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Hands-on dissections using cadaveric tissues for neuroanatomical education are not easily available in many educational institutions due to financial, safety, and ethical factors. Supplementary pedagogical tools, for instance, 3D models of anatomical specimens acquired with photogrammetry are an efficient alternative to democratize the 3D anatomical data. The aim of this study was to describe a technical guideline for acquiring realistic 3D anatomic models with photogrammetry and to improve the teaching and learning process in neuroanatomy. Seven specimens with different sizes, cadaveric tissues, and textures were used to demonstrate the step-by-step instructions for specimen preparation, photogrammetry setup, post-processing, and display of the 3D model. The photogrammetry scanning consists of three cameras arranged vertically facing the specimen to be scanned. In order to optimize the scanning process and the acquisition of optimal images, high-quality 3D models require complex and challenging adjustments in the positioning of the specimens within the scanner, as well as adjustments of the turntable, custom specimen holders, cameras, lighting, computer hardware, and its software. MeshLab® software was used for editing the 3D model before exporting it to MedReality® (Thyng, Chicago, IL) and SketchFab® (Epic, Cary, NC) platforms. Both allow manipulation of the models using various angles and magnifications and are easily accessed using mobile, immersive, and personal computer devices free of charge for viewers. Photogrammetry scans offer a 360° view of the 3D models ubiquitously accessible on any device independent of operating system and should be considered as a tool to optimize and democratize the teaching of neuroanatomy.

Introduction Although many neuroanatomic atlases have been published, few have detailed complex cranial approaches and pertinent anatomic considerations in a stepwise fashion intended for rapid comprehension by neurosurgery students, residents, and fellows. Methods Five sides of formalin-fixed latex-injected specimens were dissected under microscopic magnification. The frontotemporal and orbitozygomatic approaches were performed by neurosurgical residents and fellows at different training levels with limited previous experience in anatomical dissection mentored by the senior authors (M.P.C. and M.J.L.). Meticulous surgical anatomic dissections were performed until sufficient visual and technical completion was attained, with parameters of effectively demonstrating key surgical steps for educational training purposes. Following the completion of dissection and three-dimensional photography, illustrative case examples were reviewed to demonstrate the relative benefits and optimal applications of each approach. Results The frontotemporal and orbitozygomatic approaches afford excellent access to anterior and middle skull base pathologies, as well as the exposure of the infratemporal fossa. Key considerations include head positioning, skin incision, scalp retraction, fat pad dissection and facial nerve protection, true or false MacCarty keyhole fashioning, sphenoid wing drilling and anterior clinoidectomy, completion of the craniotomy and accessory orbital osteotomy cuts, dural opening, and intradural neurovascular access. Conclusion The frontotemporal and orbitozygomatic approaches are core craniotomies that offer distinct advantages for complex cranial operations. Learning and internalizing their key steps and nuanced applications in a clinical context is critical for trainees of many levels. The orbitozygomatic craniotomy in particular is a versatile but challenging approach; operative-style laboratory dissection is an essential component of its mastery and one that will be powerfully enhanced by the current work. [ABSTRACT FROM AUTHOR]

Introduction The clival, paraclival, and craniocervical junction regions are challenging surgical targets. To approach these areas, endoscopic endonasal transclival approaches (EETCAs) and their extensions (far-medial approach and odontoidectomy) have gained popularity as they obviate manipulating and working between neurovascular structures. Although several cadaveric studies have further refined these contemporary approaches, few provide a detailed step-by-step description. Thus, we aim to didactically describe the steps of the EETCAs and their extensions for trainees. Methods Six formalin-fixed cadaveric head specimens were dissected. All specimens were latex-injected using a six-vessel technique. Endoscopic endonasal middle and inferior clivectomies, far-medial approaches, and odontoidectomy were performed. Results Using angled endoscopes and surgical instruments, an endoscopic endonasal midclivectomy and partial inferior clivectomy were performed without nasopharyngeal tissue disruption. To complete the inferior clivectomy, far-medial approach, and partially remove the anterior arch of C1 and odontoid process, anteroinferior transposition of the Eustachian–nasopharynx complex was required by transecting pterygosphenoidal fissure tissue, but incision in the nasopharynx was not necessary. Full exposure of the craniocervical junction necessitated bilateral sharp incision and additional inferior mobilization of the posterior nasopharynx. Unobstructed access to neurovascular anatomy of the ventral posterior fossa and craniocervical junction was provided. Conclusion EETCAs are a powerful tool for the skull-base surgeon as they offer a direct corridor to the ventral posterior fossa and craniocervical junction unobstructed by eloquent neurovasculature. To facilitate easier understanding of the EETCAs and their extensions for trainees, we described the anatomy and surgical nuances in a didactic and step-by-step fashion. [ABSTRACT FROM AUTHOR]

