The purpose of this experiment is to characterize the aftereffects of myelography of canine spinal cords using rabbits, since the distal end of the spinal cord of rabbits is more caudal than that of dogs. Twelve healthy New Zealand White rabbits were divided into 4 groups of 3 animals each : a spinal puncture group, a saline injection group, an iodixanol injection group, and an iohexol injection group. The spinal puncture group consisted of rabbits which received a spinal puncture only. The saline injection group consisted of rabbits which received a spinal injection of saline. The iodixanol group consisted of rabbits which received an isotonic, non-ionic iodine contrast agent, iodixanol
®, in the same volume as the saline. The iohexol injection group consisted of rabbits which received a low osmolality, non-ionic iodine contrast agent, inhexol
®, in the same volume as the saline and at the same concentration of the iodixanol. Under general anesthesia, myelography was performed via the/umbar 5-6 intervertebral space according to the standard method for dogs. Before and 48 hours after the puncture/injection, the animals' behavior was observed, and neurological reflexes were tested. The damaged areas in the spinal cords were inspected histologically 72 hours after the puncture/injection. The rabbits in the three injection groups were neurologically abnormal. There was a marked difference in the ratio of damaged areas between the puncture group and the saline injection group. These findings indicate that neurological disorders might be caused by physical compression of the spinal tissues due to liquid injection. We suggest that it is necessary to confirm the reverse flow of cerebrospinal fluid through a spinal needle during myelography and that if there is any possibility of the contrast agent being injected into the spinal cord accidentally, the procedure should be stopped at once, and an alternative method of examination should be chosen.
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