Endovascular thrombectomy for ischemic stroke with large infarct, short- and long-term outcomes: a meta-analysis of 6 randomised control trials.

Endovascular Thrombectomy (EVT) as first-line treatment of patients with large core ischemic infarct is a subject of debate. A systematic literature search was conducted in four electronic databases for randomized control trials (RCTs) comparing EVT to best medical treatment (BMT) for large core infarcts (ASPECTS ≤ 5). Relevant studies were added after screening for titles, abstracts, and complete text. Meta-analysis was performed. The continuous outcomes were analyzed using the standardized mean difference (SMD) and 95% CI, while the binary outcomes were analyzed using the risk ratio (RR) and 95% confidence interval (CI). A funnel plot was used to visually evaluate publication bias, and if feasible, Egger's test was used to validate. We included 1918 patients from six RCTs that compared EVT plus BMT and BMT alone in patients with large core infarct due to large vessel occlusion in the anterior circulation. There were 946 patients in the EVT group and 972 patients in the BMT group. The one-year outcomes are available for 314 patients in the EVT group and 292 patents in the BMT group from two RCTs. EVT group had statistically significant higher rate of 90-day mRS 0-1 (RR = 3.1, P-value < 0.0001), mRS 0-2 (RR = 2.64, P-value < 0.0001), mRS 0-3 (RR = 1.80, P-value < 0.0001), lower 90-day mean mRS score (SMD = -0.29, P-value < 0.0001), lower 90-day mortality rate (RR = 0.85, P-value = 0.015), and greater early neurological improvement (RR = 2.16, P-value < 0.00001) compared to the BMT group. However, the rates of symptomatic intracerebral hemorrhage (sICH) (RR = 1.76, P-value = 0.01) and any ICH (RR = 2.18, P-value < 0.00001) were higher in EVT group. Our finding showed that EVT plus BMT led to in an absolute improvement of 5%, 12%, and 16% in 90-day mRS 0-1, 0-2, and 0-3, respectively. In addition, patients in EVT plus BMT group had a 3% increased probability of experiencing sICH and were 32% more susceptible to any ICH. Moreover, the one-year mRS 0-2 (RR = 2.16, P-value < 0.00001) and mRS 0-3 (RR = 1.80, P-value < 0.0001) was significantly favor the EVT plus BMT over BMT alone. Although, the one-year mortality rate was not significantly differed between two groups (RR = 0.91, P-value = 0.31). There was no statistically significant difference observed between the EVT plus BMT group and the BMT group concerning new stroke, decompressive craniectomy, and serious adverse events. Combined data from six RCTs shows that EVT plus BMT provides significantly better short- and long-term functional outcomes with minimal increase in symptomatic hemorrhage over BMT in patient with large core infarcts.

Scalp incision technique for decompressive hemicraniectomy: comparative systematic review and meta-analysis of the reverse question mark versus alternative retroauricular and Kempe incision techniques.

Decompressive hemicraniectomy (DHC) is a critical procedure used to alleviate elevated intracranial pressure (ICP) in emergent situations. It is typically performed to create space for the swelling brain and to prevent dangerous and potentially fatal increases in ICP. DHC is indicated for pathologies ranging from MCA stroke to traumatic subarachnoid hemorrhage-essentially any cause of refractory brain swelling and elevated ICPs. Scalp incisions for opening and closing the soft tissues during DHC are crucial to achieve optimal outcomes by promoting proper wound healing and minimizing surgical site infections (SSIs). Though the reverse question mark (RQM) scalp incision has gained significant traction within neurosurgical practice, alternatives-including the retroauricular (RA) and Kempe incisions-have been proposed. As choice of technique can impact postoperative outcomes and complications, we sought to compare outcomes associated with different scalp incision techniques used during DHC. We queried three databases according to PRISMA guidelines in order to identify studies comparing outcomes between the RQM versus "alternative" scalp incision techniques for DHC. Our primary outcome of interest in the present study was postoperative wound infection rates according to scalp incision type. Secondary outcomes included estimated blood loss (EBL) and operative duration. We identified seven studies eligible for inclusion in the formal meta-analysis. The traditional RQM technique shortened operative times by 36.56 min, on average. Additionally, mean EBL was significantly lower when the RQM scalp incision was used. Postoperatively, there was no significant association between DHC incision type and mean intensive care unit (ICU) length of stay (LOS), nor was there a significant difference in predisposition to developing wound complications or infections between the RQM and retroauricular/Kempe incision cohorts. Superficial temporal artery (STA) preservation and reoperation rates were collected but could not be analyzed due to insufficient number of studies reporting these outcomes. Our meta-analysis suggests that there is no significant difference between scalp incision techniques as they relate to surgical site infection and wound complications. At present, it appears that outcomes following DHC can be improved by ensuring that the bone flap is large enough to enable sufficient cerebral expansion and decompression of the temporal lobe, the latter of which is of particular importance. Although previous studies have suggested that there are several advantages to performing alternative scalp incision techniques during DHC, the present study (which is to our knowledge the first to meta-analyze the literature on outcomes in DHC by scalp incision type) does not support these findings. As such, further investigations in the form of prospective trials with high statistical power are merited.

