PubMed Health⌕ Search

Biomedical subjects

A M Demchuk

Publications and source records attributed to A M Demchuk.

At least 37 records · Page 2Linked to original sources
PubMed2001

Predictors of fatal brain edema in massive hemispheric ischemic stroke.

BACKGROUND AND PURPOSE: Early identification of stroke patients at risk for fatal brain edema may be useful in selecting patients for aggressive interventions. Prior studies suggested that early nausea/vomiting and major hypodensity on baseline computed tomography (CT) were predictive of herniation. METHODS: This study was a retrospective multicenter case-control study of patients with large middle cerebral artery (MCA) strokes admitted within 48 hours of symptom onset. Medical records, laboratory data, and CT scans were analyzed. Cases, defined as patients who died of massive brain swelling, were compared with all remaining patients as controls. RESULTS: Two hundred one patients with large MCA strokes were identified: 94 (47%) died of brain swelling, 12 (6%) died of non-neurological causes, and 95 (47%) survived at day 30. Multivariable analysis, adjusted for age and clustered by center, identified the following predictors of fatal brain edema: history of hypertension (OR 3.0, 95% CI 1.2 to 7.6, P=0.02), history of heart failure (OR 2.1, 95% CI 1.5 to 3.0, P<0.001), elevated white blood cell count (OR 1.08 per 1000 white blood cells/microL, 95% CI 1.01 to 1.14, P=0.02), >50% MCA hypodensity (OR 6.3, 95% CI 3.5 to 11.6, P<0.001), and involvement of additional vascular territories (anterior cerebral artery, posterior cerebral artery, or anterior choroidal artery; OR 3.3, 95% CI 1.2 to 9.4, P=0.02). Initial level of consciousness, National Institutes of Health Stroke Scale score, early nausea/vomiting, and serum glucose were associated with neurological death in bivariable but not multivariable analyses. CONCLUSIONS: Among patients with large MCA infarctions, an increased risk of fatal brain edema is associated with history of hypertension or heart failure, increased baseline white blood cell count, major early CT hypodensity involving >50% of the MCA territory, and involvement of additional vascular territories. These data confirm and expand on prior research with a broad-based patient population. The presence of these risk factors identifies those stroke patients who may require aggressive therapeutic approaches.

Acute Disease↗
PubMed2001

Use of the Alberta Stroke Program Early CT Score (ASPECTS) for assessing CT scans in patients with acute stroke.

BACKGROUND AND PURPOSE: Clinicians are insecure reading CT scans by using the one-third rule for acute middle cerebral artery stroke (1/3 MCA rule) before treating patients with recombinant tissue plasminogen activator. The 1/3 MCA rule is a poorly defined volumetric estimate of the size of cerebral infarction of the MCA. A 10-point quantitative topographic CT scan score, the Alberta Stroke Program Early CT Score (ASPECTS), is described and illustrated. A sharp increase in dependence and death occurs with an ASPECTS of 7 or less. We describe how to use ASPECTS and why it works with CT scans obtained on all commonly used axial baselines. We also describe interobserver reliability among clinicians from different specialties and with different experience in reading CT scans in the context of acute stroke. METHODS: The six physicians who developed ASPECTS answered a questionnaire on precisely how they interpret and use ASPECTS. The ASPECTS areas as interpreted by these physicians were compared with one another and with standards in the literature. kappa statistics were used to assess the interobserver reliability of ASPECTS versus the 1/3 MCA rule. RESULTS: The exact methods of interpretation varied among the six individual observers, with either a 3:3 or 4:2 split on the specific questions. The overall interobserver agreement was good compared with that of the 1/3 MCA rule. Normal anatomic vascular and interobserver variations explain why ASPECTS can be applied with different CT axial baselines. CONCLUSION: ASPECTS is a systematic, robust, and practical method that can be applied to different axial baselines. Clinician agreement is superior to that of the 1/3 MCA rule.

Aged↗
PubMed2000

Building a "brain attack" team to administer thrombolytic therapy for acute ischemic stroke.

Before tissue plasminogen activator (tPA) was licensed for use in Canada, in February 1999, the Calgary Regional Stroke Program spearheaded the development and organization of local resources to use thrombolytic therapy in patients who had experienced acute ischemic stroke. In 1996 special permission was obtained from the Calgary Regional Health Authority to use intravenously administered tPA for acute ischemic stroke, and ethical and scientific review boards approved the protocols. After 3 years our efforts have resulted in improved patient outcomes, shorter times from symptom onset to treatment and acceptable adverse event rates. Areas for continued improvement include the door-to-needle time and broader education of the public about the symptoms of acute ischemic stroke.

