Joseph Schindler

Impaired cerebral autoregulation in obstructive sleep apnea

Obstructive sleep apnea (OSA) increases the risk of stroke independent of known vascular and metabolic risk factors. Although patients with OSA have higher prevalence of hypertension and evidence of hypercoagulability, the mechanism of this increased risk is unknown. Obstructive apnea events are associated with surges in blood pressure, hypercapnia, and fluctuations in cerebral blood flow. These perturbations can adversely affect the cerebral circulation. We hypothesized that patients with OSA have impaired cerebral autoregulation, which may contribute to the increased risk of cerebral ischemia and stroke. We examined cerebral autoregulation in patients with and without OSA by measuring cerebral artery blood flow velocity (CBFV) by using transcranial Doppler ultrasound and arterial blood pressure using finger pulse photoplethysmography during orthostatic hypotension and recovery as well as during 5% CO(2) inhalation. Cerebral vascular conductance and reactivity were determined. Forty-eight subjects, 26 controls (age 41.0+/-2.3 yr) and 22 OSA (age 46.8+/-2.3 yr) free of cerebrovascular and active coronary artery disease participated in this study. OSA patients had a mean apnea-hypopnea index of 78.4+/-7.1 vs. 1.8+/-0.3 events/h in controls. The oxygen saturation during sleep was significantly lower in the OSA group (78+/-2%) vs. 91+/-1% in controls. The dynamic vascular analysis showed mean CBFV was significantly lower in OSA patients compared with controls (48+/-3 vs. 55+/-2 cm/s; P <0.05, respectively). The OSA group had a lower rate of recovery of cerebrovascular conductance for a given drop in blood pressure compared with controls (0.06+/-0.02 vs. 0.20+/-0.06 cm.s(-2).mmHg(-1); P <0.05). There was no difference in cerebrovascular vasodilatation in response to CO(2). The findings showed that patients with OSA have decreased CBFV at baseline and delayed cerebrovascular compensatory response to changes in blood pressure but not to CO(2). These perturbations may increase the risk of cerebral ischemia during obstructive apnea.

Missed Ischemic Stroke Diagnosis in the Emergency Department by Emergency Medicine and Neurology Services

Background and Purpose— The failure to recognize an ischemic stroke in the emergency department is a missed opportunity for acute interventions and for prompt treatment with secondary prevention therapy. Our study examined the diagnosis of acute ischemic stroke in the emergency department of an academic teaching hospital and a large community hospital. Methods— A retrospective chart review was performed from February 2013 to February 2014. Results— A total of 465 patients with ischemic stroke were included in the analysis; 280 patients from the academic hospital and 185 patients from the community hospital. One hundred three strokes were initially misdiagnosed that is 22% of the included strokes at the combined centers. Fifty-five of these were missed at the academic hospital (20%) and 48 were at the community hospital (26%, P=0.11). Thirty-three percent of missed cases presented within a 3-hour time window for recombinant tissue-type plasminogen activator eligibility. An additional 11% presented between 3 and 6 hours of symptom onset for endovascular consideration. Symptoms independently associated with greater odds of a missed stroke diagnosis were nausea/vomiting (odds ratio, 4.02; 95% confidence interval, 1.60–10.1), dizziness (odds ratio, 1.99; 95% confidence interval, 1.03–3.84), and a positive stroke history (odds ratio, 2.40; 95% confidence interval, 1.30–4.42). Thirty-seven percent of posterior strokes were initially misdiagnosed compared with 16% of anterior strokes (P<0.001). Conclusions— Atypical symptoms associated with posterior circulation strokes lead to misdiagnoses. This was true at both an academic center and a large community hospital. Future studies need to focus on the evaluation of identification systems and tools in the emergency department to improve the accuracy of stroke diagnosis.

