Skull Base Surgeons Research Articles

Endoscopic endonasal approach to the vidian nerve and its relation to the surrounding structures: an anatomic cadaver study.

The aim of this study was to investigate the neurovascular structures and their relevant anatomy with the endonasal endoscopic transpterygoid approach on fresh human cadavers. In addition, the relationship between the vidian nerve, ICA and surrounding structures were investigated METHODS: This study was carried out at an otolaryngology department of a tertiary medical center between June 2014 and June 2015. Ten fresh human cadavers were included in this study. Pterygopalatine fossa was explored via an endoscopic endonasal transpterygoid approach. Same surgical dissection procedures were performed on all cadavers: maxillary antrostomy, anterior and posterior ethmoidectomy, sphenoidotomy, transpterygoid pterygopalatine fossa and vidian canal dissection. Mean distance between the anterior nasal spine and ethmoidal crest was 60.35 ± 1.31 mm (range 59-64 mm). Mean distance between the sphenopalatine foramen and superior border of choana was 18.30 ± 1.38 mm (range 17-22 mm). Mean distance between the vidian canal and sphenopalatine foramen was 6.30 ± 0.47 mm (range 5.5-7 mm). Mean distance between the vidian canal and anterior nasal spine was 64.6 ± 1.71 mm (range 62-67 mm). Foramen rotundum was located superior lateral to the vidian canal in all specimens. Mean distance between foramen rotundum and vidian canal was 9.45 ± 0.60 mm (range 8.5-10.5 mm). Course of the greater palatine nerve was always medial to the descending palatine artery. The mean length of the vidian nerve from the petrous ICA to the point the nerve exits the vidian canal (vidian canal length) was 17.90 ± 1.59 mm (range 16-20 mm). The distances between the vidian canal and surrounding neurovascular structures would help the skull base surgeon in this narrow and complex area.

Retrosigmoid Transtentorial Approach: Technical Nuances and Quantification of Benefit From Tentorial Incision

The transtentorial extension of the retrosigmoid approach allows for improved visualization of the brainstem and petroclival region. This approach is an important tool in the skull base surgeon's armamentarium for pathologies involving the petroclival region. It has been shown that the addition of tentorial transection improves the exposed surface area of the brainstem. However, no data have been reported regarding the depth of the additional anterior and medial exposure. The goal of the present study was to describe the additional depth of exposure gained by performing tentorial transection. This information allows surgeons to preoperatively estimate the amount of operative exposure gained by this technique. Five preserved cadaveric heads were dissected using frameless image guidance. A standard retrosigmoid craniotomy was performed, followed by tentorial transection. The boundaries of the surgical exposure and depth of the surgical field were compared before and after tentorial transection. After transection, we found a 20.1-mm increase in anterior exposure (P < 0.01) and a 13-mm increase in medial exposure (P < 0.01). No significant difference was found in the extent of the superior (P= 0.32) or lateral (P= 0.07) exposure. The surgical working distance increased significantly from 68.8 to 90.3 mm (P<0.01). When performing retrosigmoid craniotomy, the addition of tentorial transection allows for a significant increase in anterior and medial exposure with no significant increase in superior or lateral exposure.

Mentorship, Education, and Teamwork in the Making of a Skull Base Surgeon: A Summary of the 28th Annual NASBS meeting: February 13-17, 2018; Loews Coronado Bay, Coronado, California, United States.

Mentorship, Education, and Teamwork in the Making of a Skull Base Surgeon: A Summary of the 28th Annual NASBS meeting: February 13-17, 2018; Loews Coronado Bay, Coronado, California, United States.

Imaging-Ambiguous Lesions of Meckel's Cave—Utility of Endoscopic Endonasal Transpterygoid Biopsy

