Matthew B. Maas

Collateral vessels on CT angiography predict outcome in acute ischemic stroke.

Background and Purpose— Despite the abundance of emerging multimodal imaging techniques in the field of stroke, there is a paucity of data demonstrating a strong correlation between imaging findings and clinical outcome. This study explored how proximal arterial occlusions alter flow in collateral vessels and whether occlusion or extent of collaterals correlates with prehospital symptoms of fluctuation and worsening since onset or predict in-hospital worsening. Methods— Among 741 patients enrolled in a prospective cohort study involving CT angiographic imaging in acute stroke, 134 cases with proximal middle cerebral artery occlusion and 235 control subjects with no occlusions were identified. CT angiography was used to identify occlusions and grade the extent of collateral vessels in the sylvian fissure and leptomeningeal convexity. History of symptom fluctuation or progressive worsening was obtained on admission. Results— Prehospital symptoms were unrelated to occlusion or collateral status. In cases, 37.5% imaged within 1 hour were found to have diminished collaterals versus 12.1% imaged at 12 to 24 hours (P=0.047). No difference in worsening was seen between cases and control subjects with adequate collaterals, but cases with diminished sylvian and leptomeningeal collaterals experienced greater risk of worsening compared with control subjects measured either by admission to discharge National Institutes of Health Stroke Scale increase ≥1 (55.6% versus 16.6%, P=0.001) or ≥4 (44.4% versus 6.4%, P<0.001). Conclusion— Most patients with proximal middle cerebral artery occlusion rapidly recruit sufficient collaterals and follow a clinical course similar to patients with no occlusions, but a subset with diminished collaterals is at high risk for worsening.

CT cerebral blood flow maps optimally correlate with admission diffusion-weighted imaging in acute stroke but thresholds vary by postprocessing platform

Background and Purpose— Admission infarct core lesion size is an important determinant of management and outcome in acute (<9 hours) stroke. Our purposes were to: (1) determine the optimal CT perfusion parameter to define infarct core using various postprocessing platforms; and (2) establish the degree of variability in threshold values between these different platforms. Methods— We evaluated 48 consecutive cases with vessel occlusion and admission CT perfusion and diffusion-weighted imaging within 3 hours of each other. CT perfusion was acquired with a “second-generation” 66-second biphasic cine protocol and postprocessed using “standard” (from 2 vendors, “A-std” and “B-std”) and “delay-corrected” (from 1 vendor, “A-dc”) commercial software. Receiver operating characteristic curve analysis was performed comparing each CT perfusion parameter—both absolute and normalized to the contralateral uninvolved hemisphere—between infarcted and noninfarcted regions as defined by coregistered diffusion-weighted imaging. Results— Cerebral blood flow had the highest accuracy (receiver operating characteristic area under the curve) for all 3 platforms (P<0.01). The maximal areas under the curve for each parameter were: absolute cerebral blood flow 0.88, cerebral blood volume 0.81, and mean transit time 0.82 and relative Cerebral blood flow 0.88, cerebral blood volume 0.83, and mean transit time 0.82. Optimal receiver operating characteristic operating point thresholds varied significantly between different platforms (Friedman test, P<0.01). Conclusions— Admission absolute and normalized “second-generation” cine acquired CT cerebral blood flow lesion volumes correlate more closely with diffusion-weighted imaging-defined infarct core than do those of CT cerebral blood volume or mean transit time. Although limited availability of diffusion-weighted imaging for some patients creates impetus to develop alternative methods of estimating core, the marked variability in quantification among different postprocessing software limits generalizability of parameter map thresholds between platforms.

