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Mark E Hudon

Publications and source records attributed to Mark E Hudon.

8 recordsLinked to original sources
PubMed2004

ASPECTS on CTA source images versus unenhanced CT: added value in predicting final infarct extent and clinical outcome.

BACKGROUND AND PURPOSE: The Alberta Stroke Program Early CT Score (ASPECTS) is a grading system to assess ischemic changes on CT in acute ischemic stroke. CT angiography-source images (CTA-SI) predict final infarct volume. We examined whether the final infarct ASPECTS and clinical outcome were more related to acute CTA-SI ASPECTS than to the acute noncontrast CT (NCCT) ASPECTS. METHODS: ASPECTS was assigned by 2 raters on the acute NCCT, CTA-SI, and follow-up imaging. The mean baseline ASPECTS of acute NCCT and CTA-SI was compared with the follow-up ASPECTS. Rate ratios (RRs) were used to quantify the relationship between the dichotomized baseline ASPECTS (categorized as 0 to 7 versus 8 to 10) and favorable patient outcome. RESULTS: Thirty-nine patients were recruited. Proximal occlusion (internal carotid artery or middle cerebral artery) was seen in 62%, M2 occlusion in 18%, and no occlusion was seen in 20% of patients. The median time between symptom onset and imaging was 1.9 (1.2 to 2.5) hours. There was a significantly larger difference of 1.4 between the mean baseline NCCT and CTA-SI ASPECTS in patients who had more ischemic changes (follow-up ASPECTS=0 to 3) than a difference of 0.6 in patients who had near-to-normal CT scans (follow-up ASPECTS=8 to 10). The rate of favorable outcome for acute NCCT ASPECTS of 8 to 10 was 51.8% versus 25.0% for 0 to 7 (RR, 2.1, 95% CI: 0.7 to 5.9, P=0.12). For acute CTA-SI ASPECTS of 8 to 10, the rate of favorable outcome was 58.8% versus 31.8% for 0 to 7 (RR, 1.8, 95% CI: 0.9 to 3.8, P=0.09). CONCLUSIONS: CTA-SI ASPECTS provides added information in the prediction of final infarct size.

Aged↗
PubMed2004

Mild neurological symptoms despite middle cerebral artery occlusion.

BACKGROUND AND PURPOSE: Only a small percentage of stroke patients are treated with thrombolytic therapy. We sought to determine whether vessel occlusion in mild strokes represented a new target population for interventional therapy. METHODS: We imaged 106 acute stroke patients with MRI. Patients were identified with evidence of middle cerebral artery (MCA) occlusion and mild or no stroke signs (National Institutes of Health Stroke Scale [NIHSS] 3, and MCA occlusion. RESULTS: We identified 5 patients with absent flow on MRA in the MCA and mild or no stroke signs (NIHSS <or=3). All 5 were functionally independent at 3 months. CONCLUSIONS: Caution should be exercised in considering thrombolytic therapy in these patients. Quantification of perfusion imaging is required to identify "at risk" mild stroke populations.

Acute Disease↗
PubMed2004

Intra-arterial thrombolysis in acute ischemic stroke: a review of pharmacologic approaches.

Ischemic stroke is a major public health problem worldwide. The potential to cure stroke patients with intravenous thrombolytic therapy has evolved to the use of intra-arterial thrombolytic agents. Fewer than 200 patients have been enrolled in randomized trials of intra-arterial therapy. In this article the authors have reviewed the literature listed in MEDLINE and EMBase, and searched relevant articles to examine the role of fibrinolytic agents in acute interventional stroke therapy. Only English language articles reporting five or more patients were included. Outcomes were defined at 90 days. Good outcome was defined on the modified Rankin Scale. Symtpomatic hemorrhage was defined as hemorrhage in the setting of clinical deterioration in the first 24 to 48 h. The search identified 57 studies of which 44 reported usable data. Only three randomized trials were reported. Of a total of 1140 patients, most (73%) were treated open-label with urokinase (Abbokinase, Abbott Laboratories). The best outcomes were reported in case series and slightly worse outcomes were reported in clinical trials. Overall, it was not possible to distinguish whether one agent was superior to the others. There is a paucity of published evidence on intra-arterial therapy for acute ischemic stroke. Alteplase (Activase, Genentech Inc.) is currently the drug of choice simply because it is available and it is the current intravenous standard. Further trials and developments are anticipated.

Brain Ischemia↗
PubMed2003

Reliability of assessing percentage of diffusion-perfusion mismatch.

BACKGROUND AND PURPOSE: Emergent neurovascular imaging holds promise in identifying new and optimum target populations for thrombolysis in stroke. Recent research has focused on patients with diffusion-weighted MRI (DWI)-perfusion-weighted MRI (PWI) mismatch as a marker of tissue at risk of infarction and a means to select the most suitable candidates for thrombolysis. The present study sought to estimate the reliability of assessing the percentage of DWI-PWI mismatch. METHODS: Thirteen patients with acute strokes had DWI and PWI within 7 hours of symptom onset. Six raters independently created relative mean transit time (rMTT) maps and then compared them with DWI images to assess the percentage of mismatch (PWI>DWI) in 10% increments. The MR scans were reassessed by 4 raters, tracing around the lesions to calculate the volume percentage of mismatch. RESULTS: Visual assessment had an interrater reliability of 0.68 (95% CI, 0.52 to 1.0; SEM=21.6%) and an intrarater reliability of 0.80 (95% CI, 0.47 to 1.0; SEM=16.9%). Hand-drawn assessment had an interrater reliability of 0.66 (95% CI, 0.45 to 1.0; SEM=26.2%) and an intrarater reliability of 0.94 (95% CI, 0.81 to 1.0; SEM=10.9%). CONCLUSIONS: Results from the present study suggest that quantifying mismatch by the human eye is reproducible but not reliable among observers. This raises doubts about using mismatch for clinical decision making and clinical trial enrollment.

Acute Disease↗
PubMed2003

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↗
PubMed2002

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↗
PubMed2002

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↗