Ischemic stroke caused by large-artery atherosclerosis: a red flag for subclinical coronary artery disease.

Background: The coronary calcium score (CAC) measured on chest computerized tomography is a risk marker of cardiac events and mortality. We compared CAC scores in two multiethnic groups without symptomatic coronary artery disease: subjects in the chronic phase after stroke or transient ischemic attack and at least one symptomatic stenosis ≥50% in the carotid or vertebrobasilar territories (Groupathero) and a control group (Groupcontrol). Methods: In this cross-sectional study, Groupathero included two subgroups: GroupExtraorIntra, with stenoses in either cervical or intracranial arteries, and GroupExtra&Intra, with stenoses in at least one cervical and one intracranial artery. Groupcontrol had no history of prior stroke/transient ischemic attacks and no stenoses ≥50% in cervical or intracranial arteries. Age and sex were comparable in all groups. Frequencies of CAC ≥100 and CAC > 0 were compared between Groupathero and Groupcontrol, as well as between GroupExtraorIntr, GroupExtra&Intra, and Groupcontrol, with bivariate logistic regressions. Multivariate analyses were also performed. Results: A total of 120 patients were included: 80 in Groupathero and 40 in Groupcontrol. CAC >0 was significantly more frequent in Groupathero (85%) than Groupcontrol (OR, 4.19; 1.74-10.07; p = 0.001). Rates of CAC ≥100 were not significantly different between Groupathero and Groupcontrol but were significantly greater in GroupExtra&Intra (n = 13) when compared to Groupcontrol (OR 4.67; 1.21-18.04; p = 0.025). In multivariate-adjusted analyses, "Groupathero" and "GroupExtra&Intra" were significantly associated with CAC. Conclusion: The frequency of coronary calcification was higher in subjects with stroke caused by large-artery atherosclerosis than in controls.

Latin American Initiative for Lifestyle Intervention to Prevent Cognitive Decline (LatAm-FINGERS): Study design and harmonization.

INTRODUCTION: Latin American Initiative for Lifestyle Intervention to Prevent Cognitive Decline (LatAm-FINGERS) is the first non-pharmacological multicenter randomized clinical trial (RCT) to prevent cognitive impairment in Latin America (LA). Our aim is to present the study design and discuss the strategies used for multicultural harmonization. METHODS: This 1-year RCT (working on a 1-year extension) investigates the feasibility of a multi-domain lifestyle intervention in LA and the efficacy of the intervention, primarily on cognitive function. An external harmonization process was carried out to follow the FINGER model, and an internal harmonization was performed to ensure this study was feasible and comparable across the 12 participating LA countries. RESULTS: Currently, 1549 participants have been screened, and 815 randomized. Participants are ethnically diverse (56% are Nestizo) and have high cardiovascular risk (39% have metabolic syndrome). DISCUSSION: LatAm-FINGERS overcame a significant challenge to combine the region's diversity into a multi-domain risk reduction intervention feasible across LA while preserving the original FINGER design.

Postmortem brain 7T MRI with minimally invasive pathological correlation in deceased COVID-19 subjects.

BACKGROUND: Brain abnormalities are a concern in COVID-19, so we used minimally invasive autopsy (MIA) to investigate it, consisting of brain 7T MR and CT images and tissue sampling via transethmoidal route with at least three fragments: the first one for reverse transcription polymerase chain reaction (RT-PCR) analysis and the remaining fixed and stained with hematoxylin and eosin. Two mouse monoclonal anti-coronavirus (SARS-CoV-2) antibodies were employed in immunohistochemical (IHC) reactions. RESULTS: Seven deceased COVID-19 patients underwent MIA with brain MR and CT images, six of them with tissue sampling. Imaging findings included infarcts, punctate brain hemorrhagic foci, subarachnoid hemorrhage and signal abnormalities in the splenium, basal ganglia, white matter, hippocampi and posterior cortico-subcortical. Punctate brain hemorrhage was the most common finding (three out of seven cases). Brain histological analysis revealed reactive gliosis, congestion, cortical neuron eosinophilic degeneration and axonal disruption in all six cases. Other findings included edema (5 cases), discrete perivascular hemorrhages (5), cerebral small vessel disease (3), perivascular hemosiderin deposits (3), Alzheimer type II glia (3), abundant corpora amylacea (3), ischemic foci (1), periventricular encephalitis foci (1), periventricular vascular ectasia (1) and fibrin thrombi (1). SARS-CoV-2 RNA was detected with RT-PCR in 5 out of 5 and IHC in 6 out 6 patients (100%). CONCLUSIONS: Despite limited sampling, MIA was an effective tool to evaluate underlying pathological brain changes in deceased COVID-19 patients. Imaging findings were varied, and pathological features corroborated signs of hypoxia, alterations related to systemic critically ill and SARS-CoV-2 brain invasion.