Elucidating the pathogenesis behind arteriovenous malformations of the central nervous system: a bibliometric analysis.

Arteriovenous malformations (AVMs) are vascular malformations of the central nervous system (CNS) with potential for significant consequences. The exact pathophysiologic mechanism of AVM formation is not fully understood. This study aims to evaluate bibliometric parameters and citations of the literature of AVMs to provide an overview of how the field has evolved. We performed an electronic search on Web of Science to identify the top 100 published and indexed articles with the highest number of citations discussing the pathogenesis of AVMs. This study yielded 1863 articles, of which the top 100 were selected based on the highest total citation count. These articles included 24% basic science, 46% clinical, and 30% review articles. The most-cited article was a clinical article from 2003, and the most recent was published in 2022. The median number of authors was 6, with the highest being 46 for a clinical article. The top 5 journals were identified, with the highest impact factor being 20.1. 13 countries were identified, with the US contributing the most articles (approximately 70%). Regarding genes of investigation, VEGF was one of the early genes investigated, while more interested in RAS/MAPK has been garnered since 2015. There is a growing interest in AVM genomics and pathogenesis research. While progress has been made in understanding clinical aspects and risk factors, the exact pathophysiological mechanisms and genetic basis of AVM formation remain incompletely understood. Further investigation of key genes in AVM pathogenesis can allow identification of potential therapeutic targets.

Toward an optimal cadaveric brain model for neurosurgical education: assessment of preservation, parenchyma, vascular injection, and imaging.

OBJECTIVE: We assessed types of cadaveric head and brain tissue specimen preparations that are used in a high throughput neurosurgical research laboratory to determine optimal preparation methods for neurosurgical anatomical research, education, and training. METHODS: Cadaveric specimens (N = 112) prepared using different preservation and vascular injection methods were imaged, dissected, and graded by 11 neurosurgeons using a 21-point scale. We assessed the quality of tissue and preservation in both the anterior and posterior circulations. Tissue quality was evaluated using a 9-point magnetic resonance imaging (MRI) scale. RESULTS: Formalin-fixed specimens yielded the highest scores for assessment (mean ± SD [17.0 ± 2.8]) vs. formalin-flushed (17.0 ± 3.6) and MRI (6.9 ± 2.0). Cadaver assessment and MRI scores were positively correlated (P < 0.001, R2 0.60). Analysis showed significant associations between cadaver assessment scores and specific variables: nonformalin fixation (ß = -3.3), preservation within ≤72 h of death (ß = 1.8), and MRI quality score (ß = 0.7). Formalin-fixed specimens exhibited greater hardness than formalin-flushed and nonformalin-fixed specimens (P ≤ 0.006). Neurosurgeons preferred formalin-flushed specimens injected with colored latex. CONCLUSION: For better-quality specimens for neurosurgical education and training, formalin preservation within ≤72 h of death was preferable, as was injection with colored latex. Formalin-flushed specimens more closely resembled live brain parenchyma. Assessment scores were lower for preparation techniques performed > 72 h postmortem and for nonformalin preservation solutions. The positive correlation between cadaver assessment scores and our novel MRI score indicates that donation organizations and institutional buyers should incorporate MRI as a screening tool for the selection of high-quality specimens.

