Carotid Plexus Sympathetic Nerves as a Landmark for the Abducens Nerve Within the Cavernous Sinus During Endoscopic Endonasal Surgery: Cadaveric Anatomic Study and Surgical Consideration.

BACKGROUND AND OBJECTIVES: The abducens nerve (CN VI) is vulnerable to injury during endoscopic endonasal transcavernous surgery. In this study, the authors aimed to develop the surgical anatomic landmark and explore the relationship between the sympathetic nerves (SNs) around the internal carotid artery (ICA) and CN VI within the cavernous sinus (CS). METHODS: The relationship and patterns between the SNs and CN VI were investigated in 15 cadaveric specimens. The intraoperative examples of anatomic landmark were presented. RESULTS: There were SNs around the ICA running into the CN VI, classified into ascending SNs and accessory sympathetic branches. The ascending SNs were divided into 3 types: (1) Type I had a single ascending SN. There were 2 subtypes of Type I (Type IA [17/30, 56.7%] was defined as a single ascending branch that ran into the CN VI, and Type IB [4/30, 13.3%] was defined as a single ascending branch with a terminal bifurcation before merging into the CN VI or lateral CS wall), (2) Type II (7/30, 23.3%) was defined as 2 ascending branches that ran into the CN VI and the lateral CS wall, and (3) Type III (2/30, 6.7%) was defined as 3 ascending branches that ran into the CN VIs and the lateral wall of the CS. The accessory branches of the SNs were defined by sympathetic branches from the posterior genu or horizontal ICA and found in 6/30 sides (20%). CONCLUSION: The authors propose a classification of the relationship between paraclival ICA SNs and the CN VI within the CS, as approached during endoscopic endonasal surgery. The consistent relationship of the ascending SN and CN VI within the CS provides a reliable anatomic landmark during the endonasal approach to the CS.

Changes in pituitary adenoma patient presentation and outcomes during the COVID pandemic at a Pituitary Center of Excellence.

PURPOSE: The COVID-19 pandemic caused significant disruption to the surgical care of patients. The aim of this study was to analyze the impact of the pandemic on endoscopic endonasal surgery (EES) for patients with a pituitary adenoma. METHODS: Patients from 2015 to 2022 that had EES for a pituitary adenoma were included in this study. Patients were separated into pre-COVID (January 2015-March 2020) and COVID (March 2020-September 2022) groups. Univariate analysis was done using chi-square, fisher exact tests, and t-tests to compare groups. RESULTS: This study included 492 patients that had EES for their pituitary adenoma. There were 314 patients in the pre-COVID group and 178 patients in the COVID group. Patients in the COVID group had a higher risk analysis index (RAI) frailty score (15 ± 10 pre-COVID vs. 20 ± 9 COVID, P < 0.001) and a higher American Society of Anesthesiology (ASA) physical status score (3 or 4) (72.0% pre-COVID vs. 81.9% COVID, P = 0.02). There were significantly more macroadenoma cases (87.6% pre-COVID vs. 94.4% COVID, P = 0.02) and extrasellar surgical approaches (45.2% pre-COVID vs. 61.2% COVID, P < 0.001) during COVID. There was no significant difference in length of stay (LOS) and readmission rates between groups. CONCLUSIONS: Patients that presented during the pandemic tended to be more frail, have more comorbidities, and require additional extrasellar surgical approaches. Despite changes in clinical presentation and operative management, the LOS and readmission rate remained stable during COVID, supporting the safety of this procedure during the recent pandemic.

Endoscopic endonasal resection of Rathke cleft cysts: a single-institution analysis of 148 consecutive patients.

