Idiopathic membranous occlusion of the foramen of Monro: an unusual cause of hydrocephalus and headache in adults.

Occlusion of foramen of Monro is an uncommon clinical entity that usually presents in children. Common causes are obstructing mass, infectious etiologies or vascular malformation. Rarely, it may be an idiopathic stricture or membrane. We report a case of idiopathic membranous obstruction of the foramen of Monro in a 45-year-old male with no past medical or surgical history. He presented with new intermittent dull and burning bifrontal severe headache for 2 d, which was alleviated slightly by non-steroidal anti-inflammatory medication. Imaging showed marked dilation of the lateral ventricles with normal third and fourth ventricles. The patient was discharged initially with conservative medical management and close follows up; however, the headache continued to progress and neurosurgical intervention was offered. The patient underwent endoscopic exploration, fenestration of the septum pellucidum, and right ventriculoperitoneal shunt placement. Bilateral membranous obstruction of foramina of Monro and an auto-fenestrated cavum septum pellucidum were identified intraoperatively. The patient reported resolution of headache post-operatively without recurrence on 1-month follow up. This case is unusual in that the patient presented without any known neurologic history or prior intracranial infections. It became apparent at the time of surgery that chronic obstruction of the bilateral foramina with collapse of the third ventricle had developed, and the safest durable treatment for him was septostomy and cerebrospinal fluid (CSF) shunt placement.

Appropriateness of Computed Tomography Scanning in the Diagnosis of Craniosynostosis.

INTRODUCTION: Although physicians from a variety of specialties encounter infants with possible craniosynostosis, judicious use of computed tomography (CT) imaging is important to avoid unnecessary radiation exposure and healthcare expense. The present study seeks to determine whether differences in specialty of ordering physician affects frequency of resulting diagnostic confirmations requiring operative intervention. METHODS: Radiology databases from 2 institutions were queried for CT reports or indications that included "craniosynostosis" or "plagiocephaly." Patient demographics, specialty of ordering physician, confirmed diagnosis, and operative interventions were recorded. Cost analysis was performed using the fixed unit cost for a head CT to calculate the expense before 1 study led to operative intervention. RESULTS: Three hundred eighty-two patients were included. 184 (48.2%) CT scans were ordered by craniofacial surgeons, 71 (18.6%) were ordered by neurosurgeons, and 127 (33.3%) were ordered by pediatricians. One hundred four (27.2%) patients received a diagnosis of craniosynostosis requiring operative intervention. Craniofacial surgeons and neurosurgeons were more likely than pediatricians to order CT scans that resulted in a diagnosis of craniosynostosis requiring operative intervention (P < 0.001), with no difference between craniofacial surgeons and neurosurgeons (P = 1.0). The estimated cost of obtaining an impact CT scan when ordered by neurosurgeons or craniofacial surgeons as compared to pediatricians was $2369.69 versus $13,493.75. CONCLUSIONS: Clinicians who more frequently encounter craniosynostosis (craniofacial and neurosurgeons) had a higher likelihood of ordering CT images that resulted in a diagnosis of craniosynostosis requiring operative intervention. This study should prompt multi-disciplinary interventions aimed at improving evaluation of pretest probability before CT imaging.

Three-dimensional printing and craniosynostosis surgery.

OVERVIEW: The goal of this study was to review the current application and status of three-dimensional printing for craniosynostosis surgery. METHODS: A literature review was performed using the PubMed/MEDLINE databases for studies published between 2010 and 2020. All studies demonstrating the utilization of three-dimensional printing for craniosynostosis surgery were included. RESULTS: A total of 15 studies were ultimately selected. This includes studies demonstrating novel three-dimensional simulation and printing workflows, studies utilizing three-dimensional printing for surgical simulation, as well as case reports describing prior experiences. CONCLUSION: The incorporation of three-dimensional printing into the domain of craniosynostosis surgery has many potential benefits. This includes streamlining surgical planning, developing patient-specific template guides, enhancing residency training, as well as aiding in patient counseling. However, the current state of the literature remains in the validation stage. Further study with larger case series, direct comparisons with control groups, and prolonged follow-up times is necessary before more widespread implementation is justified.

Use of a mini balloon microcatheter to facilitate penetration of fine vascular networks and curative embolization in vein of Galen malformations.

