Brain-stem auditory-evoked potentials during lidocaine infusion in humans

Auditory brain-stem responses (ABR) were recorded in six healthy male volunteers during intravenous infusion of lidocaine that achieved systemic blood levels similar to those seen with conduction anesthesia and antiarrhythmic therapy. Following an initial loading dose of lidocaine (1 mg/kg), subjects noted prominent tinnitus, perioral numbness, and drowsiness. All of these symptoms except drowsiness abated during continued infusion as blood concentrations reached equilibrium. All subjects noted that the click stimuli used to elicit ABR varied markedly in intensity and character throughout the lidocaine infusion. Although waves I and III were unaffected by lidocaine, wave V exhibited significant decreases in amplitude and increases in latency. Therefore, the more central components of the auditory system seem to be the prominent site of lidocaine's central nervous system effects.