Early adversity causes sex-specific deficits in perforant pathway connectivity and contextual memory in adolescent mice

BACKGROUND

Early life adversity impairs hippocampal development and function across diverse species. While initial evidence indicated potential variations between males and females, further research is required to validate these observations and better understand the underlying mechanisms contributing to these sex differences. Furthermore, most of the preclinical work in rodents was performed in adult males, with only few studies examining sex differences during adolescence when such differences appear more pronounced. To address these concerns, we investigated the impact of limited bedding (LB), a mouse model of early adversity, on hippocampal development in prepubescent and adolescent male and female mice.

METHODS

RNA sequencing, confocal microscopy, and electron microscopy were used to evaluate the impact of LB and sex on hippocampal development in prepubescent postnatal day 17 (P17) mice. Additional studies were conducted on adolescent mice aged P29-36, which included contextual fear conditioning, retrograde tracing, and ex vivo diffusion magnetic resonance imaging (dMRI).

RESULTS

More severe deficits in axonal innervation and myelination were found in the perforant pathway of prepubescent and adolescent LB males compared to LB female littermates. These sex differences were due to a failure of reelin-positive neurons located in the lateral entorhinal cortex (LEC) to innervate the dorsal hippocampus via the perforant pathway in males, but not LB females, and were strongly correlated with deficits in contextual fear conditioning.

CONCLUSIONS

LB impairs the capacity of reelin-positive cells located in the LEC to project and innervate the dorsal hippocampus in LB males but not female LB littermates. Given the critical role that these projections play in supporting normal hippocampal function, a failure to establish proper connectivity between the LEC and the dorsal hippocampus provides a compelling and novel mechanism to explain the more severe deficits in myelination and contextual freezing found in adolescent LB males.

Transient Impairment in Microglial Function Causes Sex-Specific Deficits in Synaptic and Hippocampal Function in Mice Exposed to Early Adversity

Abnormal development and function of the hippocampus are two of the most consistent findings in humans and rodents exposed to early life adversity, with males often being more affected than females. Using the limited bedding (LB) paradigm as a rodent model of early life adversity, we found that male adolescent mice that had been exposed to LB exhibit significant deficits in contextual fear conditioning and synaptic connectivity in the hippocampus, which are not observed in females. This is linked to altered developmental refinement of connectivity, with LB severely impairing microglial-mediated synaptic pruning in the hippocampus of male and female pups on postnatal day 17 (P17), but not in adolescent P33 mice when levels of synaptic engulfment by microglia are substantially lower. Since the hippocampus undergoes intense synaptic pruning during the second and third weeks of life, we investigated whether microglia are required for the synaptic and behavioral aberrations observed in adolescent LB mice. Indeed, transient ablation of microglia from P13-21, in normally developing mice caused sex-specific behavioral and synaptic abnormalities similar to those observed in adolescent LB mice. Furthermore, chemogenetic activation of microglia during the same period reversed the microglial-mediated phagocytic deficits at P17 and restored normal contextual fear conditioning and synaptic connectivity in adolescent LB male mice. Our data support an additional contribution of astrocytes in the sex-specific effects of LB, with increased expression of the membrane receptor MEGF10 and enhanced synaptic engulfment in hippocampal astrocytes of 17-day-old LB females, but not in LB male littermates. This finding suggests a potential compensatory mechanism that may explain the relative resilience of LB females. Collectively, these studies highlight a novel role for glial cells in mediating sex-specific hippocampal deficits in a mouse model of early-life adversity.

Frailty as a Predictor of Post-Surgical Outcomes in Patients With Cutaneous Malignancies of the Scalp and Neck Requiring Flap Reconstruction

BACKGROUND

Investigate the ability of frailty status to predict post-surgical outcomes in patients with cutaneous malignancies of the scalp and neck undergoing flap reconstruction.

METHODS

National Surgical Quality Improvement Program database was used to isolate patients with cutaneous malignancies of the scalp and neck who underwent surgical resection between 2015 to 2019. Univariate and multivariate analyses were performed to determine if frailty score correlated with negative post-operative outcomes. Receiver operating characteristic (ROC) curves allowed testing of the discriminative performance of age versus frailty.

RESULTS

This study demonstrated an independent correlation between frailty and major complications as well as non-home discharge. In ROC curve analysis, frailty demonstrated superior discrimination compared to age for predicting major complications.

CONCLUSION

Our study demonstrated an association between increasing frailty and major complications as well as the likelihood of a non-home discharge. When compared to age, frailty was also shown to be a better predictor of major complications.

Neuroendovascular Surgery Applications in Craniocervical Trauma

Cerebrovascular injuries resulting from blunt or penetrating trauma to the head and neck often lead to local hemorrhage and stroke. These injuries present with a wide range of manifestations, including carotid or vertebral artery dissection, pseudoaneurysm, occlusion, transection, arteriovenous fistula, carotid-cavernous fistula, epistaxis, venous sinus thrombosis, and subdural hematoma. A selective review of the literature from 1989 to 2023 was conducted to explore various neuroendovascular surgical techniques for craniocervical trauma. A PubMed search was performed using these terms: endovascular, trauma, dissection, blunt cerebrovascular injury, pseudoaneurysm, occlusion, transection, vasospasm, carotid-cavernous fistula, arteriovenous fistula, epistaxis, cerebral venous sinus thrombosis, subdural hematoma, and middle meningeal artery embolization. An increasing array of neuroendovascular procedures are currently available to treat these traumatic injuries. Coils, liquid embolics (onyx or n-butyl cyanoacrylate), and polyvinyl alcohol particles can be used to embolize lesions, while stents, mechanical thrombectomy employing stent-retrievers or aspiration catheters, and balloon occlusion tests and super selective angiography offer additional treatment options based on the specific case. Neuroendovascular techniques prove valuable when surgical options are limited, although comparative data with surgical techniques in trauma cases is limited. Further research is needed to assess the efficacy and outcomes associated with these interventions.

Machine learning algorithms for predicting outcomes of traumatic brain injury: A systematic review and meta-analysis

BACKGROUND

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. The use of machine learning (ML) has emerged as a key advancement in TBI management. This study aimed to identify ML models with demonstrated effectiveness in predicting TBI outcomes.

METHODS

We conducted a systematic review in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis statement. In total, 15 articles were identified using the search strategy. Patient demographics, clinical status, ML outcome variables, and predictive characteristics were extracted. A small meta-analysis of mortality prediction was performed, and a meta-analysis of diagnostic accuracy was conducted for ML algorithms used across multiple studies.

RESULTS

ML algorithms including support vector machine (SVM), artificial neural networks (ANN), random forest, and Naïve Bayes were compared to logistic regression (LR). Thirteen studies found significant improvement in prognostic capability using ML versus LR. The accuracy of the above algorithms was consistently over 80% when predicting mortality and unfavorable outcome measured by Glasgow Outcome Scale. Receiver operating characteristic curves analyzing the sensitivity of ANN, SVM, decision tree, and LR demonstrated consistent findings across studies. Lower admission Glasgow Coma Scale (GCS), older age, elevated serum acid, and abnormal glucose were associated with increased adverse outcomes and had the most significant impact on ML algorithms.

CONCLUSION

ML algorithms were stronger than traditional regression models in predicting adverse outcomes. Admission GCS, age, and serum metabolites all have strong predictive power when used with ML and should be considered important components of TBI risk stratification.

Acute Respiratory Distress Syndrome in Patients with Subarachnoid Hemorrhage: Incidence, Predictive Factors, and Impact on Mortality

INTRODUCTION

Acute respiratory distress syndrome (ARDS) is a known predictor of poor outcomes in critically ill patients. We sought to examine the role ARDS plays in outcomes in subarachnoid hemorrhage (SAH) patients. Prior studies investigating the incidence of ARDS in SAH patients did not control for SAH severity. Hence, we sought to determine the incidence ARDS in patients diagnosed with aneurysmal SAH and investigate the predisposing risk factors and impact upon outcomes.

