Intraoperative Neurophysiological Monitoring for Endoscopic Endonasal Approaches to the Skull Base: A Technical Guide.

Intraoperative neurophysiological monitoring during endoscopic, endonasal approaches to the skull base is both feasible and safe. Numerous reports have recently emerged from the literature evaluating the efficacy of different neuromonitoring tests during endonasal procedures, making them relatively well-studied. The authors report on a comprehensive, multimodality approach to monitoring the functional integrity of at risk nervous system structures, including the cerebral cortex, brainstem, cranial nerves, corticospinal tract, corticobulbar tract, and the thalamocortical somatosensory system during endonasal surgery of the skull base. The modalities employed include electroencephalography, somatosensory evoked potentials, free-running and electrically triggered electromyography, transcranial electric motor evoked potentials, and auditory evoked potentials. Methodological considerations as well as benefits and limitations are discussed. The authors argue that, while individual modalities have their limitations, multimodality neuromonitoring provides a real-time, comprehensive assessment of nervous system function and allows for safer, more aggressive management of skull base tumors via the endonasal route

Principles of Pituitary Surgery

Key Points 1. Understand the principles of pituitary surgery including the key-elements of surgical planning and decision-making 2. Identify the technical nuances distinguishing the endoscopic from the microscopic transsphenoidal approach 3. Understand the strategies utilized during the nasal, sphenoidal, and sellar stages of surgery that maximize tumor resection while minimizing complications and preserving sino- nasal anatomy/functio

Extended endoscopic endonasal transsphenoidal approach to the suprasellar area: Anatomic considerations - Part I

INTRODUCTION: Interest in using the extended endonasal transsphenoidal approach for management of suprasellar lesions, with either a microscopic or endoscopic technique, has increased in recent years. The most relevant benefit is that this median approach permits the exposure and removal of suprasellar lesions without the need for brain retraction. MATERIALS AND METHODS: Fifteen human cadaver heads were dissected to evaluate the surgical key steps and the advantages and limitations of the extended endoscopic endonasal transplanum sphenoidale approach. We compared this with the transcranial microsurgical view of the suprasellar area as explored using the bilateral subfrontal microsurgical approach, and with the anatomy of the same region as obtained through the endoscopic endonasal route. RESULTS: Some anatomic conditions can prevent or hinder use of the extended endonasal approach. These include a low level of sphenoid sinus pneumatization, a small sella size with small distance between the internal carotid arteries, a wide intercavernous sinus, and a thick tuberculum sellae. Compared with the subfrontal transcranial approach, the endoscopic endonasal approach offers advantages to visualizing the subchiasmatic, retrosellar, and third ventricle areas. CONCLUSION: The endoscopic endonasal transplanum sphenoidale technique is a straight, median approach to the midline areas around the sella that provides a multiangled, close-up view of all relevant neurovascular structures. Although a lack of adequate instrumentation makes it impossible to manage all structures that are visible with the endoscope, in selected cases, the extended endoscopic endonasal approach can be considered part of the armamentarium for surgical treatment of the suprasellar area

Novel concepts and strategies in skull base reconstruction after endoscopic endonasal surgery

Recently, a variety of craniofacial approaches has been adopted to enter the skull base, among those, the endonasal endoscopic technique. An effective watertight thereafter: the reconstruction can be performed using different materials, both autologous and non-autologous, individually or combined in a multilayer fashion. The current study was focused on the development of new advanced devices and techniques, aiding in reducing postoperative CSF leak rate. Additive manufacturing allows the design of devices with tailored structural and functional features and, as well, injectable semi-IPNs and composites; therefore specific mechanical/rheological and injectability studies are valuable. Accordingly, we propose new additive-manufactured and injectable devices

Endoscopic Skull Base Surgery in the Pediatric Patient

Pathology along the anterior and posterior skull base has long posed challenges to surgeons due to the difficulty accessing these locations and complexity of the surrounding neurovascular anatomy. Initial surgical management of these disorders included open craniofacial approaches and/or craniotomy and these approaches are still utilized today for selected cases. However, advances in the later half of the 20th century in optics, endoscope design, and high definition digital images allowed the development of microscopic and, more recently, endoscopic approaches to the skull base. This technology was initially developed and used in adults, but has been adapted over time for use in the pediatric patient. In this chapter, the salient points regarding pediatric endoscopic skull base surgery will be reviewed to provide the reader a framework for understanding the indications, pertinent anatomy, preoperative evaluation, and intraoperative management of skull base pathology, highlighting challenges and circumstances unique to the pediatric population

