Use of Arterial Spin-Labeling in Patients with Aneurysmal Sub-arachnoid hemorrhage

Delayed cerebral ischemia (DCI) due to cerebral vasospasm following aneurysmal subarachnoid hemorrhage (aSAH) has long been recognized as a major source of morbidity and mortality. Early detection of cerebral vasospasm and identification of patients who are likely to become symptomatic is crucial to guide aggressive medical and/or endovascular interventions. Magnetic resonance imaging using arterial spin-label (ASL) is a noninvasive mean for assessing cerebral blood flow and is based on direct magnetic labeling of arterial blood water protons. The diagnostic role of ASL in acute ischemic stroke, epilepsy, and neurodegenerative disorders has been explained in multiple studies but its ability to predict vasospasm in aSAH has not been published before. The purpose of this study is to highlight the diagnostic implications of different perfusion patterns of ASL in patients with aSAH which can be utilized to prevent DCI in such patients when other commonly used modalities are not available, contraindicated, or fail to detect vasospasm.

Examination of Racial Differences in a Posttraumatic Stress Disorder Group Therapy Program for Veterans

Posttraumatic stress disorder (PTSD) is one of the most prevalent mental health diagnoses for veterans. Group therapy can be an effective and efficient means of treating PTSD, yet the literature exploring treatment outcomes for racial minorities is mixed and limited. The present study was an evaluation across racial groups of the PTSD Recovery Program, a manualized group therapy implemented at a Veterans Affairs hospital. Data were collected from male veterans (N = 450) who identified as non-Hispanic White or non-Hispanic African American and participated in a 10-week, combat-related, group therapy program between 2010 and 2014. Participants completed the Posttraumatic Stress Disorder Checklist-Military version (PCL-M) measure at pre-treatment and post-treatment. The Program led to a statistically significant reduction in PCL-M scores (Cohen's d = .64). Symptom reduction occurred regardless of race, with no racial differences in improvement. Racial and ethnic composition of groups was not related to outcomes. The Program was effective regardless of veteran group or provider. Results imply that the PTSD Recovery Program is an effective first-line option to treating non-Hispanic White and non-Hispanic African American veterans with PTSD. Future research should continue to explore the associations between group characteristics and treatment outcomes.

Seizure Prophylaxis in the Immediate Post-Hemorrhagic Period in Patients with Aneurysmal Subarachnoid Hemorrhage

INTRODUCTION

Seizures are a well-known complication of aneurysmal subarachnoid hemorrhage (aSAH) and occur most commonly in the immediate posthemorrhagic period. Most commonly used antiepileptic drugs (AEDs) for seizure prophylaxis in aSAH include phenytoin and levetiracetam. There is no reliable data available on the safety and efficacy of restricting AED prophylaxis only till the aneurysm is secured.

METHODS

We retrospectively chart reviewed patients admitted to our neurosciences intensive care unit (NICU) with aSAH during the past two years. Seizure incidence was studied in patients treated with phenytoin versus levetiracetam and in patients treated for 3-7 days vs. those where AED was discontinued immediately after aneurysm was secured.

RESULTS

In 28 patients, AED prophylaxis was discontinued immediately after the aneurysm was secured, and in 21 patients, it was continued for 3-7 days. Of the 28 patients who received AED prophylaxis for less than or equal to two days, phenytoin was used in 20 patients and levetiracetam was used in eight patients. In patients receiving AED prophylaxis for 3-7 days, phenytoin was used in eight cases and levetiracetam was used in 13 cases. None of these patients had seizures reported during hospitalization or at three-month follow-up.

CONCLUSION

Stopping the AED prophylaxis immediately after aneurysm coiling is not associated with increased risk of seizures. Seizures at presentation in patients with aSAH are not associated with development of epilepsy at three months. Both phenytoin and levetiracetam are well tolerated in patients with aSAH when limited to the immediate posthemorrhagic period.

Consecutive Endovascular Treatment of 20 Ruptured Very Small (<3 mm) Anterior Communicating Artery Aneurysms

BACKGROUND

Small aneurysms located at the anterior communicating artery carry significant procedural challenges due to a complex anatomy. Recent advances in endovascular technologies have expanded the use of coil embolization for small aneurysm treatment. However, limited reports describe their safety and efficacy profiles in very small anterior communicating artery aneurysms.

OBJECTIVE

We sought to review and report the immediate and long-term clinical as well as radiographic outcomes of consecutive patients with ruptured very small anterior communicating artery aneurysms treated with current endovascular coil embolization techniques.

METHODS

A prospectively maintained single-institution neuroendovascular database was accessed to identify consecutive cases of very small (<3 mm) ruptured anterior communicating artery aneurysms treated endovascularly between 2006 and 2013.

RESULTS

A total of 20 patients with ruptured very small (<3 mm) anterior communicating artery aneurysms were consecutively treated with coil embolization. The average maximum diameter was 2.66 ± 0.41 mm. Complete aneurysm occlusion was achieved for 17 (85%) aneurysms and near-complete aneurysm occlusion for 3 (15%) aneurysms. Intraoperative perforation was seen in 2 (10%) patients without any clinical worsening or need for an external ventricular drain. A thromboembolic event occurred in 1 (5 %) patient without clinical worsening or radiologic infarct. Median clinical follow-up was 12 (±14.1) months and median imaging follow-up was 12 (±18.4) months.

CONCLUSION

This report describes the largest series of consecutive endovascular treatments of ruptured very small anterior communicating artery aneurysms. These findings suggest that coil embolization of very small aneurysms in this location can be performed with acceptable rates of complications and recanalization.

Aggressive medical treatment with or without stenting in high-risk patients with intracranial artery stenosis (SAMMPRIS): the final results of a randomised trial

BACKGROUND

Early results of the Stenting and Aggressive Medical Management for Preventing Recurrent stroke in Intracranial Stenosis trial showed that, by 30 days, 33 (14·7%) of 224 patients in the stenting group and 13 (5·8%) of 227 patients in the medical group had died or had a stroke (percentages are product limit estimates), but provided insufficient data to establish whether stenting offered any longer-term benefit. Here we report the long-term outcome of patients in this trial.

METHODS

We randomly assigned (1:1, stratified by centre with randomly permuted block sizes) 451 patients with recent transient ischaemic attack or stroke related to 70-99% stenosis of a major intracranial artery to aggressive medical management (antiplatelet therapy, intensive management of vascular risk factors, and a lifestyle-modification programme) or aggressive medical management plus stenting with the Wingspan stent. The primary endpoint was any of the following: stroke or death within 30 days after enrolment, ischaemic stroke in the territory of the qualifying artery beyond 30 days of enrolment, or stroke or death within 30 days after a revascularisation procedure of the qualifying lesion during follow-up. Primary endpoint analysis of between-group differences with log-rank test was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT 00576693.