Background Patients with vein of Galen malformations (VOGMs) can develop fine angiogenic networks with fistulous connections to the precursor of the vein of Galen. In these cases, transarterial embolization (TAE) with liquid embolic agents (LEAs) is challenging due to reflux in the pedicle leading to the network, causing poor penetration. Transvenous approaches carry a risk of hemorrhage from pathologic vasculature. Dual-lumen balloon microcatheters like the Scepter Mini (Microvention, Aliso Viejo, CA) improve distal pedicle access, preventing reflux.Objective Here, we report on the use of the Scepter Mini for TAE of angiogenic VOGM.Methods A single-institution retrospective chart review identified all VOGMs treated with Scepter Mini microcatheters. Clinical data, angioarchitecture, and technical parameters were reviewed.Results 17 Scepter Mini catheters were used in 12 embolization procedures of 7 patients with VOGM at a median age of 2.1 years. Patients presented with hydrocephalus (100%) and gross motor and speech delays (57.1%). Networks developed extra-axially into the subependymal zone fed by posterior choroidal, posterior cerebral, and thalamoperforator arteries. Posterior choroidal branches (n=7/17, 41.2%) were most frequently catheterized to achieve distal access to the network. Embolization with Onyx-18 and significant network penetration occurred in 17/17 uses. Near tip entrapment with LEA cast displacement occurred in 1/17 uses. Another patient experienced postprocedural intraventricular hemorrhage requiring a third ventriculostomy without permanent neurologic deficit.Conclusion The Scepter Mini provided excellent distal access with penetration to the fistula and extra-axial network reduction with few complications. The Scepter Mini provides a means for successful treatment of technically challenging angiogenic VOGM.

Milestones for neurosurgery sub-interns: a novel evaluation tool to quantitatively differentiate residency applicants.

OBJECTIVE: The study objective was to create a novel milestones evaluation form for neurosurgery sub-interns and assess its potential as a quantitative and standardized performance assessment to compare potential residency applicants. In this pilot study, the authors aimed to determine the form's interrater reliability, relationship to percentile assignments in the neurosurgery standardized letter of recommendation (SLOR), ability to quantitatively differentiate tiers of students, and ease of use. METHODS: Medical student milestones were either adapted from the resident Neurological Surgery Milestones or created de novo to evaluate a student's medical knowledge, procedural aptitude, professionalism, interpersonal and communication skills, and evidence-based practice and improvement. Four milestone levels were defined, corresponding to estimated 3rd-year medical student through 2nd-year resident levels. Faculty and resident evaluations as well as student self-evaluations were completed for 35 sub-interns across 8 programs. A cumulative milestone score (CMS) was computed for each student. Student CMSs were compared both within and between programs. Interrater reliability was determined with Kendall's coefficient of concordance (Kendall's W). Student CMSs were compared against their percentile assignments in the SLOR using analysis of variance with post hoc testing. CMS-derived percentile rankings were assigned to quantitatively distinguish tiers of students. Students and faculty were surveyed on the form's usefulness. RESULTS: The average faculty rating overall was 3.20, similar to the estimated competency level of an intern. Student and faculty ratings were similar, whereas resident ratings were lower (p < 0.001). Students were rated most highly in coachability and feedback (3.49 and 3.67, respectively) and lowest in bedside procedural aptitude (2.90 and 2.85, respectively) in both faculty and self-evaluations. The median CMS was 26.5 (IQR 21.75-29.75, range 14-32) with only 2 students (5.7%) achieving the highest rating of 32. Programs that evaluated the most students differentiated the highest-performing students from the lowest by at least 13 points. A program with 3 faculty raters demonstrated scoring agreement across 5 students (p = 0.024). The CMS differed significantly between SLOR percentile assignments, despite 25% of students being assigned to the top fifth percentile. CMS-driven percentile assignment significantly differentiated the bottom, middle, and top third of students (p < 0.001). Faculty and students strongly endorsed the milestones form. CONCLUSIONS: The medical student milestones form was well received and differentiated neurosurgery sub-interns both within and across programs. This form has potential as a replacement for numerical Step 1 scoring as a standardized, quantitative performance assessment for neurosurgery residency applicants.

Evaluation of a Role for Virtual Neurosurgical Education for Medical Students Over 2 Years of a Global Pandemic.

