Clinical-diffusion mismatch defined by NIHSS and ASPECTS in non-lacunar anterior circulation infarction

Objectives Instead of the mismatch in MRI between the perfusion-weighted imaging (PWI) lesion and the smaller diffusion-weighted imaging (DWI) lesion (PWI-DWI mismatch), clinical-DWI mismatch (CDM) has been proposed as a new diagnostic marker of brain tissue at risk of infarction in acute ischemic stroke. The Alberta Stroke Program Early CT Score (ASPECTS) has recently been applied to detect early ischemic change of acute ischemic stroke. The present study applies the CDM concept to DWI data and investigated the utility of the CDM defined by the NIH Stroke Scale (NIHSS) and ASPECTS in patients with non-lacunar anterior circulation infarction. Methods Eighty-seven patients with first ever ischemic stroke within 24 hours of onset with symptoms of non-lacunar anterior circulation infarction with the NIHSS score ≥ 8 were enrolled. Initial lesion extent was measured by the ASPECTS on DWI within 24 hours, and initial neurological score was measured by the NIHSS. As NIHSS ≥ 8 has been suggested as a clinical indicator of a large volume of ischemic brain tissue, and the majority of patients with non-lacunar anterior infarction with score of NIHSS < 8 had lesions with ASPECTS ≥ 8 on DWI, so CDM was defined as NIHSS ≥ 8 and DWI-ASPECTS 8 ≥ . We divided patients into matched and mismatched patient groups, and compared them with respect to background characteristics, neurological findings, laboratory data, radiological findings and outcome. Results There were 35 CDM-positive patients (P group, 40.2%) and 52 CDM-negative patients (N group , 59.8%). P group patients had a higher risk of early neurological deterioration (END) than N group patients (37.1% vs 13.5%, p < 0.05), which were always accompanied by lesion growth defined by 2 or more points decrease on ASPECTS (36 to 72 hours after onset on CT). The NIHSS at entry were significantly lower in the P group, but there was no difference in the outcome at three months measured by the modified Rankin Scale. However, CDM was not an independent predictor of END by multiple logistic regression analysis. Conclusions Patients with CDM had high rate of early neurological deterioration and lesion growth. CDM defined as NIHSS ≥ 8 and DWI-ASPECTS ≥ 8 can be another marker for detecting patients with tissue at risk of infarction, but more work is needed to clarify whether this CDM method is useful in acute stroke management. Received in revised form: 30 July 2006     

Pretreatment diffusion- and perfusion-MR lesion volumes have a crucial influence on clinical response to stroke thrombolysis

We hypothesized that pretreatment magnetic resonance imaging (MRI) diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) lesion volumes may have influenced clinical response to thrombolysis in the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET). In 98 patients randomized to intravenous (IV) tissue plasminogen activator (tPA) or placebo 3 to 6 h after stroke onset, we examined increasing acute DWI and PWI lesion volumes (Tmax—with 2-sec delay increments), and increasing PWI/DWI mismatch ratios, on the odds of both excellent (modified Rankin Scale (mRS): 0 to 1) and poor (mRS: 5 to 6) clinical outcome. Patients with very large PWI lesions (most had internal carotid artery occlusion) had increased odds ratio (OR) of poor outcome with IV-tPA (58% versus 25% placebo; OR=4.13, P=0.032 for Tmax +2-sec volume >190 mL). Excellent outcome from tPA treatment was substantially increased in patients with DWI lesions <18 mL (77% versus 18% placebo, OR=15.0, P<0.001). Benefit from tPA was also seen with DWI lesions up to 25 mL (69% versus 29% placebo, OR=5.5, P=0.03), but not for DWI lesions >25 mL. In contrast, increasing mismatch ratios did not influence the odds of excellent outcome with tPA. Clinical responsiveness to IV-tPA, and stroke outcome, depends more on baseline DWI and PWI lesion volumes than the extent of perfusion–diffusion mismatch.     