FINDINGS

During a median follow-up of 32·4 months, 34 (15%) of 227 patients in the medical group and 52 (23%) of 224 patients in the stenting group had a primary endpoint event. The cumulative probability of the primary endpoints was smaller in the medical group versus the percutaneous transluminal angioplasty and stenting (PTAS) group (p=0·0252). Beyond 30 days, 21 (10%) of 210 patients in the medical group and 19 (10%) of 191 patients in the stenting group had a primary endpoint. The absolute differences in the primary endpoint rates between the two groups were 7·1% at year 1 (95% CI 0·2 to 13·8%; p=0·0428), 6·5% at year 2 (-0·5 to 13·5%; p=0·07) and 9·0% at year 3 (1·5 to 16·5%; p=0·0193). The occurrence of the following adverse events was higher in the PTAS group than in the medical group: any stroke (59 [26%] of 224 patients vs 42 [19%] of 227 patients; p=0·0468) and major haemorrhage (29 [13%]of 224 patients vs 10 [4%] of 227 patients; p=0·0009).

INTERPRETATION

The early benefit of aggressive medical management over stenting with the Wingspan stent for high-risk patients with intracranial stenosis persists over extended follow-up. Our findings lend support to the use of aggressive medical management rather than PTAS with the Wingspan system in high-risk patients with atherosclerotic intracranial arterial stenosis.

FUNDING

National Institute of Neurological Disorders and Stroke (NINDS) and others.

Abstract WP427: Day Eight CT Perfusion Imaging for Evaluation of Delayed Cerebral Ischemia Risk and Decreased Length of Stay Following Aneurysmal Subarachnoid Hemorrhage

Objective: Hospital stay alone accounts for 2/3 the cost of aneurysmal subarachnoid hemorrhage (aSAH) management. Our objective was to assess the ability of CT perfusion (CTP) imaging to predict delayed cerebral ischemia (DCI) risk in those who are neurologically intact in order to safely decrease the length of hospital stay for low risk aSAH patients.

Methods: A retrospective analysis of all aSAH admitted to our neurological intensive care unit (NICU) from 3/2011-3/2012. Per our protocol all patients were admitted to the NICU for 10 days followed by a 4 day ward admission. Additionally, all patients underwent a CTP study on post-bleed day 8 to screen for evidence of radiographic vasospasm. DCI was defined as the presence of neurological deficit not attributable to other etiologies. All CTP images were interpreted by a Neuroradiologist. CTP was considered positive if there was evidence of match or mismatch. Mismatch was defined as decreased cerebral blood flow or increased mean transit time with associated blood volume loss of <20%.

Results: A total of 58 aSAH were admitted. Day 8 CTPs were performed on 42 (72%) with 71% female, mean age 52.21 (±13.25), mean Fisher 3.38 (2-4) and mean Hunt/Hess 2.39 (1-5). Eighteen (43%) patients had negative CTPs with baseline neurological exams. None of these 18 patients went on to develop DCI during their 14 day admission.

Conclusion: Our data shows that aSAH patients who are neurologically intact and have a negative post-bleed day 8 CTP are not at risk for DCI. We conclude that an 8 day NICU admission with an additional 2 day in-patient stay is sufficient to safely manage this patient population. Our data is limited by a small sample size and retrospective analysis. Future directions of research include additional prospective studies for reproducibility.

Abstract WP81: Outcomes Following X- and Y-Configuration Stent-Assisted Coil Embolization of 52 Complex Bifurcation Cerebral Aneurysms

Background: Wide-neck bifurcation cerebral aneurysms pose technical challenges in endovascular therapy. Intersecting stents are used with increasing frequency. Periprocedural, clinical, and mid-term angiographic outcomes of this approach are not well known. We report clinical and angiographic outcomes in our use of the X- and Y-configuration techniques.

Methods: We reviewed a retrospectively collected database to identify all aneurysm cases in which an X- or Y-configuration stent technique was used. Demographic, periprocedural and mid-term clinical and imaging data were collected. Outcomes included rate of thromboembolic events (TEE), intraoperative perforations (IOP), mortality, aneurysm residual at the time of the procedure and recurrence observed at follow-up.

Results: Among 807 cerebral aneurysms, we identified 52 aneurysms in 50 patients treated with X- or Y-configuration stent implantation. Mean age was 58 years (SD = 10) with 34 (65%) women. Aneurysm locations were basilar artery (n = 20), MCA (n = 13), ACA (n = 16), and ICA (n = 3). Mean aneurysm maximum diameter was 7.0 mm (SD 2.9) and the mean neck size was 4.5 mm (SD = 1.7). Fifty cases (96%) involved “Y” configuration, and two cases (4%) used an “X” configuration. Aneurysm catheterization technique was trans-stent in all cases (vs jailing). Interstices catheterization required a wire or catheter change in 13 (25%) cases. Immediate results revealed complete occlusion in 45 (86.5%), residual aneurysm in 3 (5.7%), and residual neck in 4 (7.7%). There were no mortalities, and 7 (13.5%) TEEs, of which 2 (4%) were symptomatic. There were 2 (4%) asymptomatic IOPs. Imaging follow-up was available for 40 (77%) cases, with mean interval from index procedure of 5.7 months. This mid-term outcome showed complete obliteration in 28 (70%) cases, residual neck in 8 (20%), and residual aneurysm in 4 (10%).

Conclusions: These results suggest that placement of intersecting stents in X- and Y-configurations for coil embolization of wide-neck bifurcation cerebral aneurysms is feasible and can be performed with acceptable procedural safety and good rates of aneurysm occlusion.

Complications of endovascular therapy for acute ischemic stroke and proposed management approach

Over the past decade, endovascular therapy has emerged as a promising therapeutic approach for select patients with acute ischemic stroke. However, the morbidity, mortality, and complication rates in intra-arterial recanalization trials are higher than in the National Institute of Neurological Disorders and Stroke trial of IV tissue plasminogen activator. This review discusses common complications associated with endovascular therapy for acute ischemic stroke, avoidance of complications, and management of some of the common complications.

Abstract 3747: Clinical And Imaging Outcomes For Target Aneurysm Retreatment For Remnant Intracranial Aneursym

Introduction: Aneurysmal subarachnoid hemorrhage (SAH) is a rare but devastating form of stroke. Currently surgical clipping and endovascular embolization are the two therapeutic options for treatment of intracerebral aneurysm. The reported complication rate associated with the initial endovascular treatment is about 2-40%. However, outcome and complications after target aneurysmal retreatment (TAR) is unknown. Our objective is to report clinical and imaging outcomes for TAR.

