Cerebral vasomotor reactivity of patients with acute ischemic stroke: Cortical versus subcortical infarcts: An Israeli–Turkish collaborative study
Introduction
Hemodynamic factors may play a key role in the acute phase of ischemic stroke, predict stroke severity, progression and outcome. Different methods have been developed for the evaluation of cerebral hemodynamics. One of the ways of determining cerebral hemodynamic status is by assessing cerebral vasomotor reactivity (VMR) which provides information on cerebral autoregulation and the collateral circulation [1], [2]. VMR is defined as a shift between cerebral blood flow (CBF) or cerebral blood flow velocity (BFV) before and after administration of a potent vasodilatory stimulus test. VMR of the middle cerebral artery (MCA) was frequently assessed in patients with extracranial carotid occlusive disease, and several studies showed that high-grade stenosis or occlusion of the internal carotid artery (ICA) can significantly reduce VMR of the ipsilateral MCA [3], [4], [5], [6]. Furthermore, the predictive value of impaired VMR for ischemic stroke occurrence was convincingly confirmed in subjects with carotid occlusive disease [7], [8], [9], [10], [11]. Data on the features of VMR in patients with acute ischemic stroke who do not have carotid occlusive disease, however, are very scanty [12], [13].
VMR can be assessed by using transcranial Doppler (TCD) and the Diamox test, measuring BFV before and after the administration of acetazolamide (Diamox) as a vasodilator agent [14]. TCD with the Diamox test is easy to perform and does not need the patient's cooperation. These advantages might be crucial for evaluations conducted during the acute phase of ischemic stroke.
The aim of the present study was to assess VMR in patients with acute ischemic stroke without carotid occlusive disease in order to identify and compare the cerebral hemodynamic features unique to cortical and subcortical brain infarcts.
Section snippets
Patients and methods
Forty-seven patients with first-ever acute ischemic stroke were prospectively studied within 72 h of stroke onset in this Israeli–Turkish collaborative study. Twenty-two of them were examined in the Tel Aviv Sourasky Medical Center (TASMC) and 25 in the Department of Neurology, Osmangazi University, Eskisehir, Turkey. All the study participants were recruited according to the following criteria: 1. first-ever ischemic stroke in the anterior circulation (i.e., the MCA territory); 2. no evidence
Results
Forty-seven patients (mean age ± SD, 76 ± 12.8 years, 29 men) with acute ischemic stroke in the MCA territory were studied. Based on neuroradiological data, these patients were divided into two groups, one with cortical infarcts (CIs; n = 23) and the other with subcortical infarcts (SIs; n = 24). The patients' demographics and risk factor profiles are shown in Table 1.There were no significant differences between the CI and SI groups in terms of gender, hypertension and hypercholesterolemia. The SI
Discussion
The cerebral vasculature has a unique ability to dilate during hypercapnia and to constrict during hypocapnia. The differences between CBF at rest and after the induction of hypercapnia reflect the state of VMR and, hence, cerebrovascular reserve capacity. These effects of carbon dioxide (CO2) on the cerebral circulation are mostly demonstrated in resistance brain arterioles. VMR is defined as the vasodilation capacity of resistance brain arterioles to external stimuli, such as increasing
Acknowledgment
The authors wish to thank Esther Eshkol for her assistance in preparing the manuscript.
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