The Processing Time for Recanalization and Size of Ischemic Lesions on DWI is Related With Complete Reperfusion After Mechanical Thrombectomy

Recent studies demonstrated that modified thrombolysis in cerebral infarction (TICI) 3 reperfusion have better functional outcomes than modified TICI 2b after mechanical thrombectomy in acute ischemic stroke with large vessel occlusion. The purpose of this study was to determine significant factors to forecast the presence of complete reperfusion after mechanical thrombectomy based on multimodal magnetic resonance imaging (MRI). We investigated 96 consecutive patients with acute large intracranial artery occlusion of anterior circulation who based on multimodal MRI. Also, we compared clinical and radiologic parameters between patients with modified TICI 3 and those with modified TICI 0-2b. Among 96 eligible subjects received mechanical thrombectomy, 39 patients (40.6%) showed complete reperfusion and 57 partial or nonreperfusion (mTICI 2b-26, mTICI 2a-9, mTICI 1-8, and mTICI 0-14) after mechanical thrombectomy. Patients with mTICI 3 had significantly smaller initial Diffusion weighted images (DWI) lesion volume (P < .01) and much shorter time interval from onset to reperfusion (P < .01) than those patients with mTICI (0-2b). In multivariate analysis, smaller initial DWI volume (odds ratio [OR], 1.78; 95% confidence interval [CI], 1.23-2.57; P < .01) and faster reperfusion time (OR, 1.07; 95% CI 1.01-1.14; P = .015) had an independence significance for complete reperfusion after mechanical thrombectomy. In this study, the ischemic lesion volume on DWI and faster processing time are critical factor to predict the state of complete reperfusion after mechanical thrombectomy.     

Transient Ischemic Attack: Which Determines Diffusion-Weighted Image Positivity?

Aim of the studyDiffusion-weighted image (DWI) of magnetic resonance imaging (MRI) can reveal high signal lesion in up to 50% of transient ischemic attack (TIA) patients. However, it is not well-known which factors determine developing DWI positivity. In order to answer this question, we analyzed factors relevant to DWI positivity in TIA patients.MethodsWe had 257 stroke patients at a university emergency/neurology wards. They were 140 men, 117 women, mean age 72 (45-88) years. Among them, 24 (9.3%) had TIA (14 men, 10 women, mean age 71 [58-82] years). All patients underwent a 1.5T MRI. In 24 TIA patients, we investigated the following parameters in relation with stroke maturation: ABCD2 score, smoking habits, blood profile, HbA1C, dyslipidemia, coagulation factors, carotid echography, electrocardiography, cardiac echography, chest X-ray, neurological symptom/signs, imaging, and recurrence of neurological symptom on follow-up.ResultsIn 24 TIA patients, 13 (54%) were DWI positive and 11 (46%) were DWI negative. After an extensive analysis, all parameters were not relevant to DWI positivity except for plasma osmolarity, i.e., plasma osmolarity in DWI positive cases (305.3 mOsm/l) is significantly higher than that in DWI negative cases (301.3 mOsm/l) (P = .0064). As for recurrence, 4 of 24 TIA patients recurred. They were 1 (9.0%) of 11 DWI negative cases and 3 (23.1%) of 13 DWI positive cases. Therefore, DWI positive cases recurred more frequently than DWI negative cases did, although it did not reach statistical significance.ConclusionsTIA with DWI positivity in our institute was 54%, closely associated with initial dehydration and might predict stroke recurrence.     

Combined diffusion and perfusion MRI with correlation to single-photon emission CT in acute ischemic stroke. Ischemic penumbra predicts infarct growth.

BACKGROUND AND PURPOSE: More effective imaging methods are needed to overcome the limitations of CT in the investigation of treatments for acute ischemic stroke. Diffusion-weighted MRI (DWI) is sensitive in detecting infarcted brain tissue, whereas perfusion-weighted MRI (PWI) can detect brain perfusion in the same imaging session. Combining these methods may help in identifying the ischemic penumbra, which is an important concept in the hemodynamics of acute stroke. The purpose of this study was to determine whether combined DWI and PWI in acute (<24 hours) ischemic stroke can predict infarct growth and final size. METHODS: Forty-six patients with acute ischemic stroke underwent DWI and PWI on days 1, 2, and 8. No patient received thrombolysis. Twenty-three patients underwent single-photon emission CT in the acute phase. Lesion volumes were measured from DWI, SPECT, and maps of relative cerebral blood flow calculated from PWI. RESULTS: The mean volume of infarcted tissue detected by DWI increased from 46.1 to 75.6 cm(3) between days 1 and 2 (P<0.001; n=46) and to 78.5 cm(3) after 1 week (P<0.001; n=42). The perfusion-diffusion mismatch correlated with infarct growth (r=0. 699, P<0.001). The volume of hypoperfusion on the initial PWI correlated with final infarct size (r=0.827, P<0.001). The hypoperfusion volumes detected by PWI and SPECT correlated significantly (r=0.824, P<0.001). CONCLUSIONS: Combined DWI and PWI can predict infarct enlargement in acute stroke. PWI can detect hypoperfused brain tissue in good agreement with SPECT in acute stroke.     