Assessing views and attitudes toward the use of extended reality and its implications in neurosurgical education: a survey of neurosurgical trainees.

OBJECTIVE: Extended reality (XR) systems, including augmented reality (AR), virtual reality (VR), and mixed reality, have rapidly emerged as new technologies capable of changing the way neurosurgeons prepare for cases. Thus, the authors sought to evaluate the perspectives of neurosurgical trainees on the integration of these technologies into neurosurgical education. METHODS: A 20-question cross-sectional survey was administered to neurosurgical residents and fellows to evaluate perceptions of the use of XR in neurosurgical training. Respondents evaluated each statement using a modified Likert scale (1-5). RESULTS: One hundred sixteen responses were recorded, with 59.5% of participants completing more than 90% of the questions. Approximately 59% of participants reported having institutional access to XR technologies. The majority of XR users (72%) believed it was effective for simulating surgical situations, compared with only 41% for those who did not have access to XR. Most respondents (61%) agreed that XR could become a standard in neurosurgical education and a cost-effective training tool (60%). Creating patient-specific anatomical XR models was considered relatively easy by 56% of respondents. Those with XR access reported finding it easier to create intraoperative models (58%) than those without access. A significant percentage (79%) agreed on the need for technical skill training outside the operating room (OR), especially among those without XR access (82%). There was general agreement (60%) regarding the specific need for XR. XR was perceived as effectively simulating stress in the OR. Regarding clinical outcomes, 61% believed XR improved efficiency and safety and 48% agreed it enhanced resection margins. Major barriers to XR integration included lack of ample training hours and/or time to use XR amid daily clinical obligations (63%). CONCLUSIONS: The data presented in this study indicate that there is broad agreement among neurosurgical trainees that XR holds potential as a training modality in neurosurgical education. Moreover, trainees who have access to XR technologies tend to hold more positive perceptions regarding the benefits of XR in their training. This finding suggests that the availability of XR resources can positively influence trainees' attitudes and beliefs regarding the utility of these technologies in their education and training.

Association of moyamoya vasculopathy with autoimmune disease: a systematic review and pooled analysis.

Despite more than six decades of extensive research, the etiology of moyamoya disease (MMD) remains unknown. Inflammatory or autoimmune (AI) processes have been suggested to instigate or exacerbate the condition, but the data remains mixed. The objective of the present systematic review was to summarize the available literature investigating the association of MMD and AI conditions as a means of highlighting potential treatment strategies for this subset of moyamoya patients. Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the PubMed, Embase, Scopus, Web of Science, and Cochrane databases were queried to identify studies describing patients with concurrent diagnoses of MMD and AI disease. Data were extracted on patient demographics, clinical outcomes, and treatment. Stable or improved symptoms were considered favorable outcomes, while worsening symptoms and death were considered unfavorable. Quantitative pooled analysis was performed with individual patient-level data. Of 739 unique studies identified, 103 comprising 205 unique patients (80.2% female) were included in the pooled analysis. Most patients (75.8%) identified as Asian/Pacific Islanders, and the most commonly reported AI condition was Graves' disease (57.6%), with 55.9% of these patients presenting in a thyrotoxic state. Of the 148 patients who presented with stroke, 88.5% of cases (n = 131) were ischemic. Outcomes data was available in 152 cases. There were no significant baseline differences between patients treated with supportive therapy alone and those receiving targeted immunosuppressant therapy. Univariable logistic regression showed that surgery plus medical therapy was more likely than medical therapy alone to result in a favorable outcome. On subanalysis of operated patients, 94.1% of patients who underwent combined direct and indirect bypass reported favorable outcomes, relative to 76.2% of patients who underwent indirect bypass and 82% who underwent direct bypass (p < 0.05). On univariable analysis, the presence of multiple AI disorders was associated with worse outcomes relative to having a single AI disorder. Autoimmune diseases have been uncommonly reported in patients with MMD, but the presence of multiple AI comorbidities portends poorer prognosis. The addition of surgical intervention appears to improve outcomes and for patients deemed surgical candidates, combined direct and indirect bypass appears to offer better outcomes that direct or indirect bypass alone.