Design/Methods: We identified patients who underwent TAR from a hospital neurointerventional database. We collected data on demographics, peri-procedural complications, clinical and imaging outcomes at the discharge and last follow-up. Peri-procedural complications were reported as intra operative perforation (IOP), thromboembolic event (TEE), both were considered symptomatic if patient develop new neurological deficit lasting for increase in NIHSS . Length of hospital stay, modified Ranking Scale (mRS), discharge disposition, recurrent SAH, re-treatment of the same aneurysm, and mortality were measured at discharge and follow up appointments. Complete data was available for 115/155 (74%) cases.

Results: There were total of 155/1169 (13.3%) cases underwent TAR with mean age of 55 ( 3), 98 (63%) were females, and 118 (76%) were Caucasians. One hundred four (67%), had aneurysm located in the anterior circulation, 4/116 (3%) underwent TAR for recurrent acute SAH, 72/116 (62%) required stent and 10/116 (9%) required balloon assist. There were total of 5/115 (4%) IOP, and 8/115 (7%) TEE from which 2/115 (2%), and 1/115 (1%) were symptomatic respectively for a total of 3/115 (2.6%) patients. 117/151 (77%) had complete immediate obliteration of the aneurysm after TAR. Ninety five patients (83%) had mean length of hospital stay with 143/151 (95%) patients discharged home. At discharge 99/114 (87%) patients, had mRS with 0% mortality. Total of 90/155 (58%) patients had average follow up of 14 months with 8/90 (9%) requiring a 2 nd TAR and 1/90 (1%) requiring 3 rd TAR for recanalization. There was no re-rupture after the 1 st TAR for the duration of follow-up period of 14 ( in total of 90 patients).

Conclusions: In our study the rate of symptomatic events following TAR after initial endovascular therapy is 3/115 (2.6%) with 77% obliteration rate and 0% re-repture rate. TAR after an initial endovascular treatment is safe with an acceptable rate of complications and may be effective, suggested by lower rate of re-rupture.

Endovascular embolization of head and neck tumors

Endovascular tumor embolization as adjunctive therapy for head and neck cancers is evolving and has become an important part of the tools available for their treatment. Careful study of tumor vascular anatomy and adhering to general principles of intra-arterial therapy can prove this approach to be effective and safe. Various embolic materials are available and can be suited for a given tumor and its vascular supply. This article aims to summarize current methods and agents used in endovascular head and neck tumor embolization and discuss important angiographic and treatment characteristics of selected common head and neck tumors.

Measurement of antiplatelet inhibition during neurointerventional procedures: the effect of antithrombotic duration and loading dose

BACKGROUND/OBJECTIVE

Symptomatic thromboembolic events are the most common complications associated with aneurysm coiling, and carotid and intracranial stenting. Our objective is to assess the effect of aspirin (ASA) and clopidogrel dose and duration on platelet inhibition using a point of care assay in neurointerventional (NI) suite.

METHOD

The dose, duration, and point of care platelet function assay data for clopidogrel and aspirin therapy were prospectively collected between February 2006 and November 2007. Inadequate platelet inhibition for ASA was defined as >or=550 ASA reaction units (ARU), and for clopidogrel was defined as <or=50% inhibition of the P2Y12/ADP receptor

RESULTS

We collected data from 216 consecutive patients. Inadequate platelet inhibition was noted in 13% of patients on aspirin and 66% of patients on clopidogrel (P-value < .0001). Patients taking clopidogrel 75 mg for >or=7 days, 300 mg for 24 hours, and 600 mg same day load had a mean P2Y12/ADP inhibition of 45%, 35% (P-value = .09), and 16%, respectively (P-value = .005).

CONCLUSION

Premedication with clopidogrel, in contrast to aspirin, does not achieve adequate platelet inhibition in about two-third of the patients. Same day antiplatelet loading may be insufficient to achieve adequate platelet inhibition and should be avoided if clinically feasible.

Pediatric cerebral angiography: analysis of utilization and findings

Pediatric neuroendovascular procedures are being performed with increasing frequency, for various indications. Reported here is the experience of interventionally trained neurologists performing pediatric cerebral diagnostic angiography between August 1, 2005, and April 30, 2008, at a single tertiary institution. Data regarding patient demographics, diagnostic indication and angiographic diagnosis, procedural complications, and procedural specifications were recorded to assess practice patterns and to track procedural morbidity. In all, 42 patients had 46 procedures during the study period. Mean age was 9.97 years (standard deviation S.D. = 5.39; range, 0.3-18 years); 22/42 were male (52%). Known or suspected vascular malformation was the diagnostic indication for 20 patients; of these, 12 had an arteriovenous malformation, 5 had venous abnormalities, and 3 exhibited no angiographic vascular malformations. In 13 total procedures there was no angiographic pathology. General anesthesia was used in 29/46 procedures (63%). A total of 190 cerebral arteries were individually selected, with a mean number of vessels catheterized of 4.1 (S.D. = 1.7) per procedure. No procedural thromboembolic complications, iatrogenic arterial dissection, or neurologic or vascular access site complications occurred. In conclusion, pediatric cerebral angiography seems to be generally safe, although there should be a strong diagnostic indication, given the inherent procedural risk.

Interventional acute ischemic stroke therapy with intracranial self-expanding stent

BACKGROUND AND PURPOSE

Rapid and safe recanalization of occluded intracranial arteries in acute ischemic stroke (AIS) is challenging. Newly available self-expanding intracranial atherosclerotic stents (SEIS), which can be deployed rapidly and safely, make acute stenting an option for treating AIS. We present the feasibility of this technique.

METHODS

A retrospective analysis evaluated procedural protocols and clinical response to treatment in patients with AIS treated with SEIS. Descriptive statistics are presented with initial and follow-up National Institutes of Health Stroke Scale and modified Rankin Score.

RESULTS

Nine patients with AIS underwent acute SEIS placement. There was successful deployment of the Neuroform (n=4) and Wingspan (n=4/5) stents in the M1/M2 (n=5) and M3 (n=1) middle cerebral artery segments, intracranial internal carotid artery (one of 2), and intracranial vertebrobasilar junction (one). Mean time of SEIS deployment from AIS onset was 5.1 hours. Complete (Thrombolysis in Cerebral Ischemia/Thrombolysis in Myocardial Ischemia 3) and partial/complete (Thrombolysis in Cerebral Ischemia/Thrombolysis in Myocardial Ischemia 2 or 3) recanalization occurred in 67% and 89%, respectively. One intracranial hemorrhage (11%) and one acute in-stent thrombosis (successfully treated with abciximab and balloon angioplasty) occurred. Stroke-related mortality occurred in 3 of 9 (33%) patients and survivors had modified Rankin Score < or = 2. Follow-up angiography (mean, 8 months; range, 2 to 14 months) in 4 of 9 patients showed no stent restenosis.

