Neuroenhancement of surgeons during robotic suturing

Abstract

Background: The initial phases of robotic surgical skills acquisition are associated with poor technical performance, such as low knot-tensile strength (KTS). Transcranial direct-current stimulation (tDCS) can improve force and accuracy in motor tasks but research in surgery is limited to open and laparoscopic tasks in students. More recently, robotic surgery has gained traction and is now the most common approach for certain procedures (e.g. prostatectomy). Early-phase robotic suturing performance is dependent on prefrontal cortex (PFC) activation, and this study aimed to determine whether performance can be improved with prefrontal tDCS.

Methods: Fifteen surgical residents were randomized to either active then sham tDCS or sham then active tDCS, in two counterbalanced sessions in a double-blind crossover study. Within each session, participants performed a robotic suturing task repeated in three blocks: pre-, intra- and post-tDCS. During the intra-tDCS block, participants were randomized to either active tDCS (2 mA for 15 min) to the PFC or sham tDCS. Primary outcome measures of technical quality included KTS and error scores.

Results: Significantly faster completion times were observed longitudinally, regardless of active (p < 0.001) or sham stimulation (p < 0.001). KTS was greater following active compared to sham stimulation (median: active = 44.35 N vs. sham = 27.12 N, p < 0.001). A significant reduction in error scores from "pre-" to "post-" (p = 0.029) were only observed in the active group.

Conclusion: tDCS could reduce error and enhance KTS during robotic suturing and warrants further exploration as an adjunct to robotic surgical training.

Keywords: Motor skills; Robotic surgery; Surgical training; Transcranial direct-current stimulation.

Fig. 1

Experimental overview. Experimental design (a): Participants performed a robotic suturing task three times, which was repeated in a second intervention > 1 week after the initial session. Subjects were randomly assigned to either active (2 mA for 15 min) or sham tDCS and then crossed over. Robotic suturing task (b): Participant performing task using da Vinci® Si System (Intuitive Surgical Inc., Sunnyvale, California, United States) with concurrent tDCS. The task required securing 4 knots along a Penrose drain at pre-marked entry and exit points. Technical skill assessment (c–f): Progression score (au) c with 1 point allocated for successful progression through 6 steps: mounting needle, needle entry, needle exit, double throw, first single throw and second single throw; leak volume (mL) d of saline through clamped drain in 1 min; error e in distance (mm) from pre-marked entry and exit dots; tensile strength (N) of knots f measured using a tensiometer (5565 single-axis tensiometer, Instron, UK)

Fig. 2

Transcranial direct-current stimulation. tDCS setup (a) with red anode and black cathode sponge electrodes placed on scalp and connected to tDCS device to pass 2 mA current through cortical tissue. A computational model (b) of electric field distribution for bifrontal electrode arrangement with the anode (red) over F3 and cathode (blue) over F4. The electric field strength and distribution depicted were calculated using a finite element-based approach in ROAST [47]

Fig. 3

Surgical performance metrics. Scatter plot of individual scores of time (a), knot-tensile strength (b) and error (c) within each intervention group (each knot represented by grey dots). Coloured dots and line represent median scores and interquartile range. Outliers removed to aid graphical representation. Asterisk denotes significant difference, **p < 0.01, ***p < 0.001