BACKGROUND: Subinternships are critical experiences for medical students applying into neurosurgery to acquire knowledge of the field and network with colleagues. During the coronavirus disease 2019 pandemic, in-person rotations were suspended for 2020 and reduced for 2021. In 2020, our department developed a neurosurgical course to address this need. The course was continued in 2021, enabling assessment of student perceptions as the pandemic progresses. METHODS: The virtual course consisted of weekly 1-hour seminars over a 3- to 4-month period. Prior to starting, participants were sent a comprehensive survey assessing their backgrounds, experiences, and confidences in core concepts across neurosurgical subdisciplines. Participants also completed postcourse surveys assessing the course's value and their confidence in the same topics. Responses from students completing both precourse and postcourse surveys were included, analyzed in pairwise fashion, and compared across course years. RESULTS: Students shared similar baseline characteristics in terms of demographics, educational background, and exposure to neurosurgery prior to the course. In the 2020 and 2021 cohorts, quality ratings for presentations were favorable for all seminars, and participants reported significantly increased confidence in core topics across all neurosurgical disciplines after the course (2020: 3.36 ± 0.26, P < 0.0001; 2021: 3.56 ± 0.93, P = 0.005). Most participants felt the course would remain useful following the pandemic in both the 2020 (96.9%) and 2021 (100.0%) cohorts. CONCLUSIONS: Survey results suggest that the course adds value for students seeking a basic didactic curriculum to supplement their education, and perhaps, an online curriculum for medical students would still be beneficial going forward as in-person rotations resume.

Middle Meningeal Artery Embolization for Chronic Subdural Hematoma Using N-Butyl Cyanoacrylate With D5W Push Technique.

BACKGROUND: Middle meningeal artery (MMA) embolization has been recognized as a promising treatment for patients with subdural hematoma (SDH). OBJECTIVE: To present the technical feasibility and efficacy of n-butyl cyanoacrylate (n-BCA) embolization in the largest consecutive cohort to date. METHODS: We retrospectively reviewed our consecutive cases of recurrent SDH treated with MMA embolization using diluted n-BCA with the "sugar rush" technique. In brief, a 2.1-Fr microcatheter was used to selectively catheterize the frontal and posterior branches of the MMA. 5% dextrose in water (D5W) was injected through an intermediate catheter while injecting n-BCA through the microcatheter. Complete obliteration of MMA and lack of SDH recurrence in a 3-6 months follow-up computed tomography scan were defined as efficacy outcomes. Cranial nerve palsy, vision loss, transient neurological deficit, and stroke were defined as safety outcomes. RESULTS: A total of 61 patients were identified with a mean (±standard deviation) age of 62.5 ± 9 years. In 6 patients (10%), coil embolization of the origin of the frontal or posterior branch was performed because super-selective catheterization of the branch was unsuccessful because of tortuous anatomy. Complete obliteration of frontal and posterior branches was achieved in 100% of the cases. Recurrent SDH was seen in 3 patients (5%). No incidence of cranial nerve palsy, vision loss, or stroke occurred. One patient suffered a transient neurological deficit. CONCLUSION: MMA embolization using diluted n-BCA with concomitant D5W injection is associated with a high degree of distal penetration and complete branch occlusion and minimal risk of cranial nerve palsy or other thromboembolic complications.

Bibliometric Evaluation of U.S. Neurosurgery Subspecialties and Academic Rank Using RCR Index.

INTRODUCTION: Academic productivity, a key feature of academic neurosurgery, has been linked to academic rank, subspecialty, and institutional rank. Relative Citation Ratio (RCR) has emerged as a new metric of scholarly output that can make field-normalized comparisons between researchers, a feature unavailable in prior metrics such as h-index. Here we evaluate the influence of academic rank and neurosurgical subspecialties on RCR scores. METHODS: We identified 1640 academic neurosurgeons from 115 ACGME-accredited programs in the United States, along with their neurosurgical specialty and demographic information, using publicly available data. Mean RCR (m-RCR) and weighted RCR (w-RCR) for each neurosurgeon were queried from the iCite database, which included publications from 2002-2020. m-RCR and w-RCR scores were compared across subspecialties and academic rank using multivariable regression while controlling for demographic factors. RESULTS: Multivariable analysis indicated that academic neurosurgeons in general neurosurgery (P = 0.039) and pediatric neurosurgery (P = 0.003) had lower m-RCR scores than their peers in other subspecialties. w-RCR did not differ significantly among subspecialties. Higher academic rank was associated with increased m-RCR (P < 0.05) and w-RCR scores (P < 0.0001). CONCLUSIONS: Professors have a higher m-RCR score relative to assistant professors, while general and pediatric neurosurgery were linked to lower m-RCR values. Although neurosurgical subspecialty choice did not influence w-RCR, a higher w-RCR score corresponded to a higher academic rank. Overall, the RCR metric can be utilized for field-normalized comparisons of faculty who differ in academic rank and subspecialty.