Patients with Diffusion-Perfusion Mismatch on Magnetic Resonance Imaging 48 Hours or More After Stroke Symptom Onset: Clinical and Imaging Features

BACKGROUND: Abnormalities in diffusion-weighted (DWI) and perfusion-weighted (PWI) magnetic resonance imaging (MRI) are thought to reflect the presence of brain tissue at risk for ischemic stroke. Many patients with acute ischemic stroke have a mismatch pattern in which the PWI volume is larger than the DWI lesion. This mismatch typically resolves over 24-48 hours. Little is known about the presence of DWI-PWI mismatch in later stages of stroke. METHODS: This is a retrospective study of 122 patients admitted with a diagnosis of acute ischemic stroke who had DWI and PWI abnormalities on studies performed within 7 days of onset of symptoms. Patients were divided into two groups: those with MRI performed <48 hours and those with MRI performed >or=48 hours from onset of symptoms. RESULTS: Among 42 patients with MRI performed >or=48 hours after onset of stroke symptoms, 15 of 42 (36%) showed a mismatch pattern, compared to 45 of 80 (56%) in the <48 hours group (P < 0.05). Most of the patients in the >or=48 hours group with mismatch had large artery occlusive disease and many had neurological fluctuations. A subset of these patients were treated with induced hypertension and showed clinical improvement. CONCLUSIONS: Some patients have persistent DWI-PWI mismatch up to several days after stroke onset. Further studies are needed to determine if these patients should be candidates for reperfusion therapy.     

An MRI Hyperintense Acute Reperfusion Marker Is Related to Elevated Peripheral Monocyte Count in Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Blood–brain barrier (BBB) disruption detected on magnetic resonance imaging (MRI) in acute ischemic stroke as a hyperintense acute reperfusion marker (HARM) is associated with upregulation of matrix metalloproteinase‐9 (MMP‐9). Although activated leukocytes, including monocytes, are the main source of MMPs, limited data exist to support relationship between leukocyte activation and BBB disruption in patients with acute ischemic stroke. The goal of this study is to investigate the relationship between neutrophils, lymphocytes, and monocytes with BBB disruption detected as HARM (+) in patients with acute ischemic stroke.

METHODS

We conducted a retrospective analysis of prospectively collected data in patients who did not receive any reperfusion therapy with acute (<12 hours) ischemic stroke. MRI scans were obtained at baseline, 24 hours, and 5 days. HARM was evaluated on the 24‐hour follow‐up scan.

RESULTS

Thirty‐three patients were studied. HARM was detected in 27% of patients. Median volumes of baseline perfusion (mean transit time [MTT]) deficit (219.4 mL vs. 158.4 mL, P = .029) and DWI infarct growth at 24 hours (18.50 mL vs. .14 mL, P = .017), as well as the median absolute numbers (1 × 10³/mm³) of monocytes, were significantly higher in HARM (+) versus HARM (?) patients (0.9 vs. 0.6, p = 0.011).

CONCLUSION

Increased monocyte count associated with HARM supports importance of systemic inflammation in BBB disruption in acute ischemic stroke.     

Association between the perfusion/diffusion and diffusion/FLAIR mismatch: data from the AXIS2 trial