OBJECTIVE: The traditional treatment of sellar Rathke cleft cysts (RCCs) generally involves transsellar drainage; however, suprasellar RCCs present unique challenges to appropriate management and technical complexity. Reports on overall outcomes for the endoscopic endonasal approach (EEA) for this pathology are limited. The EEA for RCCs allows three surgical techniques: marsupialization, fenestration, and fenestration with cyst wall resection. METHODS: The authors performed a retrospective review of consecutive patients with RCCs that had been treated via an EEA at a single institution between January 2004 and May 2021. Marsupialization entailed the removal of cyst contents while maintaining a drainage pathway into the sphenoid sinus. Fenestration involved the removal of cyst contents, followed by separation from the sphenoid sinus, often with a free mucosal graft or vascularized nasoseptal flap. Cyst wall resection, either partial or complete, was added to select cases. RESULTS: A total of 148 patients underwent an EEA for RCC. Marsupialization or fenestration was performed in 88 cases (59.5%) and cyst wall resection in 60 (40.5%). Cysts were classified as having a purely sellar origin (43.2%), sellar origin with suprasellar extension (37.8%), and purely suprasellar origin (18.9%). Radiological recurrence was demonstrated in 22 cases (14.9%) at an average 39.7 months' follow-up (median 45 months, range 0.5-99 months), including 13 symptomatic cases (8.8%). Cases with cyst wall resection had no significantly different rate of recurrence (11.7% vs 15.9%, p = 0.48) or postoperative permanent anterior pituitary dysfunction (21.6% vs 12.5%, p = 0.29) compared to those of fenestrated and marsupialized cases. There was no significant difference in postoperative permanent posterior pituitary dysfunction based on technique, although such dysfunction tended to worsen with cyst wall resection (13.6% vs 4.0%, p = 0.09). Based on cyst location, purely suprasellar cysts were more likely to have a radiological recurrence (28.6%) than sellar cysts with suprasellar extension (12.5%) and purely sellar cysts (9.4%; p = 0.008). Most notably, of the 28 purely suprasellar cysts, selective cyst wall resection significantly improved the long-term (10-year) recurrence risk compared to fenestration alone (17.4% vs 80.0%, p = 0.0005) without any significant added risk of endocrinopathy. CONCLUSIONS: Endoscopic endonasal marsupialization or fenestration of sellar RCCs may be the ideal treatment strategy, whereas purely suprasellar cysts benefit from partial cyst wall resection to prevent recurrence. Selective cyst wall resection reduced long-term recurrence rates without significantly increasing rates of hypopituitarism.

Multi-center study on sellar reconstruction after endoscopic transsphenoidal pituitary surgery.

INTRODUCTION: Surgical techniques for sellar reconstruction include no reconstruction, use of synthetic materials, autologous grafts, and/or vascularized flaps. The aim of this study was to conduct a multi-center study comparing the efficacy and postoperative morbidity associated with different sellar reconstruction techniques. METHODS: A retrospective chart review of patients who underwent endoscopic transsphenoidal surgery for pituitary tumors from five participating sites between January 2021 and March 2023 was performed. The variables included demographics, tumor characteristics, reconstruction technique, postoperative cerebrospinal fluid leak (CSF) leak, and 22-item Sino-Nasal Outcome Test (SNOT-22) scores. Comparisons of postoperative complications, SNOT-22 scores, and duration of surgery by type of onlay reconstruction were evaluated using Fisher's exact test, analysis of variance, and Kruskal‒Wallis test. RESULTS: Five hundred and one patients were identified. The median tumor size was 2.1 cm, and 64% were non-functioning. Intraoperative CSF leak was identified in 38% of patients. A total of 89% of patients underwent onlay reconstruction: 49% were reconstructed with mucosal grafts, 35% with nasoseptal flaps, and 5% with other onlay techniques. Nasoseptal flaps were utilized more frequently in the setting of giant pituitary adenomas (>3 cm), medial cavernous sinus wall resection, and high-flow intraoperative CSF leaks. Cases who utilized mucosal grafts had an overall shorter operating time (median: 183 min vs. 240 min; p < 0.001). Five postoperative CSF leaks were identified, and therefore, statistical analysis could not be performed for this complication. CONCLUSION: The effectiveness and morbidity of different sellar reconstruction techniques are comparable. Vascularized flaps were utilized more frequently in the setting of larger tumors and high-flow intraoperative CSF leaks.

The role of induction chemotherapy for orbital invasion in sinonasal malignancies: A systematic review.

BACKGROUND: Sinonasal malignancies (SNMs) frequently present with orbital invasion. Orbital exenteration (OE) can lead to significant morbidity. Induction chemotherapy (IC) is a promising treatment alternative that may allow for orbit preserving (OP) treatments without compromising patient survival. This systematic review was conducted to synthesize the published data on SNM patients with orbital invasion who underwent IC, including tumor response, orbital outcomes, and survival. METHODS: The study protocol was designed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Databases Embase, Cochrane, Medline, and Scopus, from inception to July 17, 2023, were searched. RESULTS: Nineteen studies were included, encompassing 305 SNM patients with orbital invasion treated with IC. Fourteen studies reported an overall IC response rate (positive response defined as complete or partial tumor volume reduction) of 77.2%. Among included studies, OE rates after IC ranged from 0 to 40%. Three studies reported a high rate of posttreatment functional orbital preservation (89.8-96.0%). Five studies specifically reported that 62.5% (60 out of 96) of patients were downgraded from planned OE to OP treatment following IC. Three studies reported a significant overall survival (OS) improvement in IC responders versus IC nonresponders. Following IC, 5-year OS ranged from 44.2 to 55.5%. Patients with olfactory neuroblastoma demonstrated the highest IC response rate and lowest OE rate (100 and 0%, respectively) versus those with sinonasal undifferentiated carcinomas (68.4 and 0%) or squamous cell carcinomas (76.7 and 16%). CONCLUSIONS: For select patients, IC may allow for OP in locally advanced SNMs with orbital involvement.

