Pediatric non-galenic pial arteriovenous fistula's characteristics and outcomes: a systematic review

INTRODUCTION

Pediatric non-galenic pial arteriovenous fistulas (pAVFs) are rare vascular malformations that are characterized by a pial arterial-venous connection without an intervening capillary bed. Outcomes and treatment strategies for pAVFs are highly individualized, owing to the rarity of the disease and lack of large-scale data guiding optimal treatment approaches.

METHODS

We performed a systematic review of pediatric patients (< 18 years at diagnosis) diagnosed with a pAVF by digital subtraction angiogram (DSA). The demographics, treatment modalities, and outcomes were documented for each patient and clinical outcome data was collected. Descriptive information stratified by outcome scores were classified as follows: 1 = excellent (no deficit and full premorbid activity), 2 = good (mild deficit and full premorbid activity), 3 = fair (moderate deficit and impaired activity), 4 = poor (severe deficit and dependent on others), 5 = death.

RESULTS

A total of 87 studies involving 231 patients were identified. Median age at diagnosis was 3 years (neonates to 18 years). There was slight male preponderance (55.4%), and 150 subjects (81.1%*) experienced excellent outcomes after treatment. Of the 189 patients treated using endovascular approaches, 80.3% experienced excellent outcomes and of the 15 patients surgically treated subjects 75% had an excellent outcome. The highest rate of excellent outcomes was achieved in patients treated with Onyx (95.2%) and other forms of EvOH (100%). High output heart failure and comorbid vascular lesions tended to result in worse outcomes, with only 54.2% and 68% of subjects experiencing an excellent outcome, respectively. *Outcomes were reported in only 185 patients.

CONCLUSION

pAVFs are rare lesions, necessitating aggregation of patient data to inform natural history and optimal treatment strategies. This review summarizes the current literature on pAVF in children, where children presenting with heart failure as a result of high flow through the lesion were less likely to experience an excellent outcome. Prospective, large-scale studies would further characterize pediatric pAVFs and enable quantitative analysis of outcomes to inform best treatment practices.

Neurosurgical Management of Myelomeningocele in Premature Infants: A Case Series

Introduction Myelomeningocele (MMC) is the most common neural tube defect, but rarely seen in premature infants. Most centers advocate for closure of MMC within 24 hours of birth. However, this is not always possible in severely premature infants. Given the rarity of this patient population, we aimed to share our institutional experience and outcomes of severely premature infants with MMC. Methods We performed a retrospective, observational review of premature infants (≤ 32 weeks gestational age) identified through our multidisciplinary spina bifida clinic (1995-2021) and surgical logs. Descriptive statistics were compiled about this sample including timing of MMC closure and incidence of adverse events such as sepsis, CSF diversion, meningitis, and death. Results Eight patients were identified (50% male) with MMC who were born ≤ 32 weeks gestational age. Mean gestational age of the population was 27.3 weeks (SD 3.5). Median time to MMC closure was 1.5 days (IQR = 1-80.8). Five patients were taken for surgery within the recommended 48 hours of birth; 2 patients underwent significantly delayed closure (107 and 139 days); and one patient's defect epithelized without surgical intervention. Six of eight patients required permanent cerebrospinal fluid (CSF) diversion (2 patients were treated with ventriculoperitoneal shunting (VPS), three were treated with endoscopic third ventriculostomy (ETV) with choroid plexus cauterization (CPC) and 1 patient treated with ETV; mean of 3 years after birth, ranging from 1 day to 16 years). Two patients required more than one permanent CSF diversion procedure. Two patients developed sepsis (defined as meeting at least 2/4 SIRS criteria), and 2 patients had intraventricular hemorrhage (both grade III). No patients developed meningitis (defined as positive CSF cultures) prior to MMC closure. Median follow up duration was 9.7 years. During this time epoch, 3 patients died: Two before 2 years of age of causes unrelated to surgical intervention. One of the two patients with grade III IVH died within 24 hours of MMC closure. Conclusions In our institutional experience with premature infants with MMC, some patients underwent delayed MMC closure. The overall rate of meningitis, sepsis, and mortality for preterm children with MMC was similar to MMC patients born at term.

