CHRONIC CATHETERIZATION OF THE EPIDURAL SPACE IN RABBITS - A MODEL FOR BEHAVIORAL AND HISTOPATHOLOGICAL STUDIES - EXAMINATION OF MEPTAZINOLNEUROTOXICITY

A technique of epidural catheterization in rabbits is described. Twelv e albino rabbits received a totally implanted epidural catheter system . The system was implanted surgically, and the functioning of the syst em tested for a period of 3 months. X-rav examinations following epidu ral contrast injections showed a distribution up to Th4 following 1.3 ml and Th8-9 following 1.0 and 1.25 ml. Epidural injection of lidocain e throughout the study period proved the system to be functioning for all 3 months. Another 12 rabbits were included for the neurotoxicologi cal examinations following epidural catheterization, without any injec tions (three rabbits), epidural injections of saline (four rabbits) an d meptazinol (five rabbits) once a day for 14 days. Histopathological examinations showed a fibrous cocoon, at the tip of the catheter, in a ll rabbits. In the group of rabbits which did not receive any injectio ns, the cocoon was slightly infiltrated with leukocytes and local depr ession of the spinal cord was observed in one rabbit. In the saline-in jected group this infiltration was more pronounced and in one rabbit i t extended into the meninges. Three rabbits showed local depression of the spinal cord and local myelopathy of the white matter in the area adjacent to the cocoon. In the group of rabbits receiving meptazinol, three out of five had local depression and myelopathy of the white mat ter. In this group these findings were more pronounced. In two rabbits the myelopathy extended transversely through the white matter into th e grey matter of the spinal cord. The number of pathological changes i n the group receiving meptazinol was significantly higher compared to the control and placebo groups. The epidural catheterization technique proved to be simple and reliable. Neurotoxicological examinations sho wed local effects following catheterization and injection of saline. F ollowing injection of meptazinol, a significant neurotoxicological pot ential was shown.