Citations

OBJECTIVE Lesions of the cerebellopontine angle (CPA) and petroclival region represent a challenging surgical target due to the complex anatomy of the involved neurovascular structures. In this scenario, cranial nerve (CN) VI is particularly exposed to potential injuries due to its deep-seated location and absence of a bony foramen that serves as a reference of its most distal cisternal point, especially when it is encased or displaced by large lesions. This study aimed to provide reliable operative guidance for preventing injuries to CN VI during the retrosigmoid approach to address CPA and petrotentorial lesions. METHODS Four formalin-fixed, latex-injected anatomical specimens were dissected to highlight and investigate the relevant anatomy of the CPA and petroclival region during the retrosigmoid approach. Additionally, 50 sides of noninjected formalin-fixed specimens were dissected for morphometric evaluation. Correlations between the petrotentorial junction (PTJ), porus acusticus (PA), and trigeminal impression (TI) with the entry point of CN VI into Dorello’s canal were evaluated. An illustrative clinical case and a 3D anatomical model generated through the photogrammetry scanning technique were described. RESULTS In the sagittal plane, CN VI entrance into Dorello’s canal was found in a trajectory parallel to the PTJ, passing through the inferior aspect of the PA and 21.5 ± 1.3 mm anteriorly. In the coronal plane, the entry point of CN VI into Dorello’s canal was estimated at 6.2 ± 1.2 mm from the anterior edge of the TI in a trajectory perpendicular to the PTJ in 47 (81%) specimens. CONCLUSIONS The obtained results demonstrated two surgical strategies to locate Dorello’s canal within the retrosigmoid route: 1) approximately 20 mm anterior along the inferior edge of the PA parallel to the PTJ; and 2) approximately 6 mm inferior to the anterior edge of the TI, perpendicular to the PTJ. The defined operative strategies provide reliable anatomical guidance to locate the entrance of CN VI into Dorello’s canal within the retrosigmoid route, potentially reducing the risk of abducens nerve palsy and improving patient outcomes.

Importance Adjuvant radiotherapy can improve locoregional control and survival in patients with olfactory neuroblastoma (ONB), particularly with advanced-stage and histologic-grade disease. Standard radiotherapy treatment is with intensity-modulated radiotherapy (IMRT). Proton beam radiotherapy (PBRT) provides theoretical advantages in greater sparing of dose to uninvolved organs at risk. Objective To investigate if there are differences in the effectiveness and radiation treatment–related adverse events (RTAEs) between adjuvant IMRT and PBRT for patients with ONB. Design, Setting, and Participants This propensity score–matched cohort study included patients with ONB treated between February 2005 and April 2021 with either IMRT or PBRT at 9 academic tertiary care centers in North America. Patients were matched 1:2 based on age, modified Kadish stage, and Hyams grade. Data were analyzed from July 2024 to January 2025. Exposure Adjuvant IMRT or adjuvant PBRT. Main Outcomes and Measures Local recurrence-free survival (RFS), any RFS, and overall survival (OS). RTAEs, ie, grade 2 events or higher based on Common Terminology Criteria for Adverse Events, were recorded for both modalities. Results Of 54 included patients, 27 (50%) were female, and the mean (SD) age was 46.2 (15.4) years. A total of 18 were treated with PBRT and 36 were treated with IMRT. Most patients had modified Kadish stage C disease (33 of 54 [61%]), and 24 patients (44%) had Hyams grade III or IV disease. The RTAE rate was 20% (8 of 40); IMRT had a rate of 21% (6 of 29), and PBRT had a rate of 18% (2 of 11). The difference in the point estimates for 10-year RFS showed a potential clinical benefit favoring IMRT, although the wide confidence interval indicates uncertainty (10-year RFS: IMRT, 63.3%; 95% CI, 44.6-89.8; PBRT, 37.8%; 95% CI, 14.2-100; difference, 25.5 percentage points; 95% CI, −17.6 to 68.6). There were no clinically meaningful differences in 10-year local RFS (IMRT, 75.6%; 95% CI, 59.8-95.4; PBRT, 72.7%; 95% CI, 45.2-100; difference, 2.9 percentage points; 95% CI, −35.9 to 41.7) or 10-year OS (IMRT, 61.8%; 95% CI, 42.8-89.1; PBRT, 57.1%; 95% CI, 24.3-100; difference, 4.7 percentage points; 95% CI, −49.2 to 58.6), although wide confidence intervals indicate considerable uncertainty. Conclusions and Relevance Due to the imprecision of estimates, no definitive conclusions can be made regarding the comparative effectiveness of IMRT vs PBRT for patients with ONB. These preliminary data may inform the design of appropriately powered prospective studies evaluating the efficacy of PBRT vs IMRT in this population.