Introduction Safe, effective access to the fourth ventricle for oncologic resection remains challenging given the depth of location, restricted posterior fossa boundaries, and surrounding eloquent neuroanatomy. Despite description in the literature, a practical step-by step dissection guide of the suboccipital approaches to the fourth ventricle targeted to all training levels is lacking. Methods Two formalin-fixed, latex-injected specimens were dissected under microscopic magnification and endoscopic visualization. Dissections of the telovelar, transvermian, and supracerebellar infratentorial-superior transvelar approaches were performed by one neurosurgery resident (D.D.D.), under guidance of senior authors. The dissections were supplemented with representative clinical cases to highlight pertinent surgical principles. Results The telovelar and transvermian corridors afford excellent access to the caudal two-thirds of the fourth ventricle with the former approach offering expanded access to the lateral recess, foramen of Luschka, adjacent skull base, and cerebellopontine angle. The supracerebellar infratentorial-superior transvelar approach reaches the rostral third of the fourth ventricle, the cerebral aqueduct, and dorsal mesencephalon. Key steps described include positioning and skin incision, myofascial dissection, burr hole and craniotomy, durotomy, the aforementioned transventricular routes, and identification of relevant skull base landmarks. Conclusion The midline suboccipital craniotomy represents a foundational cranial approach, particularly for lesions involving the fourth ventricle. Operatively oriented resources that combine stepwise neuroanatomic dissections with representative cases provide a crucial foundation for neurosurgical training. We present a comprehensive guide for trainees in the surgical anatomy laboratory to optimize familiarity with fourth ventricle approaches, mastery of relevant microsurgical anatomy, and simultaneous preparation for learning in the operating room. [ABSTRACT FROM AUTHOR]

This article, published in the journal Laryngoscope, presents a detailed anatomical description of an eyebrow approach for frontal sinus surgery. The approach allows for full exposure of the frontal sinus with a large osteoplastic bone flap while preserving the supraorbital nerve. The article discusses the challenges of frontal sinus surgery and the limitations of endoscopic procedures. It also provides a step-by-step description of the surgical technique and includes an illustrative case. The authors conclude that this approach offers good cosmetic results and functional preservation while reducing surgical morbidity. [Extracted from the article]

This article, titled "Surgical Anatomy of the Retrosigmoid Approach with Transtentorial Extension: Protecting the 4th Cranial Nerve," explores the challenges and techniques involved in safely incising the tentorium cerebelli during the Retrosigmoid Approach with Transtentorial Extension (RTA). The study was conducted on cadaver head specimens, and the researchers identified a working area for the incision, outlined by the tentorium's free edge and the trigeminal nerve. They described six different incisions for the tentorial opening, which allows access to the middle incisural space, the ventrolateral brainstem, and the base of the temporal lobe. The study provides a systematic description and illustration of the tentorial incision in the RSA, with a focus on protecting the 4th cranial nerve. [Extracted from the article]

This article compares the minipterional (MPT) and supraorbital eyebrow (SE) approaches to the parasellar region in neurosurgery. The study used cadaveric specimens to evaluate the exposures and anatomical indications of both approaches. The results showed that both approaches provided sufficient exposure along the ipsilateral parasellar region, but the viewing angle was significantly different. The MPT approach allowed for early access to the ipsilateral neurovascular structures, while the SE approach provided direct access to the anterior skull base and parasellar region bilaterally. The article concludes that both approaches minimize manipulation of the temporal muscle and may decrease retraction of brain parenchyma, but the SE approach is recommended for lesions requiring early proximal vascular control and access to the contralateral parasellar region. [Extracted from the article]

This article discusses the management of an anatomical variant called the intraosseous subarcuate loop of the Anterior Inferior Cerebellar Artery (AICA) during the resection of a trigeminal schwannoma. The intraosseous subarcuate loop occurs when the AICA is entrapped in the temporal bone, posing a surgical challenge. The article presents a case study of a 42-year-old male who underwent a retrosigmoid approach with anterior reverse petrosectomy to safely mobilize the intraosseous loop and achieve gross total resection of the schwannoma. The article emphasizes the importance of identifying and safely mobilizing the intraosseous AICA loop to avoid complications during surgery. [Extracted from the article]

This article, published in the Journal of Neurological Surgery, discusses a novel surgical technique for accessing tumors in the infratemporal fossa (ITF) that extend into the buccal space. Traditionally, a sublabial incision is made to expose the anterior wall of the maxilla, and the ITF is accessed by opening the maxillary sinus walls. However, this approach limits visibility and makes dissection behind the lateral buttress of the maxilla challenging. The authors describe a new technique involving osteotomies in the lateral buttress of the maxilla, allowing for a wider exposure of the ITF and buccal space. This approach improves visualization, safety, and the feasibility of removing large tumors. [Extracted from the article]