Inverse Association Between Hypothalamic N-Acetyl Aspartate/Creatine Ratio and Indices of Body Mass in Adolescents with Obesity.

BACKGROUND: Approximately 10% of adolescents worldwide are overweight or obese, hence the urgent and universal need to elucidate possible mechanisms that lead to obesity in the adolescent population. OBJECTIVES: We examined the hypothalamic metabolism and its relationship with physical development in obese and eutrophic adolescents. METHODS: We performed a case-control study with 115 adolescents between 11 and 18 years of age, to compare obese (BMI z-score ≥ 2) and nonobese individuals (eutrophic controls; BMI z-score ≤ 1). The following hypothalamic metabolite ratios were examined as primary outcomes: glutamate/creatine (Cr), the sum of glutamate and glutamine/Cr, N-acetylaspartate (NAA)/Cr, myoinositol/Cr, and total choline/Cr (glycerophosphocholine +  phosphocholine/Cr), quantified by magnetic resonance spectroscopy. BMI z-scores, pubertal status, and scores on the Yale Food Addiction Scale, the Binge Eating Scale, and the Child Depression Inventory were assessed as secondary outcomes. Pearson coefficients (r) or nonparametric Spearman correlation (rho) analyses were performed between hypothalamic metabolite ratios and other parameters, such as BMI z-scores, physical development, food habits, depression symptoms, and serum protein concentrations (cytokines, hormones, and neuropeptides). RESULTS: Adolescents with obesity showed a lower hypothalamic NAA/Cr ratio (0.70 ± 0.19) compared to their eutrophic counterparts (0.84 ± 0.20; P = 0.004). The NAA/Cr ratio was negatively correlated with BMI z-scores (r = -0.25; P = 0.03) and serum insulin (rho = -0.27; P = 0.04), C-peptide (rho = -0.26; P = 0.04), amylin (r = -0.27; P = 0.04), ghrelin (rho = -0.30; P = 0.02), and neuropeptide Y (r = -0.27; P = 0.04). Also, the NAA/Cr ratio was positively correlated with circulating IL-8 levels (rho = 0.26; P = 0.04). CONCLUSIONS: High BMI z-scores are associated with lower hypothalamic NAA/Cr ratios. The negative correlations found between the NAA/Cr ratio and serum cytokines, hormones, and neuropeptides suggest a broad cross-talk linking hormonal imbalances, neurohumoral alterations, and hypothalamic functions in adolescents with obesity.

Acute Disseminated Encephalomyelitis in COVID-19: presentation of two cases and review of the literature.

BACKGROUND: Neurological manifestations of COVID-19 are still incompletely understood. Neurological manifestations may be due to direct viral effect on neurons and glial cells, to an immune-mediated response to the virus, or to a hypercoagulable state and associated endothelial damage, as well as to severe systemic disease with prolonged intensive care unit stay. OBJECTIVE: To describe two patients with severe SARS-CoV-2 infection and delayed recovery of consciousness after sedation withdrawal, in whom MRI disclosed multifocal white matter brain lesions, compatible with the diagnosis of acute disseminated encephalomyelitis. METHODS: Observational report of two cases of severe COVID-19 infection in patients from two tertiary hospitals in São Paulo, Brazil. RESULTS: These patients underwent neurologic and systemic evaluation for delayed awakening after sedation withdrawal. MRI displayed multifocal centrum semiovale lesions, suggestive of demyelinating inflammation. Cerebrospinal fluid (CSF) polymerase chain reaction (PCR) for SARS-CoV-2 was negative in both cases. CONCLUSION: A recurrent pattern of multifocal white matter lesions can occur in COVID-19 patients, possibly associated with delayed awakening. Additional studies are necessary to elucidate the role of the viral infection and of inflammatory and immune-mediated associated changes in neurological manifestations of COVID-19.

