[Effects of intravenous lidocaine administration on auditory brainstem response]

The effect of lidocaine on the auditory brainstem response (ABR) was investigated in 14 neurologically normal patients. Lidocaine 1.5 mg.kg-1.min-1 was injected intravenously over a 5 min period immediately followed by a continuous infusion of lidocaine 60 micrograms.kg-1.min-1. The seven peak latencies (waves I-VII) and amplitudes (waves I-VII) of the ABR were recorded before and 7-8 min after lidocaine infusion. Peak latencies of waves IV, V, VI, VII increased after epidural anesthesia compared with control values. Amplitudes of all waves were unchanged following intravenous lidocaine injection compared with control values. Interpeak latencies (I-II, II-III, III-IV, IV-V, V-VI, VI-VII), of every second peak (I-III, II-IV, III-V, IV-VI, V-VII), of every third peak except (III-VI, IV-VII) were unchanged compared with control values. Interpeak latencies of every fourth peak, of fifth peak increased after lidocaine injection compared with control values. The data obtained in this study with lidocaine injection were similar to the data after epidural anesthesia with lidocaine. One of the reason of the latency changes of ABR after epidural anesthesia was the systemic effect of lidocaine absorbed intravenously from the epidural space.