Faculty Bibliography

BACKGROUND AND OBJECTIVES/OBJECTIVE:Adult biomechanical studies suggest a significant reduction in flexion-extension motion after occipitocervical and atlantoaxial fusion. Anecdotal experience in children suggests a lower magnitude of reduction in motion after these procedures, but high-quality quantitative assessments of this motion have not yet been performed. As such, the aim of this study was to determine the magnitude of reduction in cervical spine flexion-extension after O-C2 and C1-2 fusion in pediatric patients. METHODS:The Pediatric Spine Study Group international registry was queried for patients aged 21 years or younger who underwent O-C2 or C1-2 instrumentation and fusion. Patients with cervical spine flexion-extension radiographs preoperatively and ≥6 months postoperatively were included. Flexion, extension, and overall range of motion (ROM) of the cervical spine were measured on radiographs using McGregor line and the inferior endplate of C7. RESULTS:In total, 34 patients were included, with 19 undergoing index O-C2 and 15 undergoing index C1-2 stabilization. The mean age was 9.3 ± 4.5 years with average follow-up of 3.5 ± 2.6 years. The most common etiologies were syndromic (n = 20) and congenital (n = 9). Patients undergoing O-C2 fusion had reduced neck extension (80° vs 69.6°, P = .003) and overall ROM (92.9° vs 80°, P = .002) after stabilization, but no significant reduction in flexion (-12.9° vs -10.4°, P = .324). After C1-2 fusion, there was no significant reduction in overall ROM (85.0° vs 77.5°, P = .079), extension (70.5° vs 63.4°, P = .120), or flexion (-14.6° vs -14.0°, P = .831). CONCLUSION/CONCLUSIONS:In this cohort, children undergoing O-C2 stabilization had a 13.9% reduction in flexion-extension motion of the cervical spine, primarily due to a reduction in extension. There may be a smaller reduction in flexion-extension motion after stabilization in children when compared with adult studies. Further studies with video analysis including axial rotation and lateral bending will be necessary to comprehensively quantify cervical spine motion after fusion across the occipitocervical and atlantoaxial junctions.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Hydrocephalus after Gamma Knife® stereotactic radiosurgery (SRS) for vestibular schwannomas is a rare but manageable occurrence. Most series report post-SRS communicating hydrocephalus in about 1% of patients, thought to be related to a release of proteinaceous substances into the cerebrospinal fluid. While larger tumor size and older patient age have been associated with post-SRS hydrocephalus, the influence of baseline ventricular anatomy on hydrocephalus risk remains poorly defined. METHODS:A single-institution retrospective cohort study examining patients who developed symptomatic communicating hydrocephalus after undergoing Gamma Knife® SRS for unilateral vestibular schwannomas from 2011 to 2021 was performed. Patients with prior hydrocephalus and cerebrospinal fluid diversion or prior surgical resection were excluded. Baseline tumor volume, third ventricle width, and Evans Index (EI)-maximum width of the frontal horns of the lateral ventricles/maximum internal diameter of the skull-were measured on axial postcontrast T1-weighted magnetic resonance imaging. RESULTS:A total of 378 patients met the inclusion criteria; 14 patients (3.7%) developed symptomatic communicating hydrocephalus and 10 patients (2.6%) underwent shunt placement and 4 patients (1.1%) were observed with milder symptoms. The median age of patients who developed hydrocephalus was 69 years (IQR, 67-72) and for patients younger than age 65 years, the risk was 1%. For tumor volumes <1 cm3, the risk of requiring shunting was 1.2%. The odds of developing symptomatic hydrocephalus were 5.0 and 7.7 times higher in association with a baseline EI > 0.28 (P = .024) and tumor volume >3 cm3 (P = .007), respectively, in multivariate analysis. Fourth ventricle distortion on pre-SRS imaging was significantly associated with hydrocephalus incidence (P < .001). CONCLUSION/CONCLUSIONS:Patients with vestibular schwannoma with higher baseline EI, larger tumor volumes, and fourth ventricle deformation are at increased odds of developing post-SRS hydrocephalus. These patients should be counseled regarding risk of hydrocephalus and carefully monitored after SRS.

