A watch, wait, and rescan approach for incidental benign-appearing notochordal lesions of the skull base.

OBJECTIVE: The aim of this study was to describe the natural history of incidental benign-appearing notochordal lesions of the skull base with specific attention to features that can make differentiation from low-grade chordoma more difficult, namely contrast uptake and bone erosion. METHODS: In this retrospective case series, the authors describe the clinical outcomes of 58 patients with incidental benign-appearing notochordal lesions of the clivus, including those with minor radiological features of bone erosion or contrast uptake. RESULTS: All lesions remained stable during a median follow-up of almost 3 years. Thirty-seven (64%) patients underwent contrast-enhanced MRI; lesions in 14 (38%) of these patients exhibited minimal contrast enhancement. Twenty-seven (47%) patients underwent CT; lesions in 6 (22%) of these patients exhibited minimal bone erosion. CONCLUSIONS: These data make the case for monitoring selected cases of benign-appearing notochordal lesions of the clivus in the first instance even when there is minor contrast uptake or minimal bone erosion.

Optimizing CRISPR/Cas9 Editing of Repetitive Single Nucleotide Variants.

CRISPR/Cas9, base editors and prime editors comprise the contemporary genome editing toolbox. Many studies have optimized the use of CRISPR/Cas9, as the original CRISPR genome editing system, in substituting single nucleotides by homology directed repair (HDR), although this remains challenging. Studies describing modifications that improve editing efficiency fall short of isolating clonal cell lines or have not been validated for challenging loci or cell models. We present data from 95 transfections using a colony forming and an immortalized cell line comparing the effect on editing efficiency of donor template modifications, concentration of components, HDR enhancing agents and cold shock. We found that in silico predictions of guide RNA efficiency correlated poorly withactivity in cells. Using NGS and ddPCR we detected editing efficiencies of 5-12% in the transfected populations which fell to 1% on clonal cell line isolation. Our data demonstrate the variability of CRISPR efficiency by cell model, target locus and other factors. Successful genome editing requires a comparison of systems and modifications to develop the optimal protocol for the cell model and locus. We describe the steps in this process in a flowchart for those embarking on genome editing using any system and incorporate validated HDR-boosting modifications for those using CRISPR/Cas9.

Osteosarcoma: Novel prognostic biomarkers using circulating and cell-free tumour DNA.

AIM: Osteosarcoma (OS) is the most common primary bone tumour in children and adolescents. Circulating free (cfDNA) and circulating tumour DNA (ctDNA) are promising biomarkers for disease surveillance and prognostication in several cancer types; however, few such studies are reported for OS. The purpose of this study was to discover and validate methylation-based biomarkers to detect plasma ctDNA in patients with OS and explore their utility as prognostic markers. METHODS: Candidate CpG markers were selected through analysis of methylation array data for OS, non-OS tumours and germline samples. Candidates were validated in two independent OS datasets (n = 162, n = 107) and the four top-performing markers were selected. Methylation-specific digital droplet PCR (ddPCR) assays were designed and experimentally validated in OS tumour samples (n = 20) and control plasma samples. Finally, ddPCR assays were applied to pre-operative plasma and where available post-operative plasma from 72 patients with OS, and findings correlated with outcome. RESULTS: Custom ddPCR assays detected ctDNA in 69% and 40% of pre-operative plasma samples (n = 72), based on thresholds of one or two positive markers respectively. ctDNA was detected in 5/17 (29%) post-operative plasma samples from patients, which in four cases were associated with or preceded disease relapse. Both pre-operative cfDNA levels and ctDNA detection independently correlated with overall survival (p = 0.0015 and p = 0.0096, respectively). CONCLUSION: Our findings illustrate the potential of mutation-independent methylation-based ctDNA assays for OS. This study lays the foundation for multi-institutional collaborative studies to explore the utility of plasma-derived biomarkers in the management of OS.

Cystic glioblastoma: A systematic review and meta-analysis of characteristics and outcomes.

