Effects of glucose administered with lidocaine solution on spinal neurotoxicity in rats

To investigate whether intrathecal administration of 10% glucose increases functional impairment and histologic damage in rats when mixed with 5% lidocaine. After implanted intrathecal catheter, 32 male Sprague-Dawley rats were randomly assigned to one of four groups: lidocaine group (Group L, n=8) received 5% lidocaine 20 µL, lidocaine with glucose group (Group LG, n=8) received 5% lidocaine with 10% glucose 20 µL, glucose group (Group G, n=8) received 10% glucose 20 µL and normal saline group received normal saline 20 µL (Group NS, n=8). Four days after intrathecal injection, sensory impairments of rats in the four groups were evaluated by using the tail-flick test. The histologic changes of spinal cord and nerve roots were observed by electron microscopy and light microscopy. There was no significant difference in baseline tail-flick latencies between the four groups (P=0.284). On the 4th day after intrathecal injection, the assessment result of sensory function was similar to baseline (P=0.217) in saline-treated animals. Sensory impairment occurred after intrathecal administration of 5% lidocaine, and 10% glucose with 5% lidocaine worsen this satiation (P=0.0001); histologic changes in 10% glucose with 5% lidocaine-treated group has differ significantly from lidocaine-treated group (P=0.001). Sensory function after intrathecal administration of 10% glucose was similar to baseline and did not differ from the saline group (P=0.995); histologic changes in 10% glucose-treated rats did not differ significantly from saline controls (P=0.535). These results suggest that 5% lidocaine can induce spinal neurotoxicity and 10% glucose with 5% lidocaine could worsen spinal neurotoxicity.