Seven bypasses simulation set: description and validity assessment of novel models for microneurosurgical training

Abstract

OBJECTIVE Microsurgical training remains indispensable to master cerebrovascular bypass procedures, but simulation models for training that accurately replicate microanastomosis in narrow, deep-operating corridors are lacking. Seven simulation bypass scenarios were developed that included head models in various surgical positions with premade approaches, simulating the restrictions of the surgical corridors and hand positions for microvascular bypass training. This study describes these models and assesses their validity. METHODS Simulation models were created using 3D printing of the skull with a designed craniotomy. Brain and external soft tissues were cast using a silicone molding technique from the clay-sculptured prototypes. The 7 simulation scenarios included: 1) temporal craniotomy for a superficial temporal artery (STA)–middle cerebral artery (MCA) bypass using the M4 branch of the MCA; 2) pterional craniotomy and transsylvian approach for STA-M2 bypass; 3) bifrontal craniotomy and interhemispheric approach for side-to-side bypass using the A3 branches of the anterior cerebral artery; 4) far lateral craniotomy and transcerebellomedullary approach for a posterior inferior cerebellar artery (PICA)–PICA bypass or 5) PICA reanastomosis; 6) orbitozygomatic craniotomy and transsylvian-subtemporal approach for a posterior cerebral artery bypass; and 7) extended retrosigmoid craniotomy and transcerebellopontine approach for an occipital artery–anterior inferior cerebellar artery bypass. Experienced neurosurgeons evaluated each model by practicing the aforementioned bypasses on the models. Face and content validities were assessed using the bypass participant survey. RESULTS A workflow for model production was developed, and these models were used during microsurgical courses at 2 neurosurgical institutions. Each model is accompanied by a corresponding prototypical case and surgical video, creating a simulation scenario. Seven experienced cerebrovascular neurosurgeons practiced microvascular anastomoses on each of the models and completed surveys. They reported that actual anastomosis within a specific approach was well replicated by the models, and difficulty was comparable to that for real surgery, which confirms the face validity of the models. All experts stated that practice using these models may improve bypass technique, instrument handling, and surgical technique when applied to patients, confirming the content validity of the models. CONCLUSIONS The 7 bypasses simulation set includes novel models that effectively simulate surgical scenarios of a bypass within distinct deep anatomical corridors, as well as hand and operator positions. These models use artificial materials, are reusable, and can be implemented for personal training and during microsurgical courses.

Simulation-Based Bypass Training and Learning Curves—Resident Experience

“…8 Other authors used a stand made of Lego cubes, a 3D model of blood vessels, and artificial head models. 4 9 10…”

“…8 Other authors used a stand made of Lego cubes, a 3D model of blood vessels, and artificial head models. 4,9,10 The disadvantage of simulation training is that it does not consider the depth of the surgical field, neurovascular structures, and the different positions of the surgeon's hands during operations. After the initial training in the "open field," our residents practiced microanastomoses in a limited field, which were somewhat worse initially.…”

A Simple 3D Printed Model for Intracranial Vascular Anastomosis Practice and the Rochester Bypass Training Score

“…[5][6][7][8] Belykh et al reported the most comprehensive 3D printed training model to date based on Dr Lawton's 7 Bypasses. 4 Cikla et al 9 described a cheaper 3D printed/mold alternative which simulates one bypass type; however, it is still significantly more complicated requiring tissue molds and pumps, with a total cost of $113.49 plus the cost of a purchased skull and brain simulator.…”

“…Our goal was to recreate operative depth which is the most important factor that increases difficulty and minimize the overall complexity of the model. 4,7 In addition to depth, our model also captures another main feature of difficulty in true intracranial bypass surgery. The craniotomy surface is the buttress for the surgeon to stabilize his hands and dictates the angle of attack and freedom of motion.…”

“…scenarios. 4 We instead have devised a simple 3D model that increases the realism of practice compared with basic flat surface tube tying, without the multitissue complexity of other models which allows for accessibility, affordability and reproducibility.…”