Superior semicircular canal dehiscence postoperative outcomes: a case series of 350 repairs.

BACKGROUND: Superior Semicircular Canal Dehiscence (SSCD) is a dehiscence of the otic capsule which normally lies over the superior semicircular canal. This database constitutes the largest series of SSCD patients to date. OBJECTIVE: To determine what preoperative factors, if any, contribute to postoperative outcomes and evaluate symptom resolution in a large SSCD patient cohort. METHODS: A single-institution, retrospective chart review collected patient demographics, intraoperative findings, and pre-and postoperative symptoms. Fisher's exact t-test was performed for unpaired categorical variables, with a significance level of p < 0.05. RESULTS: 350 SSCD repairs were performed. The median age was 52 years (range: 17-86 years, ± 6.4 years), and the median follow-up duration was 4.6 months (range: 0.03-59.5 months, ± 6.8 months). Preoperative hearing loss was significantly associated with female sex (p = 0.0028). The most reported preoperative symptoms were tinnitus (77.4%), dizziness (74.0%), autophony (66.3%), amplification (63.7%), and disequilibrium (62.6%). Between patients who received unilateral versus bilateral SSCD repair, the greatest postoperative symptomatic resolution was seen in autophony (74.9%, p < 0.001), amplification (77.3%, p = 0.00027), hyperacusis (77.4%, p = 0.023), hearing (62.9%, p = 0.0063), and dizziness (54.6%, p < 0.001) for patients with unilateral SSCD repair. CONCLUSION: Surgical repair via the middle cranial fossa approach can significantly resolve auditory, vestibular, and neurological symptoms of patients with SSCD. Although this is one of the largest single-institution SSCD studies to date, future multi-institutional, prospective studies would be beneficial to validate these results.

A Case Series of DuraMatrix-Onlay® Plus in Cranial Surgery Is Associated With a Low Complication Profile.

BACKGROUND: DuraMatrix-Onlay® Plus is a collagen dura membrane derived from purified bovine Achilles tendon. The matrix provides a scaffold for collagen synthesis and is intended to be used as an onlay without the need for dural sutures. The study aims to describe our experience with 33 consecutive patients who underwent a duraplasty procedure using the novel DuraMatrix-Onlay® Plus collagen dura membrane. METHODS: This is a retrospective case series of 33 patients who underwent a duraplasty procedure at a single academic hospital in Los Angeles, CA, USA between May 2016 and March 2017. The primary outcome was the incidence rate of cerebrospinal fluid (CSF) leak. Secondary outcomes included rates of patient infection, dural substitute complication, and removal. RESULTS: Thirty-three patients underwent a duraplasty procedure using the DuraMatrix-Onlay® Plus material. The average age of the patients was 41.12±7.34 years (range 2-75 years). There were 18 (54.5%) females and 15 (45.5%) males. The majority of procedures were elective operations for the resection of a lesion (n=19, 58%), and the average graft size was 17.69±4.73 cm². At an average follow-up of 3 months, there were no postoperative CSF leaks. The rates of patient infection, dural substitute complication, and removal were 6%, 6%, and 3%, respectively. CONCLUSION: DuraMatrix-Onlay® Plus is associated with a low rate of postoperative CSF leakage and an acceptable complication profile. This result supports the use of collagen matrices for dural closure in general neurosurgical procedures.

Gender-Based Disparities in Academic Productivity Arise During Neurosurgery Residency: A Systematic Review.

BACKGROUND: Although female neurosurgery residents are increasing, women remain underrepresented in academic leadership. OBJECTIVES: To assess academic productivity differences between male and female neurosurgery residents. METHODS: We used the Accreditation Council for Graduate Medical Education records to obtain 2021-2022 recognized neurosurgery residency programs. Gender was dichotomized into male/female by male-presenting/female-presenting status. Extracted variables included degrees/fellowships from institutional websites, number of preresidency and total publications from PubMed, and h -indices from Scopus. Extraction occurred from March to July 2022. Residency publication number and h- indices were normalized by postgraduate year. Linear regression analyses were conducted to assess factors associated with numbers of in-residency publications. P < .05 was considered statistically significant. RESULTS: Of 117 accredited programs, 99 had extractable data. Information from 1406 residents (21.6% female) was successfully collected. 19 687 and 3261 publications were evaluated for male residents and female residents, respectively. Male and female residents' median preresidency publication numbers did not significantly differ (M:3.00 [IQR 1.00-8.50] vs F:3.00 [IQR 1.00-7.00], P = .09), nor did their h -indices. However, male residents had significantly higher median residency publications than female residents (M:1.40 [IQR 0.57-3.00] vs F:1.00 [IQR 0.50-2.00], P < .001). On multivariable linear regression, male residents (odds ratio [OR] 2.05, 95% CI 1.68-2.50, P < .001) and residents with more preresidency publications (OR 1.17, 95% CI 1.16-1.18, P < .001) had higher likelihood of publishing more during residency, controlling for other covariates. CONCLUSION: Without publicly available, self-identified gender designation for each resident, we were limited to review/designate gender based on male-presenting/female-presenting status from gender conventions of names/appearance. Although not an ideal measurement, this helped show that during neurosurgical residency, male residents publish significantly more than female counterparts. Given similar preresidency h- indices and publication records, this is unlikely explained by differences in academic aptitude. In-residency gender barriers to academic productivity must be acknowledged and addressed to improve female representation within academic neurosurgery.

