Early rhombic lip Protogenin+ve stem cells in a human-specific neurovascular niche initiate and maintain group 3 medulloblastoma.

We identify a population of Protogenin-positive (PRTG+ve) MYChigh NESTINlow stem cells in the four-week-old human embryonic hindbrain that subsequently localizes to the ventricular zone of the rhombic lip (RLVZ). Oncogenic transformation of early Prtg+ve rhombic lip stem cells initiates group 3 medulloblastoma (Gr3-MB)-like tumors. PRTG+ve stem cells grow adjacent to a human-specific interposed vascular plexus in the RLVZ, a phenotype that is recapitulated in Gr3-MB but not in other types of medulloblastoma. Co-culture of Gr3-MB with endothelial cells promotes tumor stem cell growth, with the endothelial cells adopting an immature phenotype. Targeting the PRTGhigh compartment of Gr3-MB in vivo using either the diphtheria toxin system or chimeric antigen receptor T cells constitutes effective therapy. Human Gr3-MBs likely arise from early embryonic RLVZ PRTG+ve stem cells inhabiting a specific perivascular niche. Targeting the PRTGhigh compartment and/or the perivascular niche represents an approach to treat children with Gr3-MB.

Bacteria from diverse habitats colonize and compete in the mouse gut.

To study how microbes establish themselves in a mammalian gut environment, we colonized germ-free mice with microbial communities from human, zebrafish, and termite guts, human skin and tongue, soil, and estuarine microbial mats. Bacteria from these foreign environments colonized and persisted in the mouse gut; their capacity to metabolize dietary and host carbohydrates and bile acids correlated with colonization success. Cohousing mice harboring these xenomicrobiota or a mouse cecal microbiota, along with germ-free "bystanders," revealed the success of particular bacterial taxa in invading guts with established communities and empty gut habitats. Unanticipated patterns of ecological succession were observed; for example, a soil-derived bacterium dominated even in the presence of bacteria from other gut communities (zebrafish and termite), and human-derived bacteria colonized germ-free bystander mice before mouse-derived organisms. This approach can be generalized to address a variety of mechanistic questions about succession, including succession in the context of microbiota-directed therapeutics.

Towards complete and error-free genome assemblies of all vertebrate species.

High-quality and complete reference genome assemblies are fundamental for the application of genomics to biology, disease, and biodiversity conservation. However, such assemblies are available for only a few non-microbial species1-4. To address this issue, the international Genome 10K (G10K) consortium5,6 has worked over a five-year period to evaluate and develop cost-effective methods for assembling highly accurate and nearly complete reference genomes. Here we present lessons learned from generating assemblies for 16 species that represent six major vertebrate lineages. We confirm that long-read sequencing technologies are essential for maximizing genome quality, and that unresolved complex repeats and haplotype heterozygosity are major sources of assembly error when not handled correctly. Our assemblies correct substantial errors, add missing sequence in some of the best historical reference genomes, and reveal biological discoveries. These include the identification of many false gene duplications, increases in gene sizes, chromosome rearrangements that are specific to lineages, a repeated independent chromosome breakpoint in bat genomes, and a canonical GC-rich pattern in protein-coding genes and their regulatory regions. Adopting these lessons, we have embarked on the Vertebrate Genomes Project (VGP), an international effort to generate high-quality, complete reference genomes for all of the roughly 70,000 extant vertebrate species and to help to enable a new era of discovery across the life sciences.

Caecilian Genomes Reveal the Molecular Basis of Adaptation and Convergent Evolution of Limblessness in Snakes and Caecilians.