Research advances in the diagnosis and treatment of moyamoya disease: a bibliometric analysis.

Moyamoya disease is a rare cerebrovascular condition involving stenotic carotid arteries and the formation of abnormal blood vessels. In this study, we aimed to characterize the key players involved in moyamoya research at the individual and institutional level and to identify the critical publications that have advanced our understanding of this disease. We performed a title-specific search of the Web of Science database using the search term "moyamoya" for publications dating from 1900 to April 2020. The 100 most frequently cited articles were obtained, screened for duplicates, and reviewed by 2 independent reviewers. These 100 articles were cited an average of 150 times each (range, 74 to 1,360 citations per article). Publication dates ranged from 1969 to 2016, with the largest number of publications (n=40) cited between 2000 and 2009. The article with the greatest number of citations (1,360 citations) was "Cerebrovascular 'moyamoya' disease: disease showing abnormal net-like vessels in base of brain," by Suzuki and Takaku, published in the Archives of Neurology, 1969. Stroke published the greatest number of the most frequently cited articles (23 of 100). The institution that contributed the most articles was Tohoku University (16%); the majority of the most frequently cited articles originated in Japan (62%). We identified the 100 most cited articles on moyamoya disease over the past 51 years to recognize significant and impactful works. These results can be used as a guide to evaluate our current understanding of moyamoya disease and to direct future efforts.

Microsurgical treatment of ruptured aneurysms beyond 72 hours after rupture: implications for advanced management.

BACKGROUND: Aneurysmal subarachnoid hemorrhage (aSAH) patients admitted to primary stroke centers are often transferred to neurosurgical and endovascular services at tertiary centers. The effect on microsurgical outcomes of the resultant delay in treatment is unknown. We evaluated microsurgical aSAH treatment > 72 h after the ictus. METHODS: All aSAH patients treated at a single tertiary center between August 1, 2007, and July 31, 2019, were retrospectively reviewed. The additional inclusion criterion was the availability of treatment data relative to time of bleed. Patients were grouped based on bleed-to-treatment time as having acute treatment (on or before postbleed day [PBD] 3) or delayed treatment (on or after PBD 4). Propensity adjustments were used to correct for statistically significant confounding covariables. RESULTS: Among 956 aSAH patients, 92 (10%) received delayed surgical treatment (delayed group), and 864 (90%) received acute endovascular or surgical treatment (acute group). Reruptures occurred in 3% (26/864) of the acute group and 1% (1/92) of the delayed group (p = 0.51). After propensity adjustments, the odds of residual aneurysm (OR = 0.09; 95% CI = 0.04-0.17; p < 0.001) or retreatment (OR = 0.14; 95% CI = 0.06-0.29; p < 0.001) was significantly lower among the delayed group. The OR was 0.50 for rerupture, after propensity adjustments, in the delayed setting (p = 0.03). Mean Glasgow Coma Scale scores at admission in the acute and delayed groups were 11.5 and 13.2, respectively (p < 0.001). CONCLUSIONS: Delayed microsurgical management of aSAH, if required for definitive treatment, appeared to be noninferior with respect to retreatment, residual, and rerupture events in our cohort after adjusting for initial disease severity and significant confounding variables.

Approaches to and outcomes of intra-arterial tPA in embolectomy for large vessel occlusion.