Preoperative meningioma vascularity index is associated with significantly increased intraoperative blood loss and greater risk of subtotal resection.

OBJECTIVE: Surgical recovery of meningiomas relies on a variety of factors, including tumor volume, vascularity, embolization status, and blood loss during excision. Although hypervascular meningiomas can potentially be amendable to embolization, methods for determining optimal vascularity for this procedure are currently lacking. Our group previously established the meningioma vascularity index (MVI) as a marker of tumor vascularity. In this study, we aim to build on our previous work and further examine the relationship between MVI and intraoperative estimated blood loss (EBL). METHODS: A retrospective data extraction was conducted between August 2010 and October 2019 from patients undergoing craniotomy for meningioma. Of the 85 intracranial meningiomas included, 39 were embolized. Demographic data, extent of resection, embolization status, and EBL were among the extracted variables. Flow void volumes were measured on T2-weighted MRI images using a segmentation software with a voxel-based segmentation method. RESULTS: MVI was a predictor of EBL within the entire cohort, when controlling for tumor volume (R2 adjusted = 0.26; P = 0.027). A high MVI (> 2.01 cm3) was associated with higher likelihood of receiving subtotal resection (STR) (OR 4.07, 95% CI 1.17-14.15; P = 0.035). Although the mean MVI and tumor volume were higher in the embolized cohort (P = 0.009 and P = 0.005), there were no significant differences in EBL, or blood transfusion rates regardless of embolization status. CONCLUSIONS: MVI may be used as a non-invasive radiological marker to gauge meningioma vascularity, predict EBL, and guide the decision-making process when it comes to embolization and surgical planning.

Epithelial membrane protein 2 (EMP2): A systematic review of its implications in pathogenesis.

OBJECTIVES: Epithelial membrane protein 2 (EMP2) is a cell surface protein composed of approximately 160 amino acids and encoded by the growth arrest-specific 3 (GAS3)/peripheral myelin protein 22 kDa (PMP22) gene family. Although EMP2 expression has been investigated in several diseases, much remains unknown regarding its mechanism of action and the extent of its role in pathogenesis. Our aim was to perform a systematic review on the involvement of EMP2 in disease processes and the current usage of anti-EMP2 therapies. METHODS: A Boolean search of the English-language medical literature was performed. PubMed, Scopus, Cochrane, and Web of Science were used to identify relevant citations. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RESULTS: 52 studies met the inclusion criteria for qualitative analysis. Of those, 28 (53.8%) were human-only studies, 11 (21.2%) were animal-only studies, and 13 (25%) studies included both human and animal models. Furthermore, 34 (65.4%) studies focused on EMP2's role in neoplasms, while the remaining 18 (34.6%) articles evaluated its role in other pathologies. CONCLUSION: Overall, the evidence suggests the mechanisms of action of EMP2 are context dependent. Promising results have been produced by utilizing EMP2 as a biomarker and therapeutic target. More studies are warranted to better understand the mechanism and comprehend the role of EMP2 in the pathogenesis of diseases.

Olfactory ensheathing cells are hybrid glial cells that promote neural repair.

Olfactory ensheathing cells (OECs) are unique glial cells found in both the central and peripheral nervous systems where they support the continuous axonal outgrowth of immature olfactory sensory neurons to their targets. Here we show that following severe spinal cord injury, olfactory bulb-derived OECs transplanted near the injury site modify the normally inhibitory glial scar and facilitate axon regeneration past the scar border and into the lesion center. To understand the mechanisms underlying the reparative properties of such transplanted OECs, we used single-cell RNA-sequencing to study their gene expression programs. Our analyses revealed five diverse subtypes of OECs, each expressing novel marker genes and pathways indicative of progenitor, axonal regeneration and repair, secreted molecules, or microglia-like functions. As expected, we found substantial overlap of OEC genes with those of Schwann cells, but also with astrocytes, oligodendrocytes and microglia. We confirmed established markers on cultured OECs, and then localized select top genes of OEC subtypes in rat olfactory bulb tissue. In addition, we present evidence that OECs secrete both Reelin and Connective tissue growth factor, extracellular matrix molecules which are important for neural repair and axonal outgrowth. Our results support that adult OECs are a unique hybrid glia, some with progenitor characteristics, and that their gene expression patterns indicate diverse functions related to wound healing, injury repair and axonal regeneration.

