experiments seem to be inaccurate because of unknown of average cross sectional area of lumbar spinal canal of rat.The aim of the present study is to make certain the cross sectional area of lumbar spinal canal in rat, and make a precise double level compression of cauda equina ( static factor) . We also want to make clear the critical point of cauda equina compression. On the basis of the above, we establish such an animal model to analyze the effects of the two dynamic factors on nerve electrophysiolog-ical property changes, which might reveal the real situation of clinic and might mimic the situation of walking of human being and hope to find a probable mechanism of NIC. We also want to verify whether or not PGE1 may work under dy-namic factors. This study might provide a useful animal model for studying of LSCS, and it would also be beneficial for the study of mechanism and treatment of human LSCS.MethodDetermination of cross - sectional area of spinal canal; Twenty - seven 9 -10 weeks old mal...