ROLE OF EXTRAVASCULAR GAS-BUBBLES IN SPINAL-CORD INJURY-INDUCED BY DECOMPRESSION-SICKNESS IN THE RAT

We have evaluated the contribution of extravascular gas bubbles to spi nal cord injury in decompression sickness. For this purpose, a model o f decompression sickness was developed by subjecting rats to simulated dives using compressed air. Various diving profiles were tested and t he presence of spinal cord injury was demonstrated by electrophysiolog ic measurements. To evaluate the space occupying lesions induced by ga s bubbles in the white matter, the spinal cord was fixed by perfusion with 10% buffered formalin. Tissue blocks from cervical, thoracic, and lumbar spinal cords were embedded in paraffin. Tissue sections were d ouble stained with luxol fast blue and hematoxylin and eosin. The spac e occupying lesions were quantified with a digitizer tablet. The fract ional area of the lesions was 0.009% in controls and 0.026% in rats su bjected to diving. We conclude that the volume of extravascular free g as present in the cord of rats with spinal decompression sickness is s mall and that artifacts of tissue preparation contribute to the volume estimate. As far as can be judged from the results in this animal mod el, the contribution of extravascular gas bubbles to spinal cord decom pression injury is minor. (C) 1994 Academic Press, Inc.