Tanriover, Necmettin

BACKGROUND AND OBJECTIVES: Access to the orbit, cavernous sinus, Meckel cave (MC), and infratemporal fossa (ITF) remains challenging due to the complex 3-dimensional anatomy and proximity to critical neurovascular structures. An extradural endoscopic orbitozygomatic (OZ) approach has the potential to provide a direct surgical corridor across these compartments while minimizing the limitations of compartment-specific corridors. METHODS: Five formalin-fixed, silicone-injected cadaveric heads (10 sides) were dissected using an extradural OZ approach under operative microscopy supplemented with 0° and 30° rigid endoscopes. After a two-piece OZ craniotomy, extradural dissection was performed toward the superior orbital fissure and foramen rotundum/ovale, combined with anterior petrosectomy and opening of MC. Anatomic exposure, corridor continuity, and visualization of key neurovascular structures were qualitatively assessed. RESULTS: The extradural endoscopic OZ approach created a direct working corridor from the lateral orbit to the ITF and petroclival region. Endoscopic augmentation enhanced visualization of the lateral cavernous sinus wall, trigeminal divisions (V 1 -V 3 ), cavernous internal carotid artery, medial orbital apex, deep infratemporal recesses, and the petroclival region. Anterior petrosectomy extended exposure toward the upper clivus and ventrolateral brainstem. Limitations included restricted microscopic visualization of the medial orbit and inferior ITF, which were partially mitigated by angled endoscopy. CONCLUSION: This cadaveric study demonstrates that the extradural OZ–anterior petrosectomy approach establishes a continuous anatomic corridor integrating the orbit, cavernous sinus/MC, ITF, and petroclival region, while defining its boundaries, areas of optimal exposure, and inherent limitations. As a qualitative study, the findings are descriptive in nature and do not include quantitative morphometric analysis.

BACKGROUND AND OBJECTIVES: Surgical approaches to the ventral brainstem and petroclival regions are complex, and standard retrosigmoid and subtemporal approaches are often inadequate. Retrosigmoid suprameatal tubercle (RSMTA) and anterior subtemporal transpetrosal (ASTA) approaches may provide extended surgical exposure with less brain retraction. The objective of this study was to evaluate advantages and disadvantages of RSMTA vs ASTA, and illustrate the surgical corridors and 3-dimensional microsurgical anatomy of the related structures. METHODS: Four silicone-injected adult cadaver heads (8 sides) were dissected to evaluate the accessibility of lesions located at the petrous apex, ventral brainstem, and pontomedullary region using ASTA and RSTMA. RESULTS: Both ASTA and RSMTA provide access from the petrous apex to the ventral lower pons and pontomedullary junction. A greater extent of safely resected bone was found in ASTA vs RSMTA. ASTA provides a larger surgical view to the ventrolateral midpons, peritrigeminal region, superior neurovascular complex, pontomesencephalic junction, and posterior cavernous sinus. Meanwhile, through cranial nerve V mobilization, RSMTA provides a larger surgical view to the lower half part of the pons, ventrolateral part of the pontomedullary junction, and middle and lower neurovascular structures. CONCLUSION: The choice of surgical approach is determined by considering the area where the lesion originates, lesion size, the anatomic structures to which it extends, and evaluation of the area that can be surgically exposed. Our study highlights the differences between these approaches and important surgical anatomic considerations.

Abstract Objective Surgical access to the third ventricle can be achieved through various corridors depending on the location and extent of the lesion; however, traditional transcranial approaches risk damage to multiple critical neural structures. Methods Endonasal approach similar to corridor of the reverse third ventriculostomy (ERTV) was surgically simulated in eight cadaveric heads. Fiber dissections were additionally performed within the third ventricle along the endoscopic route. Additionally, we present a case of ERTV in a patient with craniopharyngioma extending into the third ventricle. Results The ERTV allowed adequate intraventricular visualization along the third ventricle. The extracranial step of the surgical corridor included a bony window in the sellar floor, tuberculum sella, and the lower part of the planum sphenoidale. ERTV provided an intraventricular surgical field along the foramen of Monro to expose an area bordered by the fornix anteriorly, thalamus laterally, anterior commissure anterior superiorly, posterior commissure, habenula and pineal gland posteriorly, and aqueduct of Sylvius centered posterior inferiorly. Conclusion The third ventricle can safely be accessed through ERTV either above or below the pituitary gland. ERTV provides a wide exposure of the third ventricle through the tuber cinereum and offers access to the anterior part as far as the anterior commissure and precommissural part of fornix and the whole length of the posterior part. Endoscopic ERTV may be a suitable alternative to transcranial approaches to access the third ventricle in selected patients.

Abstract Objective Surgical access to the third ventricle can be achieved through various corridors depending on the location and extent of the lesion; however, traditional transcranial approaches risk damage to multiple critical neural structures. Methods Endonasal approach similar to corridor of the reverse third ventriculostomy (ERTV) was surgically simulated in eight cadaveric heads. Fiber dissections were additionally performed within the third ventricle along the endoscopic route. Additionally, we present a case of ERTV in a patient with craniopharyngioma extending into the third ventricle. Results The ERTV allowed adequate intraventricular visualization along the third ventricle. The extracranial step of the surgical corridor included a bony window in the sellar floor, tuberculum sella, and the lower part of the planum sphenoidale. ERTV provided an intraventricular surgical field along the foramen of Monro to expose an area bordered by the fornix anteriorly, thalamus laterally, anterior commissure anterior superiorly, posterior commissure, habenula and pineal gland posteriorly, and aqueduct of Sylvius centered posterior inferiorly. Conclusion The third ventricle can safely be accessed through ERTV either above or below the pituitary gland. ERTV provides a wide exposure of the third ventricle through the tuber cinereum and offers access to the anterior part as far as the anterior commissure and precommissural part of fornix and the whole length of the posterior part. Endoscopic ERTV may be a suitable alternative to transcranial approaches to access the third ventricle in selected patients.