This article, published in the Journal of Neurological Surgery, provides a comprehensive anatomical overview and comparison of different surgical approaches to the petrous apex. The authors performed transcranial and endoscopic endonasal approaches on specimens and took 3D images at each step. The transcranial approaches included anterior petrosectomy, transcochlear approach, and retrosigmoid approach, while the endoscopic approaches included transclival-transcavernous approach, transmaxillary-transpterygoid approach, and contralateral transmaxillary approach. The article concludes by describing the different exposures of the petrous apex and related structures through these approaches. [Extracted from the article]

This article, titled "Expanded Endoscopic Approach to the Interpeduncular and Prepontine Cisterns: Pituitary Transposition Techniques," explores different surgical approaches for accessing the prepontine and interpeduncular cisterns using an expanded endonasal approach (EEA). The study compares three pituitary transposition techniques: extradural, interdural, and intradural. The results show that the interdural route provides the largest exposure and easier manipulation of structures in the interpeduncular cistern. The article emphasizes the importance of preoperative assessment to determine the safest and most effective technique for accessing these regions. [Extracted from the article]

This article, published in the Journal of Neurological Surgery, explores the microsurgical anatomy of the peritrigeminal zone (PTZ) and compares different transcranial skull base approaches for accessing this area. The study used cadaveric head specimens and MRIs to examine the surgical exposure and intrinsic architecture of the PTZ. The results showed that the retrosigmoid (RS), retrolabyrinthine (RL), and anterior petrosectomy (AP) approaches all provided access to the PTZ, but each approach had different trajectories and depths of access. The choice of approach depends on the location and axis of development of the pontine lesion being treated. [Extracted from the article]

This article provides a detailed description of both microsurgical and endoscopic approaches to the orbit, aimed at trainees in skull base surgery. The study utilized six cadaveric head specimens to perform various approaches, including endoscopic transorbital approaches, endoscopic endonasal approaches, the Caldwell-Luc approach, and orbitotomies and cranio-orbitotomies. The results highlight the distinct anatomical landmarks and advantages of each approach, such as improved aesthetics, reduced scarring, and enhanced visibility. The article aims to enhance the understanding and learning experience for trainees in skull base surgery. [Extracted from the article]

The article discusses the Retrosigmoid Approach with Endoscopic-Assisted Reverse Anterior Petrosectomy (RAP), a surgical technique used to treat lesions in the brain. The study examines the extent of access to Meckel's cave (MC) and the middle cranial fossa (MCF) during the procedure and provides guidance for protecting the internal carotid artery (ICA). The researchers performed dissections on anatomical specimens and measured various distances to MC and ICA. The results suggest that extended inferolateral drilling of the petrous apex provides greater access to MC, but carries a higher risk of injury to the ICA. The article recommends drilling in an anterior and superior direction to achieve better MCF access and avoid ICA injury. [Extracted from the article]

Introduction The endoscopic endonasal transpterygoid approach (EETPA) with or without the addition of the endoscopic-assisted sublabial anterior transmaxillary approach (ESTA) has become increasingly utilized for lesions posterior to the pterygopalatine fossa (PPF), including infratemporal fossa (ITF), lateral recess of the sphenoid sinus, Meckel's cave, petrous apex, and parapharyngeal space. The main goal of this study is to develop an educational resource to learn the steps of the EETPA for trainees. Methods EETPA and ESTA were performed in 12 specimens by neurosurgery trainees, under supervision from the senior authors. One EETPA and one ESTA were performed on each specimen on opposite sides. Dissections were supplemented with representative cases. Results After a wide unilateral sphenoidotomy, ethmoidectomy, and partial medial maxillectomy, the anteromedial bone limits of the PPF were identified and drilled out. The pterygoid progress was modularly removed. By enlarging the opening of the posterior and lateral walls of the maxillary sinus through EETPA and ESTA, respectively, the neurovascular and muscular compartments of the PPF and ITF were better identified. The EETPA opens direct corridors to the PPF, medial ITF, middle cranial fossa, cavernous sinus, Meckel's cave, petrous apex, and internal carotid artery. If a more lateral exposure of the ITF is needed, the ESTA is an appropriate addition. Conclusion Despite the steep learning curve of the EETPA, granular knowledge of its surgical anatomy and basic surgical steps are vital for those advancing their learning in complex endoscopic approaches to the ventral skull base when expanding the approach laterally in the coronal plane. [ABSTRACT FROM AUTHOR]

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The 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. [ABSTRACT FROM AUTHOR]