Abstract
INTRODUCTION: It has been suggested that arachnoiditis predisposes to post-traumatic syringomyelia formation by obstructing subarachnoid cerebrospinal fluid flow and enhancing perivascular flow into the cord. In an animal model of post-traumatic syringomyelia (PTS), fluid flow in spinal cord perivascular spaces (PVS) is greater at the level of arachnoiditis and syrinx than at other levels and fluid enters the syrinx via the PVS. This study was performed to determine the effects of cere-brospinal fluid (CSF) diversion from the subarachnoid space on perivascular flow and syrinx formation in PTS.
METHODS: Twenty six male Sprague-Dawley rats were investigated using the CSF tracer horseradish peroxidase (HRP), the excitotoxic and arachnoiditis model of PTS, and lumboperitoneal shunt insertion. Four experimental groups consisted of syrinx only and shunt only controls, and shunt insertion before or after syrinx formation. CSF flow studies were performed six weeks following the final intervention. Grading scales were used to quantify HRP staining.
RESULTS: Syrinxes formed in all animals. Perivascular flow was greatest at the level of the syrinx. Cerebral cortex perivascular flow was significantly reduced following shunt insertion in animals with a syrinx (p< 0.05). Shunt insertion did not alter syrinx length or size, but did reduce the number of animals with evidence of sensory disturbances. There were no significant differences between shunt and syrinx first groups.
DISCUSSION: Increasing distal subarachnoid space compliance does not affect local CSF flow into the spinal cord and syrinx. These results suggest that localised alterations in compliance, as opposed to obstruction from traumatic arachnoiditis, act as an important factor in syrinx pathogenesis.
These abstracts were prepared by Dr Robert J. Moore. Correspondence should be addressed to him at Spine Society of Australia, Institute of Medical and Veterinary Science, The Adelaide Centre for Spinal Research, Frome Road, Adelaide, South Australia 5000.
