CTA source images in acute stroke.
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Acute Disease↗
Biomedical subjects
Andrew M Demchuk
Publications and source records attributed to Andrew M Demchuk.
Computed tomographic parameters predicting fatal outcome in large middle cerebral artery infarction.
BACKGROUND: Large middle cerebral artery (MCA) ischaemic stroke when associated with extensive mass effect can result in brain herniation and neurological death. As yet there are few guidelines to aid the selection of patients for aggressive interventional therapies, such as decompression hemicraniectomy and/or hypothermia. METHODS: We studied a cohort of patients from seven centres with large MCA infarction requiring neurocritical care. The purpose of this analysis was to assess the use of early radiological signs on follow-up computed tomographic (CT) signs performed within 48 h of stroke onset for predicting mortality at 30 days. The CT parameters assessed included horizontal displacement of the septum pellucidum, pineal shift, complete or partial infarction of the temporal lobe, involvement of additional vascular territories, and the presence of hydrocephalus. The primary outcome measure was in-hospital death within 30 days. RESULTS: One hundred and thirty-five patients who had follow-up CT scans within 48 h were identified from a total of 201 patients with large MCA infarction that received conventional medical therapy alone. The median age was 68 (range 29-99), 56% were female, and the median NIHSS category was 26-30 at 48 h. Among CT variables in univariable analysis, anteroseptal shift >/=5 mm, pineal shift >/=2 mm, complete temporal lobe infarction, involvement beyond the MCA territory, and moderate or severe hydrocephalus were equally predictive of death. Multivariable analysis adjusting for time to CT scan revealed the following predictors of fatal outcome: anteroseptal shift >/=5 mm (OR 10.9; 95% CI 3.2-37.6), NIHSS within 48 h >20 (OR 6.6; 95% CI 2.3-19.3), and infarction beyond the MCA territory (OR 4.9; 95% CI 1.6-15.0). CONCLUSIONS: We identified the role of early CT signs in predicting death following massive MCA infarction. The CT parameters anteroseptal shift (>5 versus </=5 mm), pineal shift >/=2 mm, hydrocephalus, temporal lobe infarction, and other vascular territory infarction if present were predictive of fatal outcome. These CT parameters require prospective validation before they should be considered reliable markers for decision-making.
Adult↗
Biochemistry of ischemic stroke.
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Acidosis↗
What is causing crescendo transient ischemic attacks?
BACKGROUND AND METHODS: We discuss a case report from a patient who had symptoms of transient neurological deficits in the presence of a chronic subdural hematoma and severe carotid stenosis. Multi-modality imaging was used to guide management. RESULTS: The symptoms settled without carotid intervention and were presumed due to the subdural hematoma. CONCLUSIONS: Severe symptomatic carotid stenosis is treated with carotid endarterectomy. In some patients with transient neurological deficits, the diagnosis is not as simple as first thought. Multi-modality imaging (MRI, TCD and CT) can help differentiate the causative lesion.
Aged↗
Markers of increased risk of intracerebral hemorrhage after intravenous recombinant tissue plasminogen activator therapy for acute ischemic stroke in clinical practice: the Multicenter rt-PA Stroke Survey.
BACKGROUND: Intravenous recombinant tissue plasminogen activator (rtPA) is an effective therapy for acute ischemic stroke, but it is associated with risk of intracerebral hemorrhage (ICH). Our aim was to identify, in a large cohort of patients, readily available baseline factors that are associated with thrombolysis-related ICH. METHODS AND RESULTS: In a multicenter retrospective and prospective investigation of individual data from 1205 patients treated in routine clinical practice with intravenous rtPA within 3 hours of stroke symptom onset, 72 patients (6%) developed symptomatic ICH and 86 additional patients (7%) had asymptomatic ICH identified on a routine follow-up CT. In analyses based on clinical variables alone, the main attributes associated with ICH were a history of diabetes mellitus and cardiac disease, increasing stroke severity, advancing age, use of antiplatelet agents other than aspirin before stroke onset, and elevated pretreatment mean blood pressure. In additional analyses that incorporated baseline CT and laboratory findings (in a subset of patients), the main associations were early ischemic CT changes, in particular if exceeding one third of middle cerebral artery territory; increasing stroke severity; diabetes mellitus or elevated serum glucose; and lower platelet counts. Final independent attributes associated with parenchymatous hematoma, defined by purely radiologically based criteria, were similar to those of symptomatic ICH. CONCLUSIONS: Readily available factors can identify acute ischemic stroke patients at high and low risk for rtPA-related ICH. These factors require confirmation in a prospective cohort before clinical implementation.