The perfusion-/diffusion-weighted imaging (PWI/DWI) mismatch and the diffusion/fluid attenuated inversion recovery (DWI/FLAIR) mismatch are magnetic resonance imaging (MRI) markers of evolving brain ischemia. We examined whether the DWI/FLAIR mismatch was independently associated with the PWI/DWI mismatch. Furthermore, we determined whether the presence of the DWI/FLAIR mismatch in patients with the PWI/DWI mismatch would provide additional information regarding last seen normal time (LTM). We used data from the ‘AX200 for ischemic stroke'' trial (AXIS 2 study {"type":"clinical-trial","attrs":{"text":"NCT00927836","term_id":"NCT00927836"}}NCT00927836). We studied the association between the presence of the DWI/FLAIR and PWI/DWI mismatch, baseline National Institute of Health Stroke Scale (NIHSS), age, ischemic-core volume, gender, intravenous (IV) tissue plasminogen activator (tPA), and perfusion-mismatch volume in univariate analysis. Significant variables (P<0.05) were added into the final multivariate model. We analyzed 197 patients. Seventy-two (37%) had both the PWI/DWI and the DWI/FLAIR mismatch. Patients with the double mismatch pattern had a shorter LTM than patients with the PWI/DWI mismatch alone (Median difference 90 minutes, P<0.01). Multivariate analysis confirmed the independent association between the two mismatch patterns (odds ratio (OR) 2.6, 95% confidence interval (CI) 1.2 to 5.4). Our study implies that the DWI/FLAIR mismatch and PWI/DWI mismatch are strongly associated, independent from LTM. Furthermore, in the presence of the PWI/DWI mismatch, the DWI/FLAIR pattern indicates a shorter LTM. This could have implications in selecting patients for reperfusion therapy.     

Stroke Volume Predicts Nocturnal Hypoxemia in the Acute Ischemic Stroke after Intravenous Thrombolysis

The Goal: The aim of the study was to investigate whether stroke volume or the presence of ischemic stroke lesion on follow-up computed tomography 1 day after admission had association with sleep apnea among ischemic stroke patients undergoing thrombolysis. Materials and Methods: We prospectively recruited 110 consecutive ischemic stroke patients and performed computed tomography on admission and after 24 hours after intravenous thrombolysis. Stroke volume was measured from post-thrombolysis computed tomography scans. Unattended cardiorespiratory polygraphy with a 3-channel device was performed during 48 hours after admission. Findings: Of 110 ischemic stroke patients treated with thrombolysis 65.5% were men. Mean age was 65.8 years and body mass index 27.5 kg/m². The mean Epworth sleepiness scale score was 4.7. Eight patients (12.7%) with visible acute stroke after thrombolysis and none in the other group had hemorrhage as complication (P ? .001). Sleep apnea, determined as a respiratory event index greater than or equal to 5/hour, was diagnosed in 96.4% patients. Respiratory event index greater than 15/h was found in 72.8% of patients. Both mean baseline oxygen desaturation index (23.9 versus 16.5, P = .028) and obstructive apneas/hour (6.2 versus 2.7, P = .007) were higher in visible stroke group. Stroke volume (mean 15.9 mL) correlated with proportion of time spent below saturation less than 90%, P = .025. Conclusions: Acute ischemic stroke patients treated with thrombolysis with visible stroke were more likely to have nocturnal hypoxemia than patients with not visible strokes. Stroke volume correlated with time spent below saturation of 90%.     

Diffusion- and perfusion-weighted MRI: influence of severe carotid artery stenosis on the DWI/PWI mismatch in acute stroke

BACKGROUND AND PURPOSE: Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) have been used increasingly in recent years to evaluate acute stroke in the emergency setting. In the present study, we compared DWI and PWI findings in acute stroke patients with and without severe extracranial internal carotid artery (ICA) disease. METHODS: Twenty-seven patients with nonlacunar ischemic stroke were selected for this analysis. DWI, PWI, and conventional MRI were performed in all patients within 24 hours of symptom onset and after 1 week. To exclude patients with partial or complete reperfusion, we included only patients with a PWI deficit larger than the DWI lesion. Severe ICA disease (>70% stenosis) was present unilaterally in 9 and bilaterally in 2 patients. Acute DWI lesion volume, the size of the acute PWI/DWI mismatch, and final infarct size (on T2-weighted images) were determined. RESULTS: The PWI/DWI mismatch was significantly larger in patients with severe ICA disease than in patients without extracranial carotid stenosis, both when time-to-peak and mean transit time maps (P<0.01) were used to calculate the mismatch. Quantitative analysis of the time-to-peak delay in the mismatch indicated that a relatively smaller fraction of the total mismatch was critically ischemic in patients with carotid stenosis than in those without. Average lesion volume increased less in the stenosis group (P=0.14), despite the larger PWI/DWI mismatch, and final infarct size was smaller in the stenosis group (P<0.05). In the 2 patients with bilateral ICA disease, variable hemodynamic involvement of the contralateral hemisphere was found in addition to the ipsilateral PWI deficit. CONCLUSIONS: In most acute stroke patients with severe ICA stenosis, a considerably smaller fraction of the total PWI/DWI mismatch is at risk than in patients without carotid disease.     

