Acute disseminated encephalomyelitis following Saint Louis encephalitis virus infection.

Saint Louis encephalitis virus (SLEV) infection is an arbovirosis associated with a broad spectrum of neurological complications. We present a case of a 55-year-old man hailing from Manaus, a city situated in the heart of the Amazon Rainforest, who exhibited symptoms of vertigo, tremors, urinary and fecal retention, compromised gait, and encephalopathy 3 weeks following SLEV infection. Neuroaxis MRI revealed diffuse, asymmetric, and poorly defined margins hyperintense lesions with peripheral and ring enhancement in subcortical white matter, as well as severe spinal cord involvement. Serology for SLEV was positive both on serum and cerebrospinal fluid. To the best of our knowledge, the present report is the first to show brain lesions along with myelitis as a post-infectious complication of SLEV infection.

Proposed public policies to improve outcomes in vascular surgery: an experts' forum.

OBJECTIVE: To evaluate outcomes of vascular surgeries and identify strategies to improve public vascular care. METHODS: This was a descriptive, qualitative, and cross-sectional survey involving 30 specialists of the Hospital Israelita Albert Einstein via Zoom. The outcomes of vascular procedures performed in the Public Health System extracted through Big Data analysis were discussed, and 53 potential strategies to improve public vascular care to improve public vascular care. RESULTS: There was a consensus on mandatory reporting of some key complications after complex arterial surgeries, such as stroke after carotid revascularization and amputations after lower limb revascularization. Participants agreed on the recommendation of screening for diabetic feet and infrarenal abdominal aortic aneurysms. The use of Telemedicine as a tool for patient follow-up, auditing of centers for major arterial surgeries, and the concentration of complex arterial surgeries in reference centers were also points of consensus, as well as the need to reduce the values of endovascular materials. Regarding venous surgery, it was suggested that there should be incentives for simultaneous treatment of both limbs in cases of varicose veins of the lower limbs, in addition to the promotion of ultrasound-guided foam sclerotherapy in the public system. CONCLUSION: After discussing the data from the Brazilian Public System, proposals were defined for standardizing measures in population health care in the area of vascular surgery. Notification of complications of arterial surgeries is essential in identifying strategies to improve surgical outcomes. Screening of prevalent and/or morbid diseases allows early intervention and prevention of complications. Use of telemedicine in vascular follow-up allows optimizing the use of resources and reducing the burden on health services. Concentrating complex cases in reference hospitals leads to improved surgical outcomes.

Time course of hemispheric cerebral volume after decompressive craniectomy in malignant middle cerebral artery stroke.

BACKGROUND: Brain edema is the leading cause of death in patients with malignant middle cerebral artery (MCA) infarction. Midline shift (MLS) has been used as a monohemispheric brain edema marker in several studies; however, it does not precisely measure brain edema. It is now possible to directly measure hemisphere brain volume. Knowledge about the time course of brain edema after malignant middle cerebral artery infarction may contribute to the condition's management. OBJECTIVE: Therefore, our goal was to evaluate the course of brain edema in patients with malignant MCA infarction treated with decompressive craniectomy (DC) using hemispheric volumetric measurements. METHODS: Patients were selected consecutively from a single tertiary hospital between 2013 and 2019. All patients were diagnosed with malignant middle cerebral artery infarction and underwent a decompressive craniectomy (DC) to treat the ischemic event. All computed tomography (CT) exams performed during the clinical care of these patients were analyzed, and the whole ischemic hemisphere volume was calculated for each CT scan. RESULTS: We analyzed 43 patients (197 CT exams). Patients' mean age at DC was 51.72 [range: 42-68] years. The mean time between the ischemic ictus and DC was 41.88 (range: 6-77) hours. The mean time between the ischemic event and the peak of hemisphere volume was 168.84 (95% confidence interval [142.08, 195.59]) hours. CONCLUSION: In conclusion, the peak of cerebral edema in malignant MCA infarction after DC occurred on the 7th day (168.84 h) after stroke symptoms onset. Further studies evaluating therapies for brain edema even after DC should be investigated.