We present genome sequences for the caecilians Geotrypetes seraphini (3.8 Gb) and Microcaecilia unicolor (4.7 Gb), representatives of a limbless, mostly soil-dwelling amphibian clade with reduced eyes, and unique putatively chemosensory tentacles. More than 69% of both genomes are composed of repeats, with retrotransposons being the most abundant. We identify 1,150 orthogroups that are unique to caecilians and enriched for functions in olfaction and detection of chemical signals. There are 379 orthogroups with signatures of positive selection on caecilian lineages with roles in organ development and morphogenesis, sensory perception, and immunity amongst others. We discover that caecilian genomes are missing the zone of polarizing activity regulatorysequence (ZRS) enhancer of Sonic Hedgehog which is also mutated in snakes. In vivo deletions have shown ZRS is required for limb development in mice, thus, revealing a shared molecular target implicated in the independent evolution of limblessness in snakes and caecilians.

Gut Microbiome Composition Is Associated With Future Onset of Crohn's Disease in Healthy First-Degree Relatives.

BACKGROUND & AIMS: The cause of Crohn's disease (CD) is unknown, but the current hypothesis is that microbial or environmental factors induce gut inflammation in genetically susceptible individuals, leading to chronic intestinal inflammation. Case-control studies of patients with CD have cataloged alterations in the gut microbiome composition; however, these studies fail to distinguish whether the altered gut microbiome composition is associated with initiation of CD or is the result of inflammation or drug treatment. METHODS: In this prospective cohort study, 3483 healthy first-degree relatives (FDRs) of patients with CD were recruited to identify the gut microbiome composition that precedes the onset of CD and to what extent this composition predicts the risk of developing CD. We applied a machine learning approach to the analysis of the gut microbiome composition (based on 16S ribosomal RNA sequencing) to define a microbial signature that associates with future development of CD. The performance of the model was assessed in an independent validation cohort. RESULTS: In the validation cohort, the microbiome risk score (MRS) model yielded a hazard ratio of 2.24 (95% confidence interval, 1.03-4.84; P = .04), using the median of the MRS from the discovery cohort as the threshold. The MRS demonstrated a temporal validity by capturing individuals that developed CD up to 5 years before disease onset (area under the curve > 0.65). The 5 most important taxa contributing to the MRS included Ruminococcus torques, Blautia, Colidextribacter, an uncultured genus-level group from Oscillospiraceae, and Roseburia. CONCLUSION: This study is the first to demonstrate that gut microbiome composition is associated with future onset of CD and suggests that gut microbiome is a contributor in the pathogenesis of CD.

Limited exposure to preserve stability and achieve complete excision of limited dorsal myeloschisis - the "Skip-Hop Laminectomy" technique: a technical note.

OBJECTIVE: The fibroneural stalk of an LDM has variable thickness, complexity, and length, which can span 5 to 6 vertebral segments from its skin attachment to its "merge point" with the dorsal spinal cord. Therefore, complete resection may require extensive multi-level laminotomies. In this technical note, a modification of the procedure is presented that avoids long segment laminectomies while ensuring complete excision of long LDM stalks. RESULTS: An illustrative case of resection of LDM is presented using skip laminectomies. The technique ensures complete removal of the stalk, thus reducing the risk of future intradural dermoid development, while at the same time minimizes the risk for delayed kyphotic deformity. CONCLUSIONS: A technique of "skip-hop" proximal and distal short segment laminectomies in cases of LDM optimizes the objectives of complete stalk resection with preservation of spinal integrity.

National multicentered retrospective review of clinical and intraoperative factors associated with the development of cerebellar mutism after pediatric posterior fossa tumor resection.