Heparin during endovascular stroke treatment seems safe

Background and purposethe effect of intravenous heparin during mechanical thrombectomy for acute ischemic stroke is not clear. We aimed to study efficacy and safety of heparin use during endovascular stroke treatment in a real-world setting.Materials and methodspatients with anterior circulation stroke were divided, based on the use of intraprocedural heparin, in those treated and those untreated. Main outcomes were successful reperfusion defined as a TICI Score ≥ 2b, 3-month functional independence defined as a modified Rankin Scale ≤ 2, symptomatic intracranial hemorrhage (sICH) and mortality.Results361 patients were eligible for analysis; 200 were (H+) and 161 (H-). The (H-) group showed higher age and ASPECTS (74 ± 14 vs. 68.9 ± 12.2; P = 0.001; 8 ± 1.6 vs. 7.4 ± 2.1; P = 0.009) without differences in vascular risk factors. Heparin untreated patients showed a shorter onset-to-reperfusion time (271 ± 57.6 min vs. 309 ± 102.2 min; P < 0.001). No differences were found in 3-month functional independence, sICH and mortality whereas the rate of successful reperfusion was higher in the (H-) group. After logistic regression analysis successful reperfusion was independently associated with CT ASPECTS (OR: 1.16; 95%CI 1.01–1.35; P = 0.040) but inversely associated with the use of heparin (OR: 0.48; 95% CI 0.24–0.98; P = 0.045).ConclusionsHeparin use during mechanical thrombectomy for anterior circulation acute ischemic stroke in a real world setting is safe.     

表观弥散系数对确定急性缺血性卒中缺血半暗带的潜在价值

目的 探讨表观弥散系数（apparent diffusion coefficient,ADC）对确定急性缺血性卒中缺血半暗带的潜在价值。 方法 选择发病9 h内完成多模式磁共振成像（magnetic resonance imaging,MRI）检查的前循环急性缺血性卒中患者49例。应用自制软件进行灌注加权像（perfusion-weighted imaging,PWI）和弥散加权像（diffusion-weighted imaging,DWI）异常区域的体积测量。缺血半暗带以PWI/DWI错配表示。同时采用全自动图像分析系统,以DWI图像计算得到的ADC图作为输入数据,来判断缺血半暗带的存在（以下简称为ADC方法）,然后比较这两种方法在判断缺血半暗带方面的差异。 结果 入选的49例患者中,存在PWI/DWI错配者为43例,符合ADC方法判断缺血半暗带标准者有41例。这两种方法在判断是否存在缺血半暗带的结果中有41例相符,对判断缺血半暗带的差异无统计学意义（P>0.05）。ADC方法判断缺血半暗带的敏感度为88.4%、特异度为50.0%。 结论 由于不需做PWI检查,ADC方法对确定缺血半暗带具有潜在的临床实用价值,有可能成为一种简便易行的确定缺血半暗带的方法。     

Migraine History: A Predictor of Negative Diffusion-Weighted Imaging in IV-tPA-Treated Stroke Mimics

Background: Migraine, seizures, and psychiatric disorders are frequently reported as “stroke mimics” in patients with negative diffusion-weighted imaging (DWI) after IV-tPA. We sought to determine predictors of negative DWI in suspected stroke patients treated with IV-tPA. Method: A retrospective case-control study encompassing all acute stroke patients treated with IV-tPA (at our hospital or “dripped and shipped”) from January 2013 to December 2014 was con- ducted. A total of 275 patients were identified with 47 negative DWI cases and 228 positive DWI controls. Variables including demographic factors, stroke characteristics, and clinical comorbidities were analyzed for statistical significance. A multivariate logistic regression was performed (SPSS-24) to identify predictors of negative DWI. Results: Approximately 17% of patients had negative DWI after IV-tPA. Compared to controls, migraine history independently predicted negative DWI (odds ratio [OR] 5.0 95% confidence interval [CI] 1.03-24.6, P = .046). Increasing age (OR .97 95% CI .94-.99, P = .02) and atrial fibrillation (OR .25 95% CI .08-.77, P = .01) predicted lower probability of negative DWI. Gender, admission NIHSS, treatment location, preadmission modified Rankin scale, diabetes mellitus, hypertension, hyperlipidemia, symptom side, seizure history, and psychiatric history did not predict negative DWI status. Conclusions: In our study, roughly 1 in 6 patients treated with IV-tPA were later found to be stroke mimics with negative DWI. Despite a high proportion of suspected stroke mimics in our study, only preexisting migraine history independently predicted negative DWI status after IV-tPA treatment in suspected stroke patients.     

