Neuropsychological and neuroimaging evidences of cerebral dysfunction in stroke-free patients with atrial fibrillation: A review.

Atrial fibrillation (AF) is the most common heart arrhythmia, with the highest prevalence in the elderly. AF has been correlated with silent lesions and cognitive impairment, even in the absence of stroke. The cognitive impairment in AF represents a risk of functional decline, morbidity, mortality and high costs, constituting a public health problem due to the increasing prevalence of this arrhythmia. Cognitive analysis of patients with AF without stroke has shown poor performance in executive, memory and learning functions. The greater loss occurs in speed processing and performance of instrumental tasks leading to functional dependence. Neuroimaging studies have shown both structural and functional abnormalities in individuals with AF even in the absence of cognitive impairment. The mechanisms related to cognitive impairment and cerebral abnormalities in the AF are still a matter of discussion in the literature and, therefore, how to stop its progression is unknown. We reviewed the recent evidence about AF and dementia in patients without stroke, with special emphasis to the reported profile of cognitive dysfunction and the neuroimaging evidence of brain abnormalities.

Cerebral vasomotor reactivity assessment using Transcranial Doppler and MRI with apnea test.

Differently from previous studies that used Transcranial Doppler (TCD) and functional MRI (fMRI) for cerebral vasomotor reactivity (CVR) assessment in patients with carotid stenosis (CS), we assessed CVR using an identical stimulus, the Breath-Holding Test (BHT). We included 15 patients with CS and 7 age-matched controls to verify whether fMRI responded differently to BHT between groups and to calculate the agreement rate between tests. For TCD, impaired CVR was defined when the mean percentage increase on middle cerebral artery velocities was ≤31% on 3 consecutive 30-s apnea intercalated by 4-min normal breathing intervals. For fMRI, the percent variation on blood oxygen level-dependent (BOLD) signal intensity in the lentiform nucleus (LN) ipsilateral to the CS (or both LNs for controls) from baseline breathing to apnea was measured. The Euclidian differences between the series of each subject and the series of controls and patients classified it into normal or impaired CVR. We found different percent variations on BOLD-signal intensities between groups (P=0.032). The agreement was good in Controls (85.7%; κ=0.69) and overall (77.3%; κ=0.54). We conclude that BHT was feasible for CVR assessment on fMRI and elicited different BOLD responses in patients and controls, with a good overall agreement between the tests.

Texture analysis of computed tomography images of acute ischemic stroke patients

Computed tomography (CT) images are routinely used to assess ischemic brain stroke in the acute phase. They can provide important clues about whether to treat the patient by thrombolysis with tissue plasminogen activator. However, in the acute phase, the lesions may be difficult to detect in the images using standard visual analysis. The objective of the present study was to determine if texture analysis techniques applied to CT images of stroke patients could differentiate between normal tissue and affected areas that usually go unperceived under visual analysis. We performed a pilot study in which texture analysis, based on the gray level co-occurrence matrix, was applied to the CT brain images of 5 patients and of 5 control subjects and the results were compared by discriminant analysis. Thirteen regions of interest, regarding areas that may be potentially affected by ischemic stroke, were selected for calculation of texture parameters. All regions of interest for all subjects were classified as lesional or non-lesional tissue by an expert neuroradiologist. Visual assessment of the discriminant analysis graphs showed differences in the values of texture parameters between patients and controls, and also between texture parameters for lesional and non-lesional tissue of the patients. This suggests that texture analysis can indeed be a useful tool to help neurologists in the early assessment of ischemic stroke and quantification of the extent of the affected areas.

Texture analysis of computed tomography images of acute ischemic stroke patients.

Computed tomography (CT) images are routinely used to assess ischemic brain stroke in the acute phase. They can provide important clues about whether to treat the patient by thrombolysis with tissue plasminogen activator. However, in the acute phase, the lesions may be difficult to detect in the images using standard visual analysis. The objective of the present study was to determine if texture analysis techniques applied to CT images of stroke patients could differentiate between normal tissue and affected areas that usually go unperceived under visual analysis. We performed a pilot study in which texture analysis, based on the gray level co-occurrence matrix, was applied to the CT brain images of 5 patients and of 5 control subjects and the results were compared by discriminant analysis. Thirteen regions of interest, regarding areas that may be potentially affected by ischemic stroke, were selected for calculation of texture parameters. All regions of interest for all subjects were classified as lesional or non-lesional tissue by an expert neuroradiologist. Visual assessment of the discriminant analysis graphs showed differences in the values of texture parameters between patients and controls, and also between texture parameters for lesional and non-lesional tissue of the patients. This suggests that texture analysis can indeed be a useful tool to help neurologists in the early assessment of ischemic stroke and quantification of the extent of the affected areas.

Perception and attitude towards stroke by professionals of emergency medical service in an urban city in southeastern Brazil.

INTRODUCTION: Stroke awareness by lay people in general is poor. It has been estimated that only as much as one third of patients with acute stroke reach emergency medical services within two hours of onset of their symptoms. We aimed to assess perception of and attitude towards a person with an acute stroke by professionals working in mobile unit of emergency medical service in the city of Campinas, Brazil. MATERIAL AND METHODS: The study was conducted during VII Stroke Workshop of Campinas in November 2007. We used an anonymous self-report questionnaire with a clinical case of an acute stroke with duration of 50 minutes. We asked two open-ended questions to gauge perception and attitude. RESULTS: One-hundred forty-nine of 205 (73%) participants answered the questionnaire; 49% were women, average age of 37 years (range 21-59). Ninety (60%) were professionals allied to medicine (nurses, health auxiliary, dentists), six (4%) were physicians, and 53 (36%) were other professionals (secretary, driver). In regard to perception, 142 of 149 (95%) had a correct perception of stroke. In regard to attitude, in general, the basic support measures have been pointed out, but only one (0.5%) mentioned an issue of time less than 3 hours for thrombolysis, four (2%) mentioned the possibility of thrombolysis, and 12 (8%) requested computed tomographic examination. DISCUSSION: It appears that professionals allied to medicine can diagnosis stroke of anterior circulation; however, they do not have thrombolytic therapy in mind, and this should be considered the default treatment for all patients with stroke within the "therapeutic window."