Alejandro M. Brunser

Accuracy of Transcranial Doppler Compared With CT Angiography in Diagnosing Arterial Obstructions in Acute Ischemic Strokes

Background and Purpose— Patients with acute ischemic stroke and intracranial arterial obstructions have a poor prognosis and a high probability of deteriorating at 24 hours. We aimed to evaluate the diagnostic accuracy of power motion mode Doppler (PMD-TCD) compared with CT angiography as standard in diagnosing intracranial arterial obstructions in patients presenting with ischemic stroke of <24 hours. Methods— Consecutive patients presenting with acute ischemic stroke to the emergency department underwent high-resolution brain CT angiography and PMD-TCD within a 6-hour difference. Results— A total of 100 patients were included. PMD-TCD demonstrated 34 intracranial occlusions and CTA 33. There were 6 false-positives and 4 false-negative diagnoses with PMD-TCD. PMD-TCD had a positive likelihood ratio of 13.7, a negative likelihood ratio of 0.19, sensitivity of 81.8%, and specificity of 94% for detecting an arterial occlusion in any specific artery. Results for the middle cerebral artery were: positive likelihood ratio 24.6, negative likelihood ratio 0.045, sensitivity 95.6%, and specificity 96.2%. For the anterior circulation, the results were: positive likelihood ratio 18.5, negative likelihood ratio 0, sensitivity 100%, and specificity 94.5%. For the posterior circulation, the results were: positive likelihood ratio >1000, negative likelihood ratio 0.42, sensitivity 57.1%, and specificity 100%. The post-test probability for any occluded artery when PMD-TCD was positive increased for any admission National Institutes of Health Stroke Scale score but was especially remarkable for National Institutes of Health Stroke Scale scores between 7 and 15 points. Conclusions— PMD-TCD is valid compared with CT angiography for the diagnosis of arterial occlusions in patients with acute ischemic stroke, especially in middle cerebral artery obstructions.

Cluster-Randomized, Crossover Trial of Head Positioning in Acute Stroke

BACKGROUND The role of supine positioning after acute stroke in improving cerebral blood flow and the countervailing risk of aspiration pneumonia have led to variation in head positioning in clinical practice. We wanted to determine whether outcomes in patients with acute ischemic stroke could be improved by positioning the patient to be lying flat (i.e., fully supine with the back horizontal and the face upwards) during treatment to increase cerebral perfusion. METHODS In a pragmatic, cluster‐randomized, crossover trial conducted in nine countries, we assigned 11,093 patients with acute stroke (85% of the strokes were ischemic) to receive care in either a lying‐flat position or a sitting‐up position with the head elevated to at least 30 degrees, according to the randomization assignment of the hospital to which they were admitted; the designated position was initiated soon after hospital admission and was maintained for 24 hours. The primary outcome was degree of disability at 90 days, as assessed with the use of the modified Rankin scale (scores range from 0 to 6, with higher scores indicating greater disability and a score of 6 indicating death). RESULTS The median interval between the onset of stroke symptoms and the initiation of the assigned position was 14 hours (interquartile range, 5 to 35). Patients in the lying‐flat group were less likely than patients in the sitting‐up group to maintain the position for 24 hours (87% vs. 95%, P<0.001). In a proportional‐odds model, there was no significant shift in the distribution of 90‐day disability outcomes on the global modified Rankin scale between patients in the lying‐flat group and patients in the sitting‐up group (unadjusted odds ratio for a difference in the distribution of scores on the modified Rankin scale in the lying‐flat group, 1.01; 95% confidence interval, 0.92 to 1.10; P=0.84). Mortality within 90 days was 7.3% among the patients in the lying‐flat group and 7.4% among the patients in the sitting‐up group (P=0.83). There were no significant between‐group differences in the rates of serious adverse events, including pneumonia. CONCLUSIONS Disability outcomes after acute stroke did not differ significantly between patients assigned to a lying‐flat position for 24 hours and patients assigned to a sitting‐up position with the head elevated to at least 30 degrees for 24 hours. (Funded by the National Health and Medical Research Council of Australia; HeadPoST ClinicalTrials.gov number, NCT02162017.)

Exclusion Criteria for Intravenous Thrombolysis in Stroke Mimics: An Observational Study

