Martínez, Jaime L.

Abstract BACKGROUND Brain mapping is the most reliable intraoperative tool for identifying surrounding functional cortical and subcortical brain parenchyma. Brain mapping procedures are nuanced and require a multidisciplinary team and a well-trained neurosurgeon. Current training methodology involves real-time observation and operation, without widely available surgical simulation. OBJECTIVE To develop a patient-specific, anatomically accurate, and electrically responsive biomimetic 3D-printed model for simulating brain mapping. METHODS Imaging data were converted into a 2-piece inverse 3D-rendered polyvinyl acetate shell forming an anatomically accurate brain mold. Functional and diffusion tensor imaging data were used to guide wire placement to approximate the projection fibers from the arm and leg areas in the motor homunculus. Electrical parameters were generated, and data were collected and processed to differentiate between the 2 tracts. For validation, the relationship between the electrical signal and the distance between the probe and the tract was quantified. Neurosurgeons and trainees were interviewed to assess the validity of the model. RESULTS Material testing of the brain component showed an elasticity modulus of 55 kPa (compared to 140 kPa of cadaveric brain), closely resembling the tactile feedback a live brain. The simulator's electrical properties approximated that of a live brain with a voltage-to-distance correlation coefficient of r 2 = 0.86. Following 32 neurosurgeon interviews, ∼96% considered the model to be useful for training. CONCLUSION The realistic neural properties of the simulator greatly improve representation of a live surgical environment. This proof-of-concept model can be further developed to contain more complicated tractography, blood and cerebrospinal fluid circulation, and more in-depth feedback mechanisms.

Abstract Neurosurgical training is being challenged by rigorous work-hour restrictions and the COVID-19 pandemic. 1 Now, more than ever, surgical simulation plays a pivotal role in resident education and psychomotor skill development. Three-dimensional (3D) printing technologies enable the construction of inexpensive, patient-specific, anatomically accurate physical models for a more convenient and realistic simulation of complex skull base approaches in a safe environment. 2 All stages of the surgical procedure can be simulated, from positioning and exposure to deep microdissection, which has an unparalleled educational value. The complex approach-specific anatomy, narrow working angles, and pathoanatomic relationships can be readily explored from the surgeon's perspective or point of view. 2,3 Furthermore, different thermoplastic polymers can be utilized to replicate the visual and tactile feedback of bone (cortical/cancellous), neurological, and vascular tissues. 4 Retrosigmoid craniectomies are widely used in neurosurgery with various applications, including microvascular decompressions in patients with trigeminal neuralgia. 5-7 Removal of the suprameatal tubercle (SMT) extends the retrosigmoid approach superiorly to the middle fossa and Meckel's cave, and anteriorly to the clivus. 8,9 This maneuver may be necessary in patients with prominent SMTs obstructing the view of the trigeminal nerve and in patients with a more anterosuperior neurovascular conflict. This video illustrates a microsurgical training tool for learning and honing the technique of retrosigmoid craniectomy and suprameatal drilling using an affordable (29.00 USD) biomimetic 3D-printed simulator that closely recapitulates not only the anatomy but also the tactile feedback of drilling and manipulating neurological tissues (see Table and Graph 1; minute 07:11) as it happens at the time of surgery.