Peris‐Celda, Maria

Abstract 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: Esthesioneuroblastoma (ENB) is a rare malignant neoplasm arising from the olfactory epithelium of the cribriform plate. Although survival is excellent with a reported 5-year overall survival (OS) of 82%, recurrence is frequent and occurs in 40–50% of cases. This study investigates the characteristics of ENB recurrence and the subsequent prognosis of patients with recurrence. Methods: The clinical records of all patients diagnosed as having ENB with subsequent recurrence at a tertiary hospital from 1 January 1960 to 1 January 2020 were retrospectively reviewed. Overall survival (OS) and progression-free survival (PFS) were reported. Results: A total of 64 out of 143 ENB patients had recurrences. In total, 45 out of 64 recurrences met the inclusion criteria and were included in this study. From these, 10 (22%) had a sinonasal recurrence, 14 (31%) had an intracranial recurrence, 15 (33%) had a regional recurrence, and 6 (13%) had a distal recurrence. The average interval from initial treatment to recurrence was 4.74 years. There were no differences in rates of recurrence with respect to age, sex, or types of surgery (endoscopic, transcranial, lateral rhinotomy, and combined). The time to recurrence was shorter for Hyams grades 3 and 4 compared to Hyams grades 1 and 2 (3.75 years vs. 5.70 years, p < 0.05). Patients with recurrence limited to the sinonasal region had a lower overall primary Kadish stage compared to recurrences beyond the sinonasal region (2.60 vs. 3.03, p < 0.05). A total of 9 (20%) out of 45 patients developed secondary recurrence. Following recurrence, the subsequent 5-year OS and PFS were 63 and 56%, respectively. The mean time to secondary recurrence after treatment of the primary recurrence was 32 months, which was significantly shorter than the time to primary recurrence (32 months vs. 57 months, p = 0.048). The mean age of the secondary recurrence group is significantly older than the primary recurrence group (59.78 years vs. 50.31 years, p = 0.02). No statistically significant differences were observed between the secondary recurrence group and the recurrence group in terms of their overall Kadish stages or Hyams grades. Conclusions: Following an ENB recurrence, salvage therapy appears to be an effective therapeutic option with a subsequent 5-year OS of 63%. However, subsequent recurrences are not infrequent and may require additional therapy.

Abstract 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 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.