BACKGROUND: Cerebellar mutism (CM) is characterized by a significant loss of speech in children following posterior fossa (PF) surgery. The biological origin of CM remains unclear and is the subject of ongoing debate. Significant recovery from CM is less likely than previously described despite rigorous multidisciplinary neuro-rehabilitational efforts. METHODS: A national multi-centered retrospective review of all children undergoing PF resection in four midsized Canadian academic pediatric institutions was undertaken. Patient, tumor and surgical factors associated with the post-operative development of CM were reviewed. Retrospective identification of PF surgery patients including those developing and those that did not (internal control). RESULTS: The study identified 258 patients across the 4 centers between 2010 and 2020 (mean age 6.73 years; 42.2% female). Overall, CM was experienced in 19.5% of patients (N = 50). Amongst children who developed CM histopathology included medulloblastoma (35.7%), pilocytic astrocytoma (32.6%) and ependymoma (17.1%). Intraoperative impression of adherence to the floor of the 4th ventricle was positive in 36.8%. Intraoperative abrupt changes in blood pressure and/or heart rate were identified in 19.4% and 17.8% of cases. The clinical resolution of CM was rated to be complete, significant resolution, slight improvement, no improvement and deterioration in 56.0%, 8.0%, 20.0%, 14.0% and 2.0%, respectively. In the cohort of children who experienced post-operative CM as compared to their no-CM counterpart, proportionally more tumors were felt to be adherent to the floor of the 4th ventricle (56.0% vs 49.5%), intraoperative extent of resection was a GTR (74% vs 68.8%) and changes in heart rate were noted (≥ 20% from baseline) (26.0% vs 15.9%). However, a multiple regression analysis identified only abrupt changes in HR (OR 5.97, CI (1.53, 23.1), p = 0.01) to be significantly associated with the development of post-operative CM. CONCLUSION: As a devastating surgical complication after posterior fossa tumor surgery with variable clinical course, identifying and understanding the operative cues and revising intraoperative plans that optimizes the child's neurooncological and clinical outcome are essential.

Os odontoideum and craniovertebral junction instability secondary to dystonia: case series and review of the literature.

INTRODUCTION: Os odontoideum refers to a rounded ossicle detached from a hypoplastic odontoid process at the body of the axis. The aetiology has been debated and believed to be either congenital or acquired (resulting from trauma). Os odontoideum results in incompetence of the transverse ligament and thus predisposes to atlantoaxial instability and spinal cord injury. METHODS/RESULTS: Three cases of children with severe dystonic cerebral palsy presenting with myelopathic deterioration secondary to atlantoaxial instability due to os odontoideum are presented. This observation supports the hypothesis of os odontoideum being an acquired phenomenon, secondary to chronic excessive movement with damage to the developing odontoid process. CONCLUSION: In children with cerebral palsy and dystonia, pre-existing motor deficits may conceal an evolving myelopathy and result in delayed diagnosis of clinically significant atlantoaxial subluxation.

Who enrolls and why? Examining center-specific underlying patterns behind enrollment: a New York City-based traumatic brain injury model systems study.

BACKGROUND: To elucidate the sociodemographic and study factors involved in enrollment in the Traumatic Brain Injury Model System (TBIMS) database, this study examined the effect of a variety of variables on enrollment at a local TBIMS center. METHODS: A sample of 654 individuals from the local TBIMS center was studied examining enrollment by age, gender, race, ethnicity, homelessness status at date of injury, history of homelessness, health insurance status, presence of social support, primary language, consenting in hospital or after discharge, and the need for an interpreter. Binary logistic regression was conducted to identify variables that predict center-based enrollment into TBIMS. RESULTS: Results demonstrated that older age was associated with decreasing enrollment (OR = 0.99, p = 0.01), needing an interpreter made enrollment less likely (OR = 0.33, p < 0.01), being primarily Spanish speaking predicted enrollment (OR = 3.20, p = 0.02), Hispanic ethnicity predicted enrollment (OR = 7.31, p = 0.03), and approaching individuals in the hospital predicted enrollment (OR = 6.94, p < 0.01). Here, OR denotes the odds ratio estimate from a logistic regression model and P denotes the corresponding p-value. CONCLUSIONS: These results can be useful in driving enrollment strategies at this center for other similar TBI research, and to contribute a representative TBI sample to the national database.

Mediterranean-Like Dietary Pattern Associations With Gut Microbiome Composition and Subclinical Gastrointestinal Inflammation.

