Abstract
Intrathecal hyperbaric local anesthetics can cause neurologic impairment; however, there have been no studies on histopathological changes of the spinal cord after injection of local anesthetics dissolved in water or 10% glucose. We studied the effects of tetracaine dissolved in water or 10% glucose on motor function and histopathologies of the spinal cord. Rats received intrathecally different concentrations of tetracaine (0%, 0.5%, 1%, 2.5%, and 5%) dissolved in water or 10% glucose. We studied motor functions and light and electron microscopic changes of the spinal cord. Movement of the hind limbs recovered significantly faster in the 10% glucose groups than in water groups at all concentrations of tetracaine. Irreversible motor dysfunction of the hind limbs occurred only in rats injected with 5% tetracaine dissolved in water. There was no significant difference in the incidence of pathological lesions between rats receiving 5%tetracaine in water and in 10% glucose (100% vs 67%); however, significantly higher rates of pathological lesions were detected in rats receiving 2.5% tetracaine in water than in 10% glucose (71% vs 0%).
All rats that received tetracaine showed significant pathological changes in the posterior roots of the spinal cord, spreading to the posterior colums with axonal degeneration. We conclude that 10% glucose, as compared with water, lessens neurotoxicity of intrathecal tetracaine in rats.