METHODS

A retrospective cohort study was conducted using the National Inpatient Sample (NIS) database for the years 2008 to 2014. Multivariate stepwise regression analysis was performed to identify the risk factors and outcome associated with developing ARDS in the setting of SAH.

RESULTS

We identified 170,869 patients with non-traumatic subarachnoid hemorrhage, of whom 6962 were diagnosed with ARDS and of those 4829 required mechanical ventilation. ARDS more frequently developed in high grade SAH patients (1.97 ± 0.05 vs. 1.15 ± 0.01; p < 0.0001). Neurologic predictors of ARDS included cerebral edema (OR 1.892, CI 1.180-3.034, p = 0.0035) and medical predictors included cardiac arrest (OR 4.642, CI 2.273-9.482, p < 0.0001) and cardiogenic shock (OR 2.984, CI 1.157-7.696, p = 0.0239). ARDS was associated with significantly worse outcomes (15.5% vs. 52.9% discharged home, 63.0% vs. 40.8% discharged to rehabilitation facility and 21.5% vs. 6.3% in-hospital mortality).

CONCLUSION

Patients with SAH who developed ARDS were less likely to be discharged home, more likely to need rehabilitation and had a significantly higher risk of mortality. The identification of risk factors contributing to ARDS is helpful for improving outcomes and resource utilization.

Low serum albumin as a risk factor for delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage: eICU collaborative research database analysis

BACKGROUND

Delayed cerebral ischemia (DCI) represents a devastating complication of aneurysmal subarachnoid hemorrhage (aSAH) and is a significant predictor of morbidity and mortality. Recent studies have implicated inflammatory processes in the pathogenesis of DCI.

METHODS

aSAH patient data were retrospectively obtained from the eICU Collaborative Research Database (eICU CRD). Multivariable logistic regression models and receiver operating characteristic (ROC) curve analyses were employed to assess the association between low serum albumin (< 3.4 g/dL) and clinical endpoints: DCI and in-hospital mortality.

RESULTS

Among 276 aSAH patients included in the analysis, 35.5% (n=98) presented with low serum albumin levels and demonstrated a higher incidence of DCI (18.4% vs. 8.4%, OR=2.45, 95% CI 1.17, 5.10; p=0.017) and in-hospital mortality (27.6% vs. 16.3%, OR=1.95, 95% CI 1.08, 3.54; p=0.027) compared to patients with normal admission albumin values. In a multivariable model controlling for age and World Federation of Neurosurgical Societies grade, low serum albumin remained significantly associated with DCI (OR=2.52, 95% CI 1.18, 5.36; p=0.017), but not with in-hospital mortality. A combined model for prediction of DCI, encompassing known risk factors in addition to low serum albumin, achieved an area under the curve of 0.65 (sensitivity=0.55, specificity=0.75).

CONCLUSIONS

Serum albumin, a routine and inexpensive laboratory measurement, can may potentially aid in the identification of patients with aSAH at risk for the development of DCI.

Enzymatic debridement in critically injured burn patients - Our experience in the intensive care setting and during burn resuscitation

BACKGROUND

Much of the recent literature on bromelain based enzymatic debridement of burn injury has focused on its use in smaller burn injury and specialist areas such as the hands or genitals (Krieger et al., 2012; Schulz et al., 2017a,b,c,d). This is despite the original papers describing its use in larger burn injury (Rosenberg et al., 2004, 2014). The current EMA license for Nexobrid™ advises that it should not be used for burn injuries of more than 15% TBSA and should be used with caution in patients with pulmonary burn trauma and suspected pulmonary burn trauma. The original safety and efficacy trial of NexoBrid™ limited its use to 15% TBSA aliquots with concern regarding the effect of bromelain on coagulation. In a European consensus paper of experienced burns clinicians, now on its second iteration, 100% of respondents agreed that "up to 30% BSA can be treated by enzymatic debridement based on individual decision" (Hirche et al., 2017). Hofmaenner et al.'s recent study on the safety of enzymatic debridement in extensive burns larger than 15% provides some further evidence that "bromelain based enzymatic debridement can be carried out safely in large-area burns" (Hofmaenner et al., 2020) but the literature is scant in these larger debridement areas. In our centre we have been using enzymatic debridement for resuscitation level burn injury since 2016. We have gained significant learning in this time; this article aims to describe our current protocol for enzymatic debridement in this patient population and highlight specific learning points that might aid other centres in using enzymatic debridement for larger burn injury.

METHOD

We performed a search of the IBID database to identify all adult patients who satisfied the inclusion criteria of resuscitation level burn injury (defined as total burn surface area (TBSA) ≥15% in patients aged >16 years), or level 3 admission following burn injury and who underwent Enzymatic Debridement. A case note review was completed, and details comprising patient demographics, TBSA, mechanism of burn, presence of inhalation injury, sequencing of debridement, length of ICU and hospital stay, blood product utilisation and the need for autografting were recorded. No ethical approval has been sought for this retrospective review.

RESULTS

We identified 29 patients satisfying the inclusion criteria (Table 1). Between June 2016 and June 2020 the average total burn size of patients who had at least some of their burn treated by enzymatic debridement increased from 21.4% in 2016/17 to 34.7% in 2019/20. In these patients the actual area treated by enzymatic debridement also increased from 11.9% TBSA to 20.3% TBSA. 19 patients (66%) had enzymatic debridement performed within 24 h of injury, a further 2 patients (7%) within 48 h after injury. Patients were more likely to have enzymatic debridement commenced in the first 24 h after injury if they had circumferential limb injury (39% vs 9%) or were planned for enzyme only debridement (78% vs 28%). Those who were planned for combination enzyme and surgical debridement were more likely to have enzymatic debridement commenced after the first 48 h (75%). We have performed enzymatic debridement overnight on one occasion, for a patient who presented with circumferential limb injury and was determined to undergo urgent debridement.

CONCLUSION

Much of the literature has described the use of enzymatic debridement in smaller burns, and specialist areas. However, it is our opinion that the advantages of enzymatic debridement appear to be greater in larger burns with a facility for whole burn excision on the day of admission in the ICU cubicle. We have demonstrated significantly reduced blood loss, improved dermal preservation, reduced need for autografting, and a reduction in the number of trips to theatre. We would advocate that both the team and the patient need to be as prepared as they would be for a traditional surgical excision. The early part of our learning curve for enzymatic debridement in resuscitation level injuries was steep, and we were able to build on experience from managing smaller injuries. We recommend any team wishing to using enzymatic debridement gain experience in the same way and develop robust local pathways prior to attempting use in larger burn injuries.

An institutional report of heparin induced thrombocytopenia type II in aneurysmal subarachnoid hemorrhage patients

BACKGROUND

Heparin induced thrombocytopenia Type II (HIT-II) is a dangerous thromboembolic complication of heparin therapy. The current literature on incidence and outcomes of HIT-II in aneurysmal subarachnoid hemorrhage (aSAH) patients remains sparse.

OBJECTIVE

We report our institution's incidence and outcomes of HIT-II in aSAH patients.

METHODS

We performed a retrospective cohort study at an academic medical center between June 2014 and July 2018. All patients had aSAH confirmed by digital subtraction angiography. Diagnosis of HIT-II was determined by positive results on both heparin PF4-platelet antibody ELISA (anti-PF4) and serotonin release assay (SRA).

RESULTS

204 patients met inclusion criteria. Seven patients (7/204, 3.5%) underwent laboratory testing, three of whom met clinical criteria. HIT-II incidence was confirmed in two of these seven patients (2/204, 0.98%), who had high BMI and T4 scores.