ANTECEDENTES: O edema cerebral é a principal causa de morte em pacientes com infarto maligno de artéria cerebral média. O desvio da linha média tem sido utilizado como marcador de edema cerebral mono-hemisférico em alguns estudos; porém, ele não mede de forma precisa o edema cerebral. Atualmente é possível mensurar diretamente o volume do hemisfério cerebral. O conhecimento sobre a evolução temporal do edema cerebral após infartos malignos da artéria cerebral média pode contribuir para o cuidado clínico desta condição. OBJETIVO: Nosso objetivo é avaliar o edema hemisférico ao longo do tempo, em pacientes com infarto maligno da artéria cerebral média, tratados com craniectomia descompressiva. MéTODOS: Os pacientes foram selecionados de forma consecutiva, em um hospital terciário, entre 2013 e 2019. Todos os pacientes apresentavam diagnóstico de infarto maligno de artéria cerebral média e foram submetidos a craniectomia descompressiva. Todas as tomografias computadorizadas de crânio destes pacientes foram analizadas, e o volume do hemisfério cerebral infartado foi mensurado. RESULTADOS: Analisamos 43 pacientes (197 tomografias de crânio). A idade média dos pacientes na craniectomia descompressiva foi 51,72 (42­68) anos. O tempo médio entre o ictus e a craniectomia descompressiva foi 41,88 (6­77) horas. O tempo médio entre o ictus e o pico do volume hemisférico foi 168,84 (142,08­195,59) horas. CONCLUSãO: O pico do volume cerebral em pacientes com infarto maligno de artéria cerebral média submetidos a craniectomia descompressiva ocorreu no 7o dia (168,84 horas) após o infarto. Mais estudos avaliando terapêuticas direcionadas ao edema cerebral seriam úteis neste contexto.

Nationwide Cross-Sectional Epidemiological Analysis of 3,306 Lower Limb Peripheral Aneurysm Repairs in Brazilian Public Hospitals Between 2008 and 2019: Trends, Mortality and Costs.

BACKGROUND: Although peripheral aneurysms can be limb- or life-threatening, the literature is scarce and there are only two large population-based epidemiological studies on peripheral aneurysm repair, comprising data from high-income countries only. METHODS: This is a retrospective cross-sectional analysis on open and endovascular peripheral aneurysm repairs performed between 2008 and 2019 in the Brazilian Public Health System, which exclusively insures more than 160 million Brazilians. RESULTS: A total of 3,306 peripheral aneurysm repairs were observed. Most patients were elderly (57.74%) and male (72.66%), and patients treated with endovascular repair were older (P = 0.008). Most repairs were emergency (59.56%) and open (93.8%), and there was an overall downward trend in procedure rates. We observed a decreasing predominance of emergency open repair over elective open repair (P < 0.001), but open repairs prevailed over endovascular procedures, with no tendency to change this predominance. Mortality rates were 3.12% and 3.67% after elective and emergency open repair, respectively, with no difference, and 0 and 4.24% for elective and emergency endovascular repair, respectively. The government reimbursed an average of $1170.05 for open PA repair and $1802.01 for endovascular repair. CONCLUSIONS: We presented the largest series of the literature analyzing all 3,306 lower limb peripheral aneurysm repairs performed in public hospitals in a middle-income country. Procedure rates tended to decrease. Open repair predominated. Mortality rates ranged from 0 to 4%. Most procedures were emergency, but there was a relative increase of elective treatments over the years.

Decompressive craniectomy index: Does the size of decompressive craniectomy matter in malignant middle cerebral artery infarction?

Background: Malignant middle cerebral artery (MCA) infarction is associated with high mortality, mainly due to intracranial hypertension. This malignant course develops when two-thirds or more of MCA territory is infarcted. Randomized clinical trials demonstrated that in patients with malignant MCA infarction, decompressive craniectomy (DC) is associated with better prognosis. In these patients, some prognostic predictors are already known, including age and time between stroke and DC. The size of bone flap was not associated with long-term prognosis in the previous studies. Therefore, this paper aims to further expand the analysis of the bone removal toward a more precise quantification and verify the prognosis implication of the bone flap area/whole supratentorial hemicranium relation in patients treated with DC for malignant middle cerebral infarcts. Methods: This study included 45 patients operated between 2015 and 2020. All patients had been diagnosed with a malignant MCA infarction and were submitted to DC to treat the ischemic event. The primary endpoint was dichotomized modified Rankin scale (mRS) 1 year after surgery (mRS≤4 or mRS>4). Results: Patients with bad prognosis (mRS 5-6) were on average: older and with a smaller decompressive craniectomy index (DCI). In multivariate analysis, with adjustments for "age" and "time" from symptoms onset to DC, the association between DCI and prognosis remained. Conclusion: In our series, the relation between bone flap size and theoretical maximum supratentorial hemicranium area (DCI) in patients with malignant MCA infarction was associated with prognosis. Further studies are necessary to confirm these findings.

