Link, Michael J.

OBJECTIVE Sylvian fissure dissection following subarachnoid hemorrhage (SAH) is a challenging but fundamental skill in microneurosurgery, and one that has become increasingly difficult to develop during residency, given the overarching management trends. The authors describe a novel rodent model for simulation of sylvian fissure dissection and cerebrovascular bypass under SAH conditions. METHODS A standardized microvascular anastomosis model comprising rat femoral arteries and veins was used for the experimental framework. In the experimental protocol, following exposure and skeletonization of the vessels, extensive, superficial (1- to 2-mm) soft-tissue debridement was conducted and followed by wound closure and delayed reexploration at intervals of 7, 14, and 28 days. Two residents dissected 1 rat each per time point (n = 6 rats), completing vessel skeletonization followed by end-to-end artery/vein anastomoses. Videos were reviewed postprocedure to assess scar score and relative difficulty of dissection by blinded raters using 4-point Likert scales. RESULTS At all time points, vessels were markedly invested in friable scar, and exposure was subjectively assessed as a reasonable surrogate for sylvian fissure dissection under SAH conditions. Scar score and relative difficulty of dissection both indicated 14 days as the most challenging time point. CONCLUSIONS The authors’ experimental model of femoral vessel skeletonization, circumferential superficial soft-tissue injury, and delayed reexploration provides a novel approximation of sylvian fissure dissection and cerebrovascular bypass under SAH conditions. The optimal reexploration interval appears to be 7–14 days. To the authors’ knowledge, this is the first model of SAH simulation for microsurgical training, particularly in a live animal system.

AbstractBackgroundPast research established that surgery plus adjuvant radiotherapy (S + AR) improves overall survival (OS) in esthesioneuroblastoma (ENB). However, it is unknown if the addition of adjuvant chemotherapy (AC) further improves survival. The primary objective of this study was to compare survival among patients treated with S + AR alone to patients who underwent S + AR + AC.MethodsRetrospective review of patient records.ResultsThirty‐eight patients met inclusion criteria for either S + AR or S + AR + AC treatment groups. The S + AR + AC group contained more patients with Kadish stage D disease, dural invasion, and positive histologic margins postsurgery. All S + AR + AC patients received platinum‐based regimens, combined with etoposide in 67%. OS and recurrence‐free survival did not differ between the two groups, even when restricting the analysis to patients with Kadish stages B and C disease.ConclusionPatients who received platinum‐based AC did not exhibit improved survival compared to S + AR alone. Further investigation, preferably prospective, into the optimal use of systemic therapy in ENB is warranted.

Background There is little data regarding postoperative outcomes of patients with obstructive sleep apnea (OSA) undergoing skull base surgery. The purpose of this study is to determine an association between risk factors and proximity of cerebrospinal fluid (CSF) leak to surgery in patients with OSA undergoing endoscopic skull base surgery. Methods A retrospective review of neurosurgical inpatients, with and without OSA, at a tertiary care institution from 2002 to 2015 that experienced a postoperative CSF leak after undergoing endoscopic skull base surgery. Results Forty patients met inclusion criteria, 12 (30%) with OSA. OSA patients had significantly higher body mass index (BMI; median 39.4 vs. 31.7, p < 0.01) and were more likely to have diabetes (41.7 vs. 10.7%, p = 0.04) than non-OSA patients; otherwise there were no significant differences in clinical comorbidities. No patients restarted positive pressure ventilation (PPV) in the inpatient setting. The type of repair was not a significant predictor of the time from surgery to leak. Patients with OSA experienced postoperative CSF leak 49% sooner than non-OSA patients (Hazard Ratio 1.49, median 2 vs. 6 days, log-rank p = 0.20). Conclusion Patients with OSA trended toward leaking earlier than those without OSA, and no OSA patients repaired with a nasoseptal flap (NSF) had a leak after postoperative day 5. Due to a small sample size this trend did not reach significance. Future studies will help to determine the appropriate timing for restarting PPV in this high risk population. This is important given PPV's significant benefit to the patient's overall health and its ability to lower intracranial pressure.