BACKGROUND:Aneurysmal bone cysts (ABCs) are slow-growing, expansile bone tumors most often observed in the long bones and lumbar and thoracic spine. Anterior column ABCs of the spine are rare, and few cases have described their surgical management, particularly for lesions with extension into the odontoid process and the bilateral C2 pedicles. In the present case, the authors describe a two-stage strategy for resection of a symptomatic 2.3 × 3.3 × 2.7-cm C2 ABC with cord compression in a 13-year-old patient. OBSERVATIONS/METHODS:Initial tumor debulking was completed via a transoral approach, and resection of the involved region spanning the odontoid process to the C2-3 disc space was continued until visualization of the posterior longitudinal ligament. After appropriate decompression was confirmed, the patient was repositioned prone for removal of the residual tumor among the bilateral C2 pedicles. Posterior instrumentation was placed from the occiput to C4, with an autologous rib graft to encourage fusion. The postoperative recovery was uneventful, and 2-month imaging demonstrated postsurgical changes, resolution of compression, and a stable position of the instrumentation and graft material. LESSONS/CONCLUSIONS:The transoral approach facilitates sufficient exposure for the resection of large odontoid ABCs, and posterior stabilization can reduce the risk of postsurgical cervical subluxation. https://thejns.org/doi/10.3171/CASE2485.

The authors present a historical overview of NYU-Bellevue Neurosurgery, highlighting key events and influential faculty. Bellevue Hospital, the first public hospital in the US, was established in 1736 and has grown via its affiliation with New York University (now NYU Langone Health) from 1898 to the present. It maintains a strong commitment to serving disadvantaged populations of New York City and beyond. NYU-Bellevue Neurosurgery began as a department in 1951 under Dr. Thomas Hoen and has since fostered notable faculty and graduates while contributing to the development of clinical neuroscience.

BACKGROUND:Although intracranial arachnoid cysts are often asymptomatic, a small subset of patients develop debilitating symptoms. A cohort of patients with arachnoid cysts with varying presentations underwent endoscopic cystoventriculostomy, with a significant reduction in symptoms. OBSERVATIONS/METHODS:Three patients presented with chronic complaints, all involving headache in addition to other symptoms, and were noted to have large intracranial arachnoid cysts on imaging. Following endoscopic cystoventriculostomy, symptom reduction was both rapid and significant. Postoperative imaging revealed slight changes in cyst size and improvement in mass effect. LESSONS/CONCLUSIONS:Endoscopic cystoventriculostomy for symptomatic arachnoid cysts in adults can decrease the chronic symptoms related to mass effect. Careful planning of the surgical trajectory to target the portion of the arachnoid cyst nearest to the ventricular wall allows for a safe and effective intervention that can lead to significant improvement in symptoms. https://thejns.org/doi/10.3171/CASE24428.