CONCLUSIONS

This preliminary experience with SEIS in refractory AIS demonstrated the technical feasibility and high rate of recanalization with acute stenting. Long-term safety and strategies to limit in-stent thrombosis and optimize periprocedural management are crucial before initiating future randomized efficacy studies with SEIS in AIS refractory to standard therapy.

Apolipoprotein E modifies the CNS response to injury via a histamine-mediated pathway

Recent evidence demonstrates that apolipoprotein E (apoE) influences the central nervous system (CNS) response to both acute and chronic injury. To address the mechanisms by which apoE influences neurological disease, we examined differential gene expression in the brains of apoE transgenic mice after closed head injury. Apart from confirming the knockout of apoE, the largest differential gene expression occurred for the interleukin-9 receptor (IL-9R), which was > 100-fold up-regulated in apoE-deficient versus wild-type mice. We observed a similar pattern of posttraumatic IL-9R up-regulation in APOE4 targeted replacement mice as compared with their APOE3 counterparts. This difference in gene expression was associated with increased neuronal protein expression of IL-9R in E4 animals compared with E3 as demonstrated by immunohistochemistry. The consequence of IL-9R binding in mast cells is the induction of proliferation and differentiation. This indirectly favors degranulation and release of histamine and inflammatory mediators, which have previously been demonstrated to exacerbate secondary neuronal injury. We found that apoE-deficient animals had increased levels of systemic histamine after injury and that pre-treatment with antihistamines improved functional outcomes in apoE-deficient but not wild-type animals after head injury. These results suggest that apoE modifies secondary neuronal injury caused by histamine release and are consistent with previous observations that apoE affects the CNS inflammatory response in an isoform-specific manner.

Simvastatin and atorvastatin improve behavioral outcome, reduce hippocampal degeneration, and improve cerebral blood flow after experimental traumatic brain injury

The treatment of traumatic brain injury (TBI) remains limited, and aside from surgical hematoma evacuation, clinical management is largely supportive and directed toward management of cerebral edema and intracranial hypertension. Secondary neuronal injury caused by ischemia and the development of cerebral edema may occur in the subacute phase, with intracranial pressures often peaking in the first several days following injury. Because inflammation contributes significantly to the pathophysiology of cerebral ischemia and endothelial dysfunction underlies the development of cerebral edema, therapeutic strategies that target the post-traumatic inflammatory cascade and reduce endothelial dysfunction hold enormous potential to improve clinical outcomes after TBI. Statins inhibit inflammation by suppressing inflammatory cytokine release, and by interfering with multiple steps of leukocyte recruitment and migration into the CNS. In this study, we demonstrate that treatment with atorvastatin and simvastatin markedly reduced functional neurological deficits after traumatic brain injury in mice. These effects were accompanied by histological reduction in degenerating hippocampal neurons and suppression of inflammatory cytokine mRNA expression in brain parenchyma. Furthermore, statin treatment improved cerebral hemodynamics following head injury. Thus, the administration of statins may represent a viable therapeutic strategy in the acute treatment of closed head injury.

Risk of cerebral vasopasm after subarachnoid hemorrhage reduced by statin therapy: a multivariate analysis of an institutional experience

Object

Impairment of endothelial nitric oxide synthase (eNOS), endothelium-dependent relaxation, and cerebrovascular autoregulation all occur in vasospastic cerebral arteries following subarachnoid hemorrhage (SAH). The 3-hy-droxy-3-methylglutaryl coenzyme A reductase inhibitors, or statins, both improve endothelial function and increase eNOS messenger RNA, protein, and enzymatic activity threefold. Increasing experimental evidence in animal models of SAH suggests that statins may ameliorate cerebral vasospasm. The authors hypothesized that patients chronically treated with statins would have a decreased risk of symptomatic vasospasm after SAH.

Methods

The authors retrospectively reviewed the charts of 115 patients with SAH who were consecutively admitted to the Neuroscience Intensive Care Unit of Duke University between 1998 and 2001. The independent association of statin therapy to symptomatic vasospasm was assessed using multivariate logistic regression analysis. Fifteen patients (13%) admitted with SAH were receiving statin therapy for at least 1 month before admission. Forty-nine patients (43%) experienced symptomatic vasospasm a mean of 5.8 ± 3 days after onset of SAH. Current statin therapy on admission (odds ratio [OR] 0.09, 95% confidence interval [CI] 0.01–0.77) was independently associated with an 11-fold reduction in the risk of symptomatic vasospasm. Fisher Grade 3 SAH (OR 2.82, 95% CI 1.50–5.71) and rupture of anterior cerebral or internal carotid artery aneurysm (OR 3.77, 95% CI 1.29–10.91) were independently associated with an increased risk of symptomatic vasospasm.

Conclusions

In this retrospective case series, patients who received statin therapy for at least 1 month demonstrated an 11-fold decrease in the risk of developing symptomatic vasospasm after SAH.

Levetiracetam is neuroprotective in murine models of closed head injury and subarachnoid hemorrhage

OBJECTIVES

Prophylactic treatment with antiepileptic drugs is common practice following subarachnoid hemorrhage (SAH) and traumatic brain injury. However, commonly used antiepileptic drugs have multiple drug interactions, require frequent monitoring of serum levels, and are associated with adverse effects that may prompt discontinuation. In the current study, we test the hypothesis that levetiracetam, an anticonvulsant with favorable interaction and adverse event profiles, is neuroprotective in clinically relevant models of SAH and closed head injury (CHI).

METHODS

A single intravenous dose of vehicle, low-dose (18 mg/kg), or high-dose (54 mg/kg) levetiracetam was administered intravenously followed CHI. Functional assessments were performed on a daily basis, and histological assessments performed at 24 hours. In a separate series of experiments, mice were randomized to receive intravenous administration of vehicle, low-dose, or high-dose levetiracetam every 12 hours for 3 days following SAH. Functional endpoints were assessed daily, followed by measurement of MCA luminal diameter on day 3.

RESULTS

A single dose of levetiracetam improved functional and histological outcomes after CHI. This effect appeared specific for levetiracetam and was not associated with fosphenytoin treatment. Treatment with levetiracetam also improved functional outcomes and reduced vasospasm following SAH.

CONCLUSION

Levetiracetam is neuroprotective in clinically relevant animal models of SAH and CHI. Levetiracetam may be a therapeutic alternative to phenytoin following acute brain injury in the clinical setting when seizure prophylaxis is indicated.