National Institutes of Health Stroke Scale Score Is Poorly Predictive of Proximal Occlusion in Acute Cerebral Ischemia

Background and Purpose— Multimodal imaging is gaining an important role in acute stroke. The benefit of obtaining additional clinically relevant information must be weighed against the detriment of increased cost, delaying time to treatment, and adverse events such as contrast-induced nephropathy. Use of National Institutes of Health Stroke Scale (NIHSS) score to predict a proximal arterial occlusion (PO) is suggested by several case series as a viable method of selecting cases appropriate for multimodal imaging. Methods— Six hundred ninety-nine patients enrolled in a prospective cohort study involving CT angiographic imaging in acute stroke were dichotomized according to the presence of a PO, including a subgroup of 177 subjects with middle cerebral artery M1 occlusion. Results— The median NIHSS score of patients found to have a PO was higher than the overall median (9 versus 5, P<0.0001). The median NIHSS score of patients with middle cerebral artery M1 occlusion was 14. NIHSS score ≥10 had 81% positive predictive value for PO but only 48% sensitivity with the majority of subjects with PO presenting with lower NIHSS scores. All patients with NIHSS score ≥2 would need to undergo angiographic imaging to detect 90% of PO. Conclusions— High NIHSS score correlates with the presence of a proximal arterial occlusion in patients presenting with acute cerebral ischemia. No NIHSS score threshold can be applied to select a subgroup of patients for angiographic imaging without failing to capture the majority of cases with clinically important occlusive lesions. The finding of minimal clinical deficits should not deter urgent angiographic imaging in otherwise appropriate patients suspected of acute stroke.

Blood Pressure Reduction, Decreased Diffusion on MRI, and Outcomes After Intracerebral Hemorrhage

Background and Purpose— Decreased diffusion (DD) consistent with acute ischemia may be detected on MRI after acute intracerebral hemorrhage (ICH), but its risk factors and impact on functional outcomes are not well-defined. We tested the hypotheses that DD after ICH is related to acute blood pressure (BP) reduction and lower hemoglobin and presages worse functional outcomes. Methods— Patients who underwent MRI were prospectively evaluated for DD by certified neuroradiologists blinded to outcomes. Hemoglobin and BP data were obtained via electronic queries. Outcomes were obtained at 14 days and 3 months with the modified Rankin Scale, a functional scale scored from 0 (no symptoms) to 6 (dead). We used logistic regression for dependence or death (modified Rankin Scale score 4–6). Results— DD distinct from the hematoma was found on MRI in 39 of 95 patients (41%). DD was associated with greater BP reductions from baseline and a higher risk of dependence or death at 3 months (odds ratio, 4.8; 95% confidence interval, 1.7–13.9; P=0.004) after correction for ICH score (1.8 per point; 95% confidence interval, 1.2–3.1; P=0.01). Lower hemoglobin was associated with worse ICH score, larger hematoma volume, and worse outcomes, but not DD. Conclusions— DD is common after ICH, associated with greater acute BP reductions, and associated with disability and death at 3 months in multivariate analysis. The potential benefits of acute BP reduction to reduce hematoma growth may be limited by DD. The prevention and treatment of cerebral ischemia manifested as DD are potential methods to improve outcomes.

CT Perfusion Mean Transit Time Maps Optimally Distinguish Benign Oligemia from True “At-Risk” Ischemic Penumbra, but Thresholds Vary by Postprocessing Technique

BACKGROUND AND PURPOSE: Various CTP parameters have been used to identify ischemic penumbra. The purpose of this study was to determine the optimal CTP parameter and threshold to distinguish true “at-risk” penumbra from benign oligemia in acute stroke patients without reperfusion. MATERIALS AND METHODS: Consecutive stroke patients were screened and 23 met the following criteria: 1) admission scanning within 9 hours of onset, 2) CTA confirmation of large vessel occlusion, 3) no late clinical or radiographic evidence of reperfusion, 4) no thrombolytic therapy, 5) DWI imaging within 3 hours of CTP, and 6) either CT or MR follow-up imaging. CTP was postprocessed with commercial software packages, using standard and delay-corrected deconvolution algorithms. Relative cerebral blood flow, volume, and mean transit time (rCBF, rCBV and rMTT) values were obtained by normalization to the uninvolved hemisphere. The admission DWI and final infarct were transposed onto the CTP maps and receiver operating characteristic curve analysis was performed to determine optimal thresholds for each perfusion parameter in defining penumbra destined to infarct. RESULTS: Relative and absolute MTT identified penumbra destined to infarct more accurately than CBF or CBV*CBF (P < .01). Absolute and relative MTT thresholds for defining penumbra were 12s and 249% for the standard and 13.5s and 150% for the delay-corrected algorithms, respectively. CONCLUSIONS: Appropriately thresholded absolute and relative MTT-CTP maps optimally distinguish “at-risk” penumbra from benign oligemia in acute stroke patients with large-vessel occlusion and no reperfusion. The precise threshold values may vary, however, depending on the postprocessing technique used for CTP map construction.