Assessment of Metabolic Markers and Osteoporosis in 250 Patients with Superior Semicircular Canal Dehiscence Treated With Middle Fossa Craniotomy.

BACKGROUND: Superior semicircular canal dehiscence (SSCD) is caused by bony defects in the osseous shell of the arcuate eminence separating the labyrinth and the intracranial space. This pathologic third window causes hydroacoustic transmission resulting in debilitating symptoms. We examine the pathophysiologic association between metabolic markers, previous medical history, and SSCD symptoms before and after middle fossa craniotomy (MFC) treatment. METHODS: This study was conducted between March 2011 and September 2020 with patients with SSCD who underwent MFC. We used a Fisher test to compare variables, including bilateral SSCD, second surgery, ear anomaly, osteoporosis, arthritis, vitamin D, and preoperative/postoperative symptoms, and others. Point-biserial correlation analysis was performed to test correlations between continuous variables and categorical variables. RESULTS: A total of 250 patients with SSCD underwent MFC repair. There was significant postoperative resolution in all symptoms (P < 0.0001). Laboratory 25-hydroxyvitamin D values correlated with preoperative aural fullness (rpb= 0.29; P = 0.03), and preoperative disequilibrium (rpb= -0.32; P = 0.02). Serum calcium values correlated with preoperative hearing loss (rpb= 0.16; P = 0.02). Osteoporosis history (n = 16; 6%) was more prevalent in female patients (P = 0.0001), associated with higher levels of preoperative hearing loss (odds ratio, 4.56; P = 0.02) and higher postoperative hearing loss resolution (odds ratio, 2.89; P = 0.0509). CONCLUSIONS: Certain metabolic markers may predict SSCD presentation before and after surgery. Previous history of osteoporosis, autoimmune conditions, or arthritis may play a role in SSCD pathophysiology and can help predict clinical outcomes. Future evaluation should take metabolic laboratory values and acquire an exact medical history.

Hypertonic Saline Treatment in Traumatic Brain Injury: A Systematic Review.

Hypertonic saline (HTS) is a widely used adjunct in the treatment of traumatic brain injury (TBI). However, there is significant variability in practice patterns. Toward the goal of optimality and standardization in the use of HTS in TBI, we performed a comprehensive review of clinical protocols reported in the neurosurgical and neurocritical care literature. PubMed, Web of Science, Cochrane, Scopus, and Embase were independently queried between October and November 2021. The PRISMA guidelines were used throughout the screening process. We identified 15 high-quality studies representing data from 535 patients. We extracted patient demographics, Glasgow Coma Scale (GCS) score, mechanism of injury, HTS dosage, and rate of administration. Various HTS concentrations including 3%, 5%, 7.2%, 7.5%, and 20% were used. Modes of HTS administration included bolus (n = 125) and infusion (n = 376). Average length of stay was 22.4 days. Patient GCS score on initiation of HTS was depressed (average mean, 7.15; average median, 4.25 for studies reporting mean and median GCS, respectively). Excluding 2 studies with ambiguous doses, the mean HTS dosage was 2.7 × 102 mL across 8 studies and 2.5 mL/kg across 5 (with average post-HTS osmolality level of 304.6 mOsm/L reported in 3 studies). Infusions of 3% and 7.5% HTS are the most used concentrations given their efficacy in reducing intracranial pressure (ICP) and improving GCS score. In addition, lower HTS concentrations strongly correlated with greater ICP reduction. Therefore, lower concentrations of HTS may be practical therapeutic agents for patients with TBI given their efficacy in ICP reduction and safer complication profile compared with greater HTS concentrations. Evidence-based parametric use of HTS stands to improve patient outcomes by standardization of varied clinical practice.

Stereotactic Radiosurgery for Glomus Jugulare Tumors: Systematic Review and Meta-Analysis.