CONCLUSION

Our institution's report of HIT-II incidence in aSAH patients is lower than previously reported in this population and more closely parallels HIT-II incidence in the general and surgical ICU setting. Widely-accepted American College of Chest Physicians (ACCP) clinical diagnostic criteria in conjunction with anti-PF4 and SRA testing is the gold standard of clinical diagnosis of HIT-II in aSAH patients.

Endovascular Thrombectomy for Pediatric Acute Ischemic Stroke

BACKGROUND

Evidence regarding the utilization and outcomes of endovascular thrombectomy (EVT) for pediatric ischemic stroke is limited, and justification for its use is largely based on extrapolation from clinical benefits observed in adults.

METHODS

Weighted discharge data from the National Inpatient Sample were queried to identify pediatric patients with ischemic stroke (<18 years old) during the period of 2010 to 2019. Complex samples statistical methods were used to characterize the profiles and clinical outcomes of EVT-treated patients. Propensity adjustment was performed to address confounding by indication for EVT based on disparities in baseline characteristics between EVT-treated patients and those medically managed.

RESULTS

Among 7365 pediatric patients with ischemic stroke identified, 190 (2.6%) were treated with EVT. Utilization significantly increased in the post-EVT clinical trial era (2016-2019; 1.7% versus 4.0%; P<0.001), while the use of decompressive hemicraniectomy decreased (2.8% versus 0.7%; P<0.001). On unadjusted analysis, 105 (55.3%) EVT-treated patients achieved favorable functional outcomes at discharge (home or to acute rehabilitation), while no periprocedural iatrogenic complications or instances of contrast-induced kidney injury were reported. Following propensity adjustment, EVT-treated patients demonstrated higher absolute but nonsignificant rates of favorable functional outcomes in comparison with medically managed patients (55.3% versus 52.8%; P=0.830; adjusted hazard ratio, 1.01 [95% CI, 0.51-2.03]; P=0.972 for unfavorable outcome). Among patients with baseline National Institutes of Health Stroke Scale score >11 (75th percentile of scores in cohort), EVT-treated patients trended toward higher rates of favorable functional outcomes compared with those treated medically only (71.4% versus 55.6%; P=0.146). In a subcohort assessment of EVT-treated patients, those administered preceding thrombolytic therapy (n=79, 41.6%) trended toward higher rates of favorable functional outcomes (63.3% versus 49.5%; P=0.060).

CONCLUSIONS

This cross-sectional evaluation of the clinical course and short-term outcomes of pediatric patients with ischemic stroke treated with EVT demonstrates that EVT is likely a safe modality which confers high rates of favorable functional outcomes.

Coronary microvascular dysfunction is only detectable in type 2 diabetes in the presence of obesity

Background

Heart failure (HF) is a leading cardiovascular complication of type 2 diabetes (T2D). Coronary microvascular dysfunction (CMD) precedes HF in diabetes and carries important prognostic information. CMD is also evident in metabolically healthy obese individuals without diabetes or hypertension. Whether diabetes causes CMD in the absence of obesity is uncertain. The interrelation among visceral adiposity and CMD has not been assessed previously.

Objectives

We sought to better understand the links between visceral and epicardial adipose tissue (VAT and EAT respectively) distribution, insulin resistance with myocardial perfusion, energetics and function in asymptomatic lean (LnT2D) and overweight/obese T2D patients (ObT2D) without cardiovascular disease.

Methods

62 participants [27 Ob-T2D, 15 Ln-T2D, and 20 overweight controls] were recruited. Subjects underwent cardiac and abdominal magnetic resonance imaging and 31P-magnetic resonance spectroscopy, for measurements of EAT and VAT areas, rest and adenosine stress myocardial blood flow (MBF), cardiac function and phosphocreatine to ATP ratio (PCr/ATP). Fasting blood samples were taken for plasma homeostasis model assessment of insulin resistance (HOMA-IR) index calculations.

Results

The biochemical characteristics and multiparametric MR results are given in Table 1 and results of Pearson's regression analysis in the entire study population are given in Table 2.

Stress MBF was lowest in ObT2D, while rest MBF was highest in LnT2D. Left ventricular ejection fraction (LVEF) and myocardial PCr/ATP were similarly reduced in diabetes groups. In the absence of obesity, there was no significant increase in VAT, EAT or HOMA-IR in T2D patients compared to controls. BMI and VAT, negatively correlated with LVEF, and strain parameters. PCr/ATP correlated with LVEF, but not HOMA-IR. BMI, EAT and VAT all correlated significantly with HOMA-IR, and HOMA-IR correlated with cardiac functional parameters. There was no association between HOMA-IR and myocardial perfusion.

Conclusions

In this study CMD was only evident in ObT2D patients, with normal rest and stress MBF in LnT2D patients. Despite normal perfusion and no significant increase in insulin resistance, LVEF and myocardial PCr/ATP were similarly reduced in LnT2D and ObT2D, and PCr/ATP correlated with LVEF. This suggests that alterations in cardiac energy metabolism are mechanistically more relevant for the pathophysiology of diabetic cardiomyopathy in LnT2D patients. In the absence of correlation between insulin resistance and myocardial perfusion, factors like inflammation and altered adipokine profile may play important roles for the pathophysiology of CMD in ObT2D patients. A better understanding of the underlying pathophysiological mechanisms of diabetic cardiomyopathy in LnT2D and ObT2D may help to develop contemporary tailored treatment and prevention strategies to tackle excess heart failure risk.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): BHFWellcome trust Table 1Table 2

Does Frailty or Age Increase the Risk of Postoperative Complications Following Cochlear Implantation?

Objective

To evaluate whether frailty or age increases the risk of postoperative complications following cochlear implant (CI) surgery.

Study Design

Retrospective cohort study.

Setting

Tertiary academic center.

Methods

An evaluation of all adult patients undergoing cochlear implantation between 2006 and 2020 was performed. The 5-item Modified Frailty Index (mFI-5, comprising preoperative history of pulmonary disease, heart failure, hypertension, diabetes, and partially/totally dependent functional status) was calculated for all patients included in analysis in addition to demographic characteristics. The primary outcome was postoperative complications following CI within a 3-month period. Major complications included myocardial infarction, bleeding, and cerebrospinal fluid leak, among others. Predictors of postoperative complications were examined using multivariable logistic regression reporting odds ratios (ORs) and 95% CIs.

Results

There were 520 patients included for review with a median age of 68 (range, 18-94) years and a slight male predominance (n = 283, 54.4%). There were 340 patients (65.4%) who were robust (nonfrail) with an mFI of 0, while 180 (34.6%) had an mFI of ≥1. There were 20 patients who experienced a postoperative complication (3.85%). There was no statistically significant association between postoperative complications as a result of preoperative frailty (OR, 1.56; 95% CI, 0.98-2.48, P = .06) or age as a continuous variable (OR, 0.99; 95% CI, 0.97-1.02, P = .51).

Conclusions

CI is safe for elderly and frail patients and carries no additional risk of complications when compared to younger, healthier patients. While medical comorbidities should always be considered perioperatively, this study supports the notion that implantation is low risk in older, frail patients.

Endovascular Thrombectomy for Treatment of Acute Ischemic Stroke During Pregnancy and the Early Postpartum Period

BACKGROUND AND PURPOSE

Acute ischemic stroke (AIS) is a rare occurrence during pregnancy and the postpartum period. Existing literature evaluating endovascular mechanical thrombectomy (MT) for this patient population is limited.

METHODS

The National Inpatient Sample was queried from 2012 to 2018 to identify and characterize pregnant and postpartum patients (up to 6 weeks following childbirth) with AIS treated with MT. Complications and outcomes were compared with nonpregnant female patients treated with MT and to other pregnant and postpartum patients managed medically. Complex samples regression models and propensity score matching were implemented to assess adjusted associations and to address confounding by indication, respectively.