Evaluation of clinical predictors of postoperative outcomes in tegmen defect patients with and without concurrent superior semicircular canal dehiscence and cerebrospinal fluid leak.

OBJECTIVES: Tegmen and superior semicircular canal defects have been well studied, yet the factors contributing to their onset and progression are widely debated. The clinical utility of intraoperative intracranial pressure measurements has yet to be tested. This report aims to use intraoperative opening pressure and concurrent superior semicircular canal dehiscence (SSCD) to analyze factors influencing disease course and clinical outcomes in patients with tegmen dehiscence. METHODS: A retrospective analysis of 61 patients who underwent tegmen defect repair was performed. Multiple variables of interest including body mass index (BMI), presence of SSCD, presence of dural venous sinus stenosis, opening pressure, and acetazolamide therapy use were recorded. The cohort was divided into those with or without concurrent SSCD and those presenting with or without cerebrospinal fluid (CSF) leak for analysis. RESULTS: A linear relationship between opening pressure and BMI (p = 0.009) was noted; however, intraoperative opening pressure was not associated with disease outcome. Concurrent SSCD was present in 25 % of patients, while 62 % presented with CSF leak. The concurrent SSCD group exhibited higher opening pressure, higher likelihood of having dural sinus stenosis, and higher likelihood of being discharged on acetazolamide. The CSF leak group had higher likelihood of obstructive sleep apnea and persistent symptoms. CONCLUSIONS: In patients undergoing tegmen defect repair, concurrent SSCD suggests increased disease severity. The presence of preoperative CSF leak predicts persistent symptoms following repair. BMI is linearly correlated with intracranial pressure in these patients.

The utility of inflammatory biomarkers in predicting overall survival and recurrence in skull base chordoma.

OBJECTIVE: Numerous studies have investigated the impact of inflammatory factors in cancer, yet few attempts have been made to investigate these markers in skull base chordoma (SBC). Inflammatory values including neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), lymphocyte-monocyte ratio (LMR), systemic immune inflammation index (SII), and systemic inflammation response index (SIRI) can serve as prognostic markers in various cancers. This study aimed to determine whether these inflammatory factors influence overall survival (OS) or progression-free survival (PFS) in patients with primary SBC. METHODS: The electronic medical records of patients with primary SBC who underwent resection from 2001 to 2020 were retrospectively reviewed for the associations of sex, age at diagnosis, preoperative steroid use, tumor volume, extent of resection, adjuvant radiation after surgery, tumor metastasis, Ki-67 index, percent homozygous deletion of 9p23 and percent 1p36 loss, and potential prognostic inflammatory markers of NLR, PLR, LMR, SII, and SIRI with the primary outcome measures of OS and PFS. Maximum log-rank statistical tests were used to determine inflammatory marker thresholds for grouping prior to Kaplan-Meier and Cox proportional hazards analysis for OS and PFS of the elucidated groups. RESULTS: The cohort included 115 primary SBC patients. The mean ± SD tumor volume was 23.0 ± 28.0 cm3, 73% of patients received gross-total resection, 40% received postoperative radiation, 25% had local recurrence, and 6% had subsequent metastatic disease (mean follow-up 47.2 months). Univariable Cox analysis revealed that NLR (p < 0.01), PLR (p = 0.04), LMR (p = 0.04), SII (p < 0.01), and SIRI (p < 0.01) were independently associated with PFS. Additionally, NLR (p = 0.05) and SII (p = 0.03) were significant in multivariable Cox analysis of PFS. However, both univariable and multivariable Cox analysis revealed no correlations with OS. CONCLUSIONS: The routine assessment of inflammatory biomarkers such as NLR and SIRI could have prognostic value in postresection SBC patients.

Immunotherapy in the Management of Sinonasal Mucosal Melanoma: A Systematic Review.

