Utilizing transcranial direct current stimulation to enhance laparoscopic technical skills training: A randomized controlled trial

Abstract

Background: Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that delivers constant, low electrical current resulting in changes to cortical excitability. Prior work suggests it may enhance motor learning giving it the potential to augment surgical technical skill acquisition.

Objectives: The aim of this study was to test the efficacy of tDCS, coupled with motor skill training, to accelerate laparoscopic skill acquisition in a pre-registered (NCT03083483), double-blind and placebo-controlled study. We hypothesized that relative to sham tDCS, active tDCS would accelerate the development of laparoscopic technical skills, as measured by the Fundamentals of Laparoscopic Surgery (FLS) Peg Transfer task quantitative metrics.

Methods: In this study, sixty subjects (mean age 22.7 years with 42 females) were randomized into sham or active tDCS in either bilateral primary motor cortex (bM1) or supplementary motor area (SMA) electrode configurations. All subjects practiced the FLS Peg Transfer Task during six 20-min training blocks, which were preceded and followed by a single trial pre-test and post-test. The primary outcome was changes in laparoscopic skill performance over time, quantified by group differences in completion time from pre-test to post-test and learning curves developed from a calculated score accounting for errors.

Results: Learning curves calculated over the six 20-min training blocks showed significantly greater improvement in performance for the bM1 group than the sham group (t = 2.07, p = 0.039), with the bM1 group achieving approximately the same amount of improvement in 4 blocks compared to the 6 blocks required of the sham group. The SMA group also showed greater mean improvement than sham, but exhibited more variable learning performance and differences relative to sham were not significant (t = 0.85, p = 0.400). A significant main effect was present for pre-test versus post-test times (F = 133.2, p < 0.001), with lower completion times at post-test, however these did not significantly differ for the training groups.

Conclusion: Laparoscopic skill training with active bilateral tDCS exhibited significantly greater learning relative to sham. The potential for tDCS to enhance the training of surgical skills, therefore, merits further investigation to determine if these preliminary results may be replicated and extended.

Keywords: Bilateral motor cortex; FLS Peg transfer task; Supplementary motor area; Transcranial direct current stimulation; Visual-motor learning.

Conflict of interest statement

Declaration of competing interest None.

Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.

Figures

Fig. 1.

Illustration of the experimental design showing activities for each visit. The first row shows the preparation activities and approximate duration. The second row show two images of the pre-test peg transfer task, one for the movement of objects from right-to-left and one for movement of objects from left-to-right. The third row illustrates the two 20-min task blocks, separated by a 5-min break. The fourth row shows the post-test which is identical to the pre-test.

Fig. 2.

Electrode configurations and underlying cortical electric field illustrations for the A) bilateral primary motor cortex montage (bM1) and B) the supplementary motor area (SMA) montage. Images on the left show transparent tissue segmentations for the scalp, skull, and cortex with electrode placements for the anode (red) and cathode (blue) sponges. Images on the right show the underlying electric field distribution on a generic T1-weighted MRI with a color scale bar indicating the electric field magnitude.

Fig. 3.

Consort diagram showing the steps in the study, including the numbers of participants who completed each stage as well as the numbers who were excluded or dropped out. Color coding for the bM1 (green), SMA (orange), and sham (grey) groups are preserved in Figs. 4 and 5.

Fig. 4.

Mean completion times in seconds for the bM1 (green), SMA (orange), and sham (grey) groups at pre-test and post-test. Whiskers denote 95% confidence intervals.

Fig. 5.

Learning curves for the bM1 (green), SMA (orange), and sham (grey) groups, reported as percent improvement in seconds normalized to block 1 performance. Whiskers denote standard error of the mean.