The aim of this project is to evaluate the consequences of spinal cord injury in an experimental model using radiologic techniques. One primary consideration is the evaluation of the hypothesis that significant cystic degeneration occurs in traumatized spinal cord within the initial few months following injury. To examine this premise a series of cats will undergo a cord contusion injury. Subseqently, the animal will be examined by CT with intrathecal contrast to document the configuration of the cord and the presence of cystic degeneration. This will be correlated with the animal's functional status. Pathologic correlation will be performed on all animals. Metrizamide, a water-soluble agent for intrathecal applications, has been reported to be eleptogenic. We have early evidence of an increased incidence of seizures in an animal with recent trauma in whom intrathecal metrizamide has been administered. We are also examining the premise that there may be differences in toxicity in an animal with recent trauma when the newer agents iopamidol, iotrol, and iohexol are used instead of metrizamide. To this end we are planning to perform the CT scans with intrathecal contrast using all four contrast agents in different groups of cats. Cats will be monitored by somatosensory evoked potentials and by electroencephalography. Water-soluble contrast agents have been noted to collect in areas of malacic change as well as in areas of syrinx formation. We again have early evidence that this may be less true in more chronically injured tissue, and will attempt to compare this type of contrast collection in early (1-2 months) versus later injury (3-6 months) in the cat trauma model. To help differentiate cystic cersus malacic change in the cord the contrast-CT examinations will be correlated with ultrasonographic examinations as well as with pathology. Treatment of spinal injury with naloxone or high dose corticosteroids in limited examples may affect the incidence of cyst formation within the spinal canal. In the third years the cats will be treated with either naloxone or methylprednisolone following the cord contusion. Radiologic studies will be performed by a protocol similar to that in the non-treatment group.