Effects of a manganese (III) porphyrin catalytic antioxidant in a mouse closed head injury model

Closed head injury induces cerebral oxidative stress. The efficacy of a Mn (III) porphyrin catalytic antioxidant was assessed in a mouse closed head injury model. Mice were subjected to closed head injury and treated 15 min later with an i.v. bolus of vehicle or 3 mg/kg MnTE-2-PyP5+. Aconitase activity, Fluoro-Jade staining, glial fibrillary acidic protein immunoreactivity, and rotarod falling latencies were measured. Closed head injury altered all variables. MnTE-2-PyP5+ had no effect on any variable with the exception of attenuation of aconitase inactivation at 2 h post-closed head injury. In a second experiment, mice received 3 mg/kg or 6 mg/kg MnTE-2-PyP5+ or vehicle i.v. 15 min post-closed head injury. Rotarod and Morris water maze latencies were measured. Closed head injury altered performance in both tests. No statistically significant effect of MnTE-2-PyP5+ was observed. We conclude that single dose MnTE-2-PyP5+ does not alter outcome in this mouse closed head injury model.

A Novel apoE-Derived Therapeutic Reduces Vasospasm and Improves Outcome in a Murine Model of Subarachnoid Hemorrhage

INTRODUCTION

Recent clinical observations demonstrate that the APOE4 genotype increases the development of delayed ischemic deficit and worsens prognosis following aneurysmal subarachnoid hemorrhage (SAH). In the current study, we use targeted replacement mice expressing only human apoE3 or apoE4 to model the isoform-specific effects of apoE following SAH. We then test the hypothesis that an apoE-derived therapeutic peptide reduces vasospasm and improves functional recovery after SAH.

METHODS

Experimental SAH was induced in APOE3- and APOE4-targeted replacement mice. For 3 days following injury, daily functional assessments were made. Mice were then sacrificed and the cerebral vasculature visualized to quantify vasospasm. In a separate experiment, C57Bl/6 mice were treated with intravenous injection of vehicle, low-dose, or high-dose apoE-mimetic peptide every 12 hours for 3 days post-SAH. Functional endpoints were assessed on a daily basis, followed by measurement of middle cerebral artery diameter.

RESULTS

Mice expressing the apoE4 isoform had greater functional deficit, mortality, cerebral edema, and vasospasm as compared with their apoE3 counterparts. Mice treated with the apoE-mimetic peptide had decreased mortality, functional deficits, and histological evidence of vasospasm as compared with vehicle-treated animals.

CONCLUSION

Consistent with the clinical literature, the apoE4 isoform is associated with an increased incidence of vasospasm and poor functional recovery after experimental SAH. An apoE-derived peptide represents a novel therapeutic approach for the treatment of SAH.

Toward Solving the Sedation-Assessment Conundrum: Bispectral Index Monitoring and Sedation Interruption

The sedation-assessment conundrum is defined by two diametrically opposed goals: to maintain an appropriate level of sedation, and to obtain a comprehensive neurologic examination that most accurately reflects the patient's neurologic status. A case presentation leads to a discussion of over-sedation and under-sedation issues that impact the care of critically ill patients. This information is useful in understanding the many methods of assessing sedation and interpreting individualized patient responses to sedation. The use of bi-spectral index monitoring and periods of sedation interruption are discussed within the context of addressing the sedation-assessment conundrum.

Simvastatin reduces vasospasm after aneurysmal subarachnoid hemorrhage: results of a pilot randomized clinical trial

BACKGROUND AND PURPOSE

Cerebral vasospasm remains a major source of morbidity after aneurysmal subarachnoid hemorrhage (SAH). We demonstrate that simvastatin reduces serum markers of brain injury and attenuates vasospasm after SAH.

METHODS

Patients with angiographically documented aneurysmal SAH were randomized within 48 hours of symptom onset to receive either simvastatin (80 mg daily; n=19) or placebo (n=20) for 14 days. Plasma alanine aminotransferase, aspartate aminotransferase, and creatine phosphokinase were recorded weekly to evaluate laboratory evidence of hepatitis or myositis. Serum markers of brain injury were recorded daily. The primary end point of vasospasm was defined as clinical impression (delayed ischemic deficit not associated with rebleed, infection, or hydrocephalus) in the presence of > or =1 confirmatory radiographic test (angiography or transcranial Doppler demonstrating mean V(MCA) >160 m/sec).

RESULTS

There were no significant differences in laboratory-defined transaminitis or myositis between groups. No patients developed clinical symptoms of myopathy or hepatitis. Plasma von Willebrand factor and S100beta were decreased 3 to 10 days after SAH (P<0.05) in patients receiving simvastatin versus placebo. Highest mean middle cerebral artery transcranial Doppler velocities were significantly lower in the simvastatin-treated group (103+/-41 versus 149+/-47; P<0.01). In addition, vasospasm was significantly reduced (P<0.05) in the simvastatin-treated group (5 of 19) compared with those who received placebo (12 of 20).

CONCLUSIONS

The use of simvastatin as prophylaxis against delayed cerebral ischemia after aneurysmal SAH is a safe and well-tolerated intervention. Its use attenuates serum markers associated with brain injury and decreases the incidence of radiographic vasospasm and delayed ischemic deficit.

A novel therapeutic derived from apolipoprotein E reduces brain inflammation and improves outcome after closed head injury

Although apolipoprotein E4 (APOE4) was initially identified as a susceptibility gene for the development of Alzheimer's disease, the presence of the APOE4 allele is also associated with poor outcome after acute brain injury. One mechanism by which apoE may influence neurological outcome is by downregulating the neuroinflammatory response. Because it does not readily cross the blood-brain barrier, the apoE holoprotein has limited therapeutic potential. We demonstrate that a single intravenous injection of a small peptide derived from the apoE receptor binding region crosses the blood-brain barrier and significantly improves histological and functional outcomes after traumatic brain injury (TBI). The development of an apoE-based intervention represents a novel therapeutic strategy in the management of acute brain injury.

Accurate patient history contributes to differentiating diabetes insipidus: a case study

This case study highlights the important contribution of nursing in obtaining an accurate health history. The case discussed herein initially appeared to be neurogenic diabetes insipidus (DI) secondary to a traumatic brain injury. The nursing staff, by reviewing the patient's health history with his family, discovered a history of polydipsia and long-standing lithium use. Lithium is implicated in drug-induced nephrogenic DI, and because the patient had not received lithium since being admitted to the hospital, his treatment changed to focus on nephrogenic DI. By combining information from the patient history, the physical examination, and radiologic and laboratory studies, the critical care team demonstrated that the patient had been self-treating his lithium-induced nephrogenic DI and developed neurogenic DI secondary to brain trauma. Thus successful treatment required that nephrogenic and neurogenic DI be treated concomitantly.

Correlation of serum brain natriuretic peptide with hyponatremia and delayed ischemic neurological deficits after subarachnoid hemorrhage

OBJECTIVE

Serum brain natriuretic peptide (BNP) is elevated after subarachnoid hemorrhage (SAH), causes diuresis and natriuresis (cerebral salt wasting), and may exacerbate delayed ischemic neurological deficits. We examined the temporal relationship between serum BNP elevation, hyponatremia, and the onset of delayed ischemic neurological deficits and determined whether serum BNP levels correlated with the 2-week outcome after SAH.