INTRODUCTION: Intra-arterial tissue plasminogen activator (IA tPA) is sometimes used in conjunction with aspiration catheters and stentrievers to achieve recanalization in endovascular thrombectomy (ET) for large vessel occlusion (LVO). Reports of safety and efficacy of this approach are limited by technical heterogeneity and sample size. METHODS: We retrospectively reviewed a data set of patients undergoing ET for LVO between August 2017 and September 2020 to identify those that received IA tPA. IA tPA usage, timing and dosage was at the discretion of the operative neurosurgeon. We identified three broad categories of IA tPA administration: (1) adjunctive with the first pass; (2) salvage with subsequent passes after first pass achieved incomplete revascularization; and (3) post-thrombectomy residual distal occlusions. Univariate and multivariate logistic regression were performed to test associations with recanalization, hemorrhage, and functional independence. RESULTS: Among 271 patients, 158 (58%) patients had IA tPA, of which 83 received adjuvant IA tPA, 60 received salvage IA tPA, and 15 received post-thrombectomy IA tPA for distal occlusions. There were no differences in demographics, stroke etiology and premorbid medications between these groups. Patients receiving salvage IA tPA had longer times from groin access to recanalization and more passes, as expected. On multivariate analysis neither adjunctive nor salvage IA tPA was significantly associated with recanalization, post-operative hemorrhage, or functional outcomes. On univariate analysis, patients receiving salvage IA tPA had lower rates of TICI 3 or 2b revascularization (80% vs. 89% adjunctive and 92% no IA tPA, p =  0.003) and higher rates of any postoperative hemorrhage (33% vs. 22% adjunctive and 19% no IA tPA, p =  0.003). CONCLUSIONS: In this retrospective, single-institution series, IA tPA used adjunctively or as salvage therapy in ET for LVO was not associated with recanalization, post-operative hemorrhage, or functional outcomes, suggesting IA tPA is an available modality that can be utilized in cases of recalcitrant clots.

Roles of Phytoestrogen in the Pathophysiology of Intracranial Aneurysm.

Background and Purpose: The incidences of intracranial aneurysm and aneurysmal subarachnoid hemorrhage are high in postmenopausal women. Although population-based studies suggest that hormone replacement therapy is beneficial for postmenopausal women with intracranial aneurysms, estrogen replacement may no longer be recommended for the prevention of chronic diseases given its association with adverse outcomes, such as cancer and ischemic stroke. The isoflavone daidzein and its intestinal metabolite equol are bioactive phytoestrogens and potent agonists of estrogen receptors. Given their estrogenic properties, we investigated whether the isoflavones daidzein and equol are protective against the formation and rupture of intracranial aneurysms in a mouse model of the postmenopausal state. Methods: We induced intracranial aneurysms in ovariectomized adult female mice using a combination of induced systemic hypertension and a single injection of elastase into the cerebrospinal fluid. We fed the mice with an isoflavone-free diet with/without daidzein supplementation, or in a combination of intraperitoneal equol, or oral vancomycin treatment. We also used estrogen receptor beta knockout mice. Results: Both dietary daidzein and supplementation with its metabolite, equol, were protective against aneurysm formation in ovariectomized mice. The protective effects of daidzein and equol required estrogen receptor-ß. The disruption of the intestinal microbial conversion of daidzein to equol abolished daidzein's protective effect against aneurysm formation. Mice treated with equol had lower inflammatory cytokines in the cerebral arteries, suggesting that phytoestrogens modulate inflammatory processes important to intracranial aneurysm pathogenesis. Conclusions: Our study establishes that both dietary daidzein and its metabolite, equol, protect against aneurysm formation in ovariectomized female mice through the activation of estrogen receptor-ß and subsequent suppression of inflammation. Dietary daidzein's protective effect required the intestinal conversion to equol. Our results indicate the potential therapeutic value of dietary daidzein and its metabolite, equol, for the prevention of the formation of intracranial aneurysms and related subarachnoid hemorrhage.

Delays in presentation and mortality among Black patients with mechanical thrombectomy after large-vessel stroke at a US hospital.

