Wagner Mauad Avelar

Brazilian guidelines for the application of transcranial ultrasound as a diagnostic test for the confirmation of brain death

Neurosonological studies, specifically transcranial Doppler (TCD) and transcranial color-coded duplex (TCCD), have high level of specificity and sensitivity and they are used as complementary tests for the diagnosis of brain death (BD). A group of experts, from the Neurosonology Department of the Brazilian Academy of Neurology, created a task force to determine the criteria for the following aspects of diagnosing BD in Brazil: the reliability of TCD methodology; the reliability of TCCD methodology; neurosonology training and skills; the diagnosis of encephalic circulatory arrest; and exam documentation for BD. The results of this meeting are presented in the current paper.

Asymptomatic carotid stenosis is associated with gray and white matter damage

Background Cognitive deficits in patients with asymptomatic carotid stenosis have been reported. The ultimate mechanism of cognitive deficits remains unclear and might be related to subtle structural brain damage. Aims The aim of the present study was to evaluate the presence of subtle white and grey matter abnormalities associated with asymptomatic carotid stenosis. Methods Twenty-five patients with asymptomatic ≥70%/occlusion carotid stenosis and 25 healthy controls, matched for gender and age, underwent 3 Tesla brain magnetic resonance imaging. Gray and white matter macrostructural abnormalities were evaluated with voxel-based morphometry using spm8 software. White matter microstructural abnormalities were evaluated with diffusion tensor images with the Diffusion Toolbox package and tract-based spatial statistics from FMRIB Software Library. Results We observed significant macro- and microstructural white matter abnormalities, and these findings were diffuse and symmetrical in both hemispheres. In contrast, gray matter atrophy was observed in the areas corresponding to the anterior circulation of the hemisphere ipsilateral to the carotid stenosis. Conclusions Patients with asymptomatic carotid stenosis have different patterns of gray and white matter abnormalities. While the white matter damage is diffuse, the gray matter atrophy is localized in the territory of anterior circulation ipsilateral to the stenosis. The role of asymptomatic carotid stenosis in the gray matter damage must be further investigated with longitudinal studies and comparison with neuropsychological evaluation.

Semantic aphasia as a sole manifestation of acute stroke

Neurology Service, Hospital e Maternidade Sao Camilo (Pompeia), Sao Paulo SP, Brazil: MD, MSc, Neurologist; MD, Neurologist. The concept of aphasia designates impairment in the symbolic domains of language (vocabulary, semantics, phonology, syntax and morphology) by one or more lesions in the dominant cerebral hemisphere, which may be manifest through spoken and written comprehension and production, but can not be explained by motor or sensory deficits in view of the preservation of phono-articulatory structures, and neither by generalized cognitive deficits (consciousness must be preserved). Stroke is the leading cause of aphasia, which may be identified in more than 20% of stroke patients, reaching up to 40% in the acute phase. These language disturbances may help forecast the vascular territories involved in brain injury. Errors in naming are more frequent when associated to grave mistakes in fluency and comprehension both for oral and written material, such as in global aphasia, motor aphasia or sensory aphasia. The diagnosis of semantic aphasia may pass unnoticed if a specific assessment is not undertaken, particularly considering that semantic errors may be produced in naming, reading, spelling, copying or drawing from memory. Prognosis is better than for other vascular aphasic syndromes, but may be related to the size of brain injury (including both the infarcted tissues and the hypoperfused areas) and to the presence of cortical involvement, among other factors. We report the case of a patient who presented with language impairment as the only symptom in the acute stroke phase, leading to a diagnosis of vascular semantic aphasia. The importance of accurate language evaluation for stroke diagnosis will be discussed.

