A randomized crossover study of the effects of lidocaine on motor- and sensory-evoked potentials during spinal surgery

Background Context

Lidocaine has emerged as a useful adjuvant anesthetic agent for cases requiring intraoperative monitoring of motor-evoked potentials (MEPs) and somatosensory-evoked potentials (SSEPs). A previous retrospective study suggested that lidocaine could be used as a component of propofol-based intravenous anesthesia without adversely affecting MEP or SSEP monitoring, but did not address the effect of the addition of lidocaine on the MEP and SSEP signals of individual patients.

Purpose

The purpose of this study was to examine the intrapatient effects of the addition of lidocaine to balanced anesthesia on MEPs and SSEPs during multilevel posterior spinal fusion.

Study Design

This is a prospective, two-treatment, two-period crossover randomized controlled trial with a blinded primary outcome assessment.

Patient Sample

Forty patients undergoing multilevel posterior spinal fusion were studied.

Outcome Measures

The primary outcome measures were MEP voltage thresholds and SSEP amplitudes. Secondary outcome measures included isoflurane concentrations and hemodynamic parameters.

Methods

Each participant received two anesthetic treatments (propofol 50?mcg/kg/h and propofol 25?mcg/kg/h+lidocaine 1?mg/kg/h) along with isoflurane, ketamine, and diazepam. In this manner, each patient served as his or her own control. The order of administration of the two treatments was determined randomly.

Results

There were no significant within-patient differences between MEP threshold voltages or SSEP amplitudes during the two anesthetic treatments.

Conclusions

Lidocaine may be used as a component of balanced anesthesia during multilevel spinal fusions without adversely affecting the monitoring of SSEPs or MEPs in individual patients.