OBJECTIVE: The incidence and severity of stroke are disproportionately greater among Black patients. In this study, the authors sought to examine clinical outcomes among Black versus White patients after mechanical thrombectomy for stroke at a single US institution. METHODS: All patients who underwent mechanical thrombectomy at a single center from January 1, 2014, through March 31, 2020, were retrospectively analyzed. Patients were grouped based on race, and demographic characteristics, preexisting conditions, clinical presentation, treatment, and stroke outcomes were compared. The association of race with mortality was analyzed in multivariable logistic regression analysis adjusted for potential confounders. RESULTS: In total, 401 patients (233 males) with a reported race of Black (n = 28) or White (n = 373) underwent mechanical thrombectomy during the study period. Tobacco use was more prevalent among Black patients (43% vs 24%, p = 0.04), but there were no significant differences between the groups with respect to insurance, coronary artery disease, diabetes, illicit drug use, hypertension, or hyperlipidemia. The mean time from stroke onset to hospital presentation was significantly greater among Black patients (604.6 vs 333.4 minutes) (p = 0.007). There were no differences in fluoroscopy time, procedural success (Thrombolysis in Cerebral Infarction grade 2b or 3), hospital length of stay, or prevalence of hemicraniectomy. In multivariable analysis, Black race was strongly associated with higher mortality (32.1% vs 14.5%, p = 0.01). The disparity in mortality rates resolved after adjusting for the average time from stroke onset to presentation (p = 0.14). CONCLUSIONS: Black race was associated with an increased risk of death after mechanical thrombectomy for stroke. The increased risk may be associated with access-related factors, including delayed presentation to stroke centers.

Treatment of octogenarians and nonagenarians with aneurysmal subarachnoid hemorrhage: a 17-year institutional analysis.

BACKGROUND: Outcomes for octogenarians and nonagenarians after an aneurysmal subarachnoid hemorrhage (aSAH) are particularly ominous, with mortality rates well above 50%. The present analysis examines the neurologic outcomes of patients ≥ 80 years of age treated for aSAH. METHOD: A retrospective review was performed of all aSAH patients treated at Barrow Neurological Institute from January 1, 2003, to July 31, 2019. Patients were placed in 2 groups by age, < 80 vs ≥ 80 years. The ≥ 80-year-old group of octogenarians and nonagenarians was subsequently analyzed to compare treatment modalities. Poor neurologic outcome was defined as a modified Rankin Scale (mRS) score of > 2. RESULTS: During the study period, 1418 patients were treated for aSAH. The mean (standard deviation) age was 55.1 (13.6) years, the mean follow-up was 24.6 (40.0) months, and the rate of functional independence (mRS 0-2) at follow-up was 54% (751/1395). Logistic regression analysis found increasing age strongly associated with declining functional independence (R2 = 0.929, p < 0.001). Forty-three patients ≥ 80 years old were significantly more likely to be managed endovascularly than with open microsurgery (67% [n = 29] vs 33% [n = 14], p < 0.001). Compared with younger patients, those ≥ 80 years old had an increased risk of mortality and poor neurologic outcomes at follow-up. In the ≥ 80-year-old group, only 4 patients had good outcomes; none of the 4 had preexisting comorbidities, and all 4 were treated endovascularly. CONCLUSIONS: Age is a significant prognostic indicator of functional outcomes and mortality after aSAH. Most octogenarians and nonagenarians with aSAH will become severely disabled or die.

Mobile stroke units: taking stroke care to the patient.

PURPOSE OF REVIEW: Since the development of intravenous tissue plasminogen activator (tPA) for acute ischemic stroke (AIS), functional outcome has improved when treatment occurs within 4.5 h of stroke onset and treatment benefits are greater with earlier treatment. Endovascular revascularization also is better the sooner it is delivered. RECENT FINDINGS: The Get with the Guidelines Stroke registry found that less than one-third of treatment-eligible AIS patients receive intravenous tPA within 60 min of hospital arrival. Initiatives have tried to improve public education and awareness of stroke symptoms to decrease time to presentation. The mobile stroke unit (MSU) facilitates earlier computed tomography scans, delivery of tPA, proper triage and on-scene goal-directed care. MSUs reduce time from stroke alarm to treatment by 25-40 min and increase the rate of intravenous tPA use without an increase in hemorrhage risk. In addition, three-month favorable outcome is increased. SUMMARY: MSUs likely will evolve further and be used for other acute neurologic disorders, help triage patients for endovascular therapy, and be incorporated into systems of care in remote areas. Further studies are awaited to fully understand the overall medical and health-economic benefit of MSUs.