OBJECTIVE: The aim of this work is to comprehensively review and synthesize the literature related to sinonasal mucosal melanoma (SNMM) treatment with immunotherapy, including potentially targetable genetic mutations, survival outcomes, and adverse events. DATA SOURCES: Embase, Cochrane, Scopus, and Web of Science. REVIEW METHODS: The study protocol was designed according to Preferred Reporting Items for Systematic Reviews and Meta-analysis statement. Databases were searched from inception through May 23, 2023. RESULTS: A total of 42 studies met inclusion criteria. Twenty-four of the included studies reported genetic mutations for a combined 787 patients with SNMM. 8.1% (95% confidence interval, CI: 7.6-8.6), 18.9% (95% CI: 18.1-19.8), and 8.5% (95% CI: 8.1-9.0) of reported patients were positive for BRAF, NRAS, and KIT mutations, respectively. The presence of brisk tumor-infiltrating lymphocytes was associated with improved recurrence-free survival and overall survival (OS). Six studies reported a combined 5-year OS after adjuvant immunotherapy treatment of 42.6% (95% CI: 39.4-45.8). Thirteen studies encompassing 117 patients reported adjuvant or salvage immune checkpoint inhibitor (ICI) immunotherapy response rates: 40.2% (95% CI: 36.8-43.6) had a positive response (tumor volume reduction or resolution). Eleven studies reported direct comparisons between SNMM patients treated with or without immunotherapy; the majority (7/11) reported survival benefit for their entire cohort or select subgroups of SNMM patients. With the transition to modern ICIs, there is a stronger trend toward survival improvement with adjuvant ICI. Tumors with Ki67 <40% may respond better to ICI's. CONCLUSION: ICI therapy can be an effective in select SNMM patients, especially those with advanced/metastatic disease.

Anterolateral keyhole transorbital routes to the skull base: a comparative anatomical study.

OBJECTIVE: Although keyhole transorbital approaches are gaining traction, their indications have not been adequately studied comparatively. In this study the authors have defined them also as transwing approaches-meaning that they use the different facies of the sphenoid wing for cranial entry-and sought to compare the four major ones: 1) lateral orbitocraniotomy through a lateral canthal incision (LatOrb); 2) modified orbitozygomatic approach through a palpebral incision (ModOzPalp); 3) modified orbitozygomatic approach through an eyebrow incision (ModOzEyB); and 4) supraorbital craniotomy through an eyebrow incision (SupraOrb), coupled with its expanded version (SupraTransOrb). METHODS: Cadaveric dissections were performed at the neuroanatomy lab. To delineate the skull base exposure, four formalin-fixed heads were used, with two sides dedicated to each approach. The outer limits were assessed via image guidance and were mapped and illustrated accordingly. A fifth head was dissected purely endoscopically, just to facilitate an overview of the transwing concept. Qualitative features were also rigorously examined. RESULTS: The LatOrb proves to be more versatile in the middle cranial fossa (MCF), whereas the anterior cranial fossa (ACF) exposure is limited to a small area above the sphenoid ridge. An anterior clinoidectomy is possible; however, the exposure of the roof of the optic canal is suboptimal. The ModOzPalp adequately exposes both the ACF and MCF. Its lateral trajectory allows the inferior to superior view, yet there is restricted access to the medial anterior skull base (olfactory groove). The ModOzEyB also provides extensive exposure of the ACF and MCF, but has a more superior to inferior trajectory compared to the ModOzPalp, making it more appropriate for pathology reaching the medial anterior skull base or even the contralateral side. The anterior clinoidectomy is performed with improved visualization of the optic canal. The SupraOrb provides mainly anterior cranial base exposure, with minimal middle fossa. An anterior clinoidectomy can be performed, but without any direct observation of the superior orbital fissure. Some MCF access can be accomplished if the lateral sphenoid wing is drilled inferiorly, leading to its highly versatile variant, the SupraTransOrb. CONCLUSIONS: All the aforementioned approaches use the sphenoid wing as skull base corridor from a specific orientation point; hence these are designated as transwing approaches. Their peculiarities mandate careful case selection for the effective and safe completion of the surgical goals.

Empty sella in somatotropic pituitary adenomas; a series of 23 cases.