BACKGROUND Glossopharyngeal neuralgia (GPN) is a rare disorder characterized by severe, episodic pain along the sensory distribution of cranial nerve (CN) IX. Bilateral GPN presents unique challenges for consideration of microsurgical treatment due to potential risks of postoperative dysphagia and cardiac arrhythmias associated with resection of bilateral CN IX/X. Here, the authors describe successful staged bilateral microsurgical rhizotomy of CN IX and upper CN X rootlets to treat bilateral GPN. OBSERVATIONS A 54-year-old female presented with right GPN and underwent a right retrosigmoid craniotomy with rhizotomy, resulting in complete resolution of pain. During the following year, the patient developed left GPN and was considered for the same surgical intervention. However, prior to pursuing surgical intervention, evaluation of her swallowing function was conducted to stratify her risk of pharyngeal sensory denervation or dysphagia, and to confirm her suitability for left-sided rhizotomy. Given the patient’s normal oropharyngeal swallowing function on videofluoroscopic swallow study, she underwent left retrosigmoid craniotomy with rhizotomy. At the 3-month follow-up, the patient described complete resolution of pain and normal swallowing function. LESSONS With the use of comprehensive patient evaluation between surgical stages, staged bilateral microsurgical rhizotomy is a feasible and safe treatment option for carefully selected patients with bilateral GPN. https://thejns.org/doi/10.3171/CASE25359

Abstract BACKGROUND Adamantinomatous craniopharyngiomas (ACPs) are rare, partially cystic central nervous system tumors driven by the WNT/β-catenin pathway. As they grow, ACPs compress the surrounding pituitary gland, optic chiasm, and third ventricle. ACPs are highly morbid tumors with enormous quality of life impact on patients, often early in life. Thus, better treatments are needed. Current ACP treatment consists of maximally safe surgical resection with radiation for residual disease. Complete surgical resection is challenging, and recurrence is common. Targeted systemic chemotherapy is not routinely used for ACP treatment. Interleukin-6 (IL-6) levels are elevated within ACPs compared to normal brain tissue, making IL-6 an intriguing therapeutic target. Treatment response of ACP to tocilizumab alone or in combination with bevacizumab has been reported in children. MATERIAL AND METHODS We retrospectively reviewed the medical records of three adults with recurrent ACP who received combination treatment with bevacizumab and tocilizumab on a compassionate basis between June 2022 and April 2025 at Mayo Clinic in Rochester, MN. We collected demographic, clinical, treatment, radiologic, and outcome data. RESULTS All three patients were male and median age at initial ACP diagnosis was 38 years (range: 32-42 years). All patients underwent subtotal resection followed by radiation therapy. One patient had repeat surgical resection and two patients required interventions for hydrocephalus. At the time of ACP recurrence, all patients had visual impairment, endocrine dysfunction, and headaches. All patients received bevacizumab (7.5 mg/kg q3 weeks) and tocilizumab (8 mg/kg q3 weeks [n=2] or 4 mg/kg q4 weeks [n=1]). While receiving combination therapy, ACP tumor volume decreased on magnetic resonance imaging for all three patients (64%, 68%, and 29% reduction). None exhibited tumor growth since starting combination therapy. One patient had a small intraparenchymal hemorrhage, suspected secondary to radiation-induced cavernous malformation, so bevacizumab was discontinued, and he remains on tocilizumab alone. The other two patients continue combination therapy (for 344 and 351 days). Two patients experienced improvement in vision, and one had improvement in cognition. Possible adverse effects of treatment included sinus infections, fatigue, neutropenia, and hypertension. CONCLUSION Treatment with combination bevacizumab and tocilizumab was associated with shrinkage of ACP tumors and clinical improvements and obviated the need for further surgery or radiation in all three patients. This combination of medications may reprogram the tumor microenvironment, leading to ACP involution. This well-tolerated regimen provides a noninvasive option for treatment of recurrent ACP, and potentially initial ACP treatment, and may improve quality of life for patients.