Alberta↗
PubMed2000

Validity and reliability of a quantitative computed tomography score in predicting outcome of hyperacute stroke before thrombolytic therapy. ASPECTS Study Group. Alberta Stroke Programme Early CT Score.

BACKGROUND: Computed tomography (CT) must be done before thrombolytic treatment of hyperacute ischaemic stroke, but the significance of early ischaemic change on CT is unclear. We tested a quantitative CT score, the Alberta Stroke Programme Early CT Score (ASPECTS). METHODS: 203 consecutive patients with ischaemic stroke were treated with intravenous alteplase within 3 h of symptom onset in two North American teaching hospitals. All pretreatment CT scans were prospectively scored. The score divides the middle-cerebral-artery territory into ten regions of interest. Primary outcomes were symptomatic intracerebral haemorrhage and 3-month functional outcome. The sensitivity and specificity of ASPECTS for the primary outcomes were calculated. Logistic regression was used to test the association between the score on ASPECTS and the primary outcomes. FINDINGS: Ischaemic changes on the baseline CT were seen in 117 (75%) of 156 treated patients with anterior-circulation ischaemia included in the analysis (23 had ischaemia in the posterior circulation and 24 were treated outside the protocol). Baseline ASPECTS value correlated inversely with the severity of stroke on the National Institutes of Health Stroke Scale (r=-0.56, p<0.001). Baseline ASPECTS value predicted functional outcome and symptomatic intracerebral haemorrhage (p<0.001, p=0.012, respectively). The sensitivity of ASPECTS for functional outcome was 0.78 and specificity 0.96; the values for symptomatic intracerebral haemorrhage were 0.90 and 0.62. Agreement between observers for ASPECTS, with knowledge of the affected hemisphere, was good (kappa statistic 0.71-0.89). INTERPRETATION: This CT score is simple and reliable and identifies stroke patients unlikely to make an independent recovery despite thrombolytic treatment.

Acute Disease↗
PubMed2000

Anaphylactoid reactions and angioedema during alteplase treatment of acute ischemic stroke.

Among 105 patients given recombinant tissue plasminogen activator (rt-PA, alteplase) intravenously for acute stroke, 2 (1.9%) had lingual angioedema, which progressed to a fatal anaphylactoid reaction in 1. The authors review the 2 cases and possible mechanisms responsible. They warn that patients who are taking an angiotensin-converting-enzyme inhibitor may be at increased risk for angioedema with concomitant alteplase therapy.

Aged↗
PubMed2000

HMG-CoA reductase inhibitors (statins): a promising approach to stroke prevention.

Statins represent a promising class of agents to prevent stroke. In randomized trials of middle-aged patients with coronary artery disease, statins reduce the incidence of stroke. The reduction in stroke may not be solely related to cholesterol or low-density lipoprotein reduction but may involve nonsterol mechanisms effects on endothelial cells, macrophages, platelets, and smooth muscle cells. Statins also reduce the size of cerebral infarction in a murine stroke model, suggesting a neuroprotective effect. The best current evidence for stroke prevention is with pravastatin and simvastatin. Pravastatin reduces the risk of stroke in patients with coronary artery disease and average cholesterol levels; simvastatin reduces the risk of the combined endpoint of stroke and transient ischemic attack in hypercholesterolemic patients with coronary artery disease. Future studies of statins are needed in stroke populations, particularly the elderly.

Humans↗
PubMed2000

Effectiveness of t-PA in acute ischemic stroke: outcome relates to appropriateness.

OBJECTIVE: To examine whether the demonstrated efficacy of tissue-type plasminogen activator (t-PA) for acute ischemic stroke can be effective in a community setting. METHODS: Sixty-eight consecutive patients with acute ischemic stroke treated with IV t-PA within 3 hours of symptom onset by attending general neurologists in a busy teaching hospital. Outcome measures at 3 months were the National Institute of Health Stroke Scale (NIHSS), functional outcome (independence [modified Rankin score 0-2], dependence [modified Rankin score 3-5], and death), and symptomatic hemorrhage. Appropriately treated patients were defined by adherence to the National Institute of Neurological Disorders and Stroke (NINDS) guidelines. Effectiveness is expressed as the absolute risk reduction in which the baseline risk is assumed to be similar to that of the NINDS control group. RESULTS: Of 68 consecutively treated patients (with a mean baseline NIHSS score of 15 +/- 6), 26 (38%) made a full recovery and 39 (57%) made an independent recovery. The 11 patients who violated protocol had a lower probability of independence (p < 0.02) and full neurologic recovery (p < 0.02) and a higher probability of symptomatic hemorrhage (p < 0.05) and death (p < 0.01) compared with those of 57 patients treated according to NINDS guidelines. CONCLUSIONS: The use of t-PA for stroke in this community is effective with a number needed to treat of six. The risk of symptomatic hemorrhage is similar to that noted in randomized trials. Treating patients who violate protocol results in excess risk with no observable benefit.

