LIDOCAINE (WITHOUT EPINEPHRINE) DOES NOT AFFECT THE FINE-STRUCTURE OR MICROTUBULES OF THE TRIGEMINAL NERVE INVIVO

The authors examined the fine structure and microtubules of unmyelinated axons and Schwann cells in the infraorbital branch of rat trigeminal nerve 1, 3.5 and 24 hours after intraneural injection of lidocaine HCl, 1-4 per cent, 0.2 ml, or saline solution, 0.2 ml; untreated control nerves were also examined. These concentrations of lidocaine are more than sufficient to block impulse conduction and rapid axonal transport in rat infraorbital nerve, but contrary to previous reports, significant structural change was not found as compared with control nerves.