Purpose: We aimed to investigate empty sella syndrome in somatotrophic pituitary adenoma for possible etiology, complications, and treatment options. Method: Among over 2,000 skull base masses that have been managed in our center since 2013, we searched for growth hormone-producing adenomas. Clinical, surgical, and imaging data were retrospectively collected from hospital records to check for sella that lacked pituitary tissue on routine imaging. Result: In 220 somatotrophic adenomas, 23 patients had an empty sella with surgical and follow-up data. The mean age of the sample was 46 years with the same male-to-female ratio. Five cases had partial empty sella and the rest were complete empty sellas. The most common simultaneous hormonal disturbance was high prolactin levels. Six had adenoma invasion into the clivus or sphenoid sinus and 10 had cavernous sinus intrusion. Peri-operative low-flow and high-flow cerebrospinal fluid (CSF) leaks were encountered in one and two patients, respectively, which were successfully sealed by abdominal fat. The majority of cases required growth hormone replacement therapy while it was controlled without any replacement therapy in nine patients. No pituitary hormonal disturbance occurred after transsphenoidal surgery except for hypothyroidism in one patient. Conclusion: An empty sella filled with fluid can be detected frequently in pituitary adenomas, especially in the setting of acromegaly. The pituitary gland may be pushed to the roof of the sella and might be visible as a narrow rim on imaging or may be detected in unusual places out of the sella. The pathophysiology behind such finding originates from soft and hard tissue changes and CSF pressure alternations during abundant growth hormone production.

A novel classification and management scheme for craniocervical junction disorders with ventral neural element compression.

OBJECTIVE: Craniocervical junction (CCJ) pathologies with ventral neural element compression are poorly understood, and appropriate management requires accurate understanding, description, and a more uniform nomenclature. The aim of this study was to evaluate patients to identify anatomical clusters and better classify CCJ disorders with ventral compression and guide treatment. METHODS: A retrospective review of adult and pediatric patients with ventral CCJ compression from 2008 to 2022 at a single center was performed. The incidence of anatomical abnormalities and compressive etiologies was assessed. Surgical approach, radiographic data, and outcomes were recorded. Association rules analysis (ARA) was used to assess variable clustering. RESULTS: Among 51 patients, the main causes of compression were either purely bony (retroflexed dens [n = 18]; basilar invagination [BI; n = 13]) or soft tissue (degenerative pannus [n = 16]; inflammatory pannus [n = 2]). The primary cluster in ARA was a retroflexed dens, platybasia, and Chiari malformation (CM), and the secondary cluster was BI, C1-2 subluxation, and reducibility. These, along with degenerative pannus, formed the three major classes. In assessing the optimal treatment strategy, reducibility was evaluated. Of the BI cases, 12 of the 13 patients had anterolisthesis of C1 that was potentially reducible, compared with 2 of the 18 patients with a retroflexed dens (both with concomitant BI), and no pannus cases. The mean C1-2 facet angle was significantly higher in BI at 32.4°, compared with -2.3° in retroflexed dens and 8.1° in degenerative pannus (p < 0.05). Endonasal decompression with posterior fixation was performed in 48 (94.0%) of the 51 patients, whereas posterior reduction/fixation alone was performed in 3 patients (6.0%). Of 16 reducible cases, open posterior reduction alone was successful in 3 (60.0%) of 5 cases, with all successes containing isolated BI. Reduction was not attempted if vertebral anatomy was unfavorable (n = 9) or the C1 lateral mass was absent (n = 5). The mean follow-up was 28 months. Symptoms improved in 88.9% of patients and were stable in the remaining 11.1%. Tracheostomy and percutaneous G-tube placement occurred in 7.8% and 11.8% of patients, respectively. Reoperation for an endonasal CSF leak repair or posterior cervical wound revision both occurred in 3.9% of patients. CONCLUSIONS: In classifying, one cluster caused decreased posterior fossa volume due to an anatomical triad of retroflexed dens, platybasia, and CM. The second cluster caused pannus formation due to degenerative hypertrophy. For both, endonasal decompression with posterior fixation was ideal. The third group contained C1 anterolisthesis characterized by a steep C1-2 facet angle causing reducible BI. Posterior reduction/fixation is the first-line treatment when anatomically feasible or endonasal decompression with in situ posterior fixation when anatomical constraints exist.

Toward Optimized and Cost-Efficient Protocols for Inferior Petrosal Sinus Sampling in the Diagnosis of Cushing Disease.