Aged↗
PubMed2000

Predictors of stroke outcome.

Recent literature has identified many of the important factors helpful in predicting outcome even at the very acute stage of stroke. Demographic factors, risk factors, clinical exam findings, clinical scales laboratory tests, and neuroimaging all provide important information that can assist the clinician in predicting outcome. Specific factors seem to influence the effect of stroke treatments such as thrombolysis. Consideration of these factors is important when treatment decisions such as thrombolysis are being contemplated. New techniques such as eco-planar MR Imaging are now being developed that seem extremely accurate in predicting outcome. These techniques represent the "crystal ball" of predicting stroke outcome.

Brain Damage, Chronic↗
PubMed2000

Doubts, fears and misconceptions. What is the future of thrombolysis in acute stroke?

Alteplase for acute ischemic stroke may be the first stroke intervention to have a significant public health impact. In February 1999, this therapy was conditionally licensed in Canada for acute ischemic stroke within three hours of symptom onset. However, considerable controversy exists regarding its safety, its wider applicability outside clinical trials, and its ultimate availability. In this article we review the thrombolytic literature, attempt to answer many of the concerns, provide new guidelines for its use, and cite the need for more information about whom we should and should not be treating with this therapy.

Brain Ischemia↗
PubMed2000

Accuracy and criteria for localizing arterial occlusion with transcranial Doppler.

The authors determined transcranial Doppler (TCD) accuracy for the proximal internal carotid artery (ICA), distal ICA, proximal middle cerebral artery (MCA), distal MCA, anterior cerebral artery (ACA), posterior cerebral artery (PCA), terminal vertebral artery (tVA), and basilar artery (BA) occlusion in cerebral ischemia patients. Detailed diagnostic criteria were prospectively applied for TCD interpretation independent of angiographic findings. Of 320 consecutive patients referred to the neurosonology service with symptoms of cerebral ischemia, 190 (59%) patients also underwent angiography (MRA or DSA). 48 of those 190 patients had angiographic occlusion and 12 of those 48 patients had involvement of multiple vessels. Median time from TCD until angiography was performed was 1 hour (41 patients had angiography before TCD). TCD showed 40 true positive, 8 false negative, 8 false positive, and 134 true negative studies with sensitivity 83.0%, specificity 94.4%, positive predictive value 83.0%, negative predictive value 94.4%, and accuracy 91.6% to determine all sites of occlusion. Sensitivity for each individual occlusion site was: proximal ICA 94%, distal ICA 81%, MCA 93% tVA 56%, BA 60%. Specificity ranged from 96% to 98%. TCD is sensitive and specific in determining the site of the arterial occlusion using detailed diagnostic criteria, including proximal ICA and distal MCA lesions. TCD has the highest accuracy for ICA and MCA occlusions. If the results of TCD are normal, there is at least a 94% chance that angiographic studies will be negative.

Arterial Occlusive Diseases↗
PubMed2000

Intracranial clot dissolution is associated with embolic signals on transcranial Doppler.

Reperfusion of intracranial arteries can be detected by transcranial Doppler (TCD). The authors report microembolic signals (MES) on TCD as a sign of clot dissolution and recanalization. Microembolic signals were detected during routine diagnostic TCD examination performed in the emergency room in patients eligible for thrombolytic therapy. Microembolic signals were found at the site of M1 middle cerebral artery (MCA) high-grade stenosis or near-occlusion. Transcranial Doppler was performed before, during, and after thrombolytic therapy. Of 16 consecutive patients, 3 (19%) had MES on TCD. All three patients had a severe MCA syndrome at 2 hours after stroke onset scored using the National Institutes of Health Stroke Scale (NIHSS). In patient #1 (NIHSS 12), clusters of MES were detected distal to a high-grade M1 MCA stenosis preceding spontaneous clinical recovery by 2 minutes. Because of subsequent fluctuating clinical deficit, intraarterial thrombolysis was given with complete recovery. In patient #2 (NIHSS 20), TCD detected an M1 MCA near-occlusion. At 1.5 hours after intravenous tissue plasminogen activator, TCD showed minimal MCA flow signals followed by MES, increased velocities, and normal flow signals in just 2 minutes. She gradually recovered up to NIHSS 8 in 5 days. In patient #3 with NIHSS 22 and an M1 MCA near-occlusion, TCD detected MES 15 minutes after TPA bolus followed by MCA flow velocity improvement from 15 cm/sec to 30 cm/sec. The patient recovered completely by the end of tissue plasminogen activator infusion. The authors conclude that embolic signals detected by TCD at the site of arterial obstruction can indicate clot dissolution. Intracranial recanalization on TCD can be associated with MES and changes in flow waveform, pulsatility, and velocity if insonation is performed at the site of arterial obstruction.