OBJECTIVE:The objective of this study was to report the results of a bibliometric analysis on the modern corpus of literature pertaining to endoscopic third ventriculostomy (ETV). Prior bibliometrics studies on ETV have focused on highly cited articles, but an advanced bibliometric analysis has not yet been conducted. METHODS:The authors queried the Web of Science (WoS) for (ALL = (endoscopic third ventriculostomy)) OR (ALL = (ETV) AND ALL = (neurosurgery)). Articles or reviews published in English were included. Articles, along with their metadata, were exported. Statistical, bibliometric, and network analyses were performed using the Bibliometrix R package and various Python packages. Reference publication year spectroscopy (RPYS), a method that analyzes the frequency with which references are cited in terms of these references' publication years, was employed to explore the historical roots of the field. RESULTS:Between 1994 and 2023, 1663 documents were identified (1382 articles) from 5457 authors. The mean annual growth rate of publications was 4.9%. International coauthorship increased 4-fold over this time period and was noted for 18.95% of published studies from 2011 to 2023. We observed that Child's Nervous System published the most articles, Journal of Neurosurgery (JNS) articles were cited most frequently, and JNS: Pediatrics articles had the highest impact. Female coauthorship increased from < 1% of published studies before 2000 to 19% by 2022, with an increase in female first authorship from 2% in 2005 to 22% in 2022 and at least 1 female coauthor rising from 3% in 2000 to 68% in 2022. Likewise, minority authorship has increased, as in the early ETV literature > 75% of authors were White while currently only 43% are White. The authors of this study also identified the most prolific authors on the subject. Early in the publication record, etiological and technical terms such as "aqueductal stenosis" and "technical note" predominated. More recently, "complications," "failure," "success," "neuroendoscopy," and "choroid plexus cauterization" were prominent. Utilizing RPYS, the authors identified 32 articles that comprise the foundational articles on ETV, published between 1966 and 2010. CONCLUSIONS:Interest in ETV increased in the 1990s with the advent of advanced endoscopic technologies-particularly digital video. The focus of research has shifted from etiology to outcomes, complication management, and technical mastery.

OBJECTIVE:Endoscopic third ventriculostomy (ETV) is a treatment option for obstructive hydrocephalus; reported success rates vary. We investigated immediate postoperative magnetic resonance imaging (MRI) to evaluate the role of imaging parameters associated with outcomes. METHODS:Retrospective chart review was performed patients undergoing initial ETV between 2005 -2019. Patients with pre- and postoperative MRI with follow-up >one year were included. The following were noted: changes in subarachnoid CSF, third ventricle diameter (TV), bowing of the TV floor, and postoperative flow void. Kaplan-Meier survival methods were used to assess ETV success, Univariable and multivariable Cox proportional-hazards models were fitted to assess factors contributing to ETV success. RESULTS:Fifty-eight subjects were included. Nineteen (32.8%) experienced failure within one year, individually, no single imaging parameter predicted success. However, all cases with failure had no identifiable flow void. Any postoperative radiological change was not consistently associated with decreased odds of failure. Obstructive hydrocephalus treated with ETV demonstrated significantly better ETV success than patients treated for non-obstructive hydrocephalus Inter-observer reliability was moderate for two of the radiological variables and substantial for one of the radiological variables. CONCLUSIONS:Individually none of the qualitative radiologic parameters measured in our study predicted ETV success. Absence of a flow void predicted ETV failure, but additional studies are needed to determine its true negative predictive value. Inability to clarify which specific parameter predicts success, reflects the limited role of immediate postoperative imaging in influencing clinical management.

BACKGROUND:Cerebrospinal fluid (CSF) circulates throughout the ventricles, cranial and spinal subarachnoid spaces, and central spinal cord canal. CSF protects the central nervous system through mechanical cushioning, regulation of intracranial pressure, regulation of metabolic homeostasis, and provision of nutrients. Recently, investigators have characterized the glial-lymphatic (glymphatic) system, the analog of the lymphatic system in the central nervous system, and described a fourth meningeal layer; the subarachnoid lymphatic-like membrane (SLYM)relevant to the CSF. METHODS:A narrative review was conducted. RESULTS:In this review, we summarize these advances. We describe the development of the original model, controversies, a revised model, and a new conceptual framework. We characterize the biological functions, influence of sleep-wake cycles, and effect of aging with relevance to the glymphatic system. We highlight the role of the glymphatic system in Alzheimer's disease, idiopathic normal pressure hydrocephalus, ischemic stroke, subarachnoid hemorrhage, and traumatic brain injury. Next, we characterize the structure and role of the SLYM. Finally, we explore the relevance of the glymphatic system and SLYM to neurosurgery. CONCLUSIONS:This manuscript will inform clinicians and scientists regarding preclinical and translational advances in the understanding of the structure, dynamics, and function of the CSF.