Should IV Thrombolysis be given in Patients with Suspected Ischemic Stroke but Unknown Symptom Onset and Without Diffusion-Weighted Imaging Lesion? – Results of a Case-Control Study

BackgroundMany acute ischemic stroke (AIS) patients present with unknown time of symptom onset (UTO). In these situations, wake-up MRI protocols can guide treatment decisions: patients with DWI (diffusion-weighted imaging) but no fluid-attenuated inversion recovery lesion were shown to benefit from IVT (intravenous thrombolysis). However, initial MRI of some stroke patients is DWI negative, leaving it unclear whether this subgroup profits from IVT. Therefore, we aimed to compare the safety and efficacy of IVT in wake-up AIS patients with or without a DWI lesion in initial imaging.MethodsWe performed a case-control study. All AIS patients with UTO who underwent wake-up MRI and were treated with IVT at a German University Hospital from 2013 to 2017 were included. Patients without (DWI-) were compared to patients with DWI lesion (DWI+) regarding clinico-radiological characteristics, adverse events, and outcome at discharge. Likely stroke mimics were excluded.ResultsEleven DWI- and 32 DWI+ patients were included. There were no statistically significant differences regarding functional scores, age, sex, door-to-needle time, bleeding complications, and death. DWI+ patients more frequently had anterior circulation stroke (P = .049) and higher modified Rankin Scale (mRS) scores at discharge (P = .048). Solely in the DWI+ group 3 bleeding complications (2 asymptomatic hemorrhagic transformations, 1 muscle hematoma) and 3 deaths occurred (P = .29). A favourable outcome (mRS≤ 2) was achieved in 82% of the DWI- and in 58% of the DWI+ group (p > .05).ConclusionsOur data suggest that IVT may be used in DWI- patients with UTO with acute neurological symptoms very likely to be related to AIS.     

Impact of genetic and renovascular chronic arterial hypertension on the acute spatiotemporal evolution of the ischemic penumbra: a sequential study with MRI in the rat

Although chronic arterial hypertension (CAH) increases the risk of stroke and the severity of the resultant lesion, it is rarely integrated in preclinical studies. Here, we analyzed the impact of CAH on the acute spatiotemporal evolution of the ischemic penumbra as defined by the perfusion-weighted imaging/diffusion-weighted imaging mismatch. Sequential 7T-MRI examinations were performed from 30 minutes up to 4 hours after permanent cerebral ischemia in genetically hypertensive rats (spontaneously hypertensive rats, SHR), renovascular-hypertensive rats (RH-WKY), and their normotensive controls (Wistar-Kyoto rats, WKY). The apparent diffusion coefficient (ADC)-defined lesion was larger in hypertensive rats than in normotensive animals as early as 30 minutes after the ischemia. The ischemic penumbra was smaller in both genetically and renovascular-hypertensive rats (at 30 minutes; SHR=66±25 mm³, RH-WKY=55±17 mm³ versus WKY=117±14 mm³; P<0.008) and there was no significant difference between the perfusion deficit and ADC lesion (mismatch definition of penumbra) as early as 90 minutes after the occlusion. Genetic hypertension and induced renovascular hypertension resulted in larger lesion and smaller penumbra that vanished rapidly. These data support the need to integrate CAH in preclinical studies relative to the treatment of stroke, as failure to do so may lead to preclinical results nonpredictive of clinical trials, which include hypertensive patients.     