RESULTS

Among 4590 pregnant and postpartum patients with AIS, 180 (3.9%) were treated with MT, and rates of utilization increased following the MT clinical trial era (2015-2018; 1.9% versus 5.3%, P=0.011). Compared with nonpregnant patients with AIS treated with MT, they experienced lower rates of intracranial hemorrhage (11% versus 24%, P=0.069) and poor functional outcome (50% versus 72%, P=0.003) at discharge. Pregnant/postpartum status was independently associated with a lower likelihood of development of intracranial hemorrhage (adjusted odds ratio, 0.26 [95% CI, 0.09-0.70]; P=0.008) following multivariable analysis adjusting for age, illness severity, and stroke severity. Following propensity score matching, pregnant and postpartum patients treated with MT and those medically managed differed in frequency of venous thromboembolism (17% versus 0%, P=0.001) and complications related to pregnancy (44% versus 64%, P=0.034), but not in functional outcome at discharge or hospital length of stay. Pregnant and postpartum women treated with MT did not experience mortality or miscarriage during hospitalization.

CONCLUSIONS

This large-scale analysis utilizing national claims data suggests that MT is a safe and efficacious therapy for AIS during pregnancy and the postpartum period. In the absence of prospective clinical trials, population-based cross-sectional analyses such as the present study provide valuable clinical insight.

Spinal Epidural Abscess Patients Have Higher Modified Frailty Indexes Than Back Pain Patients on Emergency Room Presentation: A Single-Center Retrospective Case-Control Study

OBJECTIVE

Spinal epidural abscess (SEA) patients have increased medical comorbidities and risk factors for infection compared with those without SEA. However, the association between frailty and SEA patients has not been documented.

METHODS

A total of 46 SEA patients were randomly paired and matched by age and sex with a control group of patients with back pain who had presented to our emergency department from 2012 to 2017. Statistical analysis identified the risk factors associated with SEA and frailty using the modified frailty index (mFI), and the patients were stratified into robust, prefrail, and frail groups. We examined the value of the mFI as a prognostic predictor and evaluated the classic risk factors (CRFs).

RESULTS

The SEA patients had higher mFIs and CRFs (P = 0.023 and P < 0.001, respectively) and a longer length of stay (22.89 days vs. 1.72 days; P < 0.001). Of the mFI variables, only diabetes had a significant association with SEA (odds ratio [OR], 3.60; P = 0.012). Among the stratified mFI subgroups, a frail ranking (mFI >2) was the strongest risk factor for SEA (OR, 5.18; P = 0.003). A robust ranking (mFI, 0-1) was a weak negative predictor for SEA (OR, 0.41; P = 0.058). The robust patients were also more likely to be discharged to home (OR, 7.58; P = 0.002). Of the CRF variables, only intravenous drug use had a statistically significant association with SEA (OR, 10.72; P = 0.015).

CONCLUSIONS

Patients with SEA were more frail compared with the control back pain patients. Frailty was determined to be an independent risk factor for SEA, outside of the CRFs. The use of the mFI could be potentially useful in predicting the diagnosis, prognosticating, and guiding SEA treatment.

Middle Meningeal Artery Embolization Using Combined Particle Embolization and n-BCA with the Dextrose 5% in Water Push Technique for Chronic Subdural Hematomas: A Prospective Safety and Feasibility Study

BACKGROUND AND PURPOSE

Embolization of the middle meningeal artery for treatment of refractory or recurrent chronic subdural hematomas has gained momentum during the past few years. Little has been reported on the use of the n-BCA liquid embolic system for middle meningeal artery embolization. We present the technical feasibility of using diluted n-BCA for middle meningeal artery embolization.

MATERIALS AND METHODS

We sought to examine the safety and technical feasibility of the diluted n-BCA liquid embolic system for middle meningeal artery embolization. Patients with chronic refractory or recurrent subdural hematomas were prospectively enrolled from September 2019 to June 2020. The primary outcome was the safety and technical feasibility of the use of diluted n-BCA for embolization of the middle meningeal artery. The secondary end point was the efficacy in reducing hematoma volume.

RESULTS

A total of 16 patients were prospectively enrolled. Concomitant burr-hole craniotomies were performed in 12 of the 16 patients. Two patients required an operation following middle meningeal artery embolization for persistent symptoms. The primary end point was met in 100% of cases in which there were no intra- or postprocedural complications. Distal penetration of the middle meningeal artery branches was achieved in all the enrolled cases. A 7-day post-middle meningeal artery embolization follow-up head CT demonstrated improvement (>50% reduction in subdural hematoma volume) in 9/15 (60%) patients, with 6/15 (40%) showing an unchanged or stable subdural hematoma. At day 21, available CT scans demonstrated substantial further improvement (>75% reduction in subdural hematoma volume).

CONCLUSIONS

Embolization of the middle meningeal artery using diluted n-BCA and ethiodized oil (1:6) is safe and feasible from a technical standpoint. The use of a dextrose 5% bolus improves distal penetration of the glue.

Rapid exponential increase in neurosurgery departmental scholarly output following an intensive research initiative

There has been extensive research into methods of increasing academic departmental scholarly activity (DSA) through targeted interventions. Residency programmes are responsible for ensuring sufficient scholarly opportunities for residents. We sought to discover the outcomes of an intensive research initiative (IRI) on DSA in our department in a short-time interval. IRI was implemented, consisting of multiple interventions, to rapidly produce an increase in DSA through resident/medical student faculty engagement. We compare pre-IRI (8 years) and post-IRI (2 years) research products (RP), defined as the sum of oral presentations and publications, to evaluate the IRI. The study was performed in 2020. The IRI resulted in an exponential increase in DSA with an annual RP increase of 350% from 2017 (3 RP) to 2018 (14 RP), with another 92% from 2018 (14 RP) to 2019 (27 RP). RP/year exponentially increased from 2.1/year to 10.5/year for residents and 0.5/year to 10/year for medical students, resulting in a 400% and 1900% increase in RP/year, respectively. The common methods in literature to increase DSA included instituting protected research time (23.8%) and research curriculum (21.5%). We share our department's increase in DSA over a short 2-year period after implementing our IRI. Our goal in reporting our experience is to provide an example for departments that need to rapidly increase their DSA. By reporting the shortest time interval to achieve exponential DSA growth, we hope this example can support programmes in petitioning hospitals and medical colleges for academic support resources.

Evaluating the Impact of Neurosurgical Educational Interventions on Patient Knowledge and Satisfaction: A Systematic Review of the Literature

OBJECTIVE

In this systematic review, preoperative educational interventions for patients undergoing neurosurgical treatment are identified and their impact on patient knowledge acquisition and satisfaction is assessed.

METHODS

The review was conducted in accordance with the PRISMA guidelines and used PubMed, Google Scholar, and MEDLINE databases. Studies evaluating before and after cohort or control group comparison were identified between 2007 and 2019 and were independently scored and evaluated by 3 authors.

RESULTS

Eighty-one articles were assessed for eligibility and 15 met the inclusion criteria. Patient educational interventions were text-based (2 studies), multimedia/video-based (3), mobile/tablet-based (5), or used virtual reality (2) or three-dimensional printing (3). Interventions were disease-specific for cerebrovascular lesions (5), degenerative spine disease (2), concussion/traumatic brain injury (2), movement disorders (1), brain tumor (1), adolescent epilepsy (1), and other cranial/spinal elective procedures (3). Eleven studies (n = 18-175) documented patient knowledge acquisition using self-reported knowledge questionnaires (5) or more objective assessments based on true/false or multiple-choice questions (6). Most studies (10/11) reported statistically significant increases in patient knowledge after implementation of the intervention. Ten studies (n = 14-600) documented patient satisfaction using validated satisfaction surveys (2), Likert scale surveys (6), or other questionnaires (2). Although all studies reported increases in patient satisfaction after the intervention, only 4 were statistically significant.