Acute Disseminated Encephalomyelitis in COVID-19: presentation of two cases and review of the literature / Encefalomielite disseminada aguda associada a COVID-19: relato de dois casos e revisão de literatura

ABSTRACT Background: Neurological manifestations of COVID-19 are still incompletely understood. Neurological manifestations may be due to direct viral effect on neurons and glial cells, to an immune-mediated response to the virus, or to a hypercoagulable state and associated endothelial damage, as well as to severe systemic disease with prolonged intensive care unit stay. Objective: To describe two patients with severe SARS-CoV-2 infection and delayed recovery of consciousness after sedation withdrawal, in whom MRI disclosed multifocal white matter brain lesions, compatible with the diagnosis of acute disseminated encephalomyelitis. Methods: Observational report of two cases of severe COVID-19 infection in patients from two tertiary hospitals in São Paulo, Brazil. Results: These patients underwent neurologic and systemic evaluation for delayed awakening after sedation withdrawal. MRI displayed multifocal centrum semiovale lesions, suggestive of demyelinating inflammation. Cerebrospinal fluid (CSF) polymerase chain reaction (PCR) for SARS-CoV-2 was negative in both cases. Conclusion: A recurrent pattern of multifocal white matter lesions can occur in COVID-19 patients, possibly associated with delayed awakening. Additional studies are necessary to elucidate the role of the viral infection and of inflammatory and immune-mediated associated changes in neurological manifestations of COVID-19.

RESUMO Introdução: As manifestações neurológicas causadas pela COVID-19 ainda não estão completamente elucidadas. O comprometimento neurológico pode decorrer de um efeito viral direto em neurônios ou em células gliais, a efeito imunomediado em resposta à infecção viral, ou de um efeito secundário a estados de hipercoagulabilidade e danos endoteliais, assim como decorrente de complicações sistêmicas graves relacionadas a cuidados intensivos prolongados na unidade de terapia intensiva. Objetivo: Descrever dois pacientes com recuperação tardia do nível de consciência após a retirada da sedação associados à infecção grave pelo SARS-CoV-2, que apresentaram lesões multifocais de substância branca, compatíveis com o diagnóstico de encefalomielite disseminada aguda. Métodos: Estudo observacional, com relato de dois casos de infecção grave pela COVID-19, em dois hospitais terciários na cidade de São Paulo, Brasil. Resultados: Os pacientes foram submetidos à investigação sistêmica e neurológica para avaliação de estado alterado de consciência após retirada de sedação. A ressonância magnética de crânio evidenciou lesões multifocais no centro semioval, sugestivos de processo inflamatório desmielinizante. Análise liquórica evidenciou PCR negativo para SARS-CoV-2 em ambos os casos. Conclusão: Lesões multifocais de substância branca podem ocorrer em pacientes com COVID-19, possivelmente associadas a estados alterados de consciência. Estudos adicionais são necessários para determinar o processo fisiopatológico da infecção viral e dos estados inflamatórios e imunomediados na gênese das manifestações neurológicas causadas pela COVID-19.

Aging Effects on Whole-Brain Functional Connectivity in Adults Free of Cognitive and Psychiatric Disorders.

Aging is associated with decreased resting-state functional connectivity (RSFC) within the default mode network (DMN), but most functional imaging studies have restricted the analysis to specific brain regions or networks, a strategy not appropriate to describe system-wide changes. Moreover, few investigations have employed operational psychiatric interviewing procedures to select participants; this is an important limitation since mental disorders are prevalent and underdiagnosed and can be associated with RSFC abnormalities. In this study, resting-state fMRI was acquired from 59 adults free of cognitive and psychiatric disorders according to standardized criteria and based on extensive neuropsychological and clinical assessments. We tested for associations between age and whole-brain RSFC using Partial Least Squares, a multivariate technique. We found that normal aging is not only characterized by decreased RSFC within the DMN but also by ubiquitous increases in internetwork positive correlations and focal internetwork losses of anticorrelations (involving mainly connections between the DMN and the attentional networks). Our results reinforce the notion that the aging brain undergoes a dedifferentiation processes with loss of functional diversity. These findings advance the characterization of healthy aging effects on RSFC and highlight the importance of adopting a broad, system-wide perspective to analyze brain connectivity.

Reduced prefrontal activation in pediatric patients with obsessive-compulsive disorder during verbal episodic memory encoding.