BACKGROUND & AIMS: Case-control studies have shown that patients with Crohn's disease (CD) have a microbial composition different from healthy individuals. Although the causes of CD are unknown, epidemiologic studies suggest that diet is an important contributor to CD risk, potentially via modulation of bacterial composition and gut inflammation. We hypothesized that long-term dietary clusters (DCs) are associated with gut microbiome compositions and gut inflammation. Our objectives were to identify dietary patterns and assess whether they are associated with alterations in specific gut microbial compositions and subclinical levels of gut inflammation in a cohort of healthy first-degree relatives (FDRs) of patients with CD. METHODS: As part of the Genetic, Environmental, Microbial (GEM) Project, we recruited a cohort of 2289 healthy FDRs of patients with CD. Individuals provided stool samples and answered a validated food frequency questionnaire reflecting their habitual diet during the year before sample collection. Unsupervised analysis identified 3 dietary and 3 microbial composition clusters. RESULTS: DC3, resembling the Mediterranean diet, was strongly associated with a defined microbial composition, with an increased abundance of fiber-degrading bacteria, such as Ruminococcus, as well as taxa such as Faecalibacterium. The DC3 diet was also significantly associated with lower levels of subclinical gut inflammation, defined by fecal calprotectin, compared with other dietary patterns. No significant associations were found between individual food items and fecal calprotectin, suggesting that long-term dietary patterns rather than individual food items contribute to subclinical gut inflammation. Additionally, mediation analysis demonstrated that DC3 had a direct effect on subclinical inflammation that was partially mediated by the microbiota. CONCLUSIONS: Overall, these results indicated that Mediterranean-like dietary patterns are associated with microbiome and lower intestinal inflammation. This study will help guide future dietary strategies that affect microbial composition and host gut inflammation to prevent diseases.

Altered Gut Microbiome Composition and Function Are Associated With Gut Barrier Dysfunction in Healthy Relatives of Patients With Crohn's Disease.

BACKGROUND & AIMS: The gut microbiome has been suggested to play a role in gut barrier hemostasis, but data are scarce and limited to animal studies. We therefore aimed to assess whether alterations in gut microbial composition and functional pathways are associated with gut barrier function in a cohort of healthy first-degree relatives of patients with Crohn's disease. METHODS: We used the Crohn's and Colitis Canada Genetic Environmental Microbial (CCC-GEM) cohort of healthy first-degree relatives of patients with Crohn's disease. Gut barrier function was assessed using the urinary fractional excretion of lactulose-to-mannitol ratio (LMR). Microbiome composition was assessed by sequencing fecal 16S ribosomal RNA. The cohort was divided into a discovery cohort (n = 2472) and a validation cohort (n = 655). A regression model was used to assess microbial associations with the LMR. A random forest classifier algorithm was performed to assess microbial community contribution to barrier function. RESULTS: Individuals with impaired barrier function (LMR >0.025) had reduced alpha-diversity (Chao1 index, P = 4.0e-4) and altered beta-diversity (Bray-Curtis dissimilarity index, R2 = 0.001, P = 1.0e-3) compared with individuals with an LMR ≤0.025. When taxa were assessed individually, we identified 8 genera and 52 microbial pathways associated with an LMR >0.025 (q < 0.05). Four genera (decreased prevalence of Adlercreutzia, Clostridia UCG 014, and Clostridium sensu stricto 1 and increased abundance of Colidextribacter) and 8 pathways (including decreased biosynthesis of glutamate, tryptophan, and threonine) were replicated in the validation cohort. The random forest approach revealed that the bacterial community is associated with gut barrier function (area under the curve, 0.63; P = 1.4e-6). CONCLUSIONS: The gut microbiome community and pathways are associated with changes in gut barrier function. These findings may identify potential microbial targets to modulate gut barrier.

CORE-IBD: A Multidisciplinary International Consensus Initiative to Develop a Core Outcome Set for Randomized Controlled Trials in Inflammatory Bowel Disease.