CONCLUSIONS

Patient educational interventions using various modalities are broadly applicable within neurosurgery and ubiquitously enhance patient knowledge and satisfaction. Interventions should be implemented when possible.

Chameleons, red herrings, and false localizing signs in neurocritical care

False localizing signs (FLS) and other misleading neurological signs have long been an intractable aspect of neurocritical care. Because they suggest an incorrect location or etiology of the pathological lesion, they have often led to misdiagnosis and mismanagement of the patient. Here, we reviewed the existing literature to provide an updated, comprehensive descriptive review of these difficult to diagnose signs in neurocritical care. For each sign presented, we discuss the non-false localizing presentation of symptoms, the common FLS or misleading presentation, etiology/pathogenesis of the sign, and diagnosis, as well as any other clinically relevant considerations. Within cranial neuropathies, we cover cranial nerves III, IV, V, VI, VII, VIII, as well as multiple cranial nerve involvement of IX, X, and XII. FLS ophthalmologic symptoms indicate diagnostically challenging neurological deficits, and here we discuss downbeat nystagmus, ping-pong-gaze, one-and-a-half syndrome, and wall-eyed bilateral nuclear ophthalmoplegia (WEBINO). Cranial herniation syndromes are integral to any discussion of FLS and here we cover Kernohan's notch phenomenon, pseudo-Dandy Walker malformation, and uncal herniation. FLS in the spinal cord have also been relatively well documented, but in addition to compressive lesions, we also discuss newer findings in radiculopathy and disc herniation. Finally, pulmonary syndromes may sometimes be overlooked in discussions of neurological signs but are critically important to recognize and manage in neurocritical care, and here we discuss Cheyne-Stokes respiration, cluster breathing, central neurogenic hyperventilation, ataxic breathing, Ondine's curse, and hypercapnia. Though some of these signs may be rare, the framework for diagnosing and treating them must continue to evolve with our growing understanding of their etiology and varied presentations.

Acute subdural hematomas secondary to aneurysmal subarachnoid hemorrhage confer poor prognosis: a national perspective

BACKGROUND

Aneurysmal ruptures typically cause subarachnoid bleeding with intraparenchymal and intraventricular extension. However, rare instances of acute aneurysmal ruptures present with concomitant, non-traumatic subdural hemorrhage (SDH). We explored the incidence and difference in outcomes of SDH with aneurysmal subarachnoid hemorrhage (aSAH) as compared with aSAH alone.

METHODS

Retrospective cohort study from 2012 to 2015 from the National (Nationwide) Inpatient Sample (NIS) (20% stratified sample of all hospitals in the United States). NIS database (2012 to September 2015) queried to identify all patients presenting with aSAH. From this population, the patients with concomitant SDH were identified.

RESULTS

A total of 10 075 patients with both cerebral aneurysms and aSAH were included. Of these, 335 cases of concomitant SDH and aSAH were identified. There was no significant change in the rate of SDH in aSAH over time. SDH with aSAH patients had a mortality of 24% compared with 12% (p=0.003) in the SAH only group, and only 16% were discharged home vs 37% (p=0.003) in the SAH group.

CONCLUSIONS

There is a 3.5% incidence of acute SDH in patients presenting with non-traumatic aSAH. Patients with SDH and aSAH have nearly double the mortality, higher rate of discharge to nursing home and rehabilitation, and a significantly lower rate of discharge to home and return to routine functioning. This information is useful in counseling and prognostication of patients with concomitant SDH and aSAH.

The Effect of Frailty and Patient Comorbidities on Outcomes After Acute Subdural Hemorrhage: A Preliminary Analysis

BACKGROUND

Frailty is associated with worse outcomes across a variety of neurosurgical diseases. However, its effect on acute subdural hemorrhage (aSDH) outcomes is unclear. The goal of this study is to compare 3 measures of frailty with the gold standard (i.e., initial Glasgow Coma Scale [iGCS] score) for predicting outcomes after aSDH.

METHODS

Patients who presented between January 2016 and June 2018 were retrospectively identified based on International Classification of Diseases codes for aSDH. Patients' modified Frailty Index (mFI), temporalis muscle thickness (TMT), and age-adjusted Charlson Comorbidity Index (CCI) were calculated. Primary end points were death and discharge home.

RESULTS

Of 167 patients included, the mean age was 63.4 ± 1.9 years, the average CCI was 3.4 ± 0.2, mFI was 1.4 ± 0.1, TMT was 7.1 ± 0.2 mm, and iGCS score was 11.9 ± 0.3. Sixty-nine patients (41.3%) were discharged home and 32 (19.2%) died during hospitalization. In multivariate analysis, decreasing iGCS score (odds ratio [OR], 0.84; 95% confidence interval [CI], 0.74-0.96; P = 0.0112) and midline shift (OR, 1.27; 95% CI, 1.08-1.50; P = 0.0048), but not age or frailty, predicted mortality. In addition to iGCS score (OR, 1.26; 95% CI, 1.10-1.44; P = 0.0011), lower CCI (OR, 0.32; 95% CI, 0.14-0.74; P = 0.0071) and larger TMT (OR, 2.63; 95% CI, 1.16-5.99; P = 0.0210) independently predicted increased rates of discharge home. mFI was not independently associated with either primary end point in multivariate analysis.

CONCLUSIONS

iGCS score predicts both mortality and discharge location after aSDH better than do age or frailty. However, CCI and TMT, but not mFI, are useful prognostic indicators of discharge to home after aSDH. The iGCS score should continue to be the primary prediction tool for patients with aSDH; however, frailty may be useful for resource allocation, especially when nearing discharge.

Reversible cerebral vasoconstriction syndrome and dissection in the setting of COVID-19 infection

The current COVID-19 pandemic has recently brought to attention the myriad of neuro- logic sequelae associated with Coronavirus infection including the predilection for stroke, particularly in young patients. Reversible cerebral vasoconstriction syndrome (RCVS) is a well-described clinical syndrome leading to vasoconstriction in the intracra- nial vessels, and has been associated with convexity subarachnoid hemorrhage and oc- casionally cervical artery dissection. It is usually reported in the context of a trigger such as medications, recreational drugs, or the postpartum state; however, it has not been described in COVID-19 infection. We report a case of both cervical vertebral ar- tery dissection as well as convexity subarachnoid hemorrhage due to RCVS, in a pa- tient with COVID-19 infection and no other triggers.

What Does it Mean for a Surgeon to "Run Two Rooms"? A Comprehensive Literature Review of Overlapping and Concurrent Surgery Policies

The aim of this study was to review and analyze all of the "concurrent surgery" (CS) and "overlapping surgery" (OS) literature with the goal of: standardizing terminology, defining discrepancies in the literature and proposing solutions for the current challenges of regulating surgery to achieve maximal safety and efficiency. The CS and OS literature has grown exponentially over the past two years. Before this, there were no significant publications addressing this topic. There is an extremely wide variance on how "running two rooms" is defined and whether it should be permitted. These differences affect our patients' perception of this practice. The literature lacks any comprehensive review of the topic and terminology. We performed a PubMed search to identify studies that considered the issue of OS. The terms "overlapping surgery", "concurrent surgery", and "simultaneous surgery" (SS) were used in the query. We then analyzed the publications identified. The literature contained 18 published studies analyzing OS safety between November 2016 and June 2018. Eight were neurosurgical studies, three were orthopedic, and the remaining seven articles were in other surgical specialties. A total of 1,207,155 surgical cases (range 250->500,000 patients) were analyzed among the 18 studies. There were 57,880 (5.04%) OS cases. The OS rates in the individual studies ranged from 1.2 to 68 per cent (Table 1). Neurosurgical studies had the highest average OS rate of 54 per cent (range 37-68%), whereas the average OS rate in orthopedic surgery was 43 per cent (range 2.7-68%). Approximately one-third of the studies were multicenter investigations (27.7%). The studies measured more than 20 distinct outcomes, but there were only five outcomes that were included in the majority of the studies: mortality rates, reoperation rates, procedure length of time, readmission rates, and hospital length of stay. The current body of literature repeatedly demonstrates that OS is a safe and effective option when undertaken by experienced surgeons who practice it frequently. For successful OS, the Mandatory Attending Portion for two surgeries must not overlap and Unnecessary Anesthesia Time must be prohibited. Hospitals and surgical specialty organizations must implement policies to assure the safe practice of OS.

