Hypothermic treatment of spinal cord injury : the effect of treatment temperature and duration on tissue pathogenesis

Typescript (photocopy).After 15 years of research, investigators still do not agree on the value of treating spinal cord injury with hypothermia. While there are many variables in the process from which conflict may arise, this experiment attempts to alter only the temperature and duration of treatment and thereby study the effect of these parameters on pathogenesis. A T-8 laminectomy was performed on 60 male Sprague-Dawley rats anesthetized with methoxyflurane. Injury was induced by contusion to the dorsal surface of the spinal cord with a pneumo-electric injury device. Within two minutes of injury, the lesion was perfused with saline at temperatures of 0, 10, 20 or 30 degrees centrigrade for intervals of 1, 4 or 8 hours. According to the temperature and interval of treatment, animals were arranged into groups of 4. Groups of control animals were injured and maintained without treatment for 1, 4 and 8 hours. Immediately following treatment, animals were perfused intracardially with Karnovsky's fixative. A 1 cm segment of spinal cord encompassing the lesion was removed and cross-sectioned serially at 10 microns. In addition, spinal cord adjacent to this segment was collected for study with the electron microscope. In each animal, the volume of tissue involved in hemorrhage and cavitation relative to total tissue volume was determined from measurements collected by computerized planimetry on 12 sections spaced at 800 microns. This ratio served as an index for comparison of individuals and groups of animals. The statistical analysis of data collected in this experiment suggests the temperatures does not alter vascular necrosis. However, when animals are treated at 10 degrees centigrade, pathogenesis has stabilized in contrast to the control animals and animals treated at other temperatures