METHODS

Serum BNP and sodium were measured prospectively every 12 hours for 14 days in 40 consecutive patients admitted with SAH. All patients remained euvolemic, underwent transcranial Doppler assessment every 48 hours, and underwent angiography at the onset of delayed neurological deficits. New-onset neurological deficits were attributed to vasospasm only in the absence of other causes and when supported by transcranial Doppler or cerebral angiography.

RESULTS

Sixteen patients (40%) experienced symptomatic cerebral vasospasm after SAH. A more than threefold increase in admission serum BNP was associated with the onset of hyponatremia (P < 0.05). Mean BNP levels were similar between vasospasm and nonvasospasm patients fewer than 3 days after SAH (126 +/- 39 pg/ml versus 154 +/- 40 pg/ml; P = 0.61) but were elevated in the vasospasm cohort 4 to 6 days after SAH (285 +/- 67 pg/ml versus 116 +/- 30 pg/ml; P < 0.01), 7 to 9 days after SAH (278 +/- 72 pg/ml versus 166 +/- 45 pg/ml; P < 0.01), and 9 to 12 days after SAH (297 +/- 83 pg/ml versus 106 +/- 30 pg/ml; P < 0.01). BNP level remained independently associated with vasospasm adjusting for Fisher grade and Hunt and Hess grade (odds ratio, 1.28; 95% confidence interval, 1.1-1.6). In patients in whom vasospasm developed, mean serum BNP increased 5.4-fold within 24 hours after vasospasm onset and 11.2-fold the first 3 days after vasospasm onset. Patients with increasing BNP levels from admission demonstrated no change (0 +/- 3) in Glasgow Coma Scale score 2 weeks after SAH versus a 3.0 +/- 2 (P < 0.05) improvement in Glasgow Coma Scale score in patients without increasing serum BNP levels.

CONCLUSION

Increasing serum BNP levels independently were associated with hyponatremia, significantly increased the first 24 hours after onset of delayed ischemic neurological deficits, and predicted the 2-week Glasgow Coma Scale score.

Effects of Isoflurane Versus Fentanyl–Nitrous Oxide Anesthesia on Long-term Outcome from Severe Forebrain Ischemia in the Rat

Background

This study examined long-term outcome from severe forebrain ischemia in the rat, as a function of anesthetic given during the ischemic injury.

Methods

Rats were subjected to 10 min of near-complete forebrain ischemia while anesthetized with either 1.4% isoflurane or 70% nitrous oxide-fentanyl. Neurologic and histologic outcomes were measured at 5 days, 3 weeks, or 3 months after ischemia.

Results

At 5 days, isoflurane-anesthetized rats had less damage than did fentanyl-nitrous oxide-anesthetized rats (mean +/- SD, percent alive hippocampal CA1 neurons = 58+/-29 vs. 20+/-16, respectively; P = 0.011). This was accompanied by improved motor function in the isoflurane group (P = 0.002). At 3 weeks, there was no difference between groups for either outcome variable (percent alive CA1 neurons = 35+/-26 and 36+/-28 for isoflurane and fentanyl-nitrous oxide, respectively). Similarly, at 3 months, there was no difference between groups (percent alive CA1 neurons = 56+/-27 and 60+/-27 for isoflurane and fentanyl-nitrous oxide, respectively). Morris water maze performance at 3 months was similar between anesthetic groups and was also similar to sham performance. The percent alive CA1 neurons in the fentanyl-nitrous oxide group increased with duration of recovery (P = 0.004). There were no differences among isoflurane groups over time (5 days vs. 3 weeks, P = 0.26; 5 days vs. 3 months, P = 0.99; 3 week vs. 3 months, P = 0.32).

Conclusions

This study found no change in the percent alive CA1 hippocampal neurons as a function of duration of recovery from severe forebrain ischemia in isoflurane anesthetized rats. In contrast, the percent alive CA1 neurons in fentanyl-nitrous oxide-anesthetized rats tripled over 3 months of recovery. The natural history of long-term responses to forebrain ischemia requires further study before conclusions can be drawn with respect to the permanence of isoflurane neuroprotection.

Novel diagnostic test for acute stroke

BACKGROUND AND PURPOSE

The absence of a widely available and sensitive diagnostic test for acute cerebral ischemia remains a significant limitation in the diagnosis and management of stroke. The objective of this study was to examine the feasibility of developing a diagnostic panel of blood-borne biochemical markers of cerebral ischemia.

METHODS

Serial blood samples were obtained from patients (n=65 with suspected ischemic stroke, n=157 control subjects) presenting to an academic medical center emergency department. We analyzed 26 blood-borne markers believed to play a role in the ischemic cascade and created a 3-variable logistic regression model to predict the clinical diagnosis of stroke, defined as persistent neurological symptoms of cerebral ischemia lasting >24 hours.

RESULTS

Of the 26 blood-borne markers analyzed, univariate logistic analysis revealed that 4 were highly correlated with stroke (P<0.001): a marker of glial activation (S100beta), 2 markers of inflammation (matrix metalloproteinase-9 and vascular cell adhesion molecule), and 1 marker of thrombosis (von Willebrand factor). When the outcome level was set to a cutoff of P=0.1, our logistic model provided a sensitivity and specificity of 90% for predicting stroke.

CONCLUSIONS

A panel of blood-borne biochemical markers may be helpful in identifying patients with acute cerebral ischemia who could benefit from urgent care. Such a test may also be helpful in identifying stroke patients in the prehospital setting so that they could be fast-tracked to an institution equipped to care for patients with acute stroke.

APOE genotype and an ApoE-mimetic peptide modify the systemic and central nervous system inflammatory response

Human apolipoprotein E is the major apolipoprotein expressed in the brain and exists as three isoforms, designated E2, E3, and E4. Although evidence suggests that apolipoprotein E plays an important role in modifying systemic and brain inflammatory responses, there is little data investigating apoE isoform-specific effects in vivo. In this study, we compared the inflammatory responses of targeted-replacement mice expressing the human APOE3 and APOE4 genes after intravenous administration of lipopolysaccharide. Animals expressing the E4 allele had significantly greater systemic and brain elevations of the pro-inflammatory cytokines TNFalpha and IL-6 as compared with their APOE3 counterparts, suggesting an isoform-specific effect of the immunomodulatory properties of apoE. Furthermore, intravenous administration of a small apoE-mimetic peptide derived from the receptor-binding region of the apoE holoprotein (apoE-(133-149)) similarly suppressed both systemic and brain inflammatory responses in mice after lipopolysaccharide administration. These results suggest that apoE plays an isoform-specific role in mediating the systemic and brain inflammatory responses. Moreover, because exogenous administration of this apoE mimetic peptide is effective at suppressing both systemic and brain inflammation, it may represent a novel therapeutic strategy for diseases characterized by systemic or central nervous system inflammation, such as septic shock, multiple sclerosis, and traumatic brain injury.

