Nguyen, Bachtri T.

Abstract Introduction Skull base neuroanatomy is traditionally learned through two-dimensional anatomical atlases, which while are of unquestionable value, lack the nuanced association of three-dimensional relationships between fundamental anatomical structures relevant to surgical approaches. Surgically focused step-by-step anatomical dissections can augment trainee learning of complex skull base techniques, particularly multistep and nuanced techniques such as translabyrinthine and transcochlear approaches. Methods Translabyrinthine and transcochlear approaches were performed on six sides of three formalin-fixed latex-injected specimens. The study objective was the completion and photo documentation of the steps involved in the approach in order to provide a comprehensive, intelligible, and anatomically oriented resource for multilevel trainees. Illustrative case examples were prepared to supplement approach dissections. Results The translabyrinthine and transcochlear approaches offer unique lateral windows through the temporal bone into the posterior fossa, providing excellent access to pathology at the petrous apex, internal auditory canal, Meckel's cave, and anterolateral brainstem. The transcochlear approach, which is an anterior extension of the translabyrinthine, particularly provides excellent exposure of the prepontine region and clivus. Important surgical considerations include patient position, temporal bone drilling and identification of critical landmarks, dural opening and identification of neurovascular structures, and reconstruction/closure techniques. Conclusion The translabyrinthine and transcochlear approaches are fundamental techniques for lateral skull base and posterior fossa pathologies. Both approaches are hearing-sacrificing but often require minimal to no cerebellar retraction and deliver unique visualization of prepontine neurovascular structures. This step-by-step approach guide provides a unique practical and high-yield surgically oriented learning resource for neurosurgery and otolaryngology trainees.

AbstractThe 3D stereoscopic technique consists in providing the illusional perception of depth of a given object using two different images mimicking how the right and left eyes capture the object. Both images are slightly different and when overlapped gives a three‐dimensional (3D) experience. Considering the limitations for establishing surgical laboratories and dissections courses in some educational institutions, techniques such as stereoscopy and photogrammetry seem to play an important role in neuroanatomy and neurosurgical education. The aim of this study was to describe how to combine and set up realistic models acquired with photogrammetry scans in 3D stereoscopic projections. Three donors, one dry skull, embalmed brain and head, were scanned using photogrammetry. The software used for displaying the final realistic 3D models (Blender, Amsterdam, the Netherlands) is a free software and allows stereoscopic projection without compromising the interactivity of each model. By default, the model was exported and immediately displayed as a red cyan 3D mode. The 3D projector used in the manuscript required a side‐by‐side 3D mode which was set up with simple commands on the software. The final stereoscopy projection offered depth perception and a visualization in 360° of each donor; this perception was noted especially when visualizing donors with different cavities and fossae. The combination of 3D techniques is of paramount importance for neuroanatomy education. Stereoscopic projections could provide a valuable tool for neuroanatomy instruction directed at clinical trainees and could be especially useful when access to laboratory‐based learning is limited.

BACKGROUND: Selection of skull base approaches is a critical skill for complex cranial surgery, which demands nuanced understanding of neuroanatomy and pathology. OBJECTIVE: To develop novel pedagogical resources for approach selection education and assessment. METHODS: A prospectively maintained skull base registry was screened for posterior fossa tumors amenable to 3-dimensional (3D) modeling of multiple operative approaches. Inclusion criteria were high-resolution preoperative and postoperative computed tomography and MRI studies (≤1 mm) and consensus that at least 3 posterior fossa craniotomies would provide feasible access. Cases were segmented using Mimics and modeled using 3-Matic. Clinical Vignettes, Approach Selection Questionnaire, and Clinical Application Questionnaire were compiled for implementation as a teaching/testing tool. RESULTS: Seven cases were selected, each representing a major posterior fossa approach group. 3D models were rendered using clinical imaging for the primary operative approach, as well as a combination of laboratory neuroanatomic data and extrapolation from comparable craniotomies to generate 2 alternative approaches in each patient. Modeling data for 3D figures were uploaded to an open-sourced database in a platform-neutral fashion (.x3d) for virtual/augmented reality and 3D printing applications. A semitransparent model of each approach without pathology and with key deep structures visualized was also modeled and included for comprehensive understanding. CONCLUSION: We report a novel series of open-source 3D models for skull base approach selection training, with supplemental resources. To the best of our knowledge, this is the first such series designed for pedagogical purposes in skull base surgery or centered on open-source principles.

Abstract Introduction Skull base neuroanatomy is classically taught using surgical atlases. Although these texts are critical and rich resources for learning three-dimensional (3D) relationships between key structures, we believe they could be optimized and complemented with step-by-step anatomical dissections to fully meet the learning needs of trainees. Methods Six sides of three formalin-fixed latex-injected specimens were dissected under microscopic magnification. A far lateral craniotomy was performed by each of three neurosurgery resident/fellow at varying stages of training. The study objective was the completion and photodocumentation of the craniotomy to accompany a stepwise description of the exposure to provide a comprehensive, intelligible, and anatomically oriented resource for trainees at any level. Illustrative case examples were prepared to supplement approach dissections. Results The far lateral approach provides a wide and versatile corridor for posterior fossa operation, with access spanning the entire cerebellopontine angle (CPA), foramen magnum, and upper cervical region. Key Steps Include The study includes the following steps: positioning and skin incision, myocutaneous flap, placement of burr holes and sigmoid trough, fashioning of the craniotomy bone flap, bilateral C1 laminectomy, occipital condyle/jugular tubercle drilling, and dural opening. Conclusion Although more cumbersome than the retrosigmoid approach, a far lateral craniotomy offers unparalleled access to lesions centered lower or more medially in the CPA, as well as those with significant extension into the clival or foramen magnum regions. Dissection-based neuroanatomic guides to operative approaches provide a unique and rich resource for trainees to comprehend, prepare for, practice, and perform complex cranial operations, such as the far lateral craniotomy.