Pineal region tumors: an optimal approach for simultaneous endoscopic third ventriculostomy and biopsy.

OBJECT: Simultaneous endoscopic third ventriculostomy (ETV) and tumor biopsy is a widely accepted therapeutic and diagnostic procedure for patients with noncommunicating hydrocephalus secondary to a pineal region tumor. Multiple approaches have been advocated, including the use of a steerable fiberoptic or rigid lens endoscope via 1 or 2 trajectories. However, the optimal approach has not been established based on the individual anatomical characteristics of the patient. METHODS: A retrospective review of patients undergoing simultaneous ETV and tumor biopsy was undertaken. Preoperative MR images were examined to measure the width of the anterior third ventricle and maximal diameters of the tumor, Monro foramen (right), and massa intermedia. The distances between the tumor and massa intermedia, tumor and anterior commissure, midbrain and massa intermedia, and the dorsum sella and anterior commissure were also recorded. Single and dual trajectory approaches were compared using paired t-tests for each parameter. RESULTS: Over an 8-year interval, 15 patients underwent simultaneous ETV and tumor management. These patients ranged from 6 to 71 years of age (mean 36.7 years); 5 were younger than 18 years of age. Seven were treated using a dual trajectory approach, and 8 were treated using a single trajectory approach. All cases were completed without complications or the need for an additional CSF diversionary procedure within 6 months. The diagnostic yield at biopsy was 86.7%. There were no statistically significant differences between the single and dual trajectory groups for the measured parameters. However, the dual trajectory group demonstrated a larger anterior third ventricular diameter (1.43 vs 1.21 cm, p = 0.29). The single trajectory group trended toward a smaller tumor-anterior commissure interval (2.23 vs 2.51 cm, p = 0.24) and a larger dorsum sella-anterior commissure distance (1.67 vs 1.49 cm, p = 0.28). CONCLUSIONS: These data confirm the safety and diagnostic efficacy of simultaneous ETV and biopsy for tumors of the pineal region. Although no statistically significant differences were seen in the authors' recorded measurements, several trends suggest a role for a tailored approach to selecting a single or dual trajectory approach when using a rigid endoscope.

Student Survey Results of a Virtual Medical Student Course Developed as a Platform for Neurosurgical Education During the Coronavirus Disease 2019 Pandemic.

BACKGROUND: Before the coronavirus disease 2019 (COVID-19) pandemic, medical students training in neurosurgery relied on external subinternships at institutions nationwide for immersive educational experiences and to increase their odds of matching. However, external rotations for the 2020-2021 cycle were suspended given concerns of spreading COVID-19. Our objective was to provide foundational neurosurgical knowledge expected of interns, bootcamp-style instruction in basic procedures, and preinterview networking opportunities for students in an accessible, virtual format. METHODS: The virtual neurosurgery course consisted of 16 biweekly 1-hour seminars over a 2-month period. Participants completed comprehensive precourse and postcourse surveys assessing their backgrounds, confidence in diverse neurosurgical concepts, and opinions of the qualities of the seminars. Responses from students completing both precourse and postcourse surveys were included. RESULTS: An average of 82 students participated live in each weekly lecture (range, 41-150). Thirty-two participants completed both surveys. On a 1-10 scale self-assessing baseline confidence in neurosurgical concepts, participants were most confident in neuroendocrinology (6.79 ± 0.31) and least confident in spine oncology (4.24 ± 0.44), with an average of 5.05 ± 0.32 across all topics. Quality ratings for all seminars were favorable. The mean postcourse confidence was 7.79 ± 0.19, representing an improvement of 3.13 ± 0.38 (P < 0.0001). CONCLUSIONS: Feedback on seminar quality and improvements in confidence in neurosurgical topics suggest that an interactive virtual course may be an effective means of improving students' foundational neurosurgical knowledge and providing networking opportunities before application cycles. Comparison with in-person rotations when these are reestablished may help define roles for these tools.