Meckel's cave is a dural-lined cavity in the middle fossa skull base in which lies the Gasserian ganglion, a potential site for tumors and inflammatory lesions. A variety of lesions can be predominantly isolated to Meckel's cave, including extension from head and neck cancers, other malignant tumors, as well as benign lesions. Clinical presentation and imaging findings are often insufficient to establish a diagnosis. Hence, histologic confirmation is required to determine the appropriate treatment strategy. Several surgical approaches have been used to reach this deep-seated area, often with significant morbidity and prolonged recovery. Given advancements in endoscopy and greater facility with the technique, the endoscopic endonasal approach has been used increasingly to reach lesions in the region. A single-institution, retrospective chart review over a 10-year period was performed to identify and describe patients with pathologically differing but imaging-similar lesions with their epicenter in Meckel's cave. Of a total of 21 cases of lesions in Meckel's cave approached by an endoscopic endonasal transpterygoid approach, we present 6 patients with imaging-ambiguous lesions involving Meckel's cave that were biopsied via the extended endoscopic endonasal approach. Among this diverse group, pathology included B-cell lymphoma, squamous cell carcinoma, adenocarcinoma, malignant schwannoma, benign schwannoma, and neurosarcoidosis. We explore not only the relevance of this approach in the armamentarium of the modern skull-base surgeon but also its limitations and conclude that the endoscopic endonasal approach provides a safe and relatively direct, minimally invasive corridor to many lesions of Meckel's cave.

Letter: Cranial Chordoma: A New Preoperative Grading System.

Letter: Cranial Chordoma: A New Preoperative Grading System.

Clinical Use of Navigation in Lateral Skull Base Surgery: Results of a Multispecialty National Survey among Skull Base Surgeons in Germany

Objective To analyze the current clinical use of navigation at the lateral skull base among skull base surgeons in Germany. Methods A web-based questionnaire was provided to surgeons being head of the department and member of one of the following scientific societies: German Society of Head and Neck Surgery, Maxillo-Facial Surgery, Neurosurgery, and German Skull Base Society. Replies were recorded anonymously. The questionnaire included the estimated case load per year and percent of surgery performed with navigation (middle and posterior fossa), type of navigation, estimates of intraoperative inaccuracy, and reasons for not using navigation. Results Eighty nine out of 99 replies met requirements for final analysis. Overall, 37% of skull base surgeons use navigation on a regular basis (15% use no navigation). Optical tracking is more frequently used than magnetic tracking (71 vs 19). At the middle fossa, ENT surgeons split into routine users ( n = 10/36) and rare users ( n = 16/36), the latter stating navigation inaccuracy as a major reason for neglecting navigation. Neurosurgeons use navigation at the middle fossa significantly more often and criticize navigation inaccuracy less. At the posterior fossa, navigation is used less frequently by both ENT and neurosurgeons with similar rates of estimated inaccuracy. Conclusions A moderate use of navigation at the lateral skull base was demonstrated. Insufficient accuracy causes ENT surgeons to frequently omit navigation at the middle fossa (not neurosurgeons) and posterior fossa (also neurosurgeons). Higher intraoperative navigation accuracy is needed to enhance the use of navigation at the lateral skull base.

The Tentorial Bridge to Deep Skull Base Exposure: Anatomic Morphometric Study.

Skull base surgeons split the tentorium to expand exposure, minimize brain retraction, and combine the supratentorial and infratentorial compartments for resection of large skull base lesions. The aim of this study was to describe stepwise techniques for splitting the tentorium to access deeply located skull base lesions and morphometrically assess gained exposure. Surgical exposures were performed through transsylvian, subtemporal, posterior transpetrosal, and combined posterior supratentorial/infratentorial-transsinus approaches. A custom software program was used to trace the surgical exposure region of interest for area analysis with the ability to accurately assess most irregular areas. Qualitative morphometric assessment was done of the gain in anatomic exposure achieved by splitting the tentorium. In the transsylvian transtentorial approach, mean surface area increased 154.17%, from 0.14 cm2 before expansion to 0.32 cm2 after expansion. In the subtemporal transtentorial approach, mean surface area increased 137.61%, from 0.66 cm2 before expansion to 1.52 cm2 after expansion. In the posterior transpetrosal transtentorial approach, mean surface area increased 171.06%, from 1.08cm2 before expansion to 2.81 cm2 after expansion. Inthe combined supratentorial/infratentorial-transsinus approach, mean surface area increased 222.03%, from 0.78cm2 before expansion to 2.38 cm2 after expansion. With splitting of the tentorium, a substantial area of expansion is obtained, minimizing the need for brain retraction and improving visualization of deep neurovascular structures in the skull base.

Cranial Cavernous Malformations: Natural History and Treatment.