BACKGROUND AND OBJECTIVE: Conventional protocols for inferior petrosal sinus sampling (IPSS) during the workup of hypercortisolemia require adrenocorticotrophic hormone (ACTH) measurement at multiple time points with corticotropic-releasing hormone (CRH) used as a stimulator. Modernized evidence-based protocols must also reflect the increased utilization of desmopressin (DDAVP) for ACTH stimulation as the manufacturing shortage of traditionally used CRH continues. We model the diagnostic accuracy and potential economic savings of DDAVP utilization and reduced time point sampling. METHODS: A single-institution, retrospective review of patients undergoing IPSS between 2007 and 2021 was performed. A computational search for the minimal set of time points which preserves conventional diagnostic accuracy was performed by testing all 1 through 5-point combinations generated using a binomial expansion. Economic savings were modeled using a publicly available hospital chargemaster. RESULTS: A total of 50 patients qualified for inclusion, 47 of whom were diagnosed with Cushing disease and 3 with ectopic Cushing syndrome. Single-point diagnostic accuracy for DDAVP-stimulated tests was 71.4%-92.9%, and seven 2-point combinations (5-25 procedural minutes) were found, which preserved conventional diagnostic accuracy. Single-point accuracy for CRH-stimulated tests was 67.9%-89.3%, and two 2-point combinations ( t = -15, t = +2 and t = -15, t = +10) preserved accuracy. For every time point removed, the cost of ACTH laboratory tests was reduced by $507 from $3042 for 6-point IPSS). The shortest and most economical stimulator and time point combination that preserved conventional accuracy was DDAVP sampling at t = 0 and t = +5 or t = +2 and t = +5 minutes, which cost $2028 total compared with the most expensive 6-point IPSS option with CRH ($6392). CONCLUSION: DDAVP is a cost-efficient and effective alternative to CRH during IPSS. Our results encourage prospective evaluation of potentially fewer sampling time points in the interest of time and cost efficiency balanced with preserved accuracy.

Anteromedial Petrous (Gardner's) Triangle: Surgical Anatomy and Relevance for Endoscopic Endonasal Approach to the Petrous Apex and Petroclival Region.

BACKGROUND AND OBJECTIVES: Triangular corridors have been used as reliable surgical entry points for open transcranial approaches to the petrous apex (PA) and petroclival region (PCR). The endoscopic endonasal approaches have grown rapidly in the last decade, and the indications have advanced. The knowledge of accurate and reliable anatomic landmarks through endoscopic endonasal route is essential and remain to be established. The purpose of this study was to describe the feasibility and surgical exposure of the anteromedial petrous (Gardner's) triangle as a novel corridor to the PA and PCR. METHODS: Five anatomic specimens were dissected. The PA and PCR were accessed through endoscopic endonasal approaches and contralateral transmaxillary approach. The limits of the anteromedial petrous (Gardner's) triangle were identified and dissected and associated measurements performed. RESULTS: The dissection was divided into 6 steps. The limits of the anteromedial petrous (Gardner's) triangle were identified and defined by the paraclival internal carotid artery anterolaterally, the abducens nerve posteromedially, and the petroclival synchondrosis inferiorly. Three lines were established following the limits of the triangle. The mean distance of the anterolateral limit was 10.03 mm (SD = 0.94), of the posteromedial limit was 20.06 mm (SD = 2.90), and of the inferior limit was 17.99 mm (SD = 2.99). The mean area was 87.56 mm 2 (SD = 20.06). The 3 anatomic landmarks with a critical role to safely define the triangle were the pterygosphenoidal fissure, the petrosal process of the sphenoid bone, and the petroclival synchondrosis. CONCLUSION: The anteromedial (Gardner's) triangle is a well-defined bone corridor which provides access to the entire petrous bone and petroclival junction through endoscopic endonasal route. Regardless of the anatomic variations or tumor location, the landmarks of the abducens nerve, paraclival internal carotid artery, and petroclival synchondrosis are key for understanding lateral access to tumors extending from the clivus.

Incidence of postoperative hyponatremia after endoscopic endonasal pituitary transposition for skull base pathologies.

PURPOSE: Pituitary transposition is a novel surgical approach to access the retroinfundibular space and interpeduncular cistern. Few studies have evaluated post-surgical outcomes, including incidence of hyponatremia, following pituitary transposition. METHODS: This is a retrospective study including 72 patients who underwent endoscopic endonasal surgery involving pituitary transposition for non-pituitary derived tumors over a decade at the University of Pittsburgh Medical Center. Anterior pituitary deficiencies and replacement therapy, tumor pathology and pre-operative serum sodium (Na) were recorded. Na was assessed at postoperative day 1, 3, 5, 7, and 10. Anatomical/surgical parameters included sellar height, sellar access angle to approach the tumor, and cranial extension of the tumor above the sellar floor (B) compared to the height of the gland (A) (B/A). T-test (normally distributed variables) and Wilcoxon rank-sum test (not-normally distributed) were applied for mean comparison. Logistic regression analyzed correlations between anatomical/surgical parameters and postoperative hyponatremia. RESULTS: 55.6% of patients developed post-operative transient hyponatremia. Two patients (5%) developed severe hyponatremia (sodium level < 120 mmol/L). Eleven (15.3%) patients required desmopressin replacement immediately post-operatively, and 2 other patients needed desmopressin after discharge and after sodium nadir developed. Hyponatremia was inversely associated with sellar access angle (p = 0.02) and the tumor cranial extension above the sellar floor showing a trend towards significance (p = 0.09). CONCLUSION: More than half of patients who had pituitary transposition developed transient hyponatremia. Hyponatremia was more common in those with narrower sellar access angle and smaller cranial extension of the tumor above the sellar floor. Anatomical/surgical parameters may allow risk-stratification for post-operative hyponatremia following pituitary transposition.

