Measuring Force During Subpial Resection Procedure Using a Novel Ex Vivo Calf Brain Model With Integrated Sensor

Background and Rationale: The subpial resection technique is a complex neurosurgical procedure that is essential for brain tumor and epilepsy surgery. However, opportunities for trainees to gain hands-on experience with this procedure without risk to patient safety are limited. The force applied on the brain during tool-tissue contact is a critical factor impacting patient safety. While virtual simulation platforms enable force monitoring, ex vivo animal brains cannot readily capture quantitative data. The investigators have therefore developed a prototype of a simulation platform that integrates a force sensor and a calf brain and can accurately detect real-time forces during simulated subpial resections. This study seeks to gauge the force spectrum using this ex vivo calf brain force detection system.

Hypothesis: The simulation platform will accurately measure forces applied by novice, intermediate, and expert participants with surgical instruments on an ex vivo calf brain during simulated subpial resection procedures.

Co-Primary Outcomes: To assess the individual and combined instrumental force applications during subpial resection procedures in an ex vivo calf brain model.

Secondary Outcome: To differentiate levels of expertise of trial participants.

Setting: Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada.

Participants:

Neurosurgeons (experts): Staff neurosurgeons at McGill University specializing in oncology, epilepsy, pediatric, or vascular neurosurgery

Neurosurgical residents (trainees): Neurosurgical residents at McGill University

Medical students (novices): Students enrolled in medical school at McGill University

Design: A cross-sectional case series study.

Methodology: This study was approved by the McGill University Health Centre Research Ethics Board, Neurosciences-Psychiatry. A case series study will be conducted where medical students, neurosurgical residents, and staff neurosurgeons from McGill University will be recruited to perform subpial resection tasks on an ex vivo calf brain model. Calf brains will be placed in a 3D-printed skull model to mimic a realistic human operative environment. The 3D-printed skull model was prototyped from a publicly available CT scan obtained from Embodi3D, an open-access medical imaging repository, and reconstructed in 3D using the open-source software 3D Slicer version 5.10.0. A 6-degree-of-freedom force/torque sensor (Nano17 IP68, ATI Industrial Automation Inc., North Carolina, USA) and a USB data acquisition board (NI-6210, National Instruments Inc., Texas, USA) will be used to measure real-time forces applied to the brain. Participants will use microscissors, bipolar forceps, and a SONOPET ultrasonic aspirator (Stryker, Portage, Michigan, USA) to perform simulated procedures. The tasks will be performed using an OPMI pico surgical microscope (ZEISS, Jena, Germany) and video-recorded using a Blackfly S GigE embedded microscope camera (FLIR, Wilsonville, Oregon, USA), allowing a broader instrument view for evaluation of intraoperative and postoperative performance.

Study Procedure: Upon arrival, participants will read and sign an informed consent form. They will then fill out a pre-trial questionnaire assessing their demographic characteristics (e.g., sex, gender, age, institutional affiliation, etc.). Each participant will receive standardized instructions on instrument use and function and be presented with an image outlining the location of pial cuts and the subpial resections on the ex vivo calf brain in front of them. Participants will adjust the operating microscope according to their preferences. The subpial resection experiment will be divided into three subsequent tasks. The goal is to obtain a noise-free and specific force measurement for each of the major instruments/maneuvers in a standard subpial resection. The first task entails using microscissors to create a 2-cm pial cut in ten different gyri across a calf brain hemisphere (n = 10). The time allocated for this task is 30 seconds for each cut. The second task involves utilizing bipolar forceps to grasp and lift the edge of the pia where cuts are made with the microscissors in task 1. A repetitive lift and hold maneuver will be repeated five times assuming a right to left direction across the pial incision line in 5-second intervals using the left hand. This will be repeated across each of the ten different pial cuts (n = 50). The time allocated for this task is maximum of one minute for each pial defect. Finally, an ultrasonic aspirator in the dominant (right) hand along with the bipolar in the opposite hand will be employed to perform subpial resection at three out of the ten pial cuts originally made in task 1 (n = 3). Each of the three spots would undergo subpial resection for an allocated time of 3 minutes across separate recordings.

Significance: This study will provide the first insights into a realistic operative environment where it will be possible to monitor the force applied on the brain.