Cavernous malformations (CMs), also known as cavernous angiomas or cavernomas, are low-flow vascular malformations of the brain and spinal cord that consist of clusters of dilated sinusoidal channels lined with endothelial cells that do not exhibit intervening tight junctions. The involved blood vessels lack muscular and elastic layers, and blood at various stages of thrombosis and organization often fills the thin-walled vascular caverns. CMs are grossly distinct from adjacent brain and have a lobulated appearance sometimes likened to a mulberry, with a characteristic dark red or purple color. Hemosiderin and gliosis often surround CMs of the brain and spinal cord; no neural tissue is present inside the lesion. Except for developmental venous anomalies (DVAs) present in ≈33% of CMs,1 no abnormal vascularity is typically seen on digital subtraction angiography, leading CMs to be termed cryptic or occult vascular malformations (Figure 1). Multiple small hemorrhage events lead to a pathognomonic popcorn appearance on magnetic resonance (MR) imaging because of hemosiderin staining from blood products of various ages. Calcifications may be present on computed tomographic imaging (Figure 2). Figure 1. A 48-year-old woman presented with headaches. A , Magnetic resonance imaging of the brain with T2-weighted imaging demonstrated a 1.1-cm lesion in the cerebellar vermis with mixed signal intensity. B – D , Susceptibility-weighted imaging demonstrated hemosiderin within the lesion’s core and a developmental venous anomaly associated with the cavernous malformation (arrowheads). Figure 2. A 28-year-old woman presented with partial seizures without secondary generalization. A , Noncontrast computed tomography of the head demonstrated a 1.4-cm right posterior cingulate hyperdensity, with evidence of mild hemorrhage and calcification. Magnetic resonance imaging of the brain demonstrated the cavernous malformation to have a core of mixed signal intensity, heterogeneous enhancement, and a rim of hemosiderin consistent with a cavernous malformation, as evidenced on ( B ) susceptibility-weighted imaging, ( C ) T2-weighted …

Anterolateral Triangle: A Cadaveric Study with Neurosurgical Significance.

The anterolateral triangle is one of 10 surgical triangles of the cavernous sinus and serves as an important anatomic landmark for the skull base surgeon. There are few studies in the English literature that have precisely defined and measured the borders of the anterolateral triangle and little agreement has been made regarding the nomenclature within the English literature. A total of 12 midsagittally hemisected adult human cadaveric head halves were dissected to expose the anterolateral triangle. The triangle was defined and measurements of the anterior, posterior, and lateral borders were taken. The mean lengths and standard deviations of the anterior, posterior, and lateral borders were 8.3 ± 2.2 mm, 5.9 ± 2.0 mm, and 11.5 ± 2.9 mm, respectively. The mean area and standard deviation were 20.46 ± 9.30 mm2. The anterolateral triangle is helpful in understanding and planning surgical approaches to the cavernous sinus and middle cranial fossa. As such, normal anatomic relationships and the sizes of the anterolateral triangle must first be recognized to better access the pathologic changes within and around this region.

CPA Tumors: The Learning Curve in a Surgeon's Initial 50 Cases

Objective Cerebellar pontine angle (CPA) tumors present with unique challenges for a new skull base surgeon. These include early clinical and ethical decisions in surgical patient selection, appropriate surgical approach, and safe intraoperative choices. With good training, decision making, and reflection, however, successful and safe outcomes can be achieved.

Examining Skull Base Surgeon Practice Patterns for Patients with OSA Undergoing Skull Base Surgery

Examining Skull Base Surgeon Practice Patterns for Patients with OSA Undergoing Skull Base Surgery

Extraordinary Presentations of Pediatric Pituitary Adenoma

Background Pediatric pituitary adenomas are rare tumors; when encountered, they characteristically present with headaches, visual disturbances, and frequent endocrinopathies. However, they have a penchant for unusual presentations, and due to their relative rarity in the pediatric population, are liable to be clinically misdiagnosed. Correspondingly, awareness of unusual presentations is an important educational point for skull base surgeons, and essential for ensuring early diagnosis and expedited treatment of this vulnerable patient population. We report three highly atypical cases of pediatric pituitary adenomas, both to illustrate the significant potential of the unexpected, and to demonstrate how these difficult-to-manage tumors provide a host of management challenges from early diagnosis, through protracted cycles of recurrent disease treatment.

Delayed complications from expanded endonasal surgery for intracranial tumors.