Mechanical ventilation in aneurysmal subarachnoid hemorrhage: systematic review and recommendations.

OBJECTIVE: Mechanical ventilation (MV) has a complex interplay with the pathophysiology of aneurysmal subarachnoid hemorrhage (aSAH). We aim to provide a review of the physiology of MV in patients with aSAH, give recommendations based on a systematic review of the literature, and highlight areas that still need investigation. DATA SOURCES: PubMed was queried for publications with the Medical Subject Headings (MeSH) terms "mechanical ventilation" and "aneurysmal subarachnoid hemorrhage" published between January 1, 1990, and March 1, 2020. Bibliographies of returned articles were reviewed for additional publications of interest. STUDY SELECTION: Study inclusion criteria included English language manuscripts with the study population being aSAH patients and the exposure being MV. Eligible studies included randomized controlled trials, observational trials, retrospective trials, case-control studies, case reports, or physiologic studies. Topics and articles excluded included review articles, pediatric populations, non-aneurysmal etiologies of subarachnoid hemorrhage, mycotic and traumatic subarachnoid hemorrhage, and articles regarding tracheostomies. DATA EXTRACTION: Articles were reviewed by one team member, and interpretation was verified by a second team member. DATA SYNTHESIS: Thirty-one articles met the inclusion criteria for this review. CONCLUSIONS: We make recommendations on oxygenation, hypercapnia, PEEP, APRV, ARDS, and intracranial pressure monitoring.

Spinal cord stimulators: socioeconomic disparities in four US states.

OBJECTIVES: Spinal cord stimulators (SCS) are increasingly placed in the United States in both the inpatient and outpatient setting. Although these interventions appear to be safe, the characteristics of the patients selected for ambulatory procedures have not been investigated. MATERIALS AND METHODS: We performed a retrospective cohort study involving 4843 patients who underwent outpatient and 4197 who underwent inpatient SCS placements and were registered in State Ambulatory Surgery Databases and State Inpatient Databases, respectively, for New York, California, Florida, and North Carolina from 2005 to 2008. RESULTS: In a multivariate analysis, male gender (odds ratio (OR) 1.22, 95% confidence interval (CI), 1.12, 1.33), high volume hospitals (OR 2.16, 95% CI, 1.94, 2.41), and Caucasian race (OR 1.25, 95% CI, 1.10, 1.41) were significantly associated with outpatient procedures. Higher Charlson Comorbidity Index (OR 0.36, 95% CI, 0.24, 0.54) and Medicare/Medicaid insurance (OR 0.75, 95% CI, 0.67, 0.83) were associated with a decreased chance of outpatient procedures. The rate of 30-day postoperative readmissions was higher among inpatients. Institutional charges were significantly lower for outpatient lumbar discectomies. The median total charge for inpatient hospitalization after SCS placement was $60,624 as compared with $22,288 for the outpatient setting (p < 0.0001). CONCLUSIONS: Access to ambulatory SCS placement appears to be more common for Caucasians, male patients, with private insurance, and fewer comorbidities, in the setting of higher volume hospitals. Further investigation is needed in the direction of mapping these disparities for appropriate resource utilization.

A Simple 3D Printed Model for Intracranial Vascular Anastomosis Practice and the Rochester Bypass Training Score.

