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Biomedical subjects

Imanuel Dzialowski

Publications and source records attributed to Imanuel Dzialowski.

7 recordsLinked to original sources
PubMed2006

Asymptomatic hemorrhage after thrombolysis may not be benign: prognosis by hemorrhage type in the Canadian alteplase for stroke effectiveness study registry.

BACKGROUND AND PURPOSE: There is ongoing controversy about the impact of hemorrhagic transformation after thrombolysis on long-term functional outcome. We sought to study the relation between the type of hemorrhagic transformation on CT scans and functional outcome. METHODS: Data were obtained from the Canadian Alteplase for Stroke Effectiveness Study. This study was established as a registry to prospectively collect data for acute stroke patients receiving intravenous alteplase within 3 hours from stroke onset between February 1999 and June 2001. Follow-up was completed at 90 days, and good functional outcome was defined as a modified Rankin Scale score of 0 or 1. Copies of head CT scans obtained at 24 to 48 hours after starting treatment were read in consensus by a central reading panel consisting of 1 neuroradiologist and 1 stroke neurologist. According to European Cooperative Acute Stroke Study criteria, hemorrhagic transformation was classified as none, hemorrhagic infarction (HI-1 and HI-2), or parenchymal hematoma (PH-1 and PH-2). We compared outcome across groups and performed a multivariable analysis including previously determined important predictors of good outcome in acute ischemic stroke. RESULTS: From 1135 patients enrolled at 60 centers across Canada, 954 follow-up CT scans were assessable. We observed some hemorrhagic transformation in 259 of 954 (27.1%) patients (110 HI-1, 57 HI-2, 48 PH-1, and 44 PH-2). Proportions of patients with good outcome were 41% with no hemorrhagic transformation, 30% with HI-1, 17% with HI-2, 15% with PH-1, and 7% with PH-2 (P<0.0001, chi(2) test). After adjustment for age, baseline serum glucose, baseline Alberta Stroke Program Early CT score, and baseline National Institutes of Health Stroke Scale score, HI-1 was not a predictor of outcome. However, HI-2 (odds ratio=0.38, 95% CI=0.17 to 0.83), PH-1 (odds ratio=0.32, 95% CI=0.12 to 0.80), and PH-2 (odds ratio=0.14, 95% CI=0.04 to 0.48) were all negative predictors of outcome. CONCLUSIONS: The likelihood of a poor outcome after thrombolysis was proportional to the extent of hemorrhage on CT scans. HI grades of hemorrhagic transformation may not be benign.

Adult↗
PubMed2006

Extent of early ischemic changes on computed tomography (CT) before thrombolysis: prognostic value of the Alberta Stroke Program Early CT Score in ECASS II.

BACKGROUND AND PURPOSE: The significance of early ischemic changes (EICs) on computed tomography (CT) to triage patients for thrombolysis has been controversial. The Alberta Stroke Program Early CT Score (ASPECTS) semiquantitatively assesses EICs within the middle cerebral artery territory using a10-point grading system. We hypothesized that dichotomized ASPECTS predicts response to intravenous thrombolysis and incidence of secondary hemorrhage within 6 hours of stroke onset. METHODS: Data from the European-Australian Acute Stroke Study (ECASS) II study were used in which 800 patients were randomized to recombinant tissue plasminogen activator (rt-PA) or placebo within 6 hours of symptom onset. We retrospectively assessed all baseline CT scans, dichotomized ASPECTS at < or =7 and >7, defined favorable outcome as modified Rankin Scale score 0 to 2 after 90 days, and secondary hemorrhage as parenchymal hematoma 1 (PH1) or PH2. We performed a multivariable logistic regression analysis and assessed for an interaction between rt-PA treatment and baseline ASPECTS score. RESULTS: We scored ASPECTS >7 in 557 and < or =7 in 231 patients. There was no treatment-by-ASPECTS interaction with dichotomized ASPECTS (P=0.3). This also applied for the 0- to 3-hour and 3- to 6-hour cohorts. However, a treatment-by-ASPECTS effect modification was seen in predicting PH (0.043 for the interaction term), indicating a much higher likelihood of thrombolytic-related parenchymal hemorrhage in those with ASPECTS < or =7. CONCLUSIONS: In ECASS II, the effect of rt-PA on functional outcome is not influenced by baseline ASPECTS. Patients with low ASPECTS have a substantially increased risk of thrombolytic-related PH.

Aged↗
PubMed2006

Role of CT angiography in thrombolysis decision-making for patients with presumed seizure at stroke onset.

