Anatomical step-by-step dissection of complex skull base approaches for trainees: Endoscopic endonasal approach to the orbit

Introduction: Although endonasal endoscopic approaches (EEA) to the orbit have been previously reported, a didactic resource for educating neurosurgery and otolaryngology trainees regarding the pertinent anatomy, techniques, and decision-making pearls is lacking. Methods: Six sides of three formalin-fixed, color latex-injected cadaveric specimens were dissected using 4-mm 0º and 30º rigid endoscopes, as well as standard endoscopic equipment, and a high-speed surgical drill. The anatomical dissection was documented in stepwise 3-D endoscopic images. Following dissection, representative case applications were reviewed. Results: EEA to the orbit provides excellent access to the medial and inferior orbital regions. Key steps include positioning and preoperative considerations, middle turbinate medialization, uncinate process and ethmoid bulla removal, complete ethmoidectomy, sphenoidotomy, maxillary antrostomy, lamina papyracea resection, orbital apex and optic canal decompression, orbital floor resection, periorbita opening, dissection of the extraconal fat, and final exposure of the orbit contents via the medial-inferior recti corridor. Conclusion: EEA to the orbit is challenging, in particular for trainees unfamiliar with nasal and paranasal sinus anatomy. Operatively oriented neuroanatomy dissections are crucial didactic resources in preparation for practical endonasal applications in the OR. This approach provides optimal exposure to the inferior and medial orbit to treat a wide variety of pathologies. We describe a comprehensive step-by-step curriculum directed to any audience willing to master this endoscopic skull base approach.

Microsurgical Management of Blister-Type Basilar Artery Apex Region Aneurysms: Companion Cases Demonstrate Technical Nuances of the Subtemporal Approach: 2-Dimensional Operative Video

The proportion of intracranial aneurysms treated by microsurgical clip ligation has drastically decreased in the endovascular era. However, some aneurysms cannot be treated by current endovascular techniques. Therefore, trainees and young vascular neurosurgeons must develop and maintain microsurgical skills to safely treat aneurysms that require surgery. Ruptured, basilar artery apex, blister-type aneurysms are particularly treacherous and require a high degree of skill to safely manage them surgically. In this video, 2 companion cases are exhibited to demonstrate the nuances of the subtemporal, skull base, approach to the basilar apex region. In each case, the patient consented to surgery and anonymized recording. The subtemporal approach is favored over the trans-sylvian for posteriorly directed basilar apex region aneurysms as the former affords a complete view of the relevant anatomy. Points for consideration include variations on the standard subtemporal approach, use of retractors vs lumbar drainage to mobilize the temporal lobe, and splitting the tentorium vs a suture-retraction technique for visualization of the basilar artery apex region. Techniques for successful navigation of intraoperative rupture are demonstrated. As the number of intracranial aneurysms treated by microsurgery continues to ebb, high-quality educational videos that supplement surgeon experience will become increasingly critical to ensure that a cohort of capable microvascular neurosurgeons is prepared to tackle challenging, but manageable aneurysms, such as the blister-type basilar apex variety. Video (c) Emory University School of Medicine, 2021. Used with permission.

Combined Petrosal Approach for Resection of a Large Trigeminal Schwannoma With Meckel's Cave Involvement—Part I: Anatomic Rationale and Analysis: 2-Dimensional Operative Video

Resection of large trigeminal schwannomas involving both posterior and middle cranial fossae is challenging. The depth of the surgical target in the superomedial corner of the cerebellopontine angle and the petrous apex makes for a difficult lesion to favorably access, expose, and safely resect. Judicious planning of a skull base approach is therefore the most crucial step in successful management of these formidable tumors. When properly chosen, planned, and executed, the combined petrosal approach sets the stage for an optimal exposure of such tumors that involve both posterior and middle cranial fossae. The present video is the first of a 2-part video presentation that explains the anatomic rationale of selecting a combined petrosal approach (anterior petrosectomy and retrolabyrinthine petrosectomy) for the resection of a large trigeminal schwannoma involving the posterior and middle cranial fossae with an extension into Meckel's cave in a 54-yr-old female presenting with 5-yr history of increasing headaches, left-sided face numbness, and disequilibrium. The benefits, risks, and alternatives of the surgical procedure were discussed in detail with the patient and she consented to proceed with surgery. Part I also discusses the important nuances of positioning the patient, as well as planning and execution of the skin incision, including pericranial flap harvesting. Of note, the patient consented to the publication of images obtained from her.

Anatomical Variations in the Location of Veins Draining Into the Anterior Superior Sagittal Sinus: Implications for the Transbasal Approach

BACKGROUND Many approaches are used for midline anterior cranial fossa meningioma resection. In the subfrontal approach, the anterior superior sagittal sinus (SSS) is commonly ligated to release the anterior falx. The transbasal approach allows access to the origin of the anterior SSS, allowing for maximum venous preservation. OBJECTIVE To investigate variations in the first and second veins draining into the SSS. METHODS We performed stepwise dissections for a transbasal level 1 approach on 8 anatomic specimens. We visualized the first and second veins draining into the sinus and measured the distance from the foramen cecum to these veins. We also measured the orbital bar height to determine the length of sagittal sinus that could be preserved with orbital bar removal. RESULTS The distance between the foramen cecum and the first vein ranged from 4 to 36 mm while the distance to the second vein ranged from 6 to 48 mm. The mean orbital bar height was 26.4 mm. Based on these measurements, with a traditional bicoronal craniotomy without orbital bar removal, 81% of first veins and 58% of second veins would be sacrificed. CONCLUSION A supraorbital bar or nasofrontal osteotomy, part of the transbasal skull base approach, is helpful to preserve the first and second veins when ligating the anterior SSS. Based on this study, it may be difficult to preserve these veins without orbital bar removal. Preservation of these veins may be of clinical importance when approaching midline anterior fossa pathologies.

Endoscopic Removal of Skull Base Chordoma Type III through Single Skull Base Approach: Our Early Experience

Introduction: Skull base chordomas present with headache, commonly VI cranial nerve palsy or sometimes with lower cranial nerve involvement.Sometimes in neglected case it presents with complete blindness and facial nerve palsy. Case presentation: A 60-year old man presented with headache,visual disturbance progressing to blindness and facial nerve palsy. At first, radiological imaging showed large tumor which eroded his clivus, sella floor and involved both cavernous carotid more on left side,both ethmoid sinus,middle cranial fossa entension with transdural extension posteriorly. Conclusion: Patients who present with complete blindness and facial nerve palsy, endoscopic excision in a single skull base approach of a skull base chordoma type III is challenging and who developed visual improvement following surgery, has been highlighted in this report. Bang. J Neurosurgery 2019; 9(1): 57-63

The Extended Pterional Craniotomy: A Contemporary and Balanced Approach

Pterional craniotomy is the workhorse approach among cranial operative corridors. It is a highly flexible skull base approach that affords excellent exposure of the anterior cranial fossa, the circle of Willis, and the interpeduncular region. Its strategic use via dynamic retraction can obviate the need to use a more extensive skull base route, such as orbitozygomatic osteotomy, in select cases. The focus of the surgeon should be reaching the surgical target effectively while minimizing disruption of normal anatomy. In other words, the focus should be less on “how to get there” and more on “what to do when you are there.” This multimedia presentation summarizes an efficient execution of this route and its expansion and demonstrates the surgical corridor via 3-dimensional virtual reality models.