Electroencephalography Measures are Useful for Identifying Large Acute Ischemic Stroke in the Emergency Department

Background: Early diagnosis of stroke optimizes reperfusion therapies, but behavioral measures have incomplete accuracy. Electroencephalogram (EEG) has high sensitivity for immediately detecting brain ischemia. This pilot study aimed to evaluate feasibility and utility of EEG for identifying patients with a large acute ischemic stroke during Emergency Department (ED) evaluation, as these data might be useful in the prehospital setting. Methods: A 3-minute resting EEG was recorded using a dense-array (256-lead) system in patients with suspected acute stroke arriving at the ED of a US Comprehensive Stroke Center. Results: An EEG was recorded in 24 subjects, 14 with acute cerebral ischemia (including 5 with large acute ischemic stroke) and 10 without acute cerebral ischemia. Median time from stroke onset to EEG was 6.6 hours; and from ED arrival to EEG, 1.9 hours. Delta band power (P = .004) and the alpha/delta frequency band ratio (P = .0006) each significantly distinguished patients with large acute ischemic stroke (n = 5) from all other patients with suspected stroke (n = 19), with the best diagnostic utility coming from contralesional hemisphere signals. Larger infarct volume correlated with higher EEG power in the alpha/delta frequency band ratio within both the ipsilesional (r = ?0.64, P = .013) and the contralesional (r = ?0.78, P = .001) hemispheres. Conclusions: Within hours of stroke onset, EEG measures (1) identify patients with large acute ischemic stroke and (2) correlate with infarct volume. These results suggest that EEG measures of brain function may be useful to improve diagnosis of large acute ischemic stroke in the ED, findings that might be useful to pre-hospital applications.     

Clinical and radiological correlates of reduced cerebral blood flow measured using magnetic resonance imaging

BACKGROUND: Methods for determining cerebral blood flow (CBF) using bolus-tracking magnetic resonance imaging (MRI) have recently become available. Reduced apparent diffusion coefficient (ADC) values of brain tissue are associated with reductions in regional CBF in animal stroke models. OBJECTIVES: To determine the clinical and radiological features of patients with severe reductions in CBF on MRI and to analyze the relationship between reduced CBF and ADCs in acute ischemic stroke. DESIGN: Case series. SETTING: Referral center. METHODS: We studied 17 patients with nonlacunar acute ischemic stroke in whom perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) were performed within 7 hours of symptom onset. A PWI-DWI mismatch of more than 20% was required. We compared patients with ischemic lesions that had CBF of less than 50% relative to the contralateral hemisphere with patients with lesions that had relative CBF greater than 50%. Characteristics analyzed included age, time to MRI, baseline National Institutes of Health Stroke Scale score, mean ADC, DWI and PWI lesion volumes, and 1-month Barthel Index score. RESULTS: Patients with low CBF (n = 5) had lower ADC values (median, 430 x 10 (-6) mm(2)/s vs. 506 x 10 (-6) mm(2)/s; P =.04), larger DWI volumes (median, 41.8 cm(3) vs. 14.5 cm(3); P =.001) and larger PWI lesions as defined by the mean transit time volume (median, 194.6 cm(3) vs. 69.3 cm(3); P =.01), and more severe baseline National Institutes of Health Stroke Scale scores (median, 15 vs. 9; P =.02). CONCLUSION: Ischemic lesions with severe CBF reductions, measured using bolus-tracking MRI, are associated with lower mean ADCs, larger DWI and PWI volumes, and higher National Institutes of Health Stroke Scale scores.     

Stroke magnetic resonance imaging within 6 hours after onset of hyperacute cerebral ischemia

We studied the diagnostic and prognostic value of diffusion- and perfusion-weighted magnetic resonancce imaging (DWI and PWI) for the initial evaluation and follow-up monitoring of patients with stroke that had ensued less than 6 hours previously. Further, we examined the role of vessel patency or occlusion and subsequent recanalization or persistent occlusion for further clinical and morphological stroke progression so as to define categories of patients and facilitate treatment decisions. Fifty-one patients underwent stroke magnetic resonance imaging (DWI, PWI, magnetic resonance angiography, and T2-weighted imaging) within 3.3 +/- 1.29 hours, and, of those, 41 underwent follow-up magnetic resonance imaging on day 2 and 28 on day 5. In addition, we assessed clinical scores (on the National Institutes of Health Stroke Scale, Scandinavian Stroke Scale, Barthel Index, and Modified Rankin Scale) on days 1, 2, 5, 30, and 90 and performed volumetric analysis of lesion volumes. In all, 25 patients had a proximal, 18 a distal, and 8 no vessel occlusion. Furthermore, 15 of 43 patients exhibited recanalization on day 2. Vessel occlusion was associated with a PWI-DWI mismatch on the initial magnetic resonance imaging, vessel patency with a PWI-DWI match (p < 0.0001). Outcome scores and lesion volumes differed significantly between patients experiencing recanalization and those who did not (all p < 0.0001). Acute DWI and PWI lesion volumes correlated poorly with acute clinical scores and only modestly with outcome scores. We have concluded on the basis of this study that early recanalization saves tissue at risk of ischemic infarction and results in significantly smaller infarcts and a significantly better clinical outcome. Patients with proximal vessel occlusions have a larger amount of tissue at risk, a lower recanalization rate, and a worse outcome. Urgent recanalization seems to be of utmost importance for these patients.     