BACKGROUND: Glomus jugulare tumors (GJTs) are benign paragangliomas of the jugular foramen. Traditional management of these tumors involves surgical resection; however, considering the proximity of these tumors to important neurovasculature, stereotactic radiosurgery (SRS) may be an appropriate noninvasive treatment to consider. The aim of this meta-analysis was to evaluate SRS as a treatment option for GJTs. METHODS: An online search using PubMed, Web of Science, Scopus, and Cochrane databases was performed in March 2019 for articles on radiosurgery treatment of GJTs. The screening process followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. RESULTS: The final analysis comprised 23 studies including 460 patients. Average rates of tinnitus, hearing loss, and lower cranial nerve deficit as presenting symptoms were 56% (95% confidence interval [CI], 46%-66%), 56% (95% CI, 44%-68%), and 42% (95% CI, 31%-54%), respectively. Overall clinical status improvement rate after treatment was 47% (95% CI, 37%-57%). Rates of tinnitus, hearing loss, and lower cranial nerve improvement after treatment were 54% (95% CI, 44%-63%), 28% (95% CI, 19%-40%), and 22% (95% CI, 11%-39%), respectively. The mean follow-up time across studies was 47 months (range, 4-268 months). The aggregate tumor control rate at the time of follow-up was 95% (95% CI, 93%-97%). CONCLUSIONS: The tumor control rate of 95% and 47% symptomatic improvement suggest that SRS may be a suitable treatment modality for these hypervascular skull base tumors. Future studies are warranted to further evaluate the potential role of SRS in management of GJTs.

Superior Semicircular Canal Dehiscence Outcomes in a Consecutive Series of 229 Surgical Repairs With Middle Cranial Fossa Craniotomy.

BACKGROUND: Superior semicircular canal dehiscence (SSCD) is the appearance of a third mobile window between the middle fossa and the superior semicircular canal. Surgical management is indicated in patients with persistent and debilitating symptoms. The purpose of this study was to evaluate the association between preoperative variables that may impact postoperative symptomatic resolution. METHODS: A single-institution retrospective analysis was performed on patients who were surgically treated for SSCD. Patients were divided to different cohorts based on unilateral or bilateral nature of the disease. A P value <0.05 was considered statistically significant. RESULTS: A total of 229 surgical repairs were analyzed. Mean age was 51 years (± 7.8 years), and 55.9% of patients were female. All cohorts were similar with respect to baseline demographics. The most commonly reported preoperative symptoms were tinnitus, dizziness, and autophony. The greatest symptomatic resolution was seen in autophony, internal sound amplification, hyperacusis, and oscillopsia. The unilateral SSCD cohort had significantly higher improvement of autophony (P = 0.003), aural fullness (P = 0.05), tinnitus (P = 0.006), hearing loss (P = 0.02), dizziness (P = 0.006), and headache (P = 0.007), compared with the bilateral SSCD cohorts. Among patients with bilateral disease, those with unilateral surgery reported greater symptomatic resolution with respect to hyperacusis (P = 0.03), hearing loss (P = 0.02), dizziness (P = 0.03), and disequilibrium (P < 0.001), than those with bilateral operations. CONCLUSIONS: Surgical management of SSCD leads to high rates of postoperative symptomatic improvement. Patients with unilateral SSCD benefit greater symptomatic resolution compared to those with bilateral pathology.

Analysis of academic publishing output among 1634 successful applicants in the 2011-2018 neurosurgery residency match.

BACKGROUND: Research productivity is a key criterion for applicant selection reported by residency program directors. Research volume reported on neurosurgery residency applications has risen steadily over the past decade. OBJECTIVE: Perform retrospective bibliographic searches of successful applicants who matched into U.S. neurosurgery residency programs from 2011 to 2018, and assess the relationship between academic publishing and residency placement. METHODS: Gender, MD/PhD status, U.S. News research ranking of medical school, and international medical graduate status (IMG) were determined for 1634 successful applicants from 2011 to 2018. Indexed publications before and after the start of residency were tabulated by Scopus®. Publication counts were stratified by first author, basic/clinical science, case reports, reviews, or other research. We then compared publishing trends across demographic variables and match cohorts. RESULTS: Average pre-residency publications increased from 2.6 [1.7, 3.4] in 2011 to 6.5 [5.1, 7.9] in 2018. Men, PhD-holders, Top 20 and Top 40 U.S. medical school graduates, and IMGs had higher pre-residency publication counts overall. After stratifying by match cohort, however, there was no significant effect of gender on pre-residency publications. Applicants matching into residency programs with highly ranked affiliated hospitals had significantly higher pre-residency publications. CONCLUSION: Publishing volume of successful neurosurgery applicants in the U.S. has risen recently and is associated with the stature of matched residency programs. Given the gap between verifiable and claimed research on residency applications, attention is needed to objectively evaluate research credentials in the selection process. The impending phase out of USMLE step 1 scores may increase emphasis on academic productivity.