Endoscopic Skull Base Surgery

Endoscopic skull base surgery has undergone rapid advancement in the past decade moving from pituitary surgery to suprasellar lesions and now to a myriad of lesions extending from the cribriform plate to C2 and laterally out to the infratemporal fossa and petrous apex. Evolution of several technological advances as well as advances in understanding of endoscopic anatomy and the development of surgical techniques both in resection and reconstruction have fostered this capability. Management of benign disease via endoscopic methods is largely accepted now but more data is needed before the controversy on the role of endoscopic management of malignant disease is decided. Continued advances in surgical technique, navigation systems, endoscopic imaging technology, and robotics assure continued brisk evolution in this expanding field

Transorbital transnasal endoscopic combined approach to the anterior and middle skull base: a laboratory investigation

Orbital approaches provide significant trajectory to the skull base and are used with differently designed pathways. The aim of this study is to investigate the feasibility of a combined transorbital and transnasal approach to the anterior and middle cranial fossa. Cadaveric dissection of five silicon-injected heads was used. A total of 10 bilateral transorbital approaches and 5 extended endonasal approaches were performed. Identification of surgical landmarks, main anatomical structures, feasibility of a combined approach and reconstruction of the superior orbital defect were examined. Rod lens endoscope (with 0° and 45° lenses) and endoscopic instruments were used to complete the dissection. The transorbital approach showed good versatility and provides the surgeon with a direct route to the anterior and middle cranial fossa. The transorbital avascular plane showed no conflict with major nerves or vessels. Large exposure area from crista galli to the third ventricle was demonstrated with significant control of different neurovascular structures. A combined transorbital transnasal approach provides considerable value in terms of extent of exposure and free hand movement of the two surgeons, and allows better visualisation and control of the ventral skull base, thus overcoming the current surgical limits of a single approach. Combination of these two minimally invasive approaches should reduce overall morbidity. Clinical trials are needed to evaluate the virtual applications of this approach

The transnasal approach to the skull base. From sinus surgery to skull base surgery

The indications for endonasal endoscopic approaches to diseases of the skull base and its adjacent structures have expanded considerably during the last decades. This is not only due to improved technical possibilities such as intraoperative navigation, the development of specialized instruments, and the compilation of anatomical studies from the endoscopic perspective but also related to the accumulating experience with endoscopic procedures of the skull base by multidisciplinary centers. Endoscopic endonasal operations permit new approaches to deeply seated lesions and are characterized by a reduced manipulation of neurovascular structures and brain parenchyma while at the same time providing improved visualization. They reduce the trauma caused by the approach, avoid skin incisions and minimize the surgical morbidity. Transnasal endoscopic procedures for the closure of small and large skull base defects have proven to be reliable and more successful than operations with craniotomies. The development of new local and regional vascularized flaps like the Hadad-flap have contributed to this. These reconstructive techniques are furthermore effectively utilized in tumor surgery in this region. This review delineates the classification of expanded endonasal approaches in detail. They provide access to lesions of the anterior, middle and partly also to the posterior cranial fossa. Successful management of these complex procedures requires a close interdisciplinary collaboration as well as continuous education and training of all team members

Single Versus Double Hadad-Bassagasteguy Flap in Expanded Endoscopic Skull-Base Surgery

The reconstruction of dural defects, after endoscopic removal of skull-base lesions, remains challenging when a large defect or a high flow intraoperative cerebrospinal fluid (CSF) leak is observed. The aim of this study is to describe our preliminary experience with a double Hadad-Bassagasteguy (H-B) flap technique for skull-base repair, comparing its efficacy with the use of a single H-B flap in our series. A retrospective chart review was conducted on patients who underwent exclusive endoscopic endonasal skull-base surgery at our Referral Skull Base Center from December 2014 to January 2018. Data on patient demographics, pathology, preoperative and postoperative imaging, intraoperative findings, surgical route, defect size, reconstruction techniques and repair materials, were analyzed. Patients were divided into double and single H-B flap groups. In the single and double H-B groups, the postoperative CSF leak rates were 37.5% (6 of 16 patients) and 4.5% (1 of 22 patients), respectively. The difference between the two groups was statistically significant (p = 0.0470). In patients with defects > 4 cm or high-flow intraoperative CSF leakage related to the opening of the third ventricle, the double H-B flap was successfully placed with no occurrence of postoperative CSF leakage. The double H-B flap significantly reduced the postoperative CSF leakage rate after expanded transnasal skull-base surgery. Particularly in challenging cases, where a large skull-base defect or a high-flow intraoperative CSF leak was observed, this reconstructive method proved to be very effective, with no evidence of postoperative CSF fistulas