What Does it Mean for a Surgeon to “Run Two Rooms”? A Comprehensive Literature Review of Overlapping and Concurrent Surgery Policies

The aim of this study was to review and analyze all of the “concurrent surgery” (CS) and “overlapping surgery” (OS) literature with the goal of: standardizing terminology, defining discrepancies in the literature and proposing solutions for the current challenges of regulating surgery to achieve maximal safety and efficiency. The CS and OS literature has grown exponentially over the past two years. Before this, there were no significant publications addressing this topic. There is an extremely wide variance on how “running two rooms” is defined and whether it should be permitted. These differences affect our patients’ perception of this practice. The literature lacks any comprehensive review of the topic and terminology. We performed a PubMed search to identify studies that considered the issue of OS. The terms “overlapping surgery”, “concurrent surgery”, and “simultaneous surgery” (SS) were used in the query. We then analyzed the publications identified. The literature contained 18 published studies analyzing OS safety between November 2016 and June 2018. Eight were neurosurgical studies, three were orthopedic, and the remaining seven articles were in other surgical specialties. A total of 1,207,155 surgical cases (range 250–>500,000 patients) were analyzed among the 18 studies. There were 57,880 (5.04%) OS cases. The OS rates in the individual studies ranged from 1.2 to 68 per cent (Table 1). Neurosurgical studies had the highest average OS rate of 54 per cent (range 37–68%), whereas the average OS rate in orthopedic surgery was 43 per cent (range 2.7–68%). Approximately one-third of the studies were multicenter investigations (27.7%). The studies measured more than 20 distinct outcomes, but there were only five outcomes that were included in the majority of the studies: mortality rates, reoperation rates, procedure length of time, readmission rates, and hospital length of stay. The current body of literature repeatedly demonstrates that OS is a safe and effective option when undertaken by experienced surgeons who practice it frequently. For successful OS, the Mandatory Attending Portion for two surgeries must not overlap and Unnecessary Anesthesia Time must be prohibited. Hospitals and surgical specialty organizations must implement policies to assure the safe practice of OS.

Low Risk Monitoring in Neurocritical Care

Background/Rationale: Patients are admitted to Intensive care units (ICUs) either because they need close monitoring despite a low risk of hospital mortality (LRM group) or to receive ICU specific active treatments (AT group). The characteristics and differential outcomes of LRM patients vs. AT patients in Neurocritical Care Units are poorly understood.

Methods: We classified 1,702 patients admitted to our tertiary and quaternary care center Neuroscience-ICU in 2016 and 2017 into LRM vs. AT groups. We compared demographics, admission diagnosis, goal of care status, readmission rates and managing attending specialty extracted from the medical record between groups. Acute Physiology, Age and Chronic Health Evaluation (APACHE) IVa risk predictive modeling was used to assess comparative risks for ICU and hospital mortality and length of stay between groups.

Results: 56.9% of patients admitted to our Neuroscience-ICU in 2016 and 2017 were classified as LRM, whereas 43.1% of patients were classified as AT. While demographically similar, the groups differed significantly in all risk predictive outcome measures [APACHE IVa scores, actual and predicted ICU and hospital mortality (p < 0.0001 for all metrics)]. The most common admitting diagnosis overall, cerebrovascular accident/stroke, was represented in the LRM and AT groups with similar frequency [24.3 vs. 21.3%, respectively (p = 0.15)], illustrating that further differentiating factors like symptom duration, neurologic status and its dynamic changes and neuro-imaging characteristics determine the indication for active treatment vs. observation. Patients with intracranial hemorrhage/hematoma were significantly more likely to receive active treatments as opposed to having a primary focus on monitoring [13.6 vs. 9.8%, respectively (p = 0.017)].

Conclusion: The majority of patients admitted to our Neuroscience ICU (56.9%) had <10% hospital mortality risk and a focus on monitoring, whereas the remaining 43.1% of patients received active treatments in their first ICU day. LRM Patients exhibited significantly lower APACHE IVa scores, ICU and hospital mortality rates compared to AT patients. Observed-over-expected ICU and hospital mortality ratios were better than predicted by APACHE IVa for low risk monitored patients and close to prediction for actively treated patients, suggesting that at least a subset of LRM patients may safely and more cost effectively be cared for in intermediate level care settings.

Efficacy of clip-wrapping in treatment of complex pediatric aneurysms

PURPOSE

Pediatric aneurysms (PAs) are distinct from their adult counterparts with respect to typical location, aneurysm type, and known predisposing risk factors. Many strategies have been employed to treat PAs, but although it has been used frequently in adults, clip wrapping in pediatric patients has only been reported once. We present a series of pediatric patients that underwent clip wrapping and discuss this strategy as an effective means of treating unclippable PAs.

METHODS

Pediatric patients with clip-wrapped aneurysms over a 5-year period were retrospectively identified. Clinical presentation, surgical management, and clinical and radiological outcome of the patients were evaluated.

RESULTS

Five pediatric patients with aneurysms were treated with clip wrapping during the specified period. Three had traumatic pseudoaneurysms, with two subarachnoid hemorrhages from aneurysm rupture. One patient presented with mycotic pseudoaneurysm rupture causing a large intraparenchymal and subarachnoid hemorrhage. Another patient had a dissecting complex saccular lenticulostriate aneurysm with four perforating vessels arising from the dome. Four patients had good clinical results, with Glasgow Outcome Scale (GOS) scores of 5 after at least 1-year follow-up (mean 24.2); one patient had a GOS score of 5 at discharge, but no additional follow-up. Postoperative neuroimaging demonstrated vessel patency after clip wrapping with no recurrent hemorrhages or increase in aneurysm size; however, one had progressive occlusion of the artery in a delayed fashion and had a small clinical ischemic event from which she fully recovered.

CONCLUSIONS

Clip wrapping appears to be an effective underutilized technique for treatment of pediatric complex aneurysms that cannot be treated with conventional methods.

Dynamic interspinous process stabilization: review of complications associated with the X-Stop device

OBJECT

The X-Stop interspinous device is designed for the treatment of patients with neurogenic intermittent claudication due to lumbar spinal stenosis. It distracts the posterior elements of adjacent vertebral bodies, unloading the intervertebral disc, limiting spinal extension, and improving central canal and neuroforaminal stenosis. In this paper, the authors reviewed the complications and failure/reoperation rates in a small series of patients and compared their results with other reported complication and failure/reoperation rates.

METHODS

The medical records of all patients who underwent placement of the X-Stop device for the treatment of NIC at the authors' institution were retrospectively evaluated, and demographic information, diagnosis, and preoperative pain levels were recorded. Postoperatively, patients subjectively graded the percentage (0-100%) of improvement in pain as well as the amount of residual pain and underwent imaging at 1-, 3-, and 6-month intervals. Approximately 4 years after X-Stop placement, information on long-term outcomes was obtained from patient medical records or additional follow-up.