Leukocytosis as an independent risk factor for cerebral vasospasm following aneurysmal subarachnoid hemorrhage

OBJECT

The identification of patients at an increased risk for cerebral vasospasm after subarachnoid hemorrhage (SAH) may allow for more aggressive treatment and improved patient outcomes. Note, however, that blood clot size on admission remains the only factor consistently demonstrated to increase the risk of cerebral vasospasm after SAH. The goal of this study was to assess whether clinical, radiographic, or serological variables could be used to identify patients at an increased risk for cerebral vasospasm.

METHODS

A retrospective review was conducted in all patients with aneurysmal or spontaneous nonaneurysmal SAH who were admitted to the authors' institution between 1995 and 2001. Underlying vascular diseases (hypertension or chronic diabetes mellitus), Hunt and Hess and Fisher grades, patient age, aneurysm location, craniotomy compared with endovascular aneurysm stabilization, medications on admission, postoperative steroid agent use, and the occurrence of fever, hydrocephalus, or leukocytosis were assessed as predictors of vasospasm. Two hundred twenty-four patients were treated for SAH during the review period. One hundred one patients (45%) developed symptomatic vasospasm. Peak vasospasm occurred 5.8 +/- 3 days after SAH. There were four independent predictors of vasospasm: Fisher Grade 3 SAH (odds ratio [OR] 7.5, 95% confidence interval [CI] 3.5-15.8), peak serum leukocyte count (OR 1.09, 95% CI 1.02-1.16), rupture of a posterior cerebral artery (PCA) aneurysm (OR 0.05, 95% CI 0.01-0.41), and spontaneous nonaneurysmal SAH (OR 0.14, 95% CI 0.04-0.45). A serum leukocyte count greater than 15 x 10(9)/L was independently associated with a 3.3-fold increase in the likelihood of developing vasospasm (OR 3.33, 95% CI 1.74-6.38).

CONCLUSIONS

During this 7-year period, spontaneous nonaneurysmal SAH and ruptured PCA aneurysms decreased the odds of developing vasospasm sevenfold and 20-fold, respectively. The presence of Fisher Grade 3 SAH on admission or a peak leukocyte count greater than 15 x 10(9)/L increased the odds of vasospasm sevenfold and threefold, respectively. Monitoring of the serum leukocyte count may allow for early diagnosis and treatment of vasospasm.

Protective effect of apolipoprotein E-mimetic peptides on N-methyl-D-aspartate excitotoxicity in primary rat neuronal-glial cell cultures

Apolipoprotein E (apoE) is a 34-kD protein with multiple biological properties. Recent clinical and preclinical observations implicate a role for apoE in modifying the response of the brain to focal and global ischemia. One mechanism by which apoE might exert these effects is by reducing glutamate-induced excitotoxic neuronal injury associated with ischemic insults. We demonstrate that human recombinant apoE confers a mild neuroprotective effect in primary neuronal-glial cultures exposed to 100 microM N-methyl-D-aspartate. Furthermore, a peptide derived from the receptor-binding region of apoE (residues 133-149) maintained a significant helical population as assessed by circular dichroism, and completely suppressed the neuronal cell death and calcium influx associated with N-methyl-D-aspartate exposure. Neuroprotection was greatest when the peptide was added concurrently with N-methyl-D-aspartate; however, a significant protection was observed when peptide was preincubated and washed off prior to N-methyl-D-aspartate exposure. These results suggest that one mechanism by which apoE may modify the CNS response to ischemia is by partially blocking glutamate excitotoxicity. Moreover, small peptide fragments derived from the receptor-binding region of apoE have enhanced bioactivity compared with the intact holoprotein, and may represent a novel therapeutic strategy for the treatment of brain ischemia.

Simvastatin increases endothelial nitric oxide synthase and ameliorates cerebral vasospasm resulting from subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Endothelial nitric oxide synthase (eNOS) activity is decreased after subarachnoid hemorrhage (SAH). Simvastatin increases eNOS activity. We hypothesized that simvastatin would increase eNOS protein and ameliorate SAH-induced cerebral vasospasm.

METHODS

Mice were treated with subcutaneous simvastatin or vehicle for 14 days and then subjected to endovascular perforation of the right anterior cerebral artery or sham surgery. Three days later, neurological deficits were scored (5 to 27; 27=normal), and middle cerebral artery diameter and eNOS protein were measured. The study was repeated, but simvastatin treatment was started after SAH or sham surgery.

RESULTS

In SAH mice, simvastatin pretreatment increased middle cerebral artery diameter (SAH-simvastatin=74+/-22 micro m, SAH-vehicle=52+/-18 micro m, P=0.03; sham-simvastatin=102+/-8 micro m, sham-vehicle=105+/-6 micro m). Pretreatment reduced neurological deficits (SAH-simvastatin=25+/-2, SAH-vehicle=20+/-2, P=0.005; sham-simvastatin and sham-vehicle=27+/-0). Simvastatin pretreatment also increased eNOS protein. Simvastatin posttreatment caused a modest increase in middle cerebral artery diameter in SAH mice (SAH-simvastatin=56+/-12 micro m, SAH-vehicle=45+/-4 micro m, P=0.03; sham-simvastatin=92+/-13 micro m, sham-vehicle=99+/-10 micro m) and reduced neurological deficits (SAH-simvastatin=21+/-1, SAH-vehicle=19+/-2, P=0.009). Simvastatin posttreatment did not significantly increase eNOS protein.

CONCLUSIONS

Simvastatin treatment before or after SAH attenuated cerebral vasospasm and neurological deficits in mice. The mechanism may be attributable in part to eNOS upregulation.

Serum von Willebrand factor, matrix metalloproteinase-9, and vascular endothelial growth factor levels predict the onset of cerebral vasospasm after aneurysmal subarachnoid hemorrhage

OBJECTIVE

Endothelial damage and intimal proliferation occur in vasospastic cerebral arteries after subarachnoid hemorrhage (SAH). In the peripheral vasculature, endothelial damage increases intimal matrix metalloproteinase-9 (MMP-9) and vascular endothelial growth factor (VEGF) levels, causing neointimal proliferation. We hypothesized that serum von Willebrand factor (vWF) (a marker of endothelial cell death), MMP-9, and VEGF levels could serve as prognostic markers in predicting the occurrence of cerebral vasospasm.