BACKGROUND AND PURPOSE: The presence of seizure at stroke onset is a contraindication for intravenous tissue plasminogen activator treatment. A significant proportion of these patients' deficits are not attributable to Todd's paralysis and could be attributable to reversible ischemia. Currently there are no established methods of differentiating Todd's paralysis from ischemic stroke/early seizure. We sought to determine whether computed tomographic angiography (CTA) can be helpful in differentiating the 2. METHODS: Three hundred and twenty six patients underwent noncontrast CT and CTA for acute stroke at our institution over 3 years (June 2002 to April 2005). Of them, 116 had disabling deficits and presented within 3 hours. We reviewed the clinical data, noncontrast CT, CTA, electroencephalogram and outcome of these patients and identified those who presented with presumed seizure activity at stroke onset (seizure or altered consciousness at stroke onset). RESULTS: Nine (7.7%) patients had a concern of seizure at stroke onset. Median age 73 years (range, 31 to 85 years), median National Institutes of Health Stroke Scale (NIHSS) score 12 (range, 5 to 29). CTA showed proximal middle cerebral artery occlusion in 2 and distal middle cerebral artery occlusion in 3 patients. All 5 of these patients had evidence of infarction on follow-up (stroke+early seizure group-intracranial occlusion present). Three of these patients received intravenous tissue plasminogen activator because they were deemed to have "ischemic tissue at risk". Four patients had normal CT and CTA studies and recovered completely in 24 hours (Todd's paralysis only group-intracranial occlusion negative). CONCLUSIONS: Seizure at stroke onset was relatively uncommon in a consecutive cohort of acute stroke patients. CTA was a useful modality in differentiating Todd's paralysis from early seizure and ischemia by detection of intracranial occlusion and may contribute to decision-making for thrombolysis.

Adult↗
PubMed2005

"Clinical-CT mismatch" and the response to systemic thrombolytic therapy in acute ischemic stroke.

BACKGROUND AND PURPOSE: Mismatch between clinical deficits and imaging lesions in acute stroke has been proposed as a method of identifying patients who have hypoperfused but still have viable brain, and may be especially apt to respond to reperfusion therapy. We explored this hypothesis using a combined database including 4 major clinical trials of intravenous (IV) thrombolytic therapy. METHODS: To determine what the radiological correlates of a "matched" functional deficit are, we calculated the relationship between the ASPECT score of the 24-hour (follow-up) CT scan and the 24-hour National Institutes of Health Stroke Scale (NIHSS) score on the subsample with ASPECT scores performed at this time (n=820). Based on this empirical relationship, we computed the absolute difference between the observed baseline ASPECT score and the "expected" score (ie, matched) based on baseline NIHSS for all patients (n=2131). We tested whether patients with better than expected baseline ASPECTS were more likely to benefit from IV recombinant tissue plasminogen activation (rtPA). RESULTS: At 24 hours, there was a strong, linear, negative correlation between NIHSS and ASPECTS (r2=0.33, P<0.0001); on average, an increase of 10 points on NIHSS corresponded to a decrease of approximately 3 points on ASPECTS. At baseline, the average degree of mismatch between the observed and "expected" ASPECTS was 2.1 points (interquartile range, 1.0 to 3.4). However, multiple analyses failed to reveal a consistent relationship between the degree of clinical-CT mismatch at baseline and a patient's likelihood of benefiting from IV rtPA. CONCLUSIONS: Clinical-CT mismatch using ASPECT scoring does not reliably identify patients more or less likely to benefit from IV rtPA.

Brain↗
PubMed2004

Brain tissue water uptake after middle cerebral artery occlusion assessed with CT.

BACKGROUND AND PURPOSE: To study whether computed tomography (CT) can measure the water content of early ischemic edema. METHODS: The authors obtained cranial CT in 5 groups of rats subjected to 1 hour (n = 8), 2 hours (n = 11), 3 hours (n = 13), 4 hours (n = 13), or 6 hours (n = 14) of right middle cerebral artery (MCA) occlusion. Immediately after CT, the authors removed the rats' brains and determined tissue water content by the dry-wet weight method. They correlated brain x-ray attenuation with brain tissue water content. RESULTS: Mean brain tissue water content remained constant in the nonischemic left hemispheres at 77.9% +/- 0.6% and increased up to 79.3% +/- 1.0% in the right hemispheres after 6 hours of permanent right MCA occlusion. X-ray attenuation remained constant in the left hemispheres at 75.6 + 2.2 Hounsfield units (HU) and decreased to 71.7 +/- 3.4 HU in the right hemispheres after 6 hours of right MCA occlusion. The decrease in x-ray attenuation correlated significantly with the increase in ischemic brain tissue water content (y = 217.3 - 1.8x x; r = .55, P < .0001). That means that a 1% increase in hemispheric tissue water content causes a decrease in x-ray attenuation of 1.8 HU. CONCLUSIONS: After MCA occlusion, immediate brain tissue net water uptake is associated with a decrease in x-ray attenuation. CT can monitor ischemic edema in an acute stroke.

Animals↗