Default Mode Network Disruption in Stroke-Free Patients with Atrial Fibrillation

Background: Atrial fibrillation (AF) is a widely accepted risk for causing stroke. However, recent studies show AF as a risk factor for dementia, even without causing stroke. The mechanisms by which dementia develops in stroke-free patients with AF are still poorly understood and the association of AF with abnormal function of brain networks activities, such as the default mode network (DMN), has not been previously studied. We aimed to determine whether, in the absence of stroke and dementia, patients with AF have abnormal resting-state brain networks compared to controls without AF. Methods: Twenty-one stroke-free patients with AF and 21 age- and sex-matched controls without AF underwent brain functional magnetic resonance imaging acquired at a 3.0 Tesla scanner. During the exam, the subjects were instructed to lie still with eyes closed. At first-level analysis, connectivity of the DMN was obtained for all subjects. Second-level analysis compared the DMN connectivity between AF patients and controls with a general linear model (two-sample t test, p < 0.05, False Discovery Rate corrected, minimum of 50 contiguous voxels). Results: Patients with AF compared with controls showed decreased connectivity in regions of the DMN including the frontal lobe (left medial frontal gyrus, left superior frontal gyrus and anterior cingulate), left angular gyrus, and bilateral precuneus. Conclusions: Stroke-free patients with AF have evidence of abnormal DMN connectivity. This study adds evidence to the occurrence of cerebral dysfunction in patients with AF.

Screening of genes related to the atherosclerotic plaque stability in patients with asymptomatic carotid stenosis

Carotid stenosis is the narrowing of the carotid arteries due to atherosclerosis. Our goal in this study was to search for copy number variants (CNV) in the human genome which may be related to risk of plaque formation and rupture. We obtained DNA from age matched patients at Hospital das Clínicas, in Campinas. Our cohort is composed by 15 patients with asymptomatic carotid stenosis and 15 with symptomatic carotid stenosis. All samples were genotyped using a SNP microarray and analysed. We identified various CNVs located in genes of the complement system, cytoskeletal remodelling and cell adhesion pathways. In our samples, we observed deletions in genes from both classical and lectin pathways of the complement system. Low levels of lectin binding mannose (MBL), is related to enhanced plaque formation. In addition, we found three patients with duplications in UPAR. The urokinase-type plasminogen activator receptor is part of the cytoskeletal remodelling pathway and has been previously associated to plaque rupture due to its increased expression in macrophages. Furthermore, we found a duplication in the PKC gene in one patient. It is known that Protein Kinase C, present at the cell adhesion pathway, when active stimulates the adhesion of monocytes to endothelial cells, therefore accelerating plaque formation. Overall, our results indicate that genes related to plaque formation and rupture were either duplicated or deleted in patients with asymptomatic carotid stenosis.

Electroencephalography Patterns and Prognosis in Acute Ischemic Stroke.

Background and Purpose: The prognostic significance of interictal epileptiform discharges (IED) and periodic patterns (PP) after ischemic stroke has not been assessed. We sought to test whether IED and PP, detected on standard Electroencephalography (EEG) performed during the acute phase of ischemic stroke are associated with a worse functional outcome. Methods: One-hundred-fifty-seven patients 18 years or older with a diagnosis of acute ischemic stroke presenting within 72 h from stroke onset were prospectively enrolled and followed. Patients with a pre-stroke history of seizures or epilepsy, previous debilitating neurological disease or conditions that precluded the performance of EEG were excluded. Interpretation was performed by a blinded board certified neurophysiologist. IED and PP (grouped as epileptiform activity [EA]) were defined according to proposed guidelines. Univariable and multivariable analyses were used to identify predictors of outcome (modified Rankin Scale dichotomized ≤2 vs. ≥3) at 3 months. Results: In the univariable analysis, admission NIHSS (OR 1.20, 95% CI 1.12-1.28, p = 0.001), age (OR 1.03, 95% CI 1.01-1.05, p = 0.02), and presence of EA (OR 2.94, 95% CI 1.51-5.88, p = 0.001) were significantly associated with the outcome at 3 months. In the multivariable analysis, only admission NIHSS (OR 1.19, 95% CI 1.11-1.28, p < 0.001) and the presence of EA (OR 2.27, 95% CI 1.04-5.00, p = 0.04) were independently associated with the prognosis. Significance: The importance of EEG in the prognosis of acute ischemic stroke warrants additional research, examining the role of medication therapy on the outcome and the occurrence of seizures for those patients with specific EEG patterns.