Endoscopic endonasal repair of encephaloceles of the lateral sphenoid sinus: multiinstitution confirmation of a new classification.

OBJECTIVE: Encephaloceles of the lateral sphenoid sinus are rare. Originally believed to be due to defects in a patent lateral craniopharyngeal canal (Sternberg canal), they are now thought to originate more commonly from idiopathic intracranial hypertension, not unlike encephaloceles elsewhere in the skull base. A new classification of these encephaloceles was recently introduced, which divided them in relation to the foramen rotundum. Whether this classification can be applied to a larger cohort from multiple institutions and whether it might be useful in predicting outcome is unknown. Thus, the authors' goal was to divide a multiinstitutional cohort of patients with lateral sphenoid encephaloceles into four subtypes to determine their incidence and any correlation with surgical outcome. METHODS: A multicenter retrospective review of prospectively acquired databases was carried out across three institutions. Cases were categorized into one of four subtypes (type I, Sternberg canal; type II, medial to rotundum; type III, lateral to rotundum; and type IV, both medial and lateral with rotundum enlargement). Demographic and outcome metrics were collected. Kaplan-Meyer curves were used to determine the rate of recurrence after surgical repair. RESULTS: A total of 49 patients (71% female) were included. The average BMI was 32.8. All encephaloceles fell within the classification scheme. Type III was the most common (71.4%), followed by type IV (16.3%), type II (10.2%), and type I (2%). Cases were repaired endonasally, via a transpterygoidal approach. Lumbar drains were placed in 78% of cases. A variety of materials was used for closure, with a nasoseptal flap used in 65%. After a mean follow-up of 47 months, there were 4 (8%) CSF leak recurrences, all in patients with type III or type IV leaks and all within 1 year of the first repair. Two leaks were fixed with ventriculoperitoneal shunt and reoperation, 1 with ventriculoperitoneal shunt only, and 1 with a lumbar drain only. Of 45 patients in whom detailed information was available, there were 12 (26.7%) with postoperative dry eye or facial numbness, with facial numbness occurring in type III or type IV defects only. CONCLUSIONS: Endoscopic endonasal repair of lateral sphenoid wing encephaloceles is highly successful, but repair may lead to dry eye or facial numbness. True Sternberg (type I) leaks were uncommon. Failures and facial numbness occurred only in patients with type III and type IV leaks.

Endoscopic Endonasal Far-Medial Approach: 2-Dimensional Operative Video.

INDICATIONS CORRIDOR AND LIMITS OF EXPOSURE: Endoscopic endonasal far-medial approach provides an effective and safe corridor to access the parasagittal structures of the lower clivus such as the medial jugular tubercle (JT) and occipital condyle (OC) for lesions that displace neurovascular structures laterally. ANATOMIC ESSENTIALS NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT: Parapharyngeal internal carotid arteries (ICAs) run posterolateral to the eustachian tubes and lateral to the OC. The supracondylar groove is a superficial landmark for the hypoglossal canal, which divides the lateral extension of clivus into the JT and OC. ESSENTIAL STEPS OF THE PROCEDURE: Typically, approach starts with opening of the sphenoid sinus to localize the paraclival ICA. An "inverted U" rhinopharyngeal (RP) flap exposing the supracondylar groove and lower clivus. Doppler and navigation can confirm the course of the ICA. Drilling is started in the midline in the lower clivus and extended laterally to expose the hypoglossal canal, JT, and OC. PITFALLS/AVOIDANCE OF COMPLICATIONS: Neurovascular injuries can be avoided by using intraoperative Doppler and nerve stimulator. Multilayer reconstruction with vascularized nasoseptal (NSF) and RP flaps minimize postoperative cerebrospinal fluid leak. VARIANTS AND INDICATIONS FOR THEIR USE: The contralateral transmaxillary approach provides an increased angle of access behind foramen lacerum and the petrous ICA.The endoscopic endonasal far-medial approach can be used for a variety of pathologies, including petroclival or JT meningiomas, chordomas and chondrosarcomas, and hypoglossal schwannomas, inferiorly extending cholesterol granulomas and even rare, ventral posterior inferior cerebellar artery aneurysms.The patients consented to the procedure.