Objectives: 1) Describe the genetic alterations discovered in a series of sporadic vestibular schwannomas (VS). 2) Identify if more clinically aggressive variants possess different genetic alterations compared to more indolent-behaving VS. Methods: Fresh frozen tumor and matched peripheral blood leukocytes from 23 individuals with sporadic VS were analyzed using whole-exome sequencing, tumor whole transcriptome expression profiling (mRNA-Seq), and tumor mate-pair analysis. Source cases included tumors with fast preoperative growth, giant tumors in young patients, tumors with macrocystic change, recurrent tumors following radiation or microsurgery, and indolent small tumors with minimal or no growth before surgery. Somatic and germ-line alterations of the NF2 gene and beyond the NF2 locus were identified and analyzed using complementing analyses. Results: Biallelic somatic events involving the NF2 gene were discovered in every analyzed tumor specimen with no concurrent NF2 variants identified in matching peripheral blood specimens. Thirteen tumors showed loss of one chromosome 22 (ch22), 4 tumors showed copy-neutral 22q loss of heterozygosity, and 31 unique small variants in the NF2 gene were discovered. Of the latter, 10 were essential splice site, 11 frame shift, 7 stop gain, 2 missense, and 1 in-frame mutation. No other common or recurring NF2 mutations were identified. However, several other notable large chromosomal aberrations were discovered including 2 tumors with loss of a chromosome 21, 3 with loss of an X or Y chromosome, 1 with copy-neutral loss of heterozygosity in chromosome 15, and 1 with loss of 18p and 16q. All of these other major chromosomal abnormalities only occurred in tumors demonstrating a more aggressive phenotype. Conclusions: To date, few studies have used whole-exome sequencing, mate-pair analysis, and RNA-seq to profile genome-wide alterations in sporadic VS. Using high-throughput deep sequencing, “two-hit” alterations in the NF2 gene were identified in every tumor and were not present in peripheral blood supporting that all events were somatic. Type of NF2 gene alteration and accessory mutations outside the NF2 locus may predict phenotypic expression and clinical course.

AbstractBackgroundThe purpose of this study was to determine the clinical outcomes and review the management strategies for metastatic esthesioneuroblastoma.MethodsWe conducted a systematic review and meta‐analysis.ResultsForty‐eight studies totaling 118 patients met inclusion criteria. Chemotherapy in combination with surgery and/or radiation exhibited the best overall survival when compared to monotherapy and no treatment (P < .001). However, most patients (66%) received either monotherapy or no therapy. The number and location of metastases among the 3 treatment groups did not significantly differ (P = .85). Treatment modality remained significantly associated with overall survival on multivariable analysis (P < .001). Platinum‐based chemotherapy was most commonly utilized but did not provide a survival benefit when compared with all other regimens (P = .88).ConclusionDistant metastases with esthesioneuroblastoma portend a poor prognosis. Chemotherapy in combination with surgery and/or radiation was associated with improved overall survival. Further research into the optimal systemic therapeutic regimen for patients with distant metastases is critical.

Objectives Neck metastases in patients with esthesioneuroblastoma (ENB) constitute the most significant predictor of poor long-term survival. Recently, researchers discovered the existence of dural lymphatic channels that drain to the cervical lymph nodes. From this physiologic basis, we hypothesized that patients with ENB who develop dural invasion (DI) would exhibit a proclivity for neck metastases. Design Retrospective review. Setting Tertiary referral center. Participants All patients treated for ENB from January 1, 1994 to December 31, 2015. Main Outcome Measures Incidence, laterality, and recurrence rate of neck metastases by DI status. Results Sixty-one patients were identified (38% female; median age 49, range, 10–80), 34 (56%) of whom had DI and 27 (44%) did not. Of patients with DI, 50% presented with or developed neck disease following treatment compared with just 22% of those without DI (p = 0.026). Bilateral neck disease was more common in patients with DI (11/34, 32%) compared with those without (2/27, 7%) (p = 0.018). Five-year regional recurrence-free survival rates were 88% for those without and 64% for those with DI (p = 0.022). Kadish C patients with DI were more likely to develop regional recurrence when compared with Kadish C without DI and Kadish A/B (p = 0.083). Further, Kadish C patients with DI displayed worse overall survival than Kadish C without DI and Kadish A/B. Kadish D patients displayed the worst overall survival. The difference in overall survival among these four groups was significant (p < 0.001). Conclusion DI by ENB is associated with increased incidence of cervical nodal metastases, bilateral neck disease, worse regional recurrence-free survival, and poorer overall survival. These data support the division of Kadish C by DI status.