BACKGROUND Stroke mimics (SMs) are frequent in emergency departments (EDs), but are treated infrequently with intravenous recombinant tissue plasminogen activator (rt-PA) thrombolysis. We aimed at identifying the factors that lead to the exclusion of SMs from thrombolytic therapy. METHODS Consecutive patients presenting to the ED between December 2004 and March 2011 with symptoms that suggested acute ischemic stroke were included. RESULTS Eight hundred forty-two patients were included in this study; 113 (13.4%) were considered SMs; these patients were younger (P = .01), more frequently diabetic (P = .001), arrived later to the ED (P = .03), had lower National Institutes of Health Stroke Scale scores (P < .001), and higher frequencies of negative diffusion-weighted imaging studies (P = .002). The most common causes of cases of SM were toxic metabolic disorders (n = 34 [30.1%]) and seizures (n = 22 [19.5%]). The most frequent cause of consultation was aphasia (n = 43 [37.6%]). SM patients had a total of 152 contraindications for rt-PA, with 34 (30%) patients having >1 contraindication. The most frequent of these were being beyond the therapeutic window for thrombolysis (n = 96) and having deficits not measurable by the National Institutes of Health Stroke Scale or very mild symptoms before the start of rt-PA (n = 37). Twenty-four (21.2%) patients had both contraindications simultaneously. Two patients (1.76%) in the SM group were candidates for rt-PA but did not receive this treatment because they or their family rejected it. Of 729 stroke patients, 87 (11.9%) did receive rt-PA. CONCLUSIONS SM patients frequently had exclusion criteria for systemic thrombolysis, the most frequent being presenting beyond the established thrombolytic window.

Head Position in Stroke Trial (HeadPoST)--sitting-up vs lying-flat positioning of patients with acute stroke : study protocol for a cluster randomised controlled trial

BackgroundPositioning a patient lying-flat in the acute phase of ischaemic stroke may improve recovery and reduce disability, but such a possibility has not been formally tested in a randomised trial. We therefore initiated the Head Position in Stroke Trial (HeadPoST) to determine the effects of lying-flat (0°) compared with sitting-up (≥30°) head positioning in the first 24 hours of hospital admission for patients with acute stroke.Methods/DesignWe plan to conduct an international, cluster randomised, crossover, open, blinded outcome-assessed clinical trial involving 140 study hospitals (clusters) with established acute stroke care programs. Each hospital will be randomly assigned to sequential policies of lying-flat (0°) or sitting-up (≥30°) head position as a ‘business as usual’ stroke care policy during the first 24 hours of admittance. Each hospital is required to recruit 60 consecutive patients with acute ischaemic stroke (AIS), and all patients with acute intracerebral haemorrhage (ICH) (an estimated average of 10), in the first randomised head position policy before crossing over to the second head position policy with a similar recruitment target. After collection of in-hospital clinical and management data and 7-day outcomes, central trained blinded assessors will conduct a telephone disability assessment with the modified Rankin Scale at 90 days. The primary outcome for analysis is a shift (defined as improvement) in death or disability on this scale. For a cluster size of 60 patients with AIS per intervention and with various assumptions including an intracluster correlation coefficient of 0.03, a sample size of 16,800 patients at 140 centres will provide 90 % power (α 0.05) to detect at least a 16 % relative improvement (shift) in an ordinal logistic regression analysis of the primary outcome. The treatment effect will also be assessed in all patients with ICH who are recruited during each treatment study period.DiscussionHeadPoST is a large international clinical trial in which we will rigorously evaluate the effects of different head positioning in patients with acute stroke.Trial registrationClinicalTrials.gov identifier: NCT02162017 (date of registration: 27 April 2014); ANZCTR identifier: ACTRN12614000483651 (date of registration: 9 May 2014). Protocol version and date: version 2.2, 19 June 2014.

Accuracy of Diffusion-Weighted Imaging in the Diagnosis of Stroke in Patients With Suspected Cerebral Infarct

Background and Purpose— The accuracy of diffusion-weighted imaging (DWI) for the diagnosis of acute cerebral ischemia among patients with suspected ischemic stroke arriving to an emergency room has not been studied in depth. Methods— DWI was performed in 712 patients with acute or subacute focal symptoms that suggested an acute ischemic stroke (AIS), 609 of them with AIS. Results— DWI demonstrated a sensitivity of 90% and specificity of 97%, a positive likelihood ratio of 31 and a negative likelihood ratio of 0.1 for detecting AIS. The overall accuracy was 95%. Of those patients who demonstrated abnormal DWI studies, 99.5% were AIS patients, and of those patients with normal DWI studies 63% were stroke mimics. Conclusions— DWI is accurate in detecting AIS in unselected patients with suspected AIS; a negative study should alert for nonischemic conditions.

Additional Information Given to a Multimodal Imaging Stroke Protocol by Transcranial Doppler Ultrasound in the Emergency Room: A Prospective Observational Study

Background: Transcranial Doppler (TCD) ultrasound can demonstrate dynamic information. We aimed to evaluate whether TCD generates useful additional information in the emergency room after a multimodal stroke imaging protocol and also whether this modified the management of patients with cerebral infarction. Methods: Patients admitted between April 2006 and June 2007 with ischemic stroke of less than 24 h were subjected to a protocol consisting of noncontrast brain CT, computed tomography angiography, diffusion-weighted magnetic resonance imaging and then TCD within the following 6 h by an observer blinded to the results of imaging studies. Results: Seventy-nine patients were included. The imaging protocol was performed 457 (±346) min after stroke symptoms and TCD after 572 (±376) min. TCD provided additional information in 28 cases (35.4%, 95% CI 25.7–46.4). More that one piece of additional information was obtained in 6 patients. The most frequent additional information was collateral pathways. Multivariate analysis demonstrated that intracranial vessel occlusion was the variable most associated with additional information. In 7 patients (8.8%, 95% CI 4.3–17.1), additional information changed management: in 4 an additional angiography was performed, in 2 patients angiography was suspended and in 1 aggressive neurocritical care was indicated. Patients with NIHSS >10 were significantly more likely to have their initial treatment changed (p = 0.004). Conclusions: TCD can provide additional information to a multimodal acute ischemic stroke imaging protocol in a third of patients. This can result in changes in the management in some of these patients.

