Investigation of the histological changes in spinal nerve roots post intrathecal ketamine administration

Abstract

Background: Ketamine is a general anesthetic agent, administered intramuscularly or intravenously. It is generally used for induction and less frequently for the continuation of surgical anesthesia. Although ketamine was initially thought to be used as an intrathecal agent, psychomimetic side effects were observed. Objectives: In this study, the differences in the spinal nerve roots postintrathecal ketamine injection have been examined in the light and electron microscope. Materials and Methods: 30 min, 1 h, and 24-h postintrathecal ketamine (0.5 mg/kg) injection; the rabbits were sacrificed. The tissue samples taken from the injection area fixed with 1st 2% glutaraldehyde and later 1% OsO4. Following dehydration tissue samples embedded in Araldite and sections were taken and examined in the light and electron microscope. Results: There were severe degenerations in the myelinated nerve fibers postintrathecal injection of ketamine. Fading on the myelin lamellae, shrinking and vacuolization of the axoplasm, endoneurial edema, organelle loss, and cystic parts were observed. The vacuolization and lack of organelles in the Schwann cell cytoplasm were clear. The degeneration of the large myelinated nerve fibers was observed more than unmyelinated fibers. Conclusion: The general and local anesthetics used have significant side effects such as respiratory depression or permanent neurological disorders. Therefore, new options are searched, and the effects of the drugs used in different fields of anesthesia were investigated.