Aged↗
PubMed2000

Utility of magnetic resonance imaging in acute intracerebral hemorrhage.

The authors determine whether magnetic resonance imaging (MRI) during acute hospitalization for spontaneous intracerebral hemorrhage (ICH) provides new diagnostic information. ICD-9 codes were used to identify consecutive patients with spontaneous ICH at Hermann Hospital, Houston, Texas, between January 1995 and August, 1997. Two investigators employed rigorous criteria to determine whether the MRI findings led to a specific new diagnosis. Two hundred ninety-one patients met inclusion and exclusion criteria. Sixty-seven (23%) patients underwent brain MRI during the acute hospitalization. MRI provided a new diagnosis in 15 of these 67 patients (22%). Amyloid angiopathy and vascular malformation (four each) were the most frequently identified etiologies. The yield of MRI was low in basal ganglia and thalamic hemorrhage. Two of 23 (9%) patients with deep ICH and 13 of 44 (30%) patients with lobar and infratentorial hemorrhage had etiology determined by MRI. Timing of MRI did not affect yield.

Brain↗
PubMed2000

Specific transcranial Doppler flow findings related to the presence and site of arterial occlusion.

BACKGROUND AND PURPOSE: Transcranial Doppler (TCD) can localize arterial occlusion in stroke patients. Our aim was to evaluate the frequency of specific TCD flow findings with different sites of arterial occlusion. METHODS: Using a standard insonation protocol, we prospectively evaluated the frequency of specific TCD findings in patients with or without proximal extracranial or intracranial occlusion determined by digital subtraction or MR angiography. RESULTS: Of 190 consecutive patients studied, angiography showed occlusion in 48 patients. With proximal internal carotid artery (ICA) occlusion, TCD showed abnormal middle cerebral artery (MCA) waveforms (AMCAW) in 66.7%, reversed ophthalmic artery (OA) in 70.6%, anterior cross-filling via anterior communicating artery (ACoA) in 78.6%, posterior communicating artery (PCoA) in 71.4%, and contralateral compensatory velocity increase (CVI) in 84.6% of patients. With distal ICA occlusion, TCD showed AMCAW in 88.9%, OA in 16.7%, ACoA in 50%, PCoA in 60%, and CVI in 88.9% of patients. With MCA occlusion, TCD showed AMCAW in 100%, OA in 23.5%, ACoA in 31.3%, PCoA in 23.1%, and CVI in 62.5%. With no anterior circulation occlusion at angiography, TCD showed these parameters in 1.8% to 17. 9%, chi(2) P</=0.003. Parameters localizing anterior circulation occlusion were stenotic terminal ICA velocities 46% versus 10% in patent vessels; flow diversion to perforators 73% versus 1.8%; OA 70. 6% versus 5.6%; ACoA 78.6% versus 8.2%; PCoA 71.4% versus 8.5%, all at P<0.05. In patients with basilar artery (BA) occlusion, ABAW were found in 80% versus 3% (patent BA); flow diversion to anterior vessels in 60% versus 5.7%; BA flow reversal in 20% versus 0%; and PCoA in 100% versus 13.7%, all at P<0.001. No individual parameters differentiated BA from the terminal vertebral occlusion. CONCLUSIONS: Specific TCD findings are common with major arterial occlusion and can be used to broaden diagnostic batteries and improve the predictive value of noninvasive screening in stroke patients. TCD findings useful to localize anterior circulation occlusion include collaterals, abnormal waveforms or velocities, and flow diversion to perforators.

Cerebral Arteries↗
PubMed2000

High rate of complete recanalization and dramatic clinical recovery during tPA infusion when continuously monitored with 2-MHz transcranial doppler monitoring.