Delayed complications after endoscopic endonasal approaches to the skull base, defined as complications greater than 1 month postoperatively, are uncommon. These complications are divided into categories including sinonasal, neuroanatomic, endocrine and vascular. This review highlights the most up-to-date advancements and reviews the management of delayed complications for skull base patients. Over the last 10 years, the field of endoscopic endonasal skull base surgery has expanded with new data highlighting the long-term patient outcomes. The majority of patients experience increased quality of life (QOL) after these interventions. However, delayed complications including alterations to sinonasal function, delayed encephaloceles from the bony skull base defect and resulting endocrinopathies can significantly impact patient's QOL. Awareness of these complications and their current management is valuable for endoscopic surgeons. Endonasal approaches to the skull base are safe and well tolerated in properly selected patients. This article highlights the delayed complications that require recognition and management by skull base surgeons to ensure the best possible care for patients.

Pediatric Craniopharyngiomas: A Primer for the Skull Base Surgeon.

Pediatric craniopharyngioma is a rare sellar-region epithelial tumor that, in spite of its typically benign pathology, has the potential to be clinically devastating, and presents a host of formidable management challenges for the skull base surgeon. Strategies in craniopharyngioma care have been the cause of considerable controversy, with respect to both philosophical and technical issues. Key questions remain unresolved, and include optimizing extent-of-resection goals; the ideal radiation modality and its role as an alternative, adjuvant, or salvage treatment; appropriate indications for expanded endoscopic endonasal surgery as an alternative to transcranial microsurgery; risks and benefits of skull base techniques in a pediatric population; benefits of and indications for intracavitary therapies; and the preferred management of common treatment complications. Correspondingly, we sought to review the preceding basic science and clinical outcomes literature on pediatric craniopharyngioma, so as to synthesize overarching recommendations, highlight major points of evidence and their conflicts, and assemble a general algorithm for skull base surgeons to use in tailoring treatment plans to the individual patient, tumor, and clinical course. In general terms, we concluded that safe, maximal, hypothalamic-sparing resection provides very good tumor control while minimizing severe deficits. Endoscopic endonasal, intraventricular, and transcranial skull base technique all have clear roles in the armamentarium, alongside standard craniotomies; these roles frequently overlap, and may be further optimized by using the approaches in adaptive combinations. Where aggressive subtotal resection is achieved, patients should be closely followed, with radiation initiated at the time of progression or recurrence-ideally via proton beam therapy, although three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, and stereotactic radiosurgery are very appropriate in a range of circumstances, governed by access, patient age, disease architecture, and character of the recurrence. Perhaps most importantly, outcomes appear to be optimized by consolidated, multidisciplinary care. As such, we recommend treatment in highly experienced centers wherever possible, and emphasize the importance of longitudinal follow-up-particularly given the high incidence of recurrences and complications in a benign disease that effects a young patient population at risk of severe morbidity from hypothalamic or pituitary injury in childhood.

Anatomia cirúrgica da artéria carótida intrapetrosa

O cirurgião deve conhecer minuciosamente a anatomia normal antes de considerar a idéia de atuar em una região distorcida por um processo patológico. A dissecção criteriosa a partir de pontos de referência conhecidos para áreas mais obscuras é um princípio básico de técnica cirúrgica. Há necessidade de se confiar em reparos anatômicos ósseos ou de partes moles consistentes ao mesmo tempo em que a onipresente variabilidade anatômica não deve ser esquecida. Assim a remoção completa de uma lesão e a concomitante preservação de estruturas importantes são absolutamente dependentes do completo entendimento daquilo que poderá ser encontrado. Neste sentido a artéria carótida intrapetrosa ainda representa um desafio cirúrgico formidável. O seu trajeto sinuoso na intimidade e adjacências do osso mais resistente do corpo humano e estruturas nobres que a cercam faz do estudo desta região um capítulo importante dentro das disciplinas de neurocirurgia, otorrinolaringologia e cirurgia da base do crânio. O presente estudo, através de uma análise morfométrica de cinqüenta ossos temporais humanos tenta determinar pontos de referência consistentes na identificação da artéria carótida intrapetrosa.

Finding the Petroclival Carotid Artery: The Vidian-Eustachian Junction as a Reliable Landmark.