Desmopressin Improves Platelet Activity in Acute Intracerebral Hemorrhage

Background and Purpose— Minimizing hematoma growth in high-risk patients is an attractive strategy to improve outcomes after intracerebral hemorrhage. We tested the hypothesis that desmopressin (DDAVP), which improves hemostasis through the release of von Willebrand factor, improves platelet activity after intracerebral hemorrhage. Methods— Patients with reduced platelet activity on point-of-care testing alone (5), known aspirin use alone (1), or both (8) received desmopressin 0.4 &mgr;g/kg IV. We measured Platelet Function Analyzer-epinephrine (Siemens AG, Germany) and von Willebrand factor antigen from baseline to 1 hour after infusion start and hematoma volume from the diagnostic to a follow-up computed tomographic scan. Results— We enrolled 14 patients with of mean age 66.8±14.6 years, 11 (85%) of whom were white and 8 (57%) were men. Mean Platelet Function Analyzer-epinephrine results shortened from 192±18 seconds pretreatment to 124±15 seconds (P=0.01) 1 hour later, indicating improved plate activity. von Willebrand factor antigen increased from 242±96% to 289±103% activity (P=0.004), indicating the expected increase in von Willebrand factor. Of 7 (50%) patients who received desmopressin within 12 hours of intracerebral hemorrhage symptom onset, changes in hematoma volume were modest, −0.5 (−1.4 to 8.4) mL and only 2 had hematoma growth. One patient had low blood pressure and another had a new fever within 6 hours of desmopressin administration. Conclusions— Intravenous desmopressin was well tolerated and improved platelet activity after acute intracerebral hemorrhage. Larger studies are needed to determine its potential effects on reducing hematoma growth versus platelet transfusion or placebo. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00961532.

Delayed intraventricular hemorrhage is common and worsens outcomes in intracerebral hemorrhage

Objective: To evaluate the incidence, characteristics, and clinical consequences of delayed intraventricular hemorrhage (dIVH). Methods: Patients with primary intracerebral hemorrhage (ICH) were enrolled into a prospective registry between December 2006 and February 2012. Patients were managed, and serial neuroimaging obtained, per a structured protocol. Initial and delayed IVH were identified on imaging, along with ICH volumes, with outcomes blinded. Multivariate models were developed to test whether the occurrence of dIVH was a predictor of functional outcomes independent of known predictors, including the ICH score elements and ICH growth. Results: A total of 216 patients were studied, and 104 (48%) had IVH on initial imaging. Of the 112 with no IVH, 23 (21%) subsequently developed IVH. Emergent surgical intervention, mostly ventriculostomy placement, was required after discovery of dIVH in 10 (43%) of these 23. In multivariate models adjusting for all elements of the ICH score and hematoma growth, dIVH was an independent predictor of death at 14 days (p = 0.015) and higher modified Rankin Scale scores at 3 months (all p = 0.037). The effect of dIVH remained significant in a secondary analysis that adjusted for all other variables significant in the univariate analysis. Conclusions: Similar to hematoma expansion dIVH is independently associated with death and poor outcomes. Because IVH is easily detected by serial neuroimaging and often requires emergent surgical intervention, monitoring for dIVH is recommended.

Surveillance neuroimaging and neurologic examinations affect care for intracerebral hemorrhage