OBJECTIVE: Patients with obsessive-compulsive disorder (OCD) often present with deficits in episodic memory, and there is evidence that these difficulties may be secondary to executive dysfunction, that is, impaired selection and/or application of memory-encoding strategies (mediation hypothesis). Semantic clustering is an effective strategy to enhance encoding of verbal episodic memory (VEM) when word lists are semantically related. Self-initiated mobilization of this strategy has been associated with increased activity in the prefrontal cortex, particularly the orbitofrontal cortex, a key region in the pathophysiology of OCD. We therefore studied children and adolescents with OCD during uncued semantic clustering strategy application in a VEM functional magnetic resonance imaging (fMRI)-encoding paradigm. METHOD: A total of 25 pediatric patients with OCD (aged 8.1-17.5 years) and 25 healthy controls (HC, aged 8.1-16.9) matched for age, gender, handedness, and IQ were evaluated using a block design VEM paradigm that manipulated semantically related and unrelated words. RESULTS: The semantic clustering strategy score (SCS) predicted VEM performance in HC (p < .001, R(2) = 0.635), but not in patients (p = .099). Children with OCD also presented hypoactivation in the dorsomedial prefrontal cortex (cluster-corrected p < .001). Within-group analysis revealed a negative correlation between Yale-Brown Obsessive Compulsive Scale scores and activation of orbitofrontal cortex in the group with OCD. Finally, a positive correlation between age and SCS was found in HC (p = .001, r = 0.635), but not in patients with OCD (p = .936, r = 0.017). CONCLUSION: Children with OCD presented altered brain activation during the VEM paradigm and absence of expected correlation between SCS and age, and between SCS and total words recalled. These results suggest that different neural mechanisms underlie self-initiated semantic clustering in OCD.

Avoiding pitfalls in diagnosing basilar artery occlusive disease: clinical and imaging clues - case report.

CONTEXT: The aim of this paper was to report on the characteristics that aid in establishing the diagnosis of basilar artery occlusive disease (BAOD) among patients with hemiparesis and few or minor symptoms of vertebrobasilar disease. CASE REPORT: This report describes two cases in a public university hospital in São Paulo, Brazil. We present clinical and imaging findings from two patients with hemiparesis and severe BAOD, but without clinically relevant carotid artery disease (CAD). One patient presented transient ischemic attacks consisting of spells of right hemiparesis that became progressively more frequent, up to twice a week. The neurological examination revealed slight right hemiparesis and right homonymous hemianopsia. Magnetic resonance imaging (MRI) revealed pontine and occipital infarcts. Magnetic resonance angiography and digital subtraction angiography revealed severe basilar artery stenosis. The other patient presented sudden left-side hemiparesis and hypoesthesia. One year earlier, she had reported sudden onset of vertigo that, at that time, was attributed to peripheral vestibulopathy and was not further investigated. MRI showed a right-side pontine infarct and an old infarct in the right cerebellar hemisphere. Basilar artery occlusion was diagnosed. Both patients presented their symptoms while receiving aspirin, and became asymptomatic after treatment with warfarin. CONCLUSIONS: Misdiagnosing asymptomatic CAD as the cause of symptoms in BAOD can have disastrous consequences, such as unnecessary carotid endarterectomy and exposure to this surgical risk while failing to offer the best available treatment for BAOD. Clinical and imaging features provided important clues for diagnosis in the cases presented.

Avoiding pitfalls in diagnosing basilar artery occlusive disease: clinical and imaging clues - case report / Evitando erros no diagnóstico de doença oclusiva da artéria basilar: pistas clínicas e radiológicas - relato de caso

CONTEXT: The aim of this paper was to report on the characteristics that aid in establishing the diagnosis of basilar artery occlusive disease (BAOD) among patients with hemiparesis and few or minor symptoms of vertebrobasilar disease. CASE REPORT: This report describes two cases in a public university hospital in São Paulo, Brazil. We present clinical and imaging findings from two patients with hemiparesis and severe BAOD, but without clinically relevant carotid artery disease (CAD). One patient presented transient ischemic attacks consisting of spells of right hemiparesis that became progressively more frequent, up to twice a week. The neurological examination revealed slight right hemiparesis and right homonymous hemianopsia. Magnetic resonance imaging (MRI) revealed pontine and occipital infarcts. Magnetic resonance angiography and digital subtraction angiography revealed severe basilar artery stenosis. The other patient presented sudden left-side hemiparesis and hypoesthesia. One year earlier, she had reported sudden onset of vertigo that, at that time, was attributed to peripheral vestibulopathy and was not further investigated. MRI showed a right-side pontine infarct and an old infarct in the right cerebellar hemisphere. Basilar artery occlusion was diagnosed. Both patients presented their symptoms while receiving aspirin, and became asymptomatic after treatment with warfarin. CONCLUSIONS: Misdiagnosing asymptomatic CAD as the cause of symptoms in BAOD can have disastrous consequences, such as unnecessary carotid endarterectomy and exposure to this surgical risk while failing to offer the best available treatment for BAOD. Clinical and imaging features provided important clues for diagnosis in the cases presented.