Giant chondrosarcoma of the falx in an adolescent: A case report.

BACKGROUND: Intracranial chondrosarcomas are slowly growing malignant cartilaginous tumors that are especially rare in adolescents. CASE DESCRIPTION: A 19-year-old woman with no medical history presented with symptoms of intermittent facial twitching and progressive generalized weakness for 6 months. The patient's physical examination was unremarkable. Imaging revealed a large bifrontal mass arising from the falx cerebri, with significant compression of both cerebral hemispheres and downward displacement of the corpus callosum. The patient underwent a bifrontal craniotomy for gross total resection of tumor. Neuropathologic examination revealed a bland cartilaginous lesion most consistent with low-grade chondrosarcoma. Her postoperative course was uneventful, and she was discharged to home on postoperative day 3. CONCLUSION: This is an unusual case of an extra-axial, non-skull base, low-grade chondrosarcoma presenting as facial spasm in an adolescent patient.

Middle Meningeal Artery Embolization of a Pediatric Patient With Progressive Chronic Subdural Hematoma.

BACKGROUND AND IMPORTANCE: Evidence suggests middle meningeal artery (MMA) embolization benefits adult patients with chronic subdural hematoma (CSDH) at high risk for recurrence or hemorrhagic complications. Yet, there has not been any report discussing MMA embolization in the pediatric population. Thus, we present a case of an infant with CSDH successfully managed with MMA embolization without surgical management. CLINICAL PRESENTATION: A 5-mo-old girl with idiopathic dilated cardiomyopathy underwent surgical implantation of a left ventricular assist device for a bridge to heart transplantation. This was complicated by left ventricular thrombus causing stroke. She was placed on dual antiplatelet antithrombotic therapy on top of bivalirudin infusion. She sustained a left middle cerebral artery infarction, but did not have neurological deficits. Subsequent computed tomography scans of the head showed a progressively enlarging asymptomatic CSDH, and the heart transplant was repeatedly postponed. The decision was made to proceed with MMA embolization at the age of 7 mo. Bilateral modified MMA embolization, using warmed, low-concentration n-butyl-cyanoacrylate (n-BCA) from distal microcatheter positioning, allowed the embolic material to close the distal MMA and subdural membranous vasculature. The patient underwent successful heart transplant and the CSDH improved significantly. She remained neurologically asymptomatic and had normal neurological development after the MMA embolization. CONCLUSION: MMA embolization may represent a safe and effective minimally invasive option for pediatric CSDH, especially for patients at high risk for surgery or hematoma recurrence.

Ventrolateral Tonsillar Position Defines Novel Chiari 0.5 Classification.

BACKGROUND: Cervicomedullary compression in young children has been described in the context of Chiari type 1 malformation, with symptoms associated with the extent of tonsillar herniation below McRae line. Historically, Chiari type 1 malformation has been defined by tonsillar herniation of at least 5 mm. However, in certain populations, including very young children, Chiari symptoms may be present without this finding. A new Chiari classification is thus necessary. METHODS: Cases involving patients up to 5 years of age evaluated for possible posterior fossa decompression were retrospectively reviewed. Preoperative symptoms, magnetic resonance imaging findings, surgical management, and short- and long-term outcome and follow-up were recorded. Tonsillar descent and presence of ventral herniation (VH) were recorded. We define VH as the tonsils crossing a line that bisects the caudal medulla at the level of the foramen magnum, thus creating a novel entity, Chiari type 0.5 malformation. Patients with ventrally herniated tonsils were compared with patients exhibiting more typical Chiari morphology. RESULTS: Of 41 cases retrospectively reviewed, 20 met criteria for VH. These differed from cases without VH because of the predominance of medullary symptoms. In the VH cohort, 11 patients underwent surgical decompression with symptom resolution; 9 were initially managed conservatively, but 3 subsequently required surgery. CONCLUSIONS: We define a novel Chiari entity, Chiari type 0.5 malformation, characterized by ventral tonsillar wrapping around the medulla in young children in the absence of classic Chiari type 1 malformation imaging findings. These patients are more likely to present with medullary symptoms than patients without VH. They are also more likely to require surgical decompression and respond favorably to intervention.

Repeat convection-enhanced delivery for diffuse intrinsic pontine glioma.