BACKGROUND AND PURPOSE: Clot dissolution with tissue plasminogen activator (tPA) can lead to early clinical recovery after stroke. Transcranial Doppler (TCD) with low MHz frequency can determine arterial occlusion and monitor recanalization and may potentiate thrombolysis. METHODS: Stroke patients receiving intravenous tPA were monitored during infusion with portable TCD (Multigon 500M; DWL MultiDop-T) and headframe (Marc series; Spencer Technologies). Residual flow signals were obtained from the clot location identified by TCD. National Institutes of Health Stroke Scale (NIHSS) scores were obtained before and after tPA infusion. RESULTS: Forty patients were studied (mean age 70+/-16 years, baseline NIHSS score 18.6+/-6.2, tPA bolus at 132+/-54 minutes from symptom onset). TCD monitoring started at 125+/-52 minutes and continued for the duration of tPA infusion. The middle cerebral artery was occluded in 30 patients, the internal carotid artery was occluded in 11 patients, the basilar artery was occluded in 3 patients, and occlusions were multiple in 7 patients; 4 patients had no windows; and 1 patient had a normal TCD. Recanalization on TCD was found at 45+/-20 minutes after tPA bolus: recanalization was complete in 12 (30%) and partial in 16 (40%) patients. Dramatic recovery during tPA infusion (total NIHSS score <3) occurred in 8 (20%) of all patients (baseline NIHSS range 6 to 22; all 8 had complete recanalization). Lack of improvement or worsening was associated with no recanalization, late recanalization, or reocclusion on TCD (C=0.811, P< or =0.01). Improvement by > or =10 NIHSS points or complete recovery was found in 30% of all patients at the end of tPA infusion and in 40% at 24 hours. Improvement by > or =4 NIHSS points was found in 62.5% of patients at 24 hours. CONCLUSIONS: Dramatic recovery during tPA therapy occurred in 20% of all patients when infusion was continuously monitored with TCD. Recovery was associated with recanalization on TCD, whereas no early improvement indicated persistent occlusion or reocclusion. At 24 hours, 40% of all patients improved by > or =10 NIHSS points or recovered completely. Ultrasonic energy transmission by TCD monitoring may expose more clot surface to tPA and facilitate thrombolysis and deserves a controlled trial as a way to potentiate the effect of tPA therapy.

Adult↗
PubMed2000

Deterioration following spontaneous improvement : sonographic findings in patients with acutely resolving symptoms of cerebral ischemia.

BACKGROUND AND PURPOSE: Some stroke patients will deteriorate following improvement (DFI), but the cause of such fluctuation is often unclear. While resolution of neurological deficits is usually related to spontaneous recanalization or restoration of collateral flow, vascular imaging in patients with DFI has not been well characterized. METHODS: We prospectively studied patients who presented with a focal neurological deficit that resolved spontaneously within 6 hours of symptom onset. Patients were evaluated with bedside transcranial Doppler (TCD). Digital subtraction angiography (DSA), computed tomographic angiography (CTA), or magnetic resonance angiography (MRA) were performed when feasible. DFI was defined as subsequent worsening of the neurological deficit by >/=4 National Institutes of Health Stroke Scale points within 24 hours of the initial symptom onset. RESULTS: We studied 50 consecutive patients presenting at 165+/-96 minutes from symptom onset. Mean age was 61+/-14 years; 50% were females. All patients had TCD at the time of presentation, and 68% had subsequent angiographic examinations (DSA 10%, CTA 4%, and MRA 44%). Overall, large-vessel occlusion on TCD was found in 16% of patients (n=8); stenosis was found in 18% (n=9); 54% (n=27) had normal studies; and 6 patients (12%) had no temporal windows. DFI occurred in 16% (n=8) of the 50 patients: in 62% of patients with TCD and angiographic evidence of occlusion, in 22% with stenosis, and in 4% with normal vascular studies (P<0.001, Phi=0.523, chi(2)=12.05). DFI occurred in 31% of patients with large-vessel atherosclerosis, 23% with cardioembolism, and 9% with small-vessel disease when stroke mechanisms were determined within 2 to 3 days after admission (P=0.2, NS). CONCLUSIONS: DFI is strongly associated with the presence of large-vessel occlusion or stenosis of either atherosclerotic or embolic origin. Normal vascular studies and lacunar events were associated with stable spontaneous resolution without subsequent fluctuation. Urgent vascular evaluation may help identify patients with resolving deficits and vascular lesions who may be candidates for new therapies to prevent subsequent deterioration.

Acute Disease↗