RESULTS

Thirteen patients (8 men and 5 women) underwent placement of the X-Stop device. Central canal stenosis with bilateral foraminal stenosis was diagnosed in all patients: 9 (69%) of 13 had severe stenosis and 4 (31%) of 13 had moderate stenosis. Five patients (38%) also had associated Grade I spondylolisthesis. Nine patients underwent placement of the X-Stop device at the L4-5 interspinous space and 4 at both the L3-4 and L4-5 levels. The average duration of follow-up was 42.9 months (range 3-48 months). Initially, pain improved an average of 72% (range 50-100%) in these patients; however, preoperative pain returned in 77% of the patients (10 of 13). The overall complication rate was 38%, including 3 spinous process fractures (23%) and 2 instances of new-onset radiculopathy (15%). The ultimate failure rate requiring additional spinal surgery was 85% (11 of 13 patients). These complication and failure rates are much higher than those previously reported.

CONCLUSIONS

Overdistraction, poor bone density, poor patient selection, and preexistent adjacent foraminal stenosis may all be factors in the development of the aforementioned complications. Thus, careful attention should be paid preoperatively to adjacent-level disease, bone density, appropriate implant size, and optimal patient selection.

Magnetophoresis for enhancing transdermal drug delivery: Mechanistic studies and patch design

Magnetophoresis is a method of enhancement of drug permeation across the biological barriers by application of magnetic field. The present study investigated the mechanistic aspects of magnetophoretic transdermal drug delivery and also assessed the feasibility of designing a magnetophoretic transdermal patch system for the delivery of lidocaine. In vitro drug permeation studies were carried out across the porcine epidermis at different magnetic field strengths. The magnetophoretic drug permeation "flux enhancement factor" was found to increase with the applied magnetic field strength. The mechanistic studies revealed that the magnetic field applied in this study did not modulate permeability of the stratum corneum barrier. The predominant mechanism responsible for magnetically mediated drug permeation enhancement was found to be "magnetokinesis". The octanol/water partition coefficient of drugs was also found to increase when exposed to the magnetic field. A reservoir type transdermal patch system with a magnetic backing was designed for in vivo studies. The dermal bioavailability (AUC(0-6h)) from the magnetophoretic patch system in vivo, in rats was significantly higher than the similarly designed non-magnetic control patch.

Fatal Pulmonary Microsporidiosis Due toEncephalitozoon cuniculiFollowing Allogeneic Bone Marrow Transplantation for Acute Myelogenous Leukemia

Microsporidia are ubiquitous obligate eukaryotic intracellular parasites that are now felt to be more akin to degenerate fungi than to protozoa. Microsporidia can be highly pathogenic, causing a broad range of symptoms in humans, especially individuals who are immunocompromised. The vast majority of human cases of microsporidiosis have been reported during the past 20 years, in patients with HIV/AIDS, while only relatively rare cases have been described in immunocompetent individuals. However, microsporidia infections are being increasingly reported in patients following solid-organ transplanation, where the main symptom has been diarrhea. The authors report the first case of pulmonary microsporidial infection in an allogeneic bone marrow transplant recipient in the United States and only the second case in the world. The patient, with a history of Hodgkin disease followed by acute myelogenous leukemia received a T-cell-depleted graft, but succumbed to respiratory failure 63 days post transplantation. An open lung biopsy, taken just before death, was originally thought to show toxoplasmosis. The correct diagnosis of microsporidiosis was made postmortem by light and electron microscopy. DNA polymerase chain reaction analysis confirmed the diagnosis and furthermore revealed it to be the dog strain of the microsporidia species Encephalitozoon cuniculi. Although to date rarely diagnosed, microsporidial infection should also be considered in the differential diagnosis of, e.g., unexplained pulmonary infection in bone marrow transplant patients.

Pulmonary infection with microsporidia after allogeneic bone marrow transplantation

Microsporidia are obligate, intracellular protozoal parasites that can be pathogenic in immunocompromised individuals. The majority of cases of microsporidiosis have been documented in patients with HIV, and only a few case reports exist of infection in solid organ transplant patients. We report the first case of pulmonary microsporidial infection in an allogeneic bone marrow transplant recipient in the US. The patient was a recipient of a T-cell-depleted graft who succumbed to complications from respiratory failure 63 days post transplant. The diagnosis was made post mortem by electron microscopy and confirmed with PCR. Although rare, microsporidial infection should be considered in the differential diagnosis of unexplained pulmonary infection in bone marrow transplant patients.

Isolation, sequence analysis, and expression studies of florally expressed cDNAs in Arabidopsis

Molecular genetics has identified dozens of genes that regulate flower development in Arabidopsis. However, the complexity of flower development suggests that many other genes are yet to be uncovered. To identify floral genes that are expressed at low levels in the flower, we have sequenced 1587 cDNA fragments from a subtractive floral cDNA library. A total of 1222 unique genes represented by these ESTs are distributed on all five chromosomes with similar frequencies as all predicted genes in the genome. Among these, 17 genes were shown to be expressed anywhere for the first time because they were not found in previous EST and full-length cDNA datasets. Furthermore, 724 of the genes revealed by this library were not definitively shown to be expressed in the flower by previous floral EST datasets. In addition, 49 transcriptional regulators, 31 protein kinases, 12 zinc-finger proteins and other signaling proteins were found to be present in floral buds. Moreover, the EST sequences likely extended the transcribed regions of 26 previously annotated genes, and may have uncovered several previously unrecognized genes. To obtain additional clues about possible gene function, we hybridized cDNA microarray with probes derived from wild-type Arabidopsis rosette leaves and floral buds. We estimated that over 50% of genes were expressed at levels lower than 1/30 of the highest detectable signal intensity, indicating that many floral genes are expressed at low levels. Furthermore, 97 genes were found to be expressed at a higher level in the flower than the leaf by the Significance Analysis of Microarray (SAM) method with a 1.0% false discovery rate (FDR). Further RT-PCR analyses of selected genes support the microarray results. We suggest that the genes encoding putative regulatory proteins and at least some proteins with currently unknown functions might play important roles during flowering.

Impact of automation on aircrew communication and decision-making performance

Increasing levels of automation are being introduced into the cockpit. Yet, it is difficult to predict the impact of these automatic systems on other elements of flight, such as crew communication and the ability to arrive at an effective decision. This study attempted to clarify the relation among these variables. Forty-eight pilots were assigned to two-person crews and asked to fly a simulated mission in either automated or manual conditions using a low-fidelity simulator. The scenario was designed to require crewmembers to arrive at a collective decision based on information obtained about an evolving simulated disaster. The results indicated that the introduction of automation was not associated with better performance. However, several significant differences were observed in the communications of crews flying in the automated versus manual conditions. The results are discussed in terms of their implications for communications training for advanced technology aircraft.

Automation, task difficulty, and aircrew performance

The effects of an automated system on team processes and performance were assessed in a laboratory simulation. Two-person crews were required to fly a complex emergency-response scenario under conditions of low and high workload. These flights were completed with or without the aid of an autopilot. The results indicated that the autopilot was effective in reducing subjective workload. However, the automation was associated with improved performance on only 1 of 4 performance measures. Furthermore, it was observed that problem-solving performance was worse in the autopilot condition during the high-workload flights. Investigation of crew process data indicated that workload savings afforded by the autopilot might have been invested in more explicit coordination. The results are discussed in terms of their implications for military aviators' performance, system design, and team training.

What determines whether observers recognize targeted behaviors in modeling displays?