OBJECTIVE: While the safety and efficacy of convection-enhanced delivery (CED) have been studied in patients receiving single-dose drug infusions, agents for oncological therapy may require repeated or chronic infusions to maintain therapeutic drug concentrations. Repeat and chronic CED infusions have rarely been described for oncological purposes. Currently available CED devices are not approved for extended indwelling use, and the only potential at this time is for sequential treatments through multiple procedures. The authors report on the safety and experience in a group of pediatric patients who received sequential CED into the brainstem for the treatment of diffuse intrinsic pontine glioma. METHODS: Patients in this study were enrolled in a phase I single-center clinical trial using 124I-8H9 monoclonal antibody (124I-omburtamab) administered by CED (clinicaltrials.gov identifier NCT01502917). A retrospective chart and imaging review were used to assess demographic data, CED infusion data, and postoperative neurological and surgical outcomes. MRI scans were analyzed using iPlan Flow software for volumetric measurements. Target and catheter coordinates as well as radial, depth, and absolute error in MRI space were calculated with the ClearPoint imaging software. RESULTS: Seven patients underwent 2 or more sequential CED infusions. No patients experienced Clinical Terminology Criteria for Adverse Events grade 3 or greater deficits. One patient had a persistent grade 2 cranial nerve deficit after a second infusion. No patient experienced hemorrhage or stroke postoperatively. There was a statistically significant decrease in radial error (p = 0.005) and absolute tip error (p = 0.008) for the second infusion compared with the initial infusion. Sequential infusions did not result in significantly different distribution capacities between the first and second infusions (volume of distribution determined by the PET signal/volume of infusion ratio [mean ± SD]: 2.66 ± 0.35 vs 2.42 ± 0.75; p = 0.45). CONCLUSIONS: This series demonstrates the ability to safely perform sequential CED infusions into the pediatric brainstem. Past treatments did not negatively influence the procedural workflow, technical application of the targeting interface, or distribution capacity. This limited experience provides a foundation for using repeat CED for oncological purposes.

Utility of invasive electroencephalography in children 3 years old and younger with refractory epilepsy.

OBJECTIVE: Early surgical intervention for pediatric refractory epilepsy is increasingly advocated as surgery has become safer and data have demonstrated improved outcomes with early seizure control. There is concern that the risks associated with staged invasive electroencephalography (EEG) in very young children outweigh the potential benefits. Here, the authors present a cohort of children with refractory epilepsy who were referred for invasive monitoring, and they evaluate the role and safety of staged invasive EEG in those 3 years old and younger. METHODS: The authors conducted a retrospective review of children 3 years and younger with epilepsy, who had been managed surgically at two institutions between 2001 and 2015. A cohort of pediatric patients older than 3 years of age was used for comparison. Demographics, seizure etiology, surgical management, surgical complications, and adverse events were recorded. Statistical analysis was completed using Stata version 13. A p < 0.05 was considered statistically significant. Fisher's exact test was used to compare proportions. RESULTS: Ninety-four patients (45 patients aged ≤ 3 [47.9%]) and 208 procedures were included for analysis. Eighty-six procedures (41.3%) were performed in children younger than 3 years versus 122 in the older cohort (58.7%). Forty-two patients underwent grid placement (14 patients aged ≤ 3 [33.3%]); 3 of them developed complications associated with the implant (3/42 [7.14%]), none of whom were among the younger cohort. Across all procedures, 11 complications occurred in the younger cohort versus 5 in the older patients (11/86 [12.8%] vs 5/122 [4.1%], p = 0.032). Two adverse events occurred in the younger group versus 1 in the older group (2/86 [2.32%] vs 1/122 [0.82%], p = 0.571). Following grid placement, 13/14 younger patients underwent guided resections compared to 20/28 older patients (92.9% vs 71.4%, p = 0.23). CONCLUSIONS: While overall complication rates were higher in the younger cohort, subdural grid placement was not associated with an increased risk of surgical complications in that population. Invasive electrocorticography informs management in very young children with refractory, localization-related epilepsy and should therefore be used when clinically indicated.

How long is the tail end of the learning curve? Results from 1000 consecutive endoscopic endonasal skull base cases following the initial 200 cases.