Leukoaraiosis Predicts Short-term Cognitive But not Motor Recovery in Ischemic Stroke Patients During Rehabilitation

Background: Leukoaraiosis has been shown to impact functional outcomes after acute ischemic stroke. However, its association with domain specific recovery after ischemic stroke is uncertain. We sought to determine whether pre-existing leukoaraiosis is associated with short-term motor and cognitive recovery after stroke. Methods: We retrospectively studied ischemic stroke patients admitted to acute inpatient rehabilitation (AIR) between January 2013 and September 2015. Patient baseline characteristics, infarct volume, prestroke modified Rankin Scale, stroke cause, rehabilitation length of stay, and Functional Independence Measure (FIM) scores were recorded. Leukoaraiosis severity was graded on brain magnetic resonance imaging using the Fazekas scale. Multiple linear regression was used to determine factors independently associated with the total, cognitive, and motor FIM scores at AIR discharge, respectively. Results: Of 1600 ischemic stroke patients screened, 109 patients were included in the final analysis. After adjustment, the initial National Institute of Health Stroke Scale (β ?0.541, confidence interval [CI] ?0.993 to ?0.888; P = 0.020) and pre-existing leukoaraiosis severity (β ?1.448, CI ?2.861 to ?0.034; P = 0.045) independently predicted the total FIM score. Domain specific analysis showed that infarct volume (β ?0.012, CI ?0.019 to ?0.005; P = 0.002) and leukoaraiosis severity (β ?0.822, CI ?1.223 to ?0.410; P = 0.0001) independently predicted FIM cognitive scores at discharge from AIR. Leukoaraiosis did not predict FIM motor score (P = 0.17). Conclusions: Leukoaraiosis severity is an independent predictor of total and cognitive, but not motor FIM scores after AIR for acute ischemic stroke. This highlights that leukoaraiosis affects poststroke recovery in a domain specific fashion, information that may aid counseling of patients and families as well as tailor rehabilitative efforts.     

Nephrotic Syndrome is Associated with Increased Risk of Ischemic Stroke

Background: To determine if the nephrotic syndrome (NS) is an independent risk factor of ischemic stroke. Methods: This is a retrospective nationwide cohort study through an analysis of the National Health Insurance Research Database in Taiwan. To evaluate the risk of stroke, the corresponding controls were selected at a 4:1 ratio in the number of subjects, and they were matched with the study group in age, gender, Charlson comorbidity index (CCI), and index date. Results: From a total of 16,245 surveyed subjects, ischemic stroke occurred in 1235 (7.6%) and hemorrhagic stroke in 129 (.74%) of them. The incidence of ischemic stroke was significantly higher in patients with NS (n = 3496) compared to control patients without NS (n = 13,984) (9.92 versus 7.10, per 1000 person-year, P < .001). In the multivariate analysis, the overall adjusted hazard ratio (aHR) of stroke in NS patients was 1.37 (95% CI, 1.21-1.54, P < .001). The risk factors of ischemic stroke were NS (aHR, 1.38 [95% confidence interval {CI}, 1.21-1.57]; P < .001), age greater than 45 years (aHR, 7.98 [95% CI, 6.47-9.48]; P < .001), male gender (aHR, 1.23 [95% CI, 1.10-1.38]; P < .001), CCI greater than or equal to 1 (aHR ≥ 1.25 in different CCI score groups, all at P ≤ .003), ischemic heart disease (aHR, 1.95 [95% CI, 1.67-2.29]; P < .001), heart failure (HR, 1.77 [95% CI, 1.30-2.42]; P < .001). Risk factors of hemorrhagic stroke were those aged greater than 45 years, or with systemic lupus erythematosus, but not NS. Conclusions: We provided the first evidence that patients with NS had an increased risk of ischemic stroke.