Introduction: Cystic glioblastoma is a well-recognised clinical entity but the characteristics and role of these cystic components in determining clinical outcome remains poorly understood. Research question: To determine whether (1) there is a prognostic significance to a glioblastoma having a cystic component and (2) whether the presence of cyst, and its prognosis relative to non-cystic glioblastoma, relates to patient demographics and other tumour characteristics. Material & methods: A systematic review and meta-analysis was conducted in accordance to PRISMA guidelines. Articles with histological and/or radiological diagnosis of cystic glioblastoma that reported on survival outcome and/or characteristics of cystic glioblastomas mentioned were included. Meta-analysis was performed and presented using random effect model. Results: Twenty studies met the inclusion criteria, and nine studies were included in the meta-analysis (374 glioblastoma patients with cystic components and 2477 glioblastoma patients without cystic components above 18 years of age). Search result did not yield any Level I evidence. There is statistically significant survival benefit in cystic over non-cystic glioblastomas (HR â€‹= â€‹0.81, 95%CI 0.70-0.93, p â€‹= â€‹0.004, I2 â€‹= â€‹50%). Studies reported younger average patient age, larger tumor size and slower tumor growth velocity in cystic glioblastoma. No significant difference in gender ratio and IDH-1 and MGMT methylation status between cystic and non-cystic glioblastoma were reported. Discussion & conclusion: Presence of cyst in glioblastoma tumor is associated with improved overall survival outcome. Etiology of cystic entities and why they might confer survival benefits remained to be determined, and future studies examining how to best treat cystic glioblastomas would be clinically valuable.

"It's not rocket science" and "It's not brain surgery"-"It's a walk in the park": prospective comparative study.

OBJECTIVE: To compare cognitive testing scores in neurosurgeons and aerospace engineers to help settle the age old argument of which phrase-"It's not brain surgery" or "It's not rocket science"-is most deserved. DESIGN: International prospective comparative study. SETTING: United Kingdom, Europe, the United States, and Canada. PARTICIPANTS: 748 people (600 aerospace engineers and 148 neurosurgeons). After data cleaning, 401 complete datasets were included in the final analysis (329 aerospace engineers and 72 neurosurgeons). MAIN OUTCOME MEASURES: Validated online test (Cognitron's Great British Intelligence Test) measuring distinct aspects of cognition, spanning planning and reasoning, working memory, attention, and emotion processing abilities. RESULTS: The neurosurgeons showed significantly higher scores than the aerospace engineers in semantic problem solving (difference 0.33, 95% confidence interval 0.13 to 0.52). Aerospace engineers showed significantly higher scores in mental manipulation and attention (-0.29, -0.48 to -0.09). No difference was found between groups in domain scores for memory (-0.18, -0.40 to 0.03), spatial problem solving (-0.19, -0.39 to 0.01), problem solving speed (0.03, -0.20 to 0.25), and memory recall speed (0.12, -0.10 to 0.35). When each group's scores for the six domains were compared with those in the general population, only two differences were significant: the neurosurgeons' problem solving speed was quicker (mean z score 0.24, 95% confidence interval 0.07 to 0.41) and their memory recall speed was slower (-0.19, -0.34 to -0.04). CONCLUSIONS: In situations that do not require rapid problem solving, it might be more correct to use the phrase "It's not brain surgery." It is possible that both neurosurgeons and aerospace engineers are unnecessarily placed on a pedestal and that "It's a walk in the park" or another phrase unrelated to careers might be more appropriate. Other specialties might deserve to be on that pedestal, and future work should aim to determine the most deserving profession.

A Novel Neurosurgery Referral Course: Feasibility, Validation, and Inferences for Patient Care.