Postoperative Cerebrospinal Fluid-Related Complications After Posterior Fossa and Posterolateral Skull Base Surgeries: Development of a Predictive Model and Clinical Risk Score

BACKGROUND

Postoperative pseudomeningocele (PMC) and cerebrospinal fluid (CSF) leak are common complications following posterior fossa and posterolateral skull base surgeries. We sought to 1) determine the rate of CSF-related complications and 2) develop a perioperative model and risk score to identify the highest risk patients for these events.

METHODS

We performed a retrospective cohort of 450 patients undergoing posterior fossa and posterolateral skull base procedures from 2016 to 2020. Logistic regressions were performed for predictor selection for 3 prespecified models: 1) a priori variables, 2) predictors selected by large effect sizes, and 3) predictors with P ≤ 0.100 on univariable analysis. A final model was created by elimination of nonsignificant predictors, and the integer-based postoperative CSF-related complications (POCC) clinical risk score was derived. Internal validation was done using 10-fold cross-validation and bootstrapping with uniform shrinkage.

RESULTS

A total of 115 patients (25.6%) developed PMC and/or CSF leakage. Age >55 years (odds ratio [OR], 0.560; 95% confidence interval [CI], 0.328-0.954), body mass index >30 kg/m2 (OR, 1.88; 95% CI, 1.14-3.10), and postoperative CSF diversion (OR, 2.85; 95% CI, 1.64-5.00) were associated with CSF leak and PMC. Model 2 was the most predictive (cross-validated area under the receiver operating characteristic curve, 0.690). The final risk score was devised using age, body mass index class, dural repair technique, use of bone substitute, and duration of postoperative CSF diversion. The POCC score performed well (cross-validated area under the receiver operating characteristic curve, 0.761) and was highly specific (96.1%).

CONCLUSIONS

We created the first generalizable and predictive risk score to identify patients at risk of CSF-related complications. The POCC score could improve surveillance, inform doctor-patient discussions regarding the risks of surgery, and assist in perioperative management.

Treatment of hydrocephalus following posterior fossa tumor resection: a multicenter collaboration from the Hydrocephalus Clinical Research Network

OBJECTIVE

Persistent hydrocephalus following posterior fossa brain tumor (PFBT) resection is a common cause of morbidity in pediatric brain tumor patients, for which the optimal treatment is debated. The purpose of this study was to compare treatment outcomes between VPS and ETV in patients with persistent hydrocephalus following surgical resection of a PFBT.

METHODS

A post-hoc analysis was performed of the Hydrocephalus Clinical Research Network (HCRN) prospective observational study evaluating VPS and ETV for pediatric patients. Children who experienced hydrocephalus secondary to PFBT from 2008 to 2021 were included. Primary outcomes were VPS/ETV treatment failure and time-to-failure (TTF).

RESULTS

Among 241 patients, the VPS (183) and ETV (58) groups were similar in age, extent of tumor resection, and preoperative ETV Success Score. There was no difference in overall treatment failure between VPS and ETV (33.9% vs 31.0%, p = 0.751). However, mean TTF was shorter for ETV than VPS (0.45 years vs 1.30 years, p = 0.001). While major complication profiles were similar, compared to VPS, ETV patients had relatively higher incidence of minor CSF leak (10.3% vs. 1.1%, p = 0.003) and pseudomeningocele (12.1% vs 3.3%, p = 0.02). No ETV failures were identified beyond 3 years, while shunt failures occurred beyond 5 years. Shunt infections occurred in 5.5% of the VPS cohort.

CONCLUSIONS

ETV and VPS offer similar overall success rates for PFBT-related postoperative hydrocephalus. ETV failure occurs earlier, while susceptibility to VPS failure persists beyond 5 years. Tumor histology and grade may be considered when selecting the optimal means of CSF diversion.