BACKGROUND & AIMS: End points to determine the efficacy and safety of medical therapies for Crohn's disease (CD) and ulcerative colitis (UC) are evolving. Given the heterogeneity in current outcome measures, harmonizing end points in a core outcome set for randomized controlled trials is a priority for drug development in inflammatory bowel disease. METHODS: Candidate outcome domains and outcome measures were generated from systematic literature reviews and patient engagement surveys and interviews. An iterative Delphi process was conducted to establish consensus: panelists anonymously voted on items using a 9-point Likert scale, and feedback was incorporated between rounds to refine statements. Consensus meetings were held to ratify the outcome domains and core outcome measures. Stakeholders were recruited internationally, and included gastroenterologists, colorectal surgeons, methodologists, and clinical trialists. RESULTS: A total of 235 patients and 53 experts participated. Patient-reported outcomes, quality of life, endoscopy, biomarkers, and safety were considered core domains; histopathology was an additional domain for UC. In CD, there was consensus to use the 2-item patient-reported outcome (ie, abdominal pain and stool frequency), Crohn's Disease Activity Index, Simple Endoscopic Score for Crohn's Disease, C-reactive protein, fecal calprotectin, and co-primary end points of symptomatic remission and endoscopic response. In UC, there was consensus to use the 9-point Mayo Clinic Score, fecal urgency, Robarts Histopathology Index or Geboes Score, fecal calprotectin, and a composite primary end point including both symptomatic and endoscopic remission. Safety outcomes should be reported using the Medical Dictionary for Regulatory Activities. CONCLUSIONS: This multidisciplinary collaboration involving patients and clinical experts has produced the first core outcome set that can be applied to randomized controlled trials of CD and UC.

First babies conceived with Automated Intracytoplasmic Sperm Injection.

RESEARCH QUESTION: Can an automated sperm injection robot perform Automated Intracytoplasmic Sperm Injection (ICSIA) for use in human IVF? DESIGN: The ICSIA robot automated the sperm injection procedure, including injection pipette advancement, zona pellucida and oolemma penetration with piezo pulses, and pipette removal after sperm release. The robot was first tested in mouse, hamster and rabbit oocytes, and subsequently using discarded human oocytes injected with microbeads. A small clinical pilot trial was conducted with donor oocytes to study the feasibility of the robot in a clinical setting. The ICSIA robot was controlled by engineers with no micromanipulation experience. Results were compared with those obtained with manual ICSI conducted by experienced embryologists. RESULTS: The ICSIA robot demonstrated similar results to the manual procedure in the different animal models tested as well as in the pre-clinical validations conducted in discarded human oocytes. In the clinical validation, 13 out of 14 oocytes injected with ICSIA fertilized correctly versus 16 out of 18 in the manual control; eight developed into good-quality blastocysts versus 12 in the manual control; and four were diagnosed as chromosomally normal versus 10 euploid in the manual control. Three euploid blastocysts from the ICSIA robot group have been transferred into two recipients, which resulted in two singleton pregnancies and two babies born. CONCLUSIONS: The ICSIA robot showed high proficiency in injecting animal and human oocytes when operated by inexperienced personnel. The preliminary results obtained in this first clinical pilot trial are within key performance indicators.

An effective kinase inhibition strategy for metastatic recurrent childhood medulloblastoma.