OBJECTIVE: The speciality of neurosurgery is under-represented in the majority of medical school curriculums, and those rotating within this specialty tend to be those with career aspirations within this field. Consequently, few emergency medicine trainees are exposed to this specialty. The aim of this educational project was to develop and validate a neurosurgery referral course for the target audience of emergency medics. DESIGN: Development of a single day neurosurgery referral course, developed with accreditation from the Royal College of Surgeons England. The curriculum covered commonly referred pathologies. Content validity was assessed using a 5-point Likert Scale. Median Likert scores were compared to "indifferent" (3) (indifferent = 3 in this study Likert scale) using the Wilcoxon matched-pairs signed-rank test. Construct validity was assessed using a standardized pre and postcourse 10-single best answer exam and results compared using paired t tests. SETTING: A pilot "Neurosurgery for Emergency Medics" referral course, hosted at a single UK based neurosurgery unit. PARTICIPANTS: A cohort of 19 delegates, working in emergency departments various regions within the UK. RESULTS: The subjective feedback showed significantly higher than the expected median Likert scale satisfaction scores (p = 0.0001). Construct validity was confirmed, with significant improvement in proportion of students getting the answers in the single best answer exam after the days training course (p = 0.017). CONCLUSIONS: We demonstrate feasibility, content, and construct validity and conclude that this pilot "Neurosurgery for Emergency Medics" course was beneficial. Integration of this 1-day course into local doctor's induction programmes for emergency medicine and neurosurgery may advance both local and national standards for referrals and consults alike, with the ultimate goal of improving patient care.

Frequent alterations in p16/CDKN2A identified by immunohistochemistry and FISH in chordoma.

The expression of p16/CDKN2A, the second most commonly inactivated tumour suppressor gene in cancer, is lost in the majority of chordomas. However, the mechanism(s) leading to its inactivation and contribution to disease progression have only been partially addressed using small patient cohorts. We studied 384 chordoma samples from 320 patients by immunohistochemistry and found that p16 protein was lost in 53% of chordomas and was heterogeneously expressed in these tumours. To determine if CDKN2A copy number loss could explain the absence of p16 protein expression we performed fluorescence in situ hybridisation (FISH) for CDKN2A on consecutive tissue sections. CDKN2A copy number status was altered in 168 of 274 (61%) of samples and copy number loss was the most frequent alteration acquired during clinical disease progression. CDKN2A homozygous deletion was always associated with p16 protein loss but only accounted for 33% of the p16-negative cases. The remaining immunonegative cases were associated with disomy (27%), monosomy (12%), heterozygous loss (20%) and copy number gain (7%) of CDKN2A, supporting the hypothesis that loss of protein expression might be achieved via epigenetic or post-transcriptional regulatory mechanisms. We identified that mRNA levels were comparable in tumours with and without p16 protein expression, but other events including DNA promoter hypermethylation, copy number neutral loss of heterozygosity and expression of candidate microRNAs previously implicated in the regulation of CDKN2A expression were not identified to explain the protein loss. The data argue that p16 loss in chordoma is commonly caused by a post-transcriptional regulatory mechanism that is yet to be defined.

Systematic Review of Clinical, Radiologic, and Histologic Features of Benign Notochordal Cell Tumors: Implications for Patient Management.

BACKGROUND: There are no absolute defining criteria for benign notochordal cell tumors; the diagnosis is usually based on small size and the absence of aggressive features. Therefore, by definition, the diagnosis is subjective and usually determined by multidisciplinary consensus. A benign notochordal cell tumor should not grow during surveillance, and this may be used to confirm the diagnosis, but is a tautologic definition. Diagnostic ambiguity leads to uncertainty in management. If a tumor is a small chordoma then early surgery is likely to provide a better outcome. However, unnecessary treatment of a benign tumor may incur unjustified risk. OBJECTIVE: To propose clearer guidelines for the definition and management of benign notochordal tumors. METHODS: We performed a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) review of the reported definitions for benign notochordal tumors and their management. RESULTS: The accepted features of benign notochordal tumors vary considerably: a typical tumor may be diagnosed in the absence of neurology, radiologically well-corticated bony margins, size <35 mm, no enhancement with contrast, no soft tissue extension, no dural penetration, no progression on scans, histologic absence of extracellular myxoid matrix, and low Ki67 index. If these criteria are fulfilled, it is reasonable to use radiologic surveillance in the first instance. Biopsy may be offered depending on the relative risks of performing the biopsy, or if there are atypical features. CONCLUSIONS: We suggest a clearer definition for a benign notochordal tumor and a management algorithm that incorporates a level of diagnostic uncertainty.