A comparative analysis of transcranial Doppler parameters acquired during carotid stenting and semi-eversion carotid endarterectomy

Abstract Background Carotid endarterectomy (CEA) and carotid artery stenting (CAS) have both been proposed for treatment of critical atherosclerotic stenosis located at the carotid bifurcation. Monitoring of hyperintense microembolic signals (MES) by transcranial Doppler ultrasound (TCD) is considered a method of quality control, both in CEA and in CAS. Objective To analyze temporal distribution of MES throughout both semi-eversion CEA and CAS procedures and to evaluate changes in mean velocity of blood flow through the ipsilateral middle cerebral artery (MCA). Method Thirty-three procedures (17 CEA and 16 CAS) were prospectively monitored using TCD and the data were related to three different stages of surgery (pre-cerebral protection, during cerebral protection and post-cerebral protection). Chi-square, Mann-Whitney, ANOVA and contrast tests were used for statistical analysis. Results The MES were uniformly distributed in the CEA group, but not in the CAS group (p = 0.208). The number of MES was higher in the CAS group in all stages. The average flow in the MCA was similarly lower in both groups during the protection stage. Conclusion CEA provoked a lower incidence of MES per procedure than CAS in all stages. The behavior of the averages of the mean of blood flow through the MCA was similar in both groups.

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.

Cerebral vasoreactivity with breath holding test in Transcranial Doppler and functional MRI in patients with carotid stenosis

WCN 2013 No: 1856 Topic: 3 — Stroke Cerebral vasoreactivity with breath holding test in Transcranial Doppler and functional MRI in patients with carotid stenosis C.R. Campos-Herrera, G.C. Beltramini, W.M. Avelar, L.M. Li. Neurology, Faculty of Medical Sciences, State University of Campinas, Brazil; ‘Gleb Wataghin’ Physics Institute, State University of Campinas,

Fatores de risco no tratamento de lesões do ceco com sutura primária em ratos

Purpose: Analyze the results of primary suture in the treatment of cecum traumatic injuries in rats, after the exposure to increasing time intervals between the trauma and the surgery and with different peritonitis degrees. Methods: In a randomized double-blinded study, 96 Wistar male rats, weight ranging between 200 and 250 grams, underwent laparotomy, in which a 5-milimiter-diameter-injury in the contramesenteric edge of the cecum was performed. In 12 animals of the control-group a prompt primary suture was executed, with total and separated stitches, with 7.0 polypropylene thread. In the other groups, with 12 animals each, a laparotomy for repair of the injury was executed after intervals of 30 minutes, 1, 2, 4, 6, 9 and 12 hours. At the time of injury repair, one of its edges was ressected and sent for anatomopathological examination. A daily control after the surgery was done, observing the presence of complications, specially dehiscence of the suture, and the euthanasia of the animals were done in the 1st, 4th, 7th and 14th day after the surgery. Necropsy was executed in all animals, observing the macroscopic and microscopic findings in the area of suture. Results: There was no association between the delay for surgical treatment of the injury and peritonitis degrees. The mortality in the 14 animals with diffuse peritonitis was 100%. Global mortality was 25% (24 animals), and 6 animals (25%) died before treatment. None of the animals treated that evolved to death had complications related to the suture of the injury. These early deaths were due to peritonitis and sepsis. Among the 72 surviving rats, there was dehiscence of the suture in 9 animals (12.5%). This complication was statistically significant greater in animals operated on after the sixth hour following the trauma. The incidence of dehiscence was also greater in the rats presenting more intense fecal contamination. Intensity of the peritonitis at the moment of suture observed in histological examination had no association with the occurrence of complications of the primary suture. Conclusion: The primary suture as a risky procedure to treat rats, after an interval superior to six hours after the trauma or in the period of intense contamination of the cavity by feces.