Electromyographic predictors of abducens nerve palsy after endoscopic skull base surgery.

OBJECTIVE: Recovery of abducens nerve palsy (ANP) after endoscopic endonasal skull base surgery (ESBS) has been shown to be potentially predicted by postoperative ophthalmological examination. Triggered electromyography (t-EMG) and free-run electromyography (f-EMG) activity provide an intraoperative assessment of abducens nerve function, but associations with long-term ANP outcomes have not been explored. The objective of this study was to describe intraoperative abducens EMG characteristics and determine whether these electrophysiological profiles are associated with immediately postoperative and long-term ANP outcomes after ESBS. METHODS: The authors conducted a 5-year (2011-2016) retrospective case-control study of patients who underwent ESBS in whom the abducens nerve was stimulated (t-EMG). Electrophysiological metrics were compared between patients with a new postoperative ANP (cases) and those without ANP (controls). Pathologies included chordoma, pituitary adenoma, meningioma, cholesterol granuloma, and chondrosarcoma. Electrophysiological data included the presence of abnormal f-EMG activity, t-EMG stimulation voltage, stimulation threshold, evoked compound muscle action potential (CMAP) amplitude, onset latency, peak latency, and CMAP duration at various stages of the dissection. Controls were selected such that pathologies were similarly distributed between cases and controls. RESULTS: Fifty-six patients were included, 26 with new postoperative ANP and 30 controls without ANP. Abnormal f-EMG activity (28.0% vs 3.3%, p = 0.02) and lack of response to stimulation (27% vs 0%, p = 0.006) were more frequent in patients with immediately postoperative ANP than in controls. Patients with immediately postoperative ANP also had a lower median CMAP amplitude (35.0 vs 71.2 µV, p = 0.02) and longer onset latency (5.2 vs 2.8 msec, p = 0.04). Comparing patients with transient versus persistent ANP on follow-up, those with persistent ANP tended to have a lower CMAP amplitude (12.8 vs 57 µV, p = 0.07) and higher likelihood of not responding to stimulation at the end of the case (45.5% vs 7.1%, p = 0.06). Abnormal f-EMG was not associated with long-term ANP outcomes. CONCLUSIONS: The presence of f-EMG activity, lack of CMAP response to stimulation, decreased CMAP amplitude, and increased CMAP onset latency were associated with immediately postoperative ANP. Long-term ANP outcomes may be associated with t-EMG parameters, including whether the nerve is able to be stimulated once identified and CMAP amplitude. Future prospective studies may be designed to standardize abducens nerve electrophysiological monitoring protocols to further refine operative and prognostic utility.

Trigeminal Schwannoma: A Retrospective Analysis of Endoscopic Endonasal Management, Treatment Outcomes, and Neuropathic Sequelae.

Introduction Trigeminal schwannomas (TS) are rare skull base tumors that have been associated with significant neuropathic sequalae for patients. The authors aim to evaluate the clinical features, treatment outcomes, and neuropathic sequelae following endoscopic endonasal approach (EEA) for TS. Methods The study involves a retrospective review of patients who underwent EEA for resection of TS at a single academic institution between 2004 and 2020. Radiographic and clinical data were recorded and analyzed. Results A total of 16 patients were abstracted, with a mean age at the time of surgery of 44 years with a slight female (1.83:1) predominance. Primary preoperative symptomatology included facial pain/neuralgia ( n = 5, 31.3%), facial hypoesthesia ( n = 4, 25.0%), and headache ( n = 4, 25.0%). Following TS resection, patients were found to have facial hypoesthesia ( n = 11, 68.8%), neuropathic keratopathy ( n = 4, 25.0%), and mastication musculature atrophy ( n = 3, 18.8%). Patients with preoperative facial pain/neuralgia ( n = 5, 31.3%) were significantly more likely to try adjunctive pain therapies ( p = 0.018) as well as seek pain consultation ( p = 0.018). Patients with preoperative migraines ( n = 2, 12.5%) were significantly more likely to trial adjunctive pain therapies ( p = 0.025) and undergo evaluation with pain specialists ( p = 0.025). Finally, patients with preoperative pharmacologic agent utilization were significantly more likely to trial adjunctive pain therapies ( p = 0.036) and pursue pain consultation ( p = 0.036). Conclusion Some degree of trigeminal dysfunction may be more common than previously reported following EEA for TS resection. Factors that appear to play a role in the development of trigeminal dysfunction include pre-existing pain syndromes such as facial pain/neuralgia or headache and preoperative medication utilization.