Acute Disease↗
Screening for intracranial stenosis with transcranial Doppler: the accuracy of mean flow velocity thresholds.
BACKGROUND: Patients with 50% intracranial arterial stenosis may require more intensive therapies for stroke prevention. Transcranial Doppler (TCD) is a convenient noninvasive screen for intracranial stenosis. The accuracy of different mean flow velocity (MFV) thresholds for determining the degree of stenosis remains uncertain. METHODS: The authors prospectively compared the accuracy of TCD criteria and MFV thresholds to magnetic resonance, computed tomography, and digital subtraction angiography in patients with symptoms of recent or remote stroke or transient ischemic attack. Stenosis on angiography was measured as 0%, < 50%, or > or = 50% diameter reduction. RESULTS: Of 136 consecutive patients, 33 (24%) had distal internal carotid artery (ICA), middle cerebral artery (MCA), posterior cerebral artery, or basilar artery stenosis on angiography (14 patients [10%] were excluded due to incomplete TCD examinations, mainly from a lack of temporal windows). TCD showed 31 true-positive, 9 false-positive, 2 false-negative, and 94 true-negative studies. For all vessels, TCD had a sensitivity of 93.9% (confidence interval [CI] = 89%-98%), a specificity of 91.2% (CI = 87%-96%), a positive predictive value (PPV) of 77.5%, and a negative predictive value (NPV) of 97.9%. The trade-off in sensitivity and specificity for MCA MFV thresholds was as follows: MFV > or = 80 cm/s had a sensitivity of 100%, a specificity of 96.9% (CI = 94%-99%), a PPV of 84%, and an NPV of 100%. MFV > or = 100 cm/s had a sensitivity of 100%, a specificity of 97.9% (CI = 96%-99%), a PPV of 88.8%, and an NPV of 94.9%. MFV > or = 120 cm/s had a sensitivity of 68.7% (CI = 61%-78%), a specificity of 100%, a PPV of 100%, and an NPV of 94.9%. Reasons for false-positive findings include collateralization of flow in the presence of proximal ICA stenosis and prestenotic to stenotic MCA velocity ratios of 1: < or = 2. CONCLUSION: TCD is both sensitive and specific in identifying > or = 50% intracranial arterial stenosis. A MFV threshold cutoff of 100 cm/s has an optimal sensitivity and specificity trade-off for > or = 50% MCA stenosis. To help avoid false-positive results, a prestenotic to stenotic MCA velocity ratio of 1: > or = 2 should be used in addition to the MFV threshold.
Aged↗
Intravenous tissue plasminogen activator and flow improvement in acute ischemic stroke patients with internal carotid artery occlusion.
BACKGROUND AND PURPOSE: It has been suggested that intravenous tissue plasminogen activator (TPA) would not lyse the large thrombus associated with internal carotid artery (ICA) occlusion and, therefore, would be ineffective in this setting. Vascular imaging, safety, and outcome of TPA therapy for ICA occlusion is not well described. Our goal was to determine the site of occlusion, early recanalization after TPA infusion, and its relationship to outcome. METHODS: We reviewed our database of all stroke patients treated with i.v. TPA between July 1997 and July 1999. We identified all cases with carotid occlusion suggested by transcranial Doppler (TCD) and angiography. Occlusion and recanalization were assessed by site including proximal ICA (prICA), terminal ICA (tICA), and middle cerebral artery (MCA). Baseline National Institutes of Health Stroke Scale (NIHSS) scores and follow-up Rankin scores were obtained. RESULTS: We treated 20 patients with carotid occlusion (age 63.9 +/- 10.8 years, 11 males, 9 females). Time to TPA infusion after stroke onset was 128 +/- 66 minutes. Baseline NIHSS scores were 16.4 +/- 5.4. Time to follow-up was 3.5 +/- 4.9 months (2 patients were lost to follow-up). Occlusion sites were prICA 40%, tICA 70%, and concurrent MCA 45%. Multiple sites were involved in 10/20 patients (50%). Among patients with pretreatment and posttreatment vascular imaging studies (n = 18), recanalization in the prICA and tICA was complete in 10%, partial in 16%, and none in 74%. MCA recanalization was complete in 35%, partial in 24%, and none in 41%. At follow-up, Rankin 0-1 was found in 8 patients (44%), Rankin 2-3 in 3 (17%), and Rankin 4-5 in 3 (17%). Mortality was 22% (n = 4) including 1 fatal intracerebral hemorrhage. Improvement was closely related to resumption of MCA flow (P < .01). CONCLUSIONS: Most patients did not recanalize their ICA occlusion after intravenous TPA therapy. However, recanalization of associated proximal MCA clot, found in 45% of our patients, or improved MCA collateral flow was strongly associated with good outcome.
