This work is motivated by an attempt to explain the origins of syringomyelia. This serious disease is characterized by the appearance of cavities, called syrinxes, in the central canal of the spinal cord resulting in partial or complete paralysis. The causes of syringomyelia are unknown but pressure propagation is probably implicated. Pressure pulses, caused by coughing, sneezing and similar activities, propagate up the cerebrospinal fluid (CSF) in the spinal subarachnoid space. Williams (1990) suggested a possible cause of syrinx formation is that when such pressure pulses encounter a partial or total blockage a large pressure rise would be generated in the spinal central canal. Our theoretical model modeling was undertaken to investigate Williams’ hypothesis. Essentially, we model the spinal system as a channel separated into two parts by a flexible diaphragm representing the spinal cord. The upper part (A) represents the subarachnoid space while the lower part (B), which has a much smaller cross-sectional area, represents the central canal. A theory for pressure wave propagation in such a two-chamber system is described. It has been used to study the wave characteristics of the two-chamber system. In this way it has been found that the leading edge of a pressure pulse/wall bulge tends to steepen into a shock-like wave or elastic jump. When such a pressure pulse is incident on a blockage in the subarachnoid space, a large pressure rise is generated in its vicinity. We showed that this pressure rise could be momentary or permanent depending on whether the pressure pulse bulge is positive or negative. This provides a possible mechanism for the formation of the syrinxes. An experimental rig has also been built in order to qualitatively confirm some theoretical results. The experimental wave speed agreed with the wave speed defined in the theoretical model. We were also able to confirm that the reflection of a pressure pulse from a blockage placed in the upper part A (subarachnoid space) leads to high pressure in the vicinity of the blockage.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:343120 |
| Date | January 1999 |
| Creators | Berkouk, Karim |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/111277/ |
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