OBJECTIVE: Endoscopic endonasal approaches (EEAs) to the skull base have evolved over the last 20 years to become an essential component of a comprehensive skull base practice. Many case series show a learning curve from the earliest cases, in which the authors were inexperienced or were not using advanced closure techniques. It is generally accepted that once this learning curve is achieved, a plateau is reached with little incremental improvement. Cases performed during the early steep learning curve were eliminated to examine whether the continued improvement exists over the "tail end" of the curve. METHODS: A prospectively acquired database of all EEA cases performed by the senior authors at Weill Cornell Medicine/NewYork-Presbyterian Hospital was reviewed. The first 200 cases were eliminated and the next 1000 consecutive cases were examined to avoid the bias created by the early learning curve. RESULTS: Of the 1000 cases, the most common pathologies included pituitary adenoma (51%), meningoencephalocele or CSF leak repair (8.6%), meningioma (8.4%), craniopharyngioma (7.3%), basilar invagination (3.1%), Rathke's cleft cyst (2.8%), and chordoma (2.4%). Use of lumbar drains decreased from the first half to the second half of our series (p <0.05) as did the authors' use of fat alone (p <0.005) or gasket alone (p <0.005) for dural closure, while the use of a nasoseptal flap increased (p <0.005). Although mean tumor diameter was constant (on average), gross-total resection (GTR) increased from 60% in the first half to 73% in the second half (p <0.005). GTR increased for all pathologies but most significantly for chordoma (56% vs 100%, p <0.05), craniopharyngioma (47% vs 0.71%, p <0.05) and pituitary adenoma (67% vs 75%, p <0.05). Hormonal cure for secreting adenomas also increased from 83% in the first half to 89% in the second half (p <0.05). The rate of any complication was unchanged at 6.4% in the first half and 6.2% in the latter half of cases, and vascular injury occurred in only 0.6% of cases. Postoperative CSF leak occurred in 2% of cases and was unchanged between the first and second half of the series. CONCLUSIONS: This study demonstrates that contrary to popular belief, the surgical learning curve does not plateau but can continue for several years depending on the complexity of the endpoints considered. These findings may have implications for clinical trial design, surgical education, and patient safety measures.

Lessons learned in the evolution of endoscopic skull base surgery.

OBJECTIVEEndoscopic skull base surgery (ESBS) is a relatively recent addition to the neurosurgical armamentarium. As with many new approaches, there has been significant controversy regarding its value compared with more traditional approaches to ventral skull base pathology. Although early enthusiasm for new approaches that appear less invasive is usually high, these new techniques require rigorous study to ensure that widespread implementation is in the best interest of patients.METHODSThe authors compared surgical results for ESBS with transcranial surgery (TCS) for several different pathologies over two different time periods (prior to 2012 and 2012-2017) to see how results have evolved over time. Pathologies examined were craniopharyngioma, anterior skull base meningioma, esthesioneuroblastoma, chordoma, and chondrosarcoma.RESULTSESBS offers clear advantages over TCS for most craniopharyngiomas and chordomas. For well-selected cases of planum sphenoidale and tuberculum sellae meningiomas, ESBS has similar rates of resection with higher rates of visual improvement, and more recent results with lower CSF leaks make the complication rates similar between the two approaches. TCS offers a higher rate of resection with fewer complications for olfactory groove meningiomas. ESBS is preferred for lower-grade esthesioneuroblastomas, but higher-grade tumors often still require a craniofacial approach. There are few data on chondrosarcomas, but early results show that ESBS appears to offer clear advantages for minimizing morbidity with similar rates of resection, as long as surgeons are familiar with more complex inferolateral approaches.CONCLUSIONSESBS is maturing into a well-established approach that is clearly in the patients' best interest when applied by experienced surgeons for appropriate pathology. Ongoing critical reevaluation of outcomes is essential for ensuring optimal results.

Beals syndrome with middle and inner ear dysplasia and encephalocele: A case report and review of imaging findings.

A 10-year-old male with history of Beals syndrome presented with hearing loss and was found to have middle and inner ear dysplasia and left temporal encephalocele on imaging. Beals syndrome is a rare autosomal dominant connective tissue disorder caused by a mutation in the fibrillin-2 gene. Skeletal manifestations of Beals have been reported, including anomalies of the long bones, calvarium, and spine. External ear abnormalities with "crumpled ear" deformity are seen in the majority of patients. This is the first case to report imaging findings of the middle and inner ear in a patient with Beals.