Introduction Identifying the internal carotid artery (ICA) when managing petroclival and infratemporal fossa pathology is essential for the skull base surgeon. The vidian nerve and eustachian tube (ET) cartilage come together at the foramen lacerum, the vidian-eustachian junction (VEJ). The ICA position, relative to the VEJ is described. Methods Endoscopic dissection of adult fresh-frozen cadaver ICAs and a case series of patients with petroclival pathology were performed. The relationship of the VEJ to the ICA horizontal segment, vertical segment, and second genu was assessed. The distance of the ICA second genu to VEJ was determined in coronal, axial, and sagittal planes. The length of the vidian nerve and ET was measured from the pterygopalatine fossa (PPF) and nasopharyngeal orifice to the VEJ. Results In this study, 10 cadaver dissections (82.3 ± 6.7 years, 40% female) were performed. The horizontal petrous ICA was at or behind VEJ in 100%, above VEJ in 100%, and lateral to VEJ in 80%. The vertical paraclival segment was at or behind VEJ in 100%, above in 100%, and medial in 100%. The second genu was at or behind VEJ in 100% (3.3 ± 2.4 mm), at or above in 100% (2.5 ± 1.6 mm), and medial in 100% (3.4 ± 2.0 mm). The VEJ was successfully used to locate the ICA in nine consecutive patients (53.3 ± 13.6 years, 55.6% female) where pathology was also present. The VEJ was 15.0 ± 6.0 mm from the ET and 17.4 ± 4.1 mm from the PPF. Conclusion The VEJ is an excellent landmark as it defines both superior and posterior limits when isolating the ICA in skull base surgery.

Injury of the Carotid Artery during Endoscopic Endonasal Surgery: Surveys of Skull Base Surgeons.

Objectives This study aimed to review endoscopic skull base surgeon experience with internal carotid artery (ICA) injuries during endoscopic endonasal surgery (EES) to provide an estimate of the incidence of ICA injury, the associated factors and identify the best training modalities for the management of this complication. Design Anonymous electronic survey of past participants at a well-established endoscopic skull base surgery course and a global online community of skull base surgeons. Main Outcome Measures Relative incidence of ICA injuries during EES, associated anatomic and intraoperative factors, and surgeon experience. Results At least 20% of surgeons in each surveyed population experienced a carotid artery injury. Reported carotid artery injuries were most common during tumor exposure and removal (48%). The parasellar carotid artery was the most commonly injured segment (39%). Carotid artery injuries were more common in high-volume surgeons, but only statistically significant in one of the two populations. Attendance at a skull base course or courses did not change the incidence of carotid artery injury in either surveyed population. In both surveys, respondents preferred live surgeries or active (not computer simulated) training models. Conclusions ICA injury is underreported and most common when manipulating the parasellar carotid artery for exposure and tumor dissection. Given the high morbidity and mortality associated with these injuries, vascular injury management should be prioritized and taught in a graduated approach by modern endoscopic skull base courses.

Open Anterior Skull Base Reconstruction: A Contemporary Review.

Skull base extirpative and reconstructive surgery has undergone significant changes due to technological and operative advances. While endoscopic resection and reconstruction will continue to advance skull base surgery for the foreseeable future, traditional open surgical approaches and reconstructive techniques are still contemporarily employed as best practices in certain tumors or patient-specific anatomical cases. Skull base surgeons should strive to maintain a working knowledge and technical skill set to manage these challenging cases where endoscopic techniques have previously failed, are insufficient from anatomical constraints, or tumor biology with margin control supersedes the more minimally invasive approach. This review focuses on the reconstructive techniques available to the open skull base surgeon as an adjunct to the endoscopic reconstructive options. Anatomic considerations, factors relating to the defect or patient, reconstructive options of nonvascular grafts, local and regional flaps, and free tissue transfer are outlined using the literature and author's experience. Future directions in virtual surgical planning and emerging technologies will continue to enhance open and endoscopic skull base surgeon's preparation, performance, and outcomes in this continually developing interdisciplinary field.

The Endoscopic Buccal Fat Pad Flap for Closure of Skull Base Defects: A Report of 5 Cases.

To demonstrate the clinical utility of the buccal fat pad flap (BFPF) for closing a variety of skull base defects. A retrospective chart review of 5 consecutive patients who underwent endoscopic cranial base surgery with endoscopic harvest of BFPF pedicled along the internal maxillary artery for reconstruction of the skull base between October 2013 and November2014. All 5 patients had complete take of the BFPFs with mucosalization on postoperative follow-up with no reported complications or cerebrospinal fluid leak. This is the first report on the application of endoscopic BFPF. Our experience suggests that this recently described flap is viable and a useful addition to the armamentarium of the skull base surgeon.

Esthesioneuroblastoma and Olfactory Preservation: Is it Reasonable to Attempt Smell Preservation?

Level 2b.