The TeleStroke Mimic (TM)-Score: A Prediction Rule for Identifying Stroke Mimics Evaluated in a Telestroke Network

Background Up to 30% of acute stroke evaluations are deemed stroke mimics (SM). As telestroke consultation expands across the world, increasing numbers of SM patients are likely being evaluated via Telestroke. We developed a model to prospectively identify ischemic SMs during Telestroke evaluation. Methods and Results We analyzed 829 consecutive patients from January 2004 to April 2013 in our internal New England–based Partners TeleStroke Network for a derivation cohort, and 332 cases for internal validation. External validation was performed on 226 cases from January 2008 to August 2012 in the Partners National TeleStroke Network. A predictive score was developed using stepwise logistic regression, and its performance was assessed using receiver‐operating characteristic (ROC) curve analysis. There were 23% SM in the derivation, 24% in the internal, and 22% in external validation cohorts based on final clinical diagnosis. Compared to those with ischemic cerebrovascular disease (iCVD), SM had lower mean age, fewer vascular risk factors, more frequent prior seizure, and a different profile of presenting symptoms. The TeleStroke Mimic Score (TM‐Score) was based on factors independently associated with SM status including age, medical history (atrial fibrillation, hypertension, seizures), facial weakness, and National Institutes of Health Stroke Scale >14. The TM‐Score performed well on ROC curve analysis (derivation cohort AUC=0.75, internal validation AUC=0.71, external validation AUC=0.77). Conclusions SMs differ substantially from their iCVD counterparts in their vascular risk profiles and other characteristics. Decision‐support tools based on predictive models, such as our TM Score, may help clinicians consider alternate diagnosis and potentially detect SMs during complex, time‐critical telestroke evaluations.

Evaluation for Blunt Cerebrovascular Injury: Review of the Literature and a Cost-Effectiveness Analysis

BACKGROUND AND PURPOSE: Evaluation for blunt cerebrovascular injury has generated immense controversy with wide variations in recommendations regarding the need for evaluation and the optimal imaging technique. We review the literature and determine the most cost-effective strategy for evaluating blunt cerebrovascular injury in trauma patients. MATERIALS AND METHODS: A comprehensive literature review was performed with data extracted to create a decision-tree analysis for 5 different strategies: anticoagulation for high-risk (based on the Denver screening criteria) patients, selective DSA or CTA (only high-risk patients), and DSA or CTA for all trauma patients. The economic evaluation was based on a health care payer perspective during a 1-year horizon. Statistical analyses were performed. The cost-effectiveness was compared through 2 main indicators: the incremental cost-effectiveness ratio and net monetary benefit. RESULTS: Selective anticoagulation in high-risk patients was shown to be the most cost-effective strategy, with the lowest cost and greatest effectiveness (an average cost of

Perioperative Stroke: Risk Assessment, Prevention and Treatment

21.08 and average quality-adjusted life year of 0.7231). Selective CTA has comparable utility and only a slightly higher cost (an average cost of

Cost-effectiveness Analysis of Follow-up Strategies for Thunderclap Headache Patients With Negative Noncontrast CT.

48.84 and average quality-adjusted life year of 0.7229). DSA, whether performed selectively or for all patients, was not optimal from both the cost and utility perspectives. Sensitivity analyses demonstrated these results to be robust for a wide range of parameter values. CONCLUSIONS: Selective CTA in high-risk patients is the optimal and cost-effective imaging strategy. It remains the dominant strategy over DSA, even assuming a low CTA sensitivity and irrespective of the proportion of patients at high-risk and the incidence of blunt cerebrovascular injury in high-risk patients.