Objective: We tested the hypothesis that surveillance neuroimaging and neurologic examinations identified changes requiring emergent surgical interventions in patients with intracerebral hemorrhage (ICH). Methods: Patients with primary ICH were enrolled into a prospective registry between December 2006 and July 2012. Patients were managed in a neuroscience intensive care unit with a protocol that included serial neuroimaging at 6, 24, and 48 hours, and hourly neurologic examinations using the Glasgow Coma Scale and NIH Stroke Scale. We evaluated all cases of craniotomy and ventriculostomy to determine whether the procedure was part of the initial management plan or occurred subsequently. For those that occurred subsequently, we determined whether worsening on neurologic examination or worsened neuroimaging findings initiated the process leading to intervention. Results: There were 88 surgical interventions in 84 (35%) of the 239 patients studied, including ventriculostomy in 52 (59%), craniotomy in 21 (24%), and both in 11 (13%). Of the 88 interventions, 24 (27%) occurred subsequently and distinctly from initial management, a median of 15.9 hours (8.9–27.0 hours) after symptom onset. Thirteen (54%) were instigated by findings on neurologic examination and 11 (46%) by neuroimaging. Demographics, severity of hemorrhage, and hemorrhage location were not associated with delayed intervention. Conclusions: More than 25% of surgical interventions performed after ICH were prompted by delayed imaging or clinical findings. Serial neurologic examinations and neuroimaging are important and effective surveillance techniques for monitoring patients with ICH.

Predictors of 30-day readmission after intracerebral hemorrhage: a single-center approach for identifying potentially modifiable associations with readmission.

Objective:To determine whether patient’s demographics or severity of illness predict hospital readmission within 30 days following spontaneous intracerebral hemorrhage, to identify readmission associations that may be modifiable at the single-center level, and to determine the impact of readmission on outcomes. Design:We collected demographic, clinical, and hospital course data for consecutive patients with spontaneous intracerebral hemorrhage enrolled in an observational study. Readmission within 30 days was determined retrospectively by an automated query with manual confirmation. We identified the reason for readmission and tested for associations between readmission and functional outcomes using modified Rankin Scale (a validated functional outcome measure from 0, no symptoms, to 6, death) scores before intracerebral hemorrhage and at 14 days, 28 days, and 3 months after intracerebral hemorrhage. Setting:Neurologic ICU of a tertiary care hospital. Patients:Critically ill patients with spontaneous intracerebral hemorrhage. Interventions:Patients received standard critical care management for intracerebral hemorrhage. Measurements and Main Results:Of 246 patients (mean age, 65 yr; 51% female), 193 patients (78%) survived to discharge. Of these, 22 patients (11%) were readmitted at a median of 9 days (interquartile range, 4–15 d). The most common readmission diagnoses were infections after discharge (n = 10) and vascular events (n = 6). Age, history of stroke and hypertension, severity of neurologic deficit at admission, Acute Physiology and Chronic Health Evaluation score, ICU and hospital length of stay, ventilator-free days, days febrile, and surgical procedures were not predictors of readmission. History of coronary artery disease was associated with readmission (p = 0.03). Readmitted patients had similar modified Rankin Scale and severity of neurologic deficit at 14 days but higher (worse) modified Rankin Scale scores at 3 months (median [interquartile range], 5 [3–6] vs 3 [1–4]; p = 0.01). Conclusions:Severity of illness and hospital complications were not associated with 30-day readmission. The most common indication for readmission was infection after discharge, and readmission was associated with worse functional outcomes at 3 months. Preventing readmission after intracerebral hemorrhage may depend primarily on optimizing care after discharge and may improve functional outcomes at 3 months.

Education Research: Neurology training reassessed The 2011 American Academy of Neurology Resident Survey results

Objective: To assess the strengths and weaknesses of neurology resident education using survey methodology. Methods: A 27-question survey was sent to all neurology residents completing residency training in the United States in 2011. Results: Of eligible respondents, 49.8% of residents returned the survey. Most residents believed previously instituted duty hour restrictions had a positive impact on resident quality of life without impacting patient care. Most residents rated their faculty and clinical didactics favorably. However, many residents reported suboptimal preparation in basic neuroscience and practice management issues. Most residents (71%) noted that the Residency In-service Training Examination (RITE) assisted in self-study. A minority of residents (14%) reported that the RITE scores were used for reasons other than self-study. The vast majority (86%) of residents will enter fellowship training following residency and were satisfied with the fellowship offers they received. Conclusions: Graduating residents had largely favorable neurology training experiences. Several common deficiencies include education in basic neuroscience and clinical practice management. Importantly, prior changes to duty hours did not negatively affect the resident perception of neurology residency training.