Acute Disease↗
Safety of tissue plasminogen activator for acute stroke in menstruating women.
BACKGROUND: Menses is a theoretical contraindication to intravenous tissue plasminogen activator (tPA) treatment. We sought to establish the safety of intravenous tPA in the treatment of acute ischemic stroke in women who are actively menstruating. SUMMARY OF REPORT: We provide a case report and review of the National Institute of Neurological Disorders and Stroke (NINDS) database for women coded as actively menstruating. Nine subjects were coded as actively menstruating in the NINDS trial (4 placebo and 5 in the treatment). One subject in the treatment group who had a 1-year history of dysfunctional uterine bleeding required emergent uterine artery ligation. We also report a case of a woman requiring transfusion after intravenous tPA administration for acute ischemic stroke. CONCLUSIONS: Intravenous tPA may be administered relatively safely in women who are menstruating and should be used with caution in women with a history of dysfunctional uterine bleeding. Potential patients should be advised that they might require transfusion for increased menstrual flow.
Acute Disease↗
Acute intravenous--intra-arterial revascularization therapy for severe ischemic stroke.
BACKGROUND: Intravenous alteplase for acute ischemic stroke is least efficacious for patients with proximal large-artery occlusions and clinically severe strokes. Intra-arterial therapy has the theoretical advantage of establishing a neurovascular diagnosis and high symptomatic artery patency rate but the disadvantage of requiring extra time and technical expertise. A combination of these two approaches may provide the best chance of improving outcome in severe acute ischemic stroke. We sought to assess the safety and feasibility of this approach. METHODS: This was a prospective, open-label study. Sequential patients arriving to our center within 3 hours of stroke onset who were treated with intravenous alteplase were screened for possible additional intra-arterial therapy using noninvasive neuroimaging. Clinical measures and outcomes were recorded prospectively. RESULTS: A total of 861 patients with ischemic stroke were admitted to Calgary hospitals during the study period. Eight patients over 21 months underwent a combined intravenous-intra-arterial approach. Six received intra-arterial alteplase and 1 underwent intracranial angioplasty; in a final patient, technical aspects prevented intra-arterial therapy. Early neurovascular and/or neurometabolic imaging identified the location of occlusion and tissue-at-risk (DWI-PWI mismatch) in all 8 patients. Two patients had a poor outcome, 1 patient suffered a significant groin hematoma, and there were no instances of symptomatic intracerebral hemorrhage. CONCLUSIONS: Intravenous followed by intra-arterial therapy is a promising approach to the treatment of severe acute ischemic stroke. Early noninvasive neurovascular and neurometabolic imaging is very helpful in choosing candidates for this type of therapy. On-going monitoring of alteplase-treated patients may allow the opportunity to perform rescue intra-arterial therapy.
Acute Disease↗
Improving delivery of acute stroke therapy: The TLL Temple Foundation Stroke Project.
BACKGROUND AND PURPOSE: Only a small minority of acute stroke patients receive approved acute stroke therapy. We performed a community and professional behavioral intervention project to increase the proportion of stroke patients treated with approved acute stroke therapy. METHODS: This study used a quasi-experimental design. Intervention and comparison communities were compared at baseline and during educational intervention. The communities were based in 5 nonurban East Texas counties. The multilevel intervention worked with hospitals and community physicians while changing the stroke identification skills, outcome expectations, and social norms of community residents. The primary goal was to increase the proportion of patients treated with intravenous recombinant tissue plasminogen activator (rTPA) from 1% to 6% of all cerebrovascular events in the intervention community. RESULTS: We prospectively evaluated 1733 patients and validated 1189 cerebrovascular events. Intravenous rTPA treatment increased from 1.38% to 5.75% among all cerebrovascular event patients in the intervention community (P=0.01) compared with a change from 0.49% to 0.55% in the comparison community (P=1.00). Among the ischemic stroke patients, an increase from 2.21% to 8.65% was noted in the intervention community (P=0.02). The comparison group did not appreciably change (0.71% to 0.86%, P=1.00). Of eligible intravenous rTPA candidates, treatment increased in the intervention community from 14% to 52% (P=0.003) and was unchanged in the comparison community (7% to 6%, P=1.00). CONCLUSIONS: An aggressive, multilevel stroke educational intervention program can increase delivery of acute stroke therapy. This may have important public health implications for reducing disability on a national level.
