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The lingual process of the sphenoid bone (LP) and the petrolingual ligament (PLL) surround laterally the internal carotid artery within the middle cranial fossa (MCF).To study the LP and the PLL and anatomical variations considering their relationships with different structures and landmarks within the MCF, especially oriented toward the endoscopic endonasal approaches.Seventy-two sides of dry skulls and 20 sides of embalmed specimens were studied. The measurements of the LP and the PLL were obtained, considering important landmarks in the MCF.The LP had a mean length and height of 5 mm and 3 mm, respectively. Its distance from the foramen lacerum was 6 mm, from the foramen ovale 10 mm, foramen rotundum 15 mm, and petrous apex 9 mm. In 44 sides (61.11%), the LP partially closed the lateral aspect of the carotid sulcus; in 17 sides (23.61%), it was found as a near-ring; and in 11 sides (15.2%), it was considered rudimentary. Considering the PLL, its length and height were, respectively, 9 mm, and 4 mm.The LP and PLL separate the carotid artery at the inferior aspect of Meckel's cave and constitute important landmarks for endoscopic endonasal approaches to Meckel's cave and MCF, and their identification and removal is essential for internal carotid artery mobilization in this area.

OBJECTIVE Facial nerve palsy is a debilitating condition that can arise from iatrogenic, traumatic, or congenital causes. One treatment to improve function of the facial muscles after facial nerve injury is hypoglossal-to-facial nerve anastomosis (HFA). HFA’s efficacy and predictors of its success vary in the literature. Here, the authors present a patient-level analysis of a literature-based cohort to assess outcomes and investigate predictors of success for HFA. METHODS Seven electronic databases were queried for studies providing baseline characteristics and outcomes of patients who underwent HFA. Postoperative outcomes were measured using the House-Brackmann (HB) grading scale. A change in HB grade of 3 points or more was classified as favorable. A cutoff value for time to anastomosis associated with a favorable outcome was determined using the Youden Index. RESULTS Nineteen articles with 157 patients met the inclusion criteria. The mean follow-up length was 27.4 months, and the mean time to anastomosis after initial injury was 16 months. The end-to-side and end-to-end anastomosis techniques were performed on 84 and 48 patients, respectively. Of the 130 patients who had available preoperative and postoperative HB data, 60 (46.2%) had a favorable outcome. Time from initial injury to anastomosis was significantly different between patients with favorable and unfavorable outcomes (7.3 months vs 29.2 months, respectively; p < 0.001). The optimal cutoff for time to anastomosis to achieve a favorable outcome was 6.5 months (area under the curve 0.75). Patients who underwent anastomosis within 6.5 months of injury were more likely to achieve a favorable outcome (73% vs 31%, p < 0.001). CONCLUSIONS HFA is an effective method for restoring facial nerve function. Favorable outcomes for facial nerve palsy may be more likely to occur when time to anastomosis is within a 6.5-month window.

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.

Esthesioneuroblastoma (ENB) is a rare malignant neoplasm arising from the olfactory epithelium of the cribriform plate. The goal of this study was to update our oncologic outcomes for this disease and explore prognostic factors associated with survival.We performed a retrospective analysis of patients with ENB treated at a single tertiary care institution from January 1, 1960, to January 1, 2020. Univariate and multivariate analysis was performed. Overall survival (OS), progression-free survival (PFS), and distant metastasis-free survival (DMFS) were reported.Among 143 included patients, the 5-year OS was 82.3% and the 5-year PFS was 51.6%; 5-year OS and PFS have improved in the modern era (2005-present). Delayed regional nodal metastasis was the most common site of recurrence in 22% of patients (median, 57 months). On univariate analysis, modified Kadish staging (mKadish) had a negative effect on OS, PFS, and DMFS (p 0.05). Higher Hyams grade had a negative effect on PFS and DMFS (p 0.05). Positive margin status had a negative effect on PFS (p 0.05). Orbital invasion demonstrated worsening OS (hazard ratio, 3.1; p 0.05). On multivariable analysis, high Hyams grade (3 or 4), high mKadish stage (C+D), and increasing age were independent negative prognostic factors for OS (p 0.05). High Hyams grade (3+4), high mKadish stage (C+D), age, and positive margin status were independent negative prognostic factors for PFS (p 0.05). High Hyams grade (3+4) was an independent negative prognostic factor for DMFS (p 0.05).Patients with low Hyams grade and mKadish stage have favorable 5-year OS, PFS, and DMFS.

Selection of skull base approaches is a critical skill for complex cranial surgery, which demands nuanced understanding of neuroanatomy and pathology.To develop novel pedagogical resources for approach selection education and assessment.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.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.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.

The pineal region and dorsal midbrain are among the most challenging surgical targets. To approach lesions in this region that harbor a superior to inferior long axis, we describe the basic steps of the precuneal, interhemispheric, trans-tentorial approach and illustrate anatomical landmarks of this established, but not so popular, surgical trajectory.To study the anatomical landmarks and safety of this approach, the neurovascular anatomy was studied on 22 sides of 11 formalin-fixed latex-injected anatomical specimens. A step-by-step dissection of the precuneal interhemispheric trans-tentorial approach and study of the key anatomical landmarks was performed. An illustrative clinical case of a pontomesencephalic cavernous malformation (CM) resected through this approach is also detailed.The mean distance from the transverse sinus to the most posterior cortical vein draining into the superior sagittal sinus was 6.4 cm. The mean distance from the calcarine sulcus to the most posterior cortical vein was 5.3 cm. Key steps of the dissection are as follows: craniotomy exposing the posterior aspect of the superior sagittal sinus (SSS), durotomy and gentle retraction of the SSS edge, dissection of the interhemispheric fissure, linear incision of the tentorium that extends anteriorly to the incisura and lateral reflection of the tentorium, and arachnoidal dissection and exposure of the cerebellomesencephalic fissure.The precuneal, interhemispheric, trans-tentorial approach affords excellent access to the falcotentorial junction, splenium, pineal region, quadrigeminal cistern, and dorsal pons once the cerebellomesencephalic fissure has been dissected.

While pedicled intranasal flaps, such as the nasoseptal flap (NSF), successfully reduce postoperative CSF leaks following endoscopic endonasal approaches (EEA) to the skull base, morbidity remains prevalent. This study describes the first cadaveric description and radiographic analysis of the posterior septal nasal floor mucosal flap (PSNF) designed to reduce pedicled nasal flap morbidity. A case series is also detailed.Cadaveric dissection, radiographic analysis, and case series.Seven cadaver specimens underwent harvest of the PSNF. PSNF flap dimensions were measured on the thirty deidentified sinus computed tomography (CT) scans. A retrospective case series was performed on the first set of patients who received the PSNF for reconstruction of a sellar base defect. Information concerning complications, symptoms, and the appearance of the flap was recorded from records of the patient's postoperative inpatient stay, 1-week postop visit, and 1-month postop visit.Cadaver dissection of the PSNF flap demonstrated good arc rotation along its pedicle with ability to cover both sellar and planum defects. Cadaveric flap measurements and CT-derived measurements estimated a mean surface area of 16.7 and 18.3 cmThe PSNF flap provides a sizeable pedicled region for reconstruction comparable to other pedicled nasal flaps. Our case series demonstrated good postoperative outcomes without reduced donor site morbidity.4 Laryngoscope, 132:1561-1568, 2022.

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.