PURPOSE: Medulloblastomas (MBs) constitute the most common malignant brain tumor in children and adolescents. MYC-amplified Group 3 MBs are characterized by disease recurrence, specifically in the leptomeninges, whereby patients with these metastatic tumors have a mortality rate nearing 100%. Despite limited research on such tumors, studies on MB metastases at diagnosis suggest targeting kinases to be beneficial. METHODS: To identify kinase inhibitors that eradicate cells driving therapy evasion and tumor dissemination, we utilized our established patient-derived xenograft (PDX) mouse-adapted therapy platform that models human MB metastatic recurrences following standard chemoradiotherapy. High-throughput screens of 640 kinase inhibitors were conducted against cells isolated from mouse spines in the PDX model and human fetal neural stem cells to reveal compounds that targeted these treatment-refractory, metastatic cells, whilst sparing healthy cells. Blood-brain barrier permeability assays and additional in vitro experimentation helped select top candidates for in vivo studies. RESULTS: Recurrent Group 3 MB PDX spine cells were therapeutically vulnerable to a selective checkpoint kinase 1 (CHK1) inhibitor and small molecular inhibitor of platelet-derived growth factor receptor beta (PDGFRß). Inhibitor-treated cells showed a significant reduction in MB stem cell properties associated with treatment failure. Mice also demonstrated survival advantage when treated with a CHK1 inhibitor ex vivo. CONCLUSION: We identified CHK1 and PDGFRß inhibitors that effectively target MB cells fueling treatment-refractory metastases. With limited research on effective therapies for Group 3 MB metastatic recurrences, this work highlights promising therapeutic options to treat these aggressive tumors. Additional studies are warranted to investigate these inhibitors' mechanisms and recommended in vivo administration.

The Influence of HIV Status on Acute Appendicitis: A Retrospective Study from South Africa.

BACKGROUND: Despite the human immunodeficiency virus (HIV) being the most common comorbidity in South African surgical patients, its impact on appendicitis has not been well-described. We aimed to determine HIV status' influence on patients' presentation, assessment, management and outcomes with acute appendicitis. METHODS: The retrospective chart review included all patients aged 12 years and older who were HIV-positive or HIV-negative and presented with acute appendicitis between 1 January 2013 and 31 December 2019. The primary outcome measure was survival to discharge. Secondary outcomes included analysis of the presentation (vital signs), assessment (biochemical, inflammatory markers) and management (intraoperative anatomical severity grading, length of hospital stay). RESULTS: Of the 1096 patients with appendicitis, 196 (17.9%) were HIV-positive, and CD4 counts were available for 159. The median age was 23 years, with the HIV-positive patients being older and HIV-negative group having more males (58.7%). While the HIV-positive patients had a longer median length of hospital stay, there was no statistically significant difference in the two groups' incidence of high-grade appendicitis (p = 0.670). The HIV-positive patients had a higher median shock index (OR 7.65; 95% [CI 2.042-28.64]) than their HIV-negative counterparts. HIV-positivity had a significant association with mortality (OR 9.56; 95% CI [1.68-179.39]), and of the seven HIV-positive patients who died, 66.7% (n = 4) had a CD4 < 200 cells/mm3 (OR 8.6; 95% CI [1.6-63.9]). CONCLUSION: HIV-positive patients, those with CD4 < 200 cells/mm3 or not on ART, have increased mortality risk and may benefit from increased perioperative surveillance. Patients with an unknown HIV status in a high-prevalence population should be offered HIV testing to risk stratify more accurately.

The Efficacy of VAMMFT Compared to "Bogota Bag" in Achieving Sheath Closure Following Temporary Abdominal Closure at Index Laparotomy for Trauma.