Observational learning is based on a critical assumption that trainees can and do recognize critical modeled behaviors. This assumption has been virtually untested in applied settings. We studied the effects of work experience and instructions on the ability of 59 observers to recognize target behaviors in an observational learning paradigm similar to existing ones. Additionally, we investigated the effects of two key factors that were hypothesized to affect the recognition process in observational learning. The results indicated that only observers who had a minimum of work experience (i.e., intermediate and experienced observers in the study) were able to consistently recognize targeted behaviors. Additionally, recognition was influenced by the level of detail of instructions given to the participants. Finally, characteristics of the modeled behaviors greatly affected recognition: Overall, examples of negative behaviors were better recognized than were positive examples. Behaviors whose consequence was shown were also better recognized than those that were neither reinforced nor punished in the video. The results are discussed in terms of their implications for the design of observational learning as a training strategy in complex and applied social learning situations. The applications of this work include the design of training, and the training of evaluators and observers.

Decision making in dual-task environments: analysis of hemispheric competition effects

Performance degradations in multitasking situations have been reported frequently as a predictable effect of competition that arises from different processing demands whose hemispheric locations are too proximal. This model might be useful in explaining performance deficits in complex workplaces. To test this assertion, a laboratory study was designed to create an analogue of the processing demands required by a tactical decision-making task performed by 24 right-handed men. Vocalization, dichotic listening and decision-making performance were assessed under single- and dual-task conditions. The results were consistent with the predictions from hemispheric competition in the case of dichotic listening but not with vocalization. The results are discussed in terms of their implications for both research and systems design.

A novel syndrome of radiation-associated acute myeloid leukemia involving AML1 gene translocations

AML1 is a transcriptional activator that is essential for normal hematopoietic development. It is the most frequent target for translocations in acute leukemia. We recently identified 3 patients in whom pancytopenia developed almost 50 years after high-level radiation exposure from nuclear explosions during or after World War II. In all 3 patients, acute myeloid leukemia (AML) eventually developed that had similar characteristics and clinical courses. Cytogenetics from the 3 patients revealed a t(1;21)(p36;q22), a t(18;21)(q21;q22), and a t(19;21)(q13.4;q22). By fluorescent in situ hybridization (FISH), all 3 translocations disrupted the AML1 gene. Two of these AML1 translocations, the t(18;21) and the t(19;21), have not been reported previously. It is possible that the AML1 gene is a target for radiation-induced AML. (Blood. 2000;95:4011-4013)

Prevalence of ethanol consumption may be higher in women than men in a university health service population as determined by a biochemical marker: whole blood-associated acetaldehyde above the 99th percentile for teetotalers

To estimate ethanol consumption by university students attending a student health facility, a biochemical marker of alcohol intake [whole blood associated acetaldehyde (WBAA)] was quantified by fluorimetric HPLC. Over a two year period we studied blood samples, coded by date and sex, from 645 females and 332 males, and compared the results to previously established reference ranges for teetotalers by sex. Men had higher absolute values for WBAA than women (9.9 versus 9.5 microM in the present study). However, significantly greater numbers of women (74%) than men (44%) had WBAA levels above the 99th percentile for teetotalers. Variations occurred during the academic year, with significant elevations occurring in the late fall and winter months. Testing of WBAA levels in a student health service may be important especially for women to facilitate counseling on the dangers of alcohol abuse.

A prospective, multicenter study of a pneumonia practice guideline

OBJECTIVE

To study the effect of a length of stay practice guideline on patient outcomes.

DESIGN

A prospective, nonrandomized, interventional trial.

SETTING

Six geographically distributed hospitals.

PATIENTS

Two hundred forty-two consecutively hospitalized "low-risk" patients with pneumonia.

MEASUREMENTS AND RESULTS

One hundred fifty-two patients (63%) completed the mailed postdischarge survey and were included in the analysis. Data were prospectively collected for 85 patients from the baseline observation period (B) and 67 patients from the intervention period (I). During the I, case managers provided physicians with patient risk information based on guideline recommendations. There was no significant change in guideline compliance (B vs I: 76.5% vs 83.6%; p=0.32) or length of stay (B vs I: 3.5 days [95% confidence interval, 3.2 to 3.8] vs 3.6 days [95% confidence interval, 3.3 to 4.0]). Also, there were no statistically significant effects of the intervention on patient outcomes, care following hospital discharge, and patient satisfaction scores.

CONCLUSION

Patients in this study often had shorter lengths of stay than recommended by the practice guideline. This suggests that the external environment may have had a greater effect on physician behavior and length of stay than the practice guideline itself. Moreover, it demonstrates the importance of continuous assessment of physician practices immediately prior to, during, and after application of the clinical practice guideline.

Can practice guidelines safely reduce hospital length of stay? Results from a multicenter interventional study

BACKGROUND

Although practice guidelines about appropriate lengths of stay have been widely promulgated, their effects on patient outcomes are not clear. Our objective was to study the effects of length of stay practice guidelines on patient outcomes.

PATIENTS AND METHODS

We performed a prospective, nonrandomized, interventional trial in six geographically distributed hospitals, among consecutively hospitalized "low-risk" patients with total hip replacement, hip fracture, or knee replacement. Case managers provided physicians with patient risk information based on guideline recommendations. We measured length of stay, compliance with recommended guideline length of stay, health status, hospital readmission rates, return to emergency department, return to work and recreation, and patient satisfaction.

RESULTS

A total of 560 patients were included in the study. For patients with knee replacement, there was a statistically significant increase in practice guideline compliance (27% baseline versus 53% intervention, P <0.0001) and reduction in length of stay (5.2 days versus 4.6 days, P <0.001) when compared with the baseline period. For hip replacement patients, there similarly was an increase in practice guideline compliance (66% baseline versus 82% intervention, P = 0.01) and reduction in length of stay (5.1 days versus 4.8 days, P = 0.03). Significant reductions in length of stay were not observed for patients recovering after hip fracture despite a significant increase in guideline compliance. There were few statistically significant changes in patient outcomes related to reductions in lengths of stay, including health status, hospital readmission rates, return to emergency department, return to work and recreation, and patient satisfaction. For patients undergoing hip replacement, very short lengths of stay (shorter than the guideline recommendation) were associated with an increased rate of discharging patients to nursing homes and rehabilitation facilities (21% versus 7%, P = 0.01), and hip fracture patients with very short lengths of stay required more visits to the doctor after discharge (56% versus 25%, P = 0.04).

CONCLUSION

Reductions in lengths of stay were most often associated with no significant change in patient outcomes. However, very short lengths of stay were associated with increased intensity of care following discharge for patients undergoing hip surgery, indicating possible cost shifting (the cost incurred by transferring patients to rehabilitation facilities may have been greater than had the patients remained in the acute care hospital for an additional 1 or 2 days and been sent directly home). These results emphasize the importance of monitoring the effects of cost containment and other systematic efforts to change patient care at the local level.

Using a nursing framework to measure client satisfaction at a nurse-managed clinic

There is considerable literature on nurse-managed clinics and client satisfaction with nurse practitioner care. However, the methodological weaknesses of satisfaction measures which are often used limits confidence in the study findings. Satisfaction measures typically lack reliability analysis and/or have limited validity testing. This descriptive, correlational study investigates the validity and reliability of a new measure, the Client Satisfaction Tool (CST) and determines the degree of satisfaction that clients at a newly established senior health clinic had with the primary care services they were receiving. The CST is based upon Cox's Interactional Model of Client Health Behavior and thus was explicitly developed to measure client satisfaction with a nurse practitioner model of care. A convenience sample of 38 clients completed the CST. Responses to the CST indicated that users of the senior health clinic were satisfied with the care they received. Reliability testing showed that the tool has high internal consistency (Chronbach's alpha was 0.956) and high stability (r = 0.974). Construct validity testing with measures of perceived health changes showed that the tool has both convergent (r = 0.599, P < 0.01) and divergent (r = 0.194, P > 0.10) validity. Thus, the CST is a methodologically sound measure of client satisfaction that can be used in future research that examines client satisfaction with nurse practitioner care.