METHODS

Venous serum vWF, MMP-9, and VEGF levels were prospectively measured daily, for 12 days or until the onset of vasospasm, for 45 consecutive patients admitted with SAH (n = 38) or admitted for elective aneurysm clipping (control subjects, n = 7). The development of transcranial Doppler flow velocities of more than 180 cm/s and/or new focal neurological deficits with angiographically confirmed vasospasm was considered the onset of vasospasm. To establish whether these markers were specific for vasospasm versus ischemia, blood samples were obtained from a concurrent group of 42 patients within 24 hours after stroke onset unrelated to SAH.

RESULTS

Fifty-seven percent of patients (22 of 38 patients) developed vasospasm, 4 to 11 days after SAH (median, 7 d). Mean peak serum vWF, MMP-9, and VEGF levels were increased in the SAH prevasospasm cohort, compared with the SAH nonvasospasm cohort (vWF, 5526 +/- 929 versus 4934 +/- 599 ng/ml, P = 0.01; MMP-9, 705 +/- 338 versus 438 +/- 154 ng/ml, P = 0.006; VEGF, 0.12 +/- 0.06 versus 0.06 +/- 0.06 ng/ml, P = 0.023). Mean peak vWF, MMP-9, and VEGF levels for the focal ischemia cohort (vWF, 4645 +/- 875 ng/ml, P = 0.01; MMP-9, 250 +/- 308 ng/ml, P = 0.001; VEGF, 0.03 +/- 0.04 ng/ml, P = 0.001) were markedly lower in comparison with the SAH prevasospasm cohort and were unchanged in comparison with the control cohort. vWF levels of more than 5500 ng/ml, VEGF levels of more than 0.12 ng/ml, and MMP levels of more than 700 ng/ml each independently increased the odds of subsequent vasospasm (18-, 20-, and 25-fold, respectively).

CONCLUSION

The development of cerebral vasospasm after SAH was preceded by increases in serum vWF, MMP-9, and VEGF levels. Increased serum vWF, MMP-9, and VEGF levels could accurately predict the onset of cerebral vasospasm after SAH. These factors were not elevated by SAH alone or in a separate cohort of patients with ischemic stroke, suggesting that these factors might play a role in the pathogenesis of human cerebral vasospasm.

Apolipoprotein E affects the central nervous system response to injury and the development of cerebral edema

Apolipoprotein E has been implicated in modifying neurological outcome after traumatic brain injury, although the mechanisms by which this occurs remain poorly defined. To investigate the role of endogenous apolipoprotein E following acute brain injury, noninvasive magnetic resonance imaging was performed on anesthetized mice following closed head injury. Effacement of the lateral ventricle was used as a radiographic surrogate for cerebral edema. At 24 hours following injury, apolipoprotein E-deficient animals had a greater degree of cerebral edema as compared to matched controls. In addition, the brains of apolipoprotein E-deficient animals had a significantly greater upregulation of tissue necrosis factor alpha messenger ribonucleic acid as compared to controls as early as 1-hr post injury. Thus, modulation of the endogenous central nervous system inflammatory response may be one mechanism by which apolipoprotein E affects outcome following acute brain injury.

Apolipoprotein E modulates glial activation and the endogenous central nervous system inflammatory response

Apolipoprotein E (apoE) is a 299 amino acid protein that is associated with risk of developing Alzheimer's Disease (AD) and outcome after acute brain injury. To investigate the possibility that apoE modulates glial activation we studied the effect of endogenous apoE on inflammatory gene regulation in vitro and in vivo. Our results indicate that apoE downregulates CNS production of TNFalpha, Il-1beta, and Il-6 mRNA following stimulation with lipopolysaccharide (LPS). This effect of endogenous apoE on inflammatory gene regulation appears to be specific, and may account for the biological role that apoE plays in acute and chronic human neurological disease.

Quantitative level of protection offered to workers by ACGIH threshold limit values occupational exposure limits

The details of the example or modeling methodologies used herein are not critical to the general point of this article, which advises the estimation of residual risk at the OEL by using some quantitative modeling structure. Specifically, the authors believe that an explicit attempt to gauge the level of residual risk at the OEL based on conceptual stochastic models with transparent and testable assumptions could be seen as an important enhancement to the process. This is especially true in sharing the OEL deliberations and explaining OEL decisions to the stakeholders. Indeed, if this approach is used, it is critically important to understand and continually communicate that this "cloud of uncertainty" represents model estimates in which the true risk would most likely be less than worst case estimates and could possibly be zero. It is also possible but highly unlikely that it could be higher than the worst case upper-bound estimate. The above quantitative estimation scheme represents a possible improvement that could provide a reasoned attempt on the part of the risk assessors to use rational science (i.e., conceptual models with transparent and testable assumptions) to inform all of the OEL users and stakeholders of their meaning.

Survival and outcome after endotracheal intubation for acute stroke

OBJECTIVE

To assess survival and functional outcome in patients endotracheally intubated after ischemic stroke (IS) or spontaneous intracerebral hemorrhage (ICH).

BACKGROUND

Endotracheal intubation is both a necessary life support intervention and a measure of severity in IS or ICH. Knowledge of associated clinical variables may improve the estimation of early prognosis and guide management in these patients.

METHODS

We reviewed 131 charts of patients with IS or ICH who were admitted to the Neurosciences Intensive Care Unit at Duke University Medical Center between July 1994 and June 1997 and required endotracheal intubation. Stroke risk factors, stroke type (IS or ICH) and location (hemispheric, brainstem, or cerebellum), circumstances surrounding intubation, neurologic assessment (Glasgow Coma Score [GCS] and brainstem reflexes), comorbidities, and disposition at discharge were documented. Survivors were interviewed for Barthel Index (BI) scores.

RESULTS

Survival was 51% at 30 days and 39% overall. Variables that significantly correlated with 30-day survival in multivariate analysis included GCS at intubation (p = 0.03) and absent pupillary light response (p = 0.008). Increase in the GCS also correlated with improved functional outcome measured by the BI (p = 0.0003). In patients with IS, age and GCS at intubation predicted survival, and in patients with ICH, absent pupillary light response predicted survival.

CONCLUSIONS

Predictors for mortality differ between patients with IS and ICH; however, decreased level of consciousness is the most important determinant of increased mortality and poor functional outcome. Absent pupillary light responses also correspond with a poor prognosis for survival, but further validation of this finding is needed.

Hospital closure: an efficiency analysis

Logistic regression analysis was used to test the hypothesis that market forces have led to recent hospital closures. Specifically, inefficient and underutilized hospitals in competitive markets were hypothesized to be at greater risk for closure. While past studies used crude measures of hospital efficiency to predict closure, this study used data envelopment analysis to construct an efficiency index. Mixed support was found for the market forces hypothesis; however, contrary to expectations, inefficient hospitals were not shown to be at increased risk for closure. In fact, efficiency proved to be a weak, but positive, predictor of closure.