Acute Disease↗
Comparison of pre- and postcontrast 3D time-of-flight MR angiography for the evaluation of distal intracranial branch occlusions in acute ischemic stroke.
BACKGROUND AND PURPOSE: Three-dimensional time-of-flight (TOF) MR angiography is used routinely in stroke workup to detect arterial occlusions, but a major drawback is its inadequate depiction of vessels with slow or in-plane flow. We hypothesized that the use of contrast-enhanced MR angiography improves delineation of vessels with diminished or absent flow on precontrast MR angiograms. METHODS: Pre- and postcontrast 3D TOF MR angiograms were acquired in 55 consecutive patients with acute stroke. Patency of 480 intracranial vessels was assessed on both the pre- and postcontrast angiograms. Diffusion-weighted (DW) and perfusion-weighted (PW) imaging data were also obtained and results correlated with those of pre- and postcontrast MR angiography. RESULTS: For 50 abnormal vessel segments seen on precontrast MR angiograms, postcontrast MR angiograms resulted in change in the vascular signal intensity in 70% (35 vessel segments); 94% of these changes showed a greater extent of vessel patency. Venous and soft-tissue contrast enhancement had no effect on assessment in 95% of all 480 vessels examined. Interobserver reliability was moderate, with postcontrast interpretation (kappa = 0.48) showing a slight improvement over precontrast interpretation (kappa = 0.41). Good agreement was found between the TOF results and the pooled DW and PW imaging results. CONCLUSIONS: Compared with precontrast 3D TOF MR angiograms, postcontrast 3D TOF angiograms improve assessment of intracranial vessel patency in acutely ischemic vascular territories. In some patients, an improved understanding of acute ischemic stroke was obtained by viewing the pre- and postcontrast images. Postcontrast MR angiography should be included in the MR evaluation of acute stroke.
Acute Disease↗
Insonation method and diagnostic flow signatures for transcranial power motion (M-mode) Doppler.
BACKGROUND AND PURPOSE: Power motion mode Doppler (PMD) simultaneously displays flow signal intensity and direction over several centimeters of intracranial space. Insonation protocol for PMD and spectral transcranial Doppler (TCD) with typical PMD flow signatures is described in serial patients with acute stroke symptoms examined via conventional windows with a PMD/TCD unit. RESULTS: Thirty-five patients were studied within 12 hours after stroke onset (age 64 +/- 15 years; 8 received intravenous and 3 intra-arterial thrombolysis). One patient had no temporal window, and 3 patients had suboptimal windows. In 90% of patients, PMD showed more than 1 ipsilateral temporal windows. In 63% of patients (n = 22), PMD simultaneously displayed the entire M1 (65-45 mm) and proximal M2 (45-30 mm) flows, leading to spectral TCD examination of the proximal M2 middle cerebral artery (MCA) in 28 of 35 patients (80%). All patients had sufficient foraminal (depth display = 60-110 mm) and orbital (depth display = 30-80 mm) windows. PMD displayed the entire basilar artery stem (75-100+ mm) in 69% (n = 24) of patients, and the distal basilar flow was detected in all patients by both PMD and TCD. TCD results were normal (12), proximal intracranial stenosis (5), large vessel occlusion (17), and cerebral circulatory arrest (1). Compared to spectral TCD, PMD signatures of similar diagnostic significance were low resistance (vessel identification and recanalization), high resistance (ophthalmic artery identification and distal obstruction), collateral (communicating arteries and leptomeningeal flow), reverberating (circulatory arrest), and branch embolization. CONCLUSIONS: PMD is a window-finding tool and a guide for spectral TCD gate placement. PMD facilitates flow detection in the M2 branches and the distal basilar artery. PMD can demonstrate recanalization of the entire MCA main stem and proximal branches, increase the yield of embolus detection and procedure monitoring, and facilitate abnormal flow pattern recognition.
Aged↗