Multimaterial and multicolor 3D-printed model in training of transnasal endoscopic surgery for pituitary adenoma

OBJECTIVE

The aim of the present study was to investigate the practical value of a multimaterial and multicolor 3D-printed model in anatomical teaching, surgical training, and preoperative planning of transnasal endoscopic surgery for pituitary adenoma.

METHODS

Multimodality neuroimaging data were obtained in a 42-year-old healthy male volunteer and a 40-year-old female patient with an invasive nonfunctional pituitary adenoma. Three 3D-printed models were produced: a monomaterial and monocolor model, a monomaterial and multicolor model, and a multimaterial and multicolor model. The effects on anatomical teaching and surgical training for exposing the vidian nerve were assessed by 12 residents, and the training effect was validated on cadavers. The practical values for preoperative planning were evaluated by 6 experienced neurosurgeons. All evaluations were based on 5-point Likert questionnaires.

RESULTS

The multimaterial and multicolor model was superior to the monomaterial models in surgical training for exposing the vidian nerve (Fisher test; p < 0.05). In addition, the multimaterial and multicolor model was superior to the monomaterial models in anatomical teaching and preoperative planning (Friedman test; p < 0.05).

CONCLUSIONS

Multimaterial and multicolor 3D printing technology makes it convenient and efficient to produce a practical model for simulating individualized and complex anatomical structures in the sellar region. Furthermore, the multimaterial model can provide a more realistic manipulative experience for surgical training and facilitate the preoperative planning.

Computational fluid dynamics as a risk assessment tool for aneurysm rupture

OBJECTIVE

The authors reviewed the clinical role of computational fluid dynamics (CFD) in assessing the risk of intracranial aneurysm rupture.

METHODS

A literature review was performed to identify reports on CFD assessment of aneurysms using PubMed. The usefulness of various hemodynamic parameters, such as wall shear stress (WSS) and the Oscillatory Shear Index (OSI), and their role in aneurysm rupture risk analysis, were analyzed.

RESULTS

The authors identified a total of 258 published articles evaluating rupture risk, growth, and endovascular device assessment. Of these 258 articles, 113 matching for CFD and hemodynamic parameters that contribute to the risk of rupture (such as WSS and OSI) were identified. However, due to a lack of standardized methodology, controversy remains on each parameter's role.

CONCLUSIONS

Although controversy continues to exist on which risk factors contribute to predict aneurysm rupture, CFD can provide additional parameters to assess this rupture risk. This technology can contribute to clinical decision-making or evaluation of efficacy for endovascular methods and devices.

An innovative prone positioning system for advanced deformity and frailty in complex spine surgery

The authors present a technical note for a prone positioning system developed to facilitate cervical extension osteotomy for ankylosing spondylitis in the presence of severe deformity and frailty. Chin-on-chest deformity represents one of the most debilitating changes of ankylosing spondylitis. Where the chin-brow angle approaches or exceeds 90°, prone positioning becomes problematic due to the fixed position of the head. Furthermore, the challenge is compounded where physiological deconditioning leads to frailty, and the side effects of medical therapies decrease muscle mass and skin quality. Conventional prone positioning equipment is not able to cater to all patients. A versatile system was developed using a 3D reconstruction to enable a positioning simulation and verification tool. The tool was used to comprehensively plan the perioperative episode, including spatial orientation and associated equipment. Three-dimensional printing was used to manufacture a bespoke positioning device that precisely matched the contours of the patient, reducing contact pressure and risk of skin injury. The authors were able to safely facilitate surgery for a patient whose deformity and frailty may otherwise have precluded this possibility. The system has potential safety and economic implications that may be of significant utility to other institutions engaging in complex spinal surgery.

Low-cost endoscopic third ventriculostomy simulator with mimetic endoscope

OBJECTIVE Hydrocephalus affects approximately 1 in 500 people in the US, yet ventricular shunting, the gold standard of treatment, has a nearly 85% failure rate. Endoscopic third ventriculostomy (ETV) is an alternative surgical approach for a specific subset of hydrocephalic patients, but can be limited by the inability of neurosurgical residents to practice prior to patient contact. The goal of this study was to create an affordable ETV model and endoscope for resident training. METHODS Open-source software was used to isolate the skull and brain from the CT and MR images of a 2-year-old boy with hydrocephalus. A 3D printer created the skull and a 3D mold of the brain. A mixture of silicone and silicone tactile mutator was used to cast the brain mold prior to subsequent compression and shearing modulus testing. A mimetic endoscope was then created from basic supplies and a 3D printed frame. A small cohort of neurosurgical residents and attending physicians evaluated the ETV simulator with mimetic endoscope. RESULTS The authors successfully created a mimetic endoscope and ETV simulator. After compression and shearing modulus testing, a silicone/Slacker ratio between 10:6 and 10:7 was found to be similar to that of human brain parenchyma. Eighty-seven percent of participants strongly agreed that the simulator was useful for resident training, and 93% strongly agreed that the simulator helped them understand how to orient themselves with the endoscope. CONCLUSIONS The authors created an affordable (US$123, excluding 3D printer), easy-to-use ETV simulator with endoscope. Previous models have required expensive software and costly operative endoscopes that may not be available to most residents. Instead, this attempt takes advantage of open-source software for the manipulation and fabrication of a patient-specific mold. This model can assist with resident development, allowing them to safely practice use of the endoscope in ETV.