ABSTRACT Objective Sacrifice of pterygopalatine fossa (PPF) neurovascular structures during endoscopic endonasal transpterygoid approach (EETPA) may impact a patient's comorbidity. We present anatomical and surgical techniques for maximizing PPF transposition while preserving its neurovascular structures through orbito‐pterygo‐sphenoidal (OPS) ligament release and descending palatine canal (DPC) decompression. Methods The EETPA was performed on six specimens. Two measurements were obtained to assess PPF transposition: (1) Inferior transposition (distance between the superior margins of the base of the pterygoid process and PPF); (2) lateral transposition (distance from Eustachian tube lateral margin to PPF medial margin). Results After incising the OPS ligament, a mean gain of PPF inferior transposition of 7 mm (4–11 mm, p = 0.03) was observed, with a total inferior transposition of 12 mm (6–15 mm). Subsequently, the posterior half of the inferior turbinate was removed and the DPC was decompressed, with a mean gain of PPF lateral transposition of 12 mm (range 8–15 mm, p = 0.01). Conclusion The OPS ligament release offers a significant advantage for the PPF inferior transposition, allowing access to the inferolateral recess of the sphenoid sinus, cavernous sinus, and paramedian middle cranial fossa, while the DPC decompression provides a significant advantage for the PPF lateral transposition, granting access to the Eustachian tube and ITF. Level of Evidence N/A.

BACKGROUND AND OBJECTIVE: In skull base surgery, endoscopic endonasal approaches require precise evaluation of the area of exposure and the maneuverability provided by each approach. Current neuroanatomical methodologies for quantifying these parameters primarily rely on computed tomography (CT) scans and neuronavigation systems, which entail significant financial investment. The aim of this study was to develop and validate an innovative, cost-effective methodology using an endoscopic photogrammetric model to measure the exposure area and maneuverability in endoscopic endonasal approaches, offering an accessible alternative to existing techniques. METHODS: Six cadaveric specimens were used to validate the accuracy of endoscopic photogrammetric measurements by comparing them with direct measurements. Subsequently, the exposure area, angle of attack, and surgical freedom were analyzed for 3 endoscopic approaches to the parasellar region: contralateral transmaxillary, single-nostril, and double-nostril approaches. RESULTS: Photogrammetric measurements demonstrated a high level of concordance with direct cadaveric measurements, with a mean difference of 0.02 mm as shown in the Bland-Altman plot. In addition, measurements obtained in comparative analysis describing the exposure area and maneuverability of 3 endoscopic approaches were congruent with those reported in existing literature derived using CT scans and neuronavigation systems. CONCLUSION: To our knowledge, this study is the first to validate endoscopic photogrammetric models as a measurement tool in neuroanatomy. Performing direct measurements on 3D models might eliminate the necessity of expensive CT and neuronavigation systems for volumetric quantification. Our cost-effective methodology allows for the widespread democratization of anatomical quantification within skull base neuroanatomy.