OBJECTIVE:The purpose of this study was to identify factors associated with fusion success among pediatric patients undergoing occiput-C2 rigid instrumentation and fusion. METHODS:The Pediatric Spine Study Group registry was queried to identify patients ≤ 21 years of age who underwent occiput-C2 posterior spinal rigid instrumentation and fusion and had a 2-year minimum clinical and radiographic (postoperative lateral cervical radiograph or CT scan) follow-up. Fusion failure was defined clinically if a patient underwent hardware revision surgery > 30 days after the index procedure or radiographically by the presence of hardware failure or screw haloing on the most recent follow-up imaging study. Univariate comparisons and multivariable logistic regression analyses were subsequently performed. RESULTS:Seventy-six patients met inclusion criteria. The median age at surgery was 9 years (range 1.5-17.2 years), and 51% of the cohort was male. Overall, 75% of patients had syndromic (n = 41) or congenital (n = 15) etiologies, with the most frequent diagnoses of Down syndrome (28%), Chiari malformation (13%), and Klippel-Feil syndrome (12%). Data were available to determine if there was a fusion failure in 97% (74/76) of patients. Overall, 38% (28/74) of patients had fusion failure (95% CI 27%-50%). Univariate analysis demonstrated that use of a rigid cervical collar postoperatively (p = 0.04) and structural rib autograft (p = 0.02) were associated with successful fusion. Multivariable logistic regression analysis determined that patients who had rib autograft used in surgery had a 73% decrease in the odds of fusion failure (OR 0.27, 95% CI 0.09-0.82; p = 0.02). Age, etiology including Down syndrome, instrumentation type, unilateral instrumentation, use of recombinant human bone morphogenetic protein, and other variables did not influence the risk for fusion failure. CONCLUSIONS:In this multicenter, multidisciplinary, international registry of children undergoing occiput-C2 instrumentation and fusion, fusion failure was seen in 38% of patients, a higher rate than previously reported in the literature. The authors' data suggest that postoperative immobilization in a rigid cervical collar may be beneficial, and the use of structural rib autograft should be considered, as rib autograft was associated with a 75% higher chance of successful fusion.

OBJECTIVE:Pediatric data regarding treatment via an auditory brainstem implant (ABI) remains sparse. The authors aimed to describe their experience at their institution and to delineate associated demographic data, audiometric outcomes, and surgical parameters. METHODS:An IRB-approved, retrospective chart review was conducted among the authors' pediatric patients who had undergone auditory brainstem implantation between 2012 and 2021. Demographic information including sex, age, race, coexisting syndrome(s), history of cochlear implant placement, average duration of implant use, and follow-up outcomes were collected. Surgical parameters collected included approach, intraoperative findings, number of electrodes activated, and complications. RESULTS:A total of 19 pediatric patients had an ABI placed at the authors' institution, with a mean age at surgery of 4.7 years (range 1.5-17.8 years). A total of 17 patients (89.5%) had bilateral cochlear nerve aplasia/dysplasia, 1 (5.3%) had unilateral cochlear nerve aplasia/dysplasia, and 1 (5.3%) had a hypoplastic cochlea with ossification. A total of 11 patients (57.9%) had a history of cochlear implants that were ineffective and required removal. The mean length of implant use was 5.31 years (0.25-10 years). Two patients (10.5%) experienced CSF-related complications requiring further surgical intervention. The most recent audiometric outcomes demonstrated that 15 patients (78.9%) showed improvement in their hearing ability: 5 with sound/speech awareness, 5 able to discriminate among speech and environmental sounds, and 5 able to understand common phrases/conversation without lip reading. Nine patients (47.4%) are in a school for the deaf and 7 (36.8%) are in a mainstream school with support. CONCLUSIONS:The authors' surgical experience with a multidisciplinary team demonstrates that the retrosigmoid approach for ABI placement in children with inner ear pathologies and severe sensorineural hearing loss is a safe and effective treatment modality. Audiometric outcome data showed that nearly 79% of these patients had an improvement in their environmental and speech awareness. Further multicenter collaborations are necessary to improve these outcomes and potentially standardize/enhance electrode placement.