INTRODUCTION: The open abdomen (OA) is a necessary component of damage control surgery and closure is often challenging. Our aim was to review our ten-year experience with OA in trauma patients and to compare the success of a dual closure technique termed vacuum-assisted, mesh-mediated fascial traction (VAMMFT) to an exclusively Bogota Bag (BB) approach. METHODS: A retrospective analysis was performed using the HEMR database from 2012 to 2022, comparing demographics, mechanism of injury, admission vitals and biochemistry between patients with BB and VAMMFT applications. Rate of secondary abdominal closure and complications were assessed in both groups. Logistic regression was used to find predictors of closure. RESULTS: OA was required by 348 patients at index laparotomy. Of these, 133 (38.2%) were managed with VAMMFT and 215 (61.8%) exclusively with a BB. There were no statistical differences between the BB and VAMMFT groups in terms of demographics, injuries, admission vitals and biochemistry. The VAMMFT group achieved a closure rate of 73% compared to 54.9% in the BB group (OR of 2.2 [1.4-3.7]). There was no significant difference in fistulation rate between the two groups (p = 0.103). Length of hospital stay was 30 versus 17 days in the VAMMFT and BB groups, respectively (OR 1.41 [1.30-1.54]). There were no independent predictors of closure identified in the VAMMFT group. Older patients were less likely to achieve closure when BB was used (OR 0.97 [0.95-0.99]). VAMMFT failure was commonly due to lack of stock (39%) and protocol violations (33%). CONCLUSION: The VAMMFT approach to the OA is efficacious and safe. VAMMFT achieves a much higher rate of secondary closure than BB alone with a low rate of enteric fistula formation.

Work-up and Management of Asymptomatic Extracranial Traumatic Vertebral Artery Injury.

BACKGROUND: Non-penetrating head and neck trauma is associated with extracranial traumatic vertebral artery injury (eTVAI) in approximately 1-2% of cases. Most patients are initially asymptomatic but have an increased risk for delayed stroke and mortality. Limited evidence is available to guide the management of asymptomatic eTVAI. As such, we sought to investigate national practice patterns regarding screening, treatment, and follow-up domains. METHODS: A cross-sectional, electronic survey was distributed to members of the Canadian Neurosurgical Society and Canadian Spine Society. We presented two cases of asymptomatic eTVAI, stratified by injury mechanism, fracture type, and angiographic findings. Screening questions were answered prior to presentation of angiographic findings. Survey responses were analyzed using descriptive statistics. RESULTS: One hundred-eight of 232 (46%) participants, representing 20 academic institutions, completed the survey. Case 1: 78% of respondents would screen for eTVAI with computed topography angiography (CTA) (97%), immediately (88%). The majority of respondents (97%) would treat with aspirin (89%) for 3-6 months (46%). Respondents would follow up clinically (89%) or radiographically (75%), every 1-3 months. Case 2: 73% of respondents would screen with CTA (96%), immediately (88%). Most respondents (94%) would treat with aspirin (50%) for 3-6 months (35%). Thirty-six percent of respondents would utilize endovascular therapy. Respondents would follow up clinically (97%) or radiographically (89%), every 1-3 months. CONCLUSION: This survey of Canadian practice patterns highlights consistency in the approach to screening, treatment, and follow-up of asymptomatic eTVAI. These findings are relevant to neurosurgeons, spinal surgeons, stroke neurologists, and neuro-interventionalists.

Subarachnoid Hemorrhage, Delayed Cerebral Ischemia, and Milrinone Use in Canada.

INTRODUCTION: Delayed cerebral ischemia (DCI) is a complication of aneurysmal subarachnoid hemorrhage (aSAH) and is associated with significant morbidity and mortality. There is little high-quality evidence available to guide the management of DCI. The Canadian Neurosurgery Research Collaborative (CNRC) is comprised of resident physicians who are positioned to capture national, multi-site data. The objective of this study was to evaluate practice patterns of Canadian physicians regarding the management of aSAH and DCI. METHODS: We performed a cross-sectional survey of Canadian neurosurgeons, intensivists, and neurologists who manage aSAH. A 19-question electronic survey (Survey Monkey) was developed and validated by the CNRC following a DCI-related literature review (PubMed, Embase). The survey was distributed to members of the Canadian Neurosurgical Society and to Canadian members of the Neurocritical Care Society. Responses were analyzed using quantitative and qualitative methods. RESULTS: The response rate was 129/340 (38%). Agreement among respondents was limited to the need for intensive care unit admission, use of clinical and radiographic monitoring, and prophylaxis for the prevention of DCI. Several inconsistencies were identified. Indications for starting hyperdynamic therapy varied. There was discrepancy in the proportion of patients who felt to require IV milrinone, IA vasodilators, or physical angioplasty for treatment of DCI. Most respondents reported their facility does not utilize a standardized definition for DCI. CONCLUSION: DCI is an important clinical entity for which no homogeneity and standardization exists in management among Canadian practitioners. The CNRC calls for the development of national standards in the definition, identification, and treatment of DCI.