Thrombolysis for acute stroke in patients with vasculitis: Case report and literature discussion

Opinion statementNumerous risk factors for perioperative stroke have been identified and many are modifiable. Surgical patients with a history of cerebrovascular disease should be evaluated by a neurologist. Cardiac and cerebrovascular testing is critical in identifying patients at high risk for perioperative stroke. The identification and treatment of carotid disease in the context of upcoming surgery has been a source of controversy. Routine carotid revascularization performed with coronary artery bypass graft (CABG) surgery for incidentally discovered carotid stenosis is not recommended. Prior to aortic manipulation during CABG, epiaortic ultrasound should be performed to identify aortic atheromatous plaques. If possible, preoperative aspirin, beta blocker, statin, and angiotensin converting-enzyme (ACE) inhibitor therapy should be continued in the perioperative period. Patients who are prescribed anticoagulation at high risk of thromboembolism should receive bridging anticoagulation during the perioperative period. The identification and prevention of postoperative atrial fibrillation (AF) is central to stroke prevention. CABG patients should be initiated on beta blockade +/− amiodarone to prevent postoperative AF. Many practitioners have been traditionally nihilistic towards acute perioperative stroke treatment. Given the narrow therapeutic window of treatment options, candidacy is dependent on timely recognition. Intravenous and endovascular thrombolysis/therapies are viable options in selected patients under the guidance and expertise of a neurologist. This article will present the epidemiology of perioperative stroke, the pathophysiology, risk assessment and stratification for common surgeries. The article will additionally focus on treatment options including modifiable risk factor reduction and the perioperative management of medications.

Screening for Pediatric Blunt Cerebrovascular Injury: Review of Literature and a Cost-Effectiveness Analysis

OBJECTIVES Accurate diagnosis of acute subarachnoid hemorrhage (SAH) is critical in thunderclap headache patients due to high morbidity and mortality associated with missed aneurysmal bleeds. The objective of this study was to determine the utility of computed tomography angiography (CTA) in managing patients with acute, severe headaches and negative noncontrast CT and assess the cost-effectiveness of three different screening strategies-no follow up, CTA, and lumbar puncture (LP). METHODS A modeling-based economic evaluation was performed with a time horizon of 1 year for thunderclap headache patients in the emergency department with negative noncontrast CT for SAH. Sensitivity analyses were performed to determine the effect of sensitivity of CT and the prevalence of SAH on cost-effectiveness. RESULTS Lumbar puncture follow-up has the lowest cost and the highest utility in the mathematical model. The Monte Carlo simulation shows noncontrast CT with LP follow-up to be the most cost-effective strategy in 85.3% of all cases even at a

Acute Central Retinal Artery Occlusion Treated with Intravenous Recombinant Tissue Plasminogen Activator

1 million/quality-adjusted life-years willingness-to-pay. Sensitivity analyses demonstrate that LP follow-up should be performed, except for when CT sensitivity exceeds 99.2% and the SAH prevalence is below 3.2%, where no follow-up may be considered. CONCLUSIONS Although CTA is frequently used for evaluation of thunderclap headache patients, its utility is not clearly defined. LP follow-up is shown to be the most cost-effective strategy for evaluation of thunderclap headache patients in most clinical settings.

Tissue plasminogen activator via cross-collateralization for tandem internal carotid and middle cerebral artery occlusion

1. IntroductionTreatment with tissue plasminogen activator (tPA) is standardof care treatment of acute ischemic stroke. Various risk factorshave been associated with the development of intracranial hem-orrhage (ICH) following thrombolysis, but there is no literature onthe useoftPAinpatientswithknownvasculitiswhodevelopacuteischemic stroke. We present a case of ICH after tPA administrationin apatientwithknownChurg–StraussSyndrome(CSS)anddiscussthe implications of thrombolysis in patients with vasculitis.2. Case reportA 53-year old right-handed man with a past medical history ofwell controlled hyperlipidemia, negative anti-neutrophil cytoplas-mic antibodies (ANCA) CSS characterized by asthma, eosinophilia,nail-fold infarcts and peripheral neuropathy presented acutelywith dysarthria, left facial weakness and partial sensory loss overthe left upper extremity. CSS was diagnosed eleven years ear-lier based on the clinical presentation and with a skin biopsythat demonstrated vasculitis. There was no history of hyperten-sion or diabetes. His disease has not been well controlled since