BACKGROUND AND OBJECTIVES: Surgical simulation models in cranial neurosurgery are needed to allow affordable, accessible, and validated practice in resident education. Current bypass anastomosis practice models revolve around basic tube tying or complex animal and 3-dimensional models. This study sought to design and validate a 3-dimensional printed model for intracranial anastomosis training. METHODS: A computer-aided design (CAD) generic skull was uploaded into Meshmixer (v.3.5), and a 55-mm opening was created on the right side, mimicking a standard orbitozygomatic craniotomy. The model was rotated 15° upward and 35° left, before a 10-mm square frame was added 80-mm deep to the right orbit. The CAD model was uploaded to GrabCAD and printed using a J750 PolyJet 3D printer before being paired with a vascular anastomosis kit. The model was validated with standardized assessments of residents and attendings by simulating an "M2 to P2" bypass. The Rochester Bypass Training Score (RBTS) was created to assess bypass patency, back wall suturing, and suture quality. Postsimulation survey data regarding the realism and usefulness of the simulation were collected. RESULTS: Five junior residents (Postgraduate Year 1-4), 3 senior residents (Postgraduate Year 5-7), and 2 attendings were participated. The mean operative time in minutes was as follows: junior residents 78, senior residents 33, and attendings 50. The RBTS means were as follows: junior residents 2.4, senior residents 4.0, and attendings 5.0. Participants agreed that the model was realistic, useful for improving operative technique, and would increase comfort in bypass procedures. There are a few different printing options, varying in model infill and printing material used. For this experiment, a mix of Vero plastics were used totaling $309.09 per model; however, using the more common printing material polylactic acid brings the cost to $17.27 for a comparable model. CONCLUSION: This study presents an affordable, realistic, and educational intracranial vascular anastomosis simulator and introduces the RBTS for assessment.

Safety and efficacy comparison of embolic agents for middle meningeal artery embolization for chronic subdural hematoma.

OBJECTIVE: To perform a systematic review and meta-analysis evaluating the efficacy of middle meningeal artery embolization in terms of both clinical and radiographic outcomes, when performed with different embolic agents. METHODS: A systematic literature review and meta-analysis was performed to evaluate the impact of embolic agents on outcomes for middle meningeal artery (MMA) embolization. The use of polyvinyl alcohol (PVA) with or without (±) coils, N-butyl cyanoacrylate (n-BCA) ± coils, and Onyx alone were separately evaluated. Primary outcome measures were recurrence, the need for surgical rescue and in-hospital periprocedural complications. RESULTS: Thirty-one studies were identified with a total of 1,134 patients, with 786 receiving PVA, 167 receiving n-BCA, and 181 patients receiving Onyx. There was no difference in the recurrence rate (5.5% for PVA, 4.5% for n-BCA, and 6.5% for Onyx, with P=0.71) or need for surgical rescue (5.0% for PVA, 4.0% for n-BCA, and 6.9% for Onyx, with P=0.89) based on the embolic agent. Procedural complications also did not differ between embolic agents (1.8% for PVA, 3.6% for n-BCA, and 1.6% for Onyx, with P=0.48). CONCLUSIONS: Rates of recurrence, need for surgical rescue, and periprocedural complication following MMA embolization are not impacted by the type of embolic agent utilized. Ongoing clinical trials may be used to further investigate these findings.

Mandibular Fossa Approach to Petroclival and Anterior Pontine Lesions.

Objective To describe the anatomy related to a novel approach to the petroclival region through the mandibular fossa for the treatment of petroclival and anterior pontine lesions. Design Five dry skulls were examined for surgical approach. Three adult cadaveric heads underwent bilateral dissection. One cadaveric head was evaluated with computed tomography after dissection. Setting This study was performed in an academic medical center. Participants Neurosurgical anatomy researchers performed this study using dry skulls and cadaveric heads. Main Outcome Measurements This was a proof-of-concept anatomical study. Results The mandibular fossa approach uses a vertical preauricular incision above the facial nerve branches. Removal of the temporomandibular joint exposes the mandibular fossa. The anterior boundary is the mandibular nerve at the foramen ovale, and the posterior boundary is the jugular foramen. The chorda tympani, eustachian tube, and tensor tympani muscle are sectioned. The carotid artery is transposed out of the petrous canal, and a petrosectomy is performed from Meckel's cave to the foramen magnum and anterior occipital condyle. Dural opening exposes the anterior pons, vertebrobasilar junction, bilateral vertebral arteries, and the ipsilateral anterior and posterior inferior cerebellar arteries. At completion, the temporomandibular joint is reconstructed with a prosthetic joint utilizing a second incision along the mandible. Conclusions The mandibular fossa approach is a new trajectory to the petroclival region and the anterior pons. It combines the more anterior angle of endoscopic approaches along with the enhanced control of open approaches. Further study is necessary before this approach is used clinically.