Summary: Anatomy is a critical component of surgical training; however, traditional resources—such as Netter’s Surgical Anatomy , Gray’s Anatomy , and anatomy applications—often fall short in delivering surgically relevant, 3-dimensional (3D) perspectives of facial anatomy. Although cadaveric dissection remains a valuable teaching tool, its accessibility is limited by cost, ethical concerns, and the lack of structured curricula, making it less feasible for ongoing surgical education. To address these limitations, this article introduced a novel educational approach that integrates 3D photogrammetry and virtual reality technology into the surgical anatomy curriculum for craniofacial and aesthetic surgery. Six fresh cadaveric specimens were meticulously dissected by a plastic surgeon to illustrate the intricate layered anatomy of the face and neck. At each stage of the dissection, a photogrammetry technique was used to capture 360-degree images using 5 digital single-lens reflex cameras alongside a 3D handheld camera. This approach not only ensured high-quality imaging but also facilitated the creation of detailed, lifelike virtual 3D models, enhancing the understanding of facial and neck anatomy within a surgical context. Additionally, we present some technical refinements of the 3D volume renderings to capture precise anatomical details during our dissections. Preliminary results from the use of this technology in anatomy courses and workshops indicated trainee engagement, a clearer grasp of the spatial anatomical relationships, and greater confidence in applying this knowledge to hands-on surgical procedures.

BACKGROUND AND OBJECTIVES: Photogrammetry application is rapidly growing within the anatomical field as a new technique, underlining the need for the development of a comprehensive step-by-step methodology and guide to facilitate the pursuit of high-definition photogrammetry. Therefore, the aim of this study was to describe 2 photogrammetry techniques and their step-by-step from positioning and preparing the specimens for photodocumentation to the final 3-dimensional (3D) model displayed on online platforms. METHODS: Two dry skulls, 2 embalmed brains, and 30 embalmed and latex-injected heads were used for the study, rendering a total of 130 3D models. The specimens were placed on a turntable and photodocumented using a digital single-lens reflex camera or smartphone, and the key steps and notes were methodically described. RESULTS: The photogrammetry technique using either a digital single-lens reflex camera or smartphone required images captured in 3 different steps: overview images, close range photographs, and images of depth-located structures. All images were then upload to Agisoft Metashape software, postprocessed and rendered into the final 3D model and displayed using Sketchfab ® . CONCLUSION: This article provided a detailed description of a high-resolution photogrammetry scanning technique, highlighting the advantages and relevance of acquiring 3D models through mobile devices to demystify and clarify the technique to enhance the experience in clinical and neuroanatomical application.

Abstract Professor Albert J. Rhoton Jr., MD, is renowned for his groundbreaking dissections, marking a monumental achievement in the field of neuroanatomy. Alongside his anatomical contributions, he also passed on his knowledge and skills to numerous fellows, leaving behind a profound legacy. Despite the widespread recognition of his influence, little quantitative work has been done to characterize the scholarly impact of his alumni. Data were collected on Rhoton fellows, including fellowship years, country of origin, current institutions, and titles, practice settings, and leadership roles. Scholarly productivity was evaluated by assessing publication counts, including publications before and after the fellowship, and publications focused on surgical anatomy. Additionally, H-indices and citation counts were recorded. Other variables analyzed included ownership of a surgical anatomy laboratory, and participation in organizing hands-on courses. We analyzed 118 alumni from diverse countries. There was a significant increase in publication output following the fellowship, with publications rising from an average of 7 to 76 (p < 0.001). Fellows from high-income countries had higher research productivity than those from middle-income countries, with greater average H-index (p = 0.003), publication count (p = 0.01), and citation score (p = 0.003). Overall, 65% of fellows pursued academic practice, with 18% owning a laboratory and 30% involved in hands-on courses. Dr. Rhoton's mentorship has shaped a generation of neurosurgeons who continue his legacy. His fellows have established careers worldwide, leading in academia, professional organizations, and surgical training. Their global impact underscores the lasting value of structured mentorship in neurosurgery.