Validez del Doppler transcraneal en el diagnóstico de muerte encefálica

BACKGROUND The clinical diagnosis of brain death is complex. AIM To evaluate the diagnostic accuracy of transcranial Doppler (TCD) for brain death. PATIENTS AND METHODS Patients seen on the intensive care unit of a private hospital between January 2004 to December 2008, were included if they were in structural coma, had no craniectomy and had a blind evaluation by a neurologist and TCD done in less than three hours. The diagnosis of brain death was based on a clinical evaluation that considered the absence of sedative drugs, median blood pressure>60 mmHg, body temperature over 35 masculine Celsius and complete absence of brainstem reflexes. An expert neurosonologist, with a TCD-PMD-100, 2 Mhz transducer, used an institutional protocol that considers the examination as positive for brain circulatory arrest when there is presence of reverberating, small systolic peaks or the disappearance of a previous signal present on both middle cerebral arteries and intracranial vertebral arteries. RESULTS Fifty three patients were evaluated, 25 with clinical brain death. On 45 cases (84.9%), the interval between both evaluations was less than one hour. The sensitivity, specificity, positive and negative predictive values for the diagnosis of brain death with TCD were 100, 96, 96.1 and 100% respectively. Positive and negative likelihood ratios for brain death were 28 and 0, respectively. CONCLUSIONS TCD is a valid and useful technique for the diagnosis of brain death and can be used on complicated cases.

Transcranial Doppler in a Hispanic-Mestizo population with neurological diseases: a study of sonographic window and its determinants.

Between 5% and 37% of patients are not suitable for transtemporal insonation with transcranial Doppler (TCD). This unsuitability is particularly frequent in elderly females and non‐Caucasians. We aim to evaluate TCD efficiency in a mixed Hispanic population in Santiago, Chile and to determine whether factors associated with the presence of optimal windows depend exclusively on patient‐related elements. Seven hundred forty‐nine patients were evaluated with power mode TCD. Optimal temporal windows (TWs) included detection of the middle, anterior, posterior cerebral arteries and terminal carotid. The patients age and sex, the location of the examination, the time of day, whether the test was conducted on weekends and whether mechanical ventilation was used were recorded. Percentages of optimal windows were calculated. Examinations were deemed ideal if both TWs were optimal. TWs were obtained in 82% of cases. In univariate analyses, male sex (P < 0.001), an age below 60 years (P < 0.0001) and mechanical ventilation (P= 0.04) correlated with ideal TWs. Using logistic regression where dependent variable was a non‐ideal window only male sex odds ratio (OR) 2.3 (1.51–3.45) and age below 60 OR 13.8 (7.8–24.6) were statistically significant. Our findings indicate that Hispanic populations have detection rates for TWs similar to Europeans and are affected by patient‐related elements.

Head position and cerebral blood flow in acute ischemic stroke patients: Protocol for the pilot phase, cluster randomized, Head Position in Acute Ischemic Stroke Trial (HeadPoST pilot)

Rationale Few proven interventions exist for acute ischemic stroke (AIS), and most are expensive and restricted in applicability. Lying flat ‘head down’ positioning of AIS patients has been shown to increase by as much as 20%, mean cerebral blood flow velocities (CBFV) measured by transcranial Doppler (TCD) but whether this translates into clinical improvement is uncertain. Aim To determine if the lying flat position increases mean CBFV in the affected territory as compared to the sitting up position in AIS patients. Methods and design Head Position in Acute Ischemic Stroke Trial (HeadPoST pilot) is a cluster randomized (clusters being months), assessor-blinded end-point, phase IIb trial, where consecutive adults with anterior circulation AIS within 12 h of symptom onset are positioned to a randomized position for 48 h with TCD performed serially. Study outcomes Primary outcome is mean CBFV on TCD at 1 and 24 h after positioning. Secondary outcomes include: serious adverse events, neurological impairment at seven days, and death and disability at 90 days. Sample size estimates Assuming an increase of 8.3 (SD 11.4) cm/s in average of mean CBFV when tilted from 30° to 0°, 46 clusters are required (92 patients in total) to detect a 20% increase of mean CBFV with 90% power and 5% level of significance. Conclusion HeadPoST pilot is a cluster randomized multicenter clinical trial investigating the effect of head positioning on mean CBFV in anterior circulation AIS.

The Role of TCD in the Evaluation of Acute Stroke.

The additional information that transcranial Doppler (TCD) can provide as part of a multimodal imaging stroke protocol in the setting of hyper acute strokes has not been evaluated.