Feasibility of source images of computed tomographic angiography to detect the extent of ischemia in hyperacute stroke.

BACKGROUND AND PURPOSE: Computed tomographic angiography (CTA) is suggested to be a promising tool for patient selection for thrombolytic therapy of acute stroke. It does not only provide information on intracranial vasculature, but also on the capacity of the collateral circulation and the pattern of poorly perfused brain tissue. The objective of our study was to evaluate whether the presence and size of critically hypoperfused tissue assessed with flow positron emission tomography (PET) as a gold standard can reliably be identified on CTA source images. METHODS: Fifteen potential candidates for early thrombolysis underwent CTA 65-170 min (mean 107 min) after the onset of acute anterior circulation stroke. Regional cerebral perfusion was measured between 27 and 86 min (mean 59 min) later with [(15)O]-H(2)O and PET, and the volume of critically hypoperfused cortical tissue was assessed. CTA source images were evaluated by a neuroradiologist and an experienced stroke neurologist. The patients were classified into three groups according to the presumed size of the perfusion deficit on CTA (large, small, no perfusion deficit). RESULTS: PET revealed the presence of critical cortical hypoperfusion in 10 patients, 5 had no critical cortical hypoperfusion. The neuroradiologist correctly identified the presence of a perfusion deficit in all patients, the neurologist had two false negative and one false positive ratings. Concerning the size of the perfusion deficit, there was considerable inaccuracy in both raters. CONCLUSIONS: The usefulness of CTA source images in yielding information about the perfusion state of stroke patients in clinical routine should not be overestimated.

Predictive value of neurochemical monitoring in large middle cerebral artery infarction.

BACKGROUND AND PURPOSE: Space-occupying brain edema is a life-threatening complication in patients with large hemispheric stroke. Early identification of patients at risk is necessary to decide on invasive therapies such as decompressive hemicraniectomy or hypothermia. To assess potential predictors of malignant brain edema by measurement of intracranial pressure (ICP) and microdialysis in patients with large hemispheric stroke and different clinical course. METHODS: In an ongoing prospective clinical study, an ICP and microdialysis probe were placed into the parenchyma of the ipsilateral frontal lobe of 10 patients. Extracellular concentrations of glutamate, lactate, pyruvate, and glycerol were measured continuously. Repeated cranial CT scans were scrutinized for size of infarction and presence of mass effect. RESULTS: The dynamics of the different substances varied in accordance with the clinical course, size of infarction, and local brain edema: Increase in ICP and in glutamate concentration and lactate-pyruvate ratio was followed by massive edema and large infarcts; generally low and stable ICP and substrate concentrations were found in patients without progressive space-occupying infarcts. CONCLUSIONS: In patients with large hemispheric infarction, bedside monitoring with microdialysis is feasible and might be helpful together with ICP recording to follow the development of malignant brain edema.

Intravenous thrombolysis in proximal middle cerebral artery occlusion.

Subgroup analyses of data from an open-label study of intravenous recombinant tissue plasminogen activator (rt-PA) administered to stroke patients were performed. Clinical outcome and incidence of intracranial hemorrhage were evaluated in 20 patients diagnosed by transcranial Doppler ultrasound as having proximal middle cerebral artery (MCA) occlusion. Additionally early infarct signs and size of final infarction were assessed. A favorable outcome (mRS 0-2) was seen in 30% of all patients. The incidence of symptomatic intracranial hematoma (10%) in patients with proximal MCA occlusion was higher than the overall hemorrhage rate of intravenous rt-PA treatment, but comparable to the data on intra-arterial thrombolysis in this stroke subgroup. All patients except 1 developed ischemic infarction in the MCA territory. Intravenous rt-PA treatment within 3 h may also be effective in patients with proximal MCA occlusion. The risk of intracerebral hematoma does not seem to be greater than in intra-arterial thrombolysis.

Early intravenous thrombolysis for acute ischemic stroke in a community-based approach.

BACKGROUND AND PURPOSE: Controlled multicenter studies have demonstrated the efficacy of systemic recombinant tissue-type plasminogen activator (rtPA) treatment in selected cases of acute ischemic stroke. The feasibility of this therapeutic option in clinical practice was assessed in a community-based approach. METHODS: We offered rtPA treatment to stroke patients in a prospective open-label monocenter study applying inclusion criteria similar to those of the National Institute of Neurological Disorders, and Stroke study. In order to treat patients within 3 hours of symptom onset, a referral system was used by which eligible patients from all over the city of Cologne, Federal Republic of Germany, were rushed to the Department of Neurology of the University Hospital. We present data on the effectiveness of the referral system and the outcome results of the first 100 consecutive patients treated within an 18-month period. RESULTS: Of 453 consecutive patients with a presumed diagnosis of acute stroke referred to our department between March 1996 and August 1997, 100 patients (22%) were treated with intravenous thrombolysis, 26% of them within 90 minutes of symptom onset. The average time from stroke onset to arrival at our department was 78 minutes, and from arrival to treatment 48 minutes. After 3 months, 53 patients recovered to fully independent function. The rates of total, symptomatic, and fatal intracerebral hemorrhage were 11%, 5%, and 1%, respectively. Overall mortality was 12%. CONCLUSIONS: Thrombolysis with rtPA was effectively applied in routine management of stroke patients in a community-based approach with acceptable efforts and without additional costs. Under these circumstances, outcome and complication rates were comparable to those of multicenter trials.

Preoperative risk assessment for carotid occlusion by transcranial Doppler ultrasound.

OBJECTIVES: An endovascular carotid balloon occlusion test with continuous intracranial monitoring by transcranial Doppler sonography was performed in 55 patients for prediction of tolerance of a required permanent occlusion of the carotid artery. METHODS: Blood flow velocities of the ipsilateral middle cerebral artery during occlusion were recorded and compared with clinical tolerance during an occlusion test as well as with postoperative outcome after an eventual permanent occlusion. To stress the capacity of the cerebral circulation to tolerate the occlusion acetazolamide was injected before occlusion in all patients. RESULTS: The onset of neurological symptoms during temporary occlusion was dependent on the percentage fall of mean blood flow velocity relative to baseline rather than on absolute flow velocities during the time of occlusion. Patients with a fall of mean flow velocity of less than 30% tolerated temporary and permanent occlusion, with the exception of two patients who developed an infarction due to thromboembolism after iatrogenic sacrifice of the carotid artery. Patients with a major decrease developed neurological symptoms during occlusion in 55% and, in cases of carotid ligation, a haemodynamic infarction occurred. CONCLUSION: The results show that transcranial Doppler monitoring as a part of an endovascular balloon occlusion test may be a reliable technique for preoperative risk assessment for permanent occlusion of the carotid artery.