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The complexity of intracranial anatomy and pathologies warrants the optimization of multimodal techniques to ensure safe and effective surgical treatment. Endoscopy is being more widely implemented in intracranial procedures as an important visualization tool, as it can offer panoramic views of deep structures while reducing the invasiveness of approaches. Fluorophores are frequently utilized to augment the identification of intracranial anatomic landmarks and pathologies. This chapter discusses the integration of these two surgical adjuncts, highlighting the key fluorophores used in endoscopic neurosurgery and their clinical applications., (© 2024. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Microvascular decompression is a widely accepted surgical treatment for compressive cranial nerve pathologies such as trigeminal neuralgia, hemifacial spasm, glossopharyngeal neuralgia, and other craniofacial pain syndromes. Endoscopy has risen as a safe and effective minimally invasive tool to optimize microvascular decompression. Endoscopy offers improved visualization, minimizes retraction, and allows for smaller surgical openings compared to traditional microscopic approaches. There are several reports of improved neuralgia outcomes and reduced post-operative complications after endoscopic microvascular decompression. In skilled surgical hands, endoscopy is an excellent option for microvascular decompression as stand-alone tool or adjunct to the microscope. An overview of the history, operative considerations, and techniques is provided in this chapter., (© 2024. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Objective: To determine the in-hospital cost implications of an endoscopic expanded endonasal approach (EEEA) for meningioma resection relative to the open transcranial approach., Methods: All anterior skull base meningioma surgeries performed over a period from January 1 st , 2015 to October 31th, 2017 were evaluated. The electronic medical record was reviewed for patient factors, tumor characteristics, and cost variables associated with each hospital stay and univariate analysis was performed using R software. All cost data were converted into August 2021-equivalent dollar amounts using the United States Bureau of Labor Statistics consumer price index., Results: Thirty-five patients met study criteria, including 27 patients undergoing an open transcranial approach and 8 undergoing an EEEA. Average length of stay for patients undergoing an open approach was 9.3 days compared to 5.6 within the EEEA group ( P  = .126). The average total in-hospital cost of patient undergoing an EEEA was $35417.1 compared to $46406.9 among patients undergoing an open transcranial approach ( P  = .168). On univariate analysis, the cost of an open transcranial approach relative to the EEEA was $10989.8 ( P  = .411)., Conclusions: The open transcranial approach remained the dominant surgical approach to anterior skull base meningiomas over our study time period. However, despite limited patient numbers the EEEA was associated with decreased total in-hospital costs.

Tumor recurrence in pituitary adenomas is as high as 20% after surgery. Conventional neuronavigation and white light visualization are not sufficiently accurate in detecting residual neoplastic tissue. Fluorescence-guided surgery offers accurate, real-time visualization of neoplastic tissue. The authors' group has explored the use of near-infrared imaging, which is superior to visible-light fluorescence in both signal contrast and tissue penetration, in transsphenoidal endoscopic surgeries for pituitary adenomas using 2 techniques: second window indocyanine green, in which indocyanine green passively accumulates in the tumor, and OTL38, which actively targets folate receptors on adenoma cells. This work establishes the foundation of intraoperative near-infrared imaging for fluorescence-guided neurosurgery., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Near-infrared (NIR) tumor contrast is achieved through the "second-window ICG" technique, which relies on passive accumulation of high doses of indocyanine green (ICG) in neoplasms via the enhanced permeability and retention effect., Objective: To report early results and potential challenges associated with the application of second-window ICG technique in endonasal endoscopic, ventral skull-base surgery, and to determine potential predictors of NIR signal-to-background ratio (SBR) using endoscopic techniques., Methods: Pituitary adenoma (n = 8), craniopharyngioma (n = 3), and chordoma (n = 4) patients received systemic infusions of ICG (5 mg/kg) approximately 24 h before surgery. Dual-channel endoscopy with visible light and NIR overlay were photodocumented and analyzed post hoc., Results: All tumors (adenoma, craniopharyngioma, chordoma) demonstrated NIR positivity and fluoresced with an average SBR of 3.9 ± 0.8, 4.1 ± 1.7, and 2.1 ± 0.6, respectively. Contrast-enhanced T1 signal intensity proved to be the single best predictor of observed SBR (P = .0003). For pituitary adenomas, the sensitivity, specificity, positive predictive value, and negative predictive value of NIR-guided identification of tumor was 100%, 20%, 71%, and 100%, respectively., Conclusion: In this preliminary study of a small set of patients, we demonstrate that second-window ICG can provide NIR optical tumor contrast in 3 types of ventral skull-base tumors. Chordomas demonstrated the weakest NIR signal, suggesting limited utility in those patients. Both nonfunctional and functional pituitary adenomas appear to accumulate ICG, but utility for margin detection for the adenomas is limited by low specificity. Craniopharyngiomas with third ventricular extension appear to be a particularly promising target given the clean brain parenchyma background and strong SBR., (Copyright © 2018 by the Congress of Neurological Surgeons.)