Assessing the Impact of Changes to USMLE Step 1 Grading on Evaluation of Neurosurgery Residency Applicants in the United States: A Program Director Survey

BACKGROUND

Neurosurgery (NS) is among the most selective specialties in the United States. As the United States Medical Licensing Examination (USMLE) Step 1 transitions to a binary pass/fail score, residency programs face unclear challenges in screening and evaluating applicants. The aim of this study is to provide insights into the perceived impact of changes to the USMLE Step 1 grading in the applicant selection process.

METHODS

We created a survey using questions regarding NS program demographics, the perceived predictive abilities of Step 1 and Step 2 clinical knowledge (CK), and several factors that programs consider when assessing applicants. We queried program directors (PDs), program coordinators (PCs), and assistant PDs at 117 NS residency programs. Respondents were asked to rank these factors in order of importance for selection at their respective training program. We used descriptive statistics and a Wilcoxon matched-pairs signed-rank test to evaluate the effects of these changes using STATA 17.

RESULTS

A total of 35 (30%) residency programs responded with 26 (74%) completing the factor ranking questions. 86% (95% confidence interval, 71.5%-94.3%) disagreed that the changes will better prepare students clinically. USMLE Step 2 CK scores, class rank, and away rotations saw significant increases in priority in the absence of a graded Step 1, whereas letters of recommendation and surrogates for research productivity saw notable, but not significant, changes after adjusting for multiple testing.

CONCLUSIONS

Reporting binary Step 1 grades marks a significant shift in assessing applicants for NS residency by emphasizing Step 2 CK, class rank, and research productivity.

Outcomes of endovascular embolization for Vein of Galen malformations: An individual participant data meta-analysis

Introduction

Understanding outcomes after Vein of Galen malformation (VOGM) embolization has been limited by small sample size in reported series and predominantly single center studies. To address these limitations, we perform an individual-participant meta-analysis (IPMA) to identify risk factors associated with all-cause mortality and clinical outcome after VOGM endovascular embolization.

Methods

We performed a systematic review and IPMA of VOGM endovascular outcomes according to PRISMA guidelines. Individual patient characteristics including demographic, intra/post-operative adverse events, treatment efficacy (partial or complete occlusion), and clinical outcome were collected. Mixed-effects logistic regression with random effects modeling and Bonferroni correction was used (p ≤ 0.003 threshold for statistical significance). The primary and secondary outcomes were all-cause mortality and poor clinical outcome (moderate/severe developmental delay or permanent disabling injury), respectively. Data are expressed as (mean ± standard deviation (SD)) or (odds ratio (OR), 95% confidence interval (CI), I 2, p-value).

Results

Thirty-five studies totaling 307 participants quantifying outcomes after endovascular embolization for VOGM were included. Follow up time was 42 (±57) months. Our analysis contained 42% neonates (<1 month) at first embolization, 45% infants (1 month ≤2 years), and 13% children (>2 years). Complete occlusion was reported in 48% of participants. Overall all-cause mortality was 16%. Overall, good clinical outcome was achieved in 68% of participants. First embolization as a neonate [OR = 6.93; 95% CI (1.99-24.08); I 2 < 0.01; p < 0.001] and incomplete embolization [OR = 10.87; 95% CI (1.86-63.55); I 2 < 0.01; p < 0.001] were associated with mortality. First embolization as a neonate [OR = 3.24; 95% CI (1.47-7.15); I 2 < 0.01; p < 0.001], incomplete embolization [OR = 5.26; 95% CI (2.06-13.43); I 2 < 0.01; p < 0.001], and heart failure at presentation [OR = 3.10; 95% CI (1.03-9.33); I 2 < 0.01; p = 0.002] were associated with poor clinical outcomes. Sex, angioarchitecture of lesion, embolization approach (transvenous vs. transarterial), and single or multistage embolization were not associated with mortality or clinical outcome.

Conclusions

We identify incomplete VOGM embolization independently associated with mortality and poor clinical outcome. While this study provides the highest level of evidence for VOGM embolization to date, prospective multicenter studies are needed to understand the optimal treatment strategies, outcomes, and natural history after VOGM embolization.