A Canadian National Survey of the Neurosurgical Management of Intracranial Abscesses.

OBJECTIVE: Intracerebral abscess is a life-threatening condition for which there are no current, widely accepted neurosurgical management guidelines. The purpose of this study was to investigate Canadian practice patterns for the medical and surgical management of primary, recurrent, and multiple intracerebral abscesses. METHODS: A self-administered, cross-sectional, electronic survey was distributed to active staff and resident members of the Canadian Neurosurgical Society and Canadian Neurosurgery Research Collaborative. Responses between subgroups were analyzed using the Chi-square test. RESULTS: In total, 101 respondents (57.7%) completed the survey. The majority (60.0%) were staff neurosurgeons working in an academic, adult care setting (80%). We identified a consensus that abscesses >2.5 cm in diameter should be considered for surgical intervention. The majority of respondents were in favor of excising an intracerebral abscess over performing aspiration if located superficially in non-eloquent cortex (60.4%), located in the posterior fossa (65.4%), or causing mass effect leading to herniation (75.3%). The majority of respondents were in favor of reoperation for recurrent abscesses if measuring greater than 2.5 cm, associated with progressive neurological deterioration, the index operation was an aspiration and did not include resection of the abscess capsule, and if the recurrence occurred despite prior surgery combined with maximal antibiotic therapy. There was no consensus on the use of topical intraoperative antibiotics. CONCLUSION: This survey demonstrated heterogeneity in the medical and surgical management of primary, recurrent, and multiple brain abscesses among Canadian neurosurgery attending staff and residents.

The Association Between Payer Source and Traumatic Brain Injury Rehabilitation Outcomes: A TBI Model Systems Study.

OBJECTIVE: To examine the relationship between payer source for acute rehabilitation, residential median household income (MHI), and outcomes at rehabilitation discharge after traumatic brain injury (TBI). SETTING: Acute inpatient rehabilitation facilities. PARTICIPANTS: In total, 8558 individuals enrolled in the Traumatic Brain Injury Model Systems (TBIMS) National Database who were admitted to inpatient rehabilitation between 2006 and 2019 and were younger than 64 years. DESIGN: Secondary data analysis from a multicenter longitudinal cohort study. MAIN MEASURES: Payer source was divided into 4 categories: uninsured, public insurance, private insurance, and workers' compensation/auto. Relationships between payer source with residential MHI, rehabilitation length of stay (RLOS), and the FIM Instrument at discharge were examined. Covariates included age, injury severity, FIM at admission, and a number of sociodemographic characteristics including minority status, preinjury limitations, education level, and employment status. RESULTS: Individuals with workers' compensation/auto or private insurance had longer RLOS than uninsured individuals or those with public insurance after controlling for demographics and injury characteristics. An adjusted model controlling for demographics and injury characteristics showed a significant main effect of payer source on FIM scores at discharge, with the highest scores noted among those with workers' compensation/auto insurance. The main effect of payer source on FIM at discharge became nonsignificant after RLOS was added to the model as a covariate, suggesting a mediating effect of RLOS. CONCLUSION: Payer source was associated with preinjury residential MHI and predicted RLOS. While prior studies have demonstrated the effect of payer source on long-term outcomes due to lack of inpatient rehabilitation or quality follow-up care, this study demonstrated that individuals with TBI who are uninsured or have public insurance may be at risk for poorer functional status at the point of rehabilitation discharge than those with private insurance, particularly compared with those with workers' compensation/auto insurance. This effect may be largely driven by having a shorter length of stay in acute rehabilitation.