The introduction of the endoscope into the neurosurgeon's armamentarium has revolutionized ventral and anterior skull-base surgery and, more recently, has been used in the surgical treatment of cerebellopontine angle (CPA) pathology. The utilization of the endoscope in microvascular decompression (MVD) for trigeminal neuralgia and other associated cranial nerve hyperactivity syndromes allows for unparalleled panoramic views and illumination of the neurovascular structures within the CPA and identification of vessel-nerve contact traditionally unseen using the microscope. In this article, the technical advantages and challenges of using the endoscope for MVD, operative technique, and patient outcomes of endoscopic MVD are discussed., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Purpose: Purely endoscopic endonasal approaches to surgical resection of pediatric suprasellar craniopharyngiomas are uncommonly performed. The aim of the study is to assess the feasibility and to describe the short-term outcomes of endonasal endoscopic approaches for the gross total resection of suprasellar craniopharyngiomas in the pediatric population., Methods: A combined neurosurgical-otolaryngologic team performed gross total resection of craniopharyngiomas in seven pediatric patients (mean age 9.6 years) at The Children's Hospital of Philadelphia over 2011-2012. Short-term outcomes were analyzed over a mean follow-up period of 6.3 months., Results: All tumors involved the sellar and/or suprasellar space and contained some cystic component. The mean maximal tumor diameter was 31.5 mm (range 18.5-62.0 mm). Using a binostril approach, gross total tumor resection was obtained in all patients (100 %). All patients with preoperative visual dysfunction demonstrated improvement in visual acuity. New or stable panhypopituitarism was observed in all cases. All patients developed postoperative diabetes insipidus, and cerebrospinal fluid leak occurred in one patient (15 %)., Conclusions: Complete radiographic resection of pediatric craniopharyngioma can be achieved via a purely endoscopic endonasal approach. In particular, this approach can be performed safely using the "two-nostrils-four-hands" technique with intraoperative neuronavigation. This approach should be highly considered in patients with progressive visual dysfunction. Further studies are needed to characterize the long-term surgical and clinical outcome of pediatric patients treated with this surgical approach.

Background: Meningiomas of the anterior skull base are attractive tumors for resection via an endoscopic endonasal route. The use of the vascularized Hadad-Bassagasteguy nasoseptal flap has dramatically reduced the cerebrospinal fluid (CSF) leak rate-the veritable Achilles heel of this surgical approach. Benign meningiomas, however, can erode through the nasal mucosa-the very same mucosa that is used to reconstruct the anterior cranial fossa floor. The goal of this study was to describe the presence of meningioma invasion into the mucosa in patients who underwent endoscopic endonasal resection of ventral skull base meningiomas. The implications of this finding are discussed with respect to resection, reconstruction, and recurrence., Patients, Materials, and Methods: This is a retrospective review of three patients who underwent endoscopic endonasal complete resection of ventral skull base meningiomas. Surgically excised tissues were processed for routine histopathological analysis., Results: A complete resection of the bone, dura, and tumor was performed in all three cases. Both patients with visual deficits improved. The first patient to undergo endoscopic surgical resection developed a CSF leak, but the later two patients with larger tumors did not. Histopathological analysis demonstrated mucosal invasion by World Health Organization (WHO) grade I meningioma in two of the three cases., Conclusion: Ventral anterior skull base meningiomas can invade through bone into the mucosa. Because the endoscopic endonasal resection of these meningiomas often requires the use of a vascularized nasoseptal flap to minimize CSF leak complications, it is possible that the nasoseptal flap itself may be compromised by tumor tissue. The creation of the nasoseptal flap should take the findings of this study into consideration to minimize late recurrence., (Georg Thieme Verlag KG Stuttgart · New York.)

Background and Importance: Hemorrhagic, symptomatic cavernous malformations in the brainstem are difficult to access. Conventional approaches such as the transpetrosal approach often require significant brain retraction. We present the successful purely endoscopic, endonasal, transclival resection of a symptomatic cavernoma located in the ventromedial pons., Clinical Presentation: A 17-year-old male patient presented with acute onset of headache, facial numbness, and tingling. Magnetic resonance imaging demonstrated an enhancing lesion in the pons consistent with a cavernous malformation. Over the course of the next 3 weeks, the patient had 2 additional episodes of acutely worsening neurological deficits that left him with left-sided hemiparesis, a right sixth nerve palsy, and dysphagia. A purely endoscopic, endonasal, transclival approach was used to resect the cavernoma. Postoperatively, he had a transient worsening of his left-side motor function and restricted horizontal gaze, but at the last follow-up, his hemiparesis had improved and his magnetic resonance imaging demonstrated a radiographic cure. He developed a cerebrospinal fluid (CSF) leak despite prophylactic lumbar CSF drainage for 2 days and the use of bilateral vascularized nasoseptal flaps. The CSF leak was repaired with CSF diversion and a second surgical procedure; at the last follow-up, he had no recurrence of the leak., Conclusion: An endoscopic, endonasal, transclival approach is a novel and effective approach to cavernous malformations presenting to the ventral surface of the pons. Recently developed techniques for closure and repair of the skull base defect have minimized but have not eliminated the risk of CSF leak in these procedures.

Background/aims: Microvascular decompression (MVD) of the trigeminal nerve is a widely accepted treatment for patients with trigeminal neuralgia caused by vascular compression. The neuroendoscope is rapidly becoming a complementary tool in minimally invasive neurosurgery of the ventral anterior skull base. Its adoption in the lateral approach to the posterior fossa has been slower and has been used primarily as an adjunct to conventional microscopic surgical techniques, e.g. endoscope-assisted microsurgery., Methods: In this paper, we describe a stepwise, technical commentary on a purely endoscopic MVD of the trigeminal nerve via the retrosigmoid route., Results: From our experience, the endoscope provides excellent visualization of the neurovascular relationship. By allowing full visualization of the trigeminal nerve, endoscopy may likely lead to an increase in the number of successful MVDs and a decrease in the number of complications., Conclusion: We believe endoscopic MVD is a safe and effective method of accessing the trigeminal nerve in the cerebellopontine angle and of performing MVD. This endoscopic technique can be implemented in other neurosurgical and neuro-otological procedures such as resection of cerebellopontine angle masses., (Copyright © 2012 S. Karger AG, Basel.)