CONTEXTO: O objetivo deste artigo foi de relatar as características que auxiliam no estabelecimento do diagnóstico da doença oclusiva da artéria basilar (DOAB) em pacientes com hemiparesia e poucos sintomas, ou sintomas leves de doença vertebrobasilar. RELATO DE CASO: Descrição de dois casos em um hospital público universitário em São Paulo, Brasil. Apresentamos características clínicas e radiológicas de dois pacientes com hemiparesia e DOAB grave, na ausência de doença carotídea (DCA) relevante. Um paciente apresentou ataques isquêmicos transitórios consistindo de hemiparesia direita transitória, que se tornaram progressivamente mais frequentes, até duas vezes por semana. O exame neurológico revelou hemiparesia direita e hemianopsia homônima direita. A ressonância magnética (RM) revelou infartos pontinos e occipitais. As angiografias por ressonância magnética e por subtração digital revelaram estenose grave da artéria basilar. Outra paciente apresentou hemiparesia e hipoestesia de instalação súbita, à esquerda. Um ano antes, ela havia apresentado vertigem súbita, na ocasião atribuída a vestibulopatia periférica, não investigada em maior profundidade. A RM mostrou infarto pontino à direita e infarto antigo no hemisfério cerebelar direito. Foi diagnosticada oclusão da artéria basilar. Ambos os pacientes apresentaram os sintomas enquanto faziam tratamento com aspirina, e se tornaram assintomáticos após tratamento com warfarina. CONCLUSÕES: O diagnóstico errôneo de DCA como causa de sintomas na DOAB pode ter conseqüências desastrosas, como a endarterectomia carotídea desnecessária e a exposição a tal risco cirúrgico, ao invés de oferecimento do melhor tratamento disponível para a DOAB. Características clínicas e radiológicas forneceram pistas importantes para o diagnóstico nos casos apresentados.

Evaluating SVM and MLDA in the extraction of discriminant regions for mental state prediction.

Pattern recognition methods have been successfully applied in several functional neuroimaging studies. These methods can be used to infer cognitive states, so-called brain decoding. Using such approaches, it is possible to predict the mental state of a subject or a stimulus class by analyzing the spatial distribution of neural responses. In addition it is possible to identify the regions of the brain containing the information that underlies the classification. The Support Vector Machine (SVM) is one of the most popular methods used to carry out this type of analysis. The aim of the current study is the evaluation of SVM and Maximum uncertainty Linear Discrimination Analysis (MLDA) in extracting the voxels containing discriminative information for the prediction of mental states. The comparison has been carried out using fMRI data from 41 healthy control subjects who participated in two experiments, one involving visual-auditory stimulation and the other based on bi-manual fingertapping sequences. The results suggest that MLDA uses significantly more voxels containing discriminative information (related to different experimental conditions) to classify the data. On the other hand, SVM is more parsimonious and uses less voxels to achieve similar classification accuracies. In conclusion, MLDA is mostly focused on extracting all discriminative information available, while SVM extracts the information which is sufficient for classification.

Hyperplane navigation: a method to set individual scores in fMRI group datasets.

Recent studies have demonstrated that spatial patterns of fMRI BOLD activity distribution over the brain may be used to classify different groups or mental states. These studies are based on the application of advanced pattern recognition approaches and multivariate statistical classifiers. Most published articles in this field are focused on improving the accuracy rates and many approaches have been proposed to accomplish this task. Nevertheless, a point inherent to most machine learning methods (and still relatively unexplored in neuroimaging) is how the discriminative information can be used to characterize groups and their differences. In this work, we introduce the Maximum Uncertainty Linear Discrimination Analysis (MLDA) and show how it can be applied to infer groups' patterns by discriminant hyperplane navigation. In addition, we show that it naturally defines a behavioral score, i.e., an index quantifying the distance between the states of a subject from predefined groups. We validate and illustrate this approach using a motor block design fMRI experiment data with 35 subjects.

Intervention models in functional connectivity identification applied to FMRI.

Recent advances in neuroimaging techniques have provided precise spatial localization of brain activation applied in several neuroscience subareas. The development of functional magnetic resonance imaging (fMRI), based on the BOLD signal, is one of the most popular techniques related to the detection of neuronal activation. However, understanding the interactions between several neuronal modules is also an important task, providing a better comprehension about brain dynamics. Nevertheless, most connectivity studies in fMRI are based on a simple correlation analysis, which is only an association measure and does not provide the direction of information flow between brain areas. Other proposed methods like structural equation modeling (SEM) seem to be attractive alternatives. However, this approach assumes prior information about the causality direction and stationarity conditions, which may not be satisfied in fMRI experiments. Generally, the fMRI experiments are related to an activation task; hence, the stimulus conditions should also be included in the model. In this paper, we suggest an intervention analysis, which includes stimulus condition, allowing a nonstationary modeling. Furthermore, an illustrative application to real fMRI dataset from a simple motor task is presented.