Deep learning for Alzheimer's disease: Mapping large-scale histological tau protein for neuroimaging biomarker validation.

Abnormal tau inclusions are hallmarks of Alzheimer's disease and predictors of clinical decline. Several tau PET tracers are available for neurodegenerative disease research, opening avenues for molecular diagnosis in vivo. However, few have been approved for clinical use. Understanding the neurobiological basis of PET signal validation remains problematic because it requires a large-scale, voxel-to-voxel correlation between PET and (immuno) histological signals. Large dimensionality of whole human brains, tissue deformation impacting co-registration, and computing requirements to process terabytes of information preclude proper validation. We developed a computational pipeline to identify and segment particles of interest in billion-pixel digital pathology images to generate quantitative, 3D density maps. The proposed convolutional neural network for immunohistochemistry samples, IHCNet, is at the pipeline's core. We have successfully processed and immunostained over 500 slides from two whole human brains with three phospho-tau antibodies (AT100, AT8, and MC1), spanning several terabytes of images. Our artificial neural network estimated tau inclusion from brain images, which performs with ROC AUC of 0.87, 0.85, and 0.91 for AT100, AT8, and MC1, respectively. Introspection studies further assessed the ability of our trained model to learn tau-related features. We present an end-to-end pipeline to create terabytes-large 3D tau inclusion density maps co-registered to MRI as a means to facilitate validation of PET tracers.

Task-related brain activity and functional connectivity in upper limb dystonia: a functional magnetic resonance imaging (fMRI) and functional near-infrared spectroscopy (fNIRS) study.

Significance: Dystonia is a dynamic and complex disorder. Real-time analysis of brain activity during motor tasks may increase our knowledge on its pathophysiology. Functional near-infrared spectroscopy (fNIRS) is a noninvasive method that enables the measurement of cortical hemodynamic activity in unconstrained environments. Aim: We aimed to explore the feasibility of using fNIRS for the study of task-related brain activity in dystonia. Task-related functional magnetic resonance imaging (fMRI) and resting-state functional connectivity were also analyzed. Approach: Patients with idiopathic right-upper limb dystonia and controls were assessed through nonsimultaneous fMRI and fNIRS during a finger-tapping task. Seed-based connectivity analysis of resting-state fMRI was performed in both groups. Results: The fMRI results suggest nonspecific activation of the cerebellum and occipital lobe in dystonia patients during the finger-tapping task with the affected hand. Moreover, fNIRS data show lower activation in terms of oxyhemoglobin and total hemoglobin in the frontal, ipsilateral cortex, and somatosensory areas during this task. In dystonia, both fMRI and fNIRS data resulted in hypoactivation of the frontal cortex during finger tapping with both hands simultaneously. Resting-state functional connectivity analysis suggests that the cerebellar somatomotor network in dystonia has an increased correlation with the medial prefrontal cortex and the paracingulate gyrus. Conclusions: These data suggest that unbalanced activation of the cerebellum, somatosensory, and frontal cortical areas are associated with dystonia. To our knowledge, this is the first study using fNIRS to explore the pathophysiology of dystonia. We show that fNIRS and fMRI are complementary methods and highlight the potential of fNIRS for the study of dystonia and other movement disorders as it can overcome movement restrictions, enabling experiments in more naturalistic conditions.

Genetic risk for Alzheimer's disease and functional brain connectivity in children and adolescents.

Research suggested accumulation of tau proteins might lead to the degeneration of functional networks. Studies investigating the impact of genetic risk for Alzheimer's disease (AD) on early brain connections might shed light on mechanisms leading to AD development later in life. Here, we aim to investigate whether the polygenic risk score for Alzheimer's disease (AD-PRS) influences the connectivity among regions susceptible to tau pathology during childhood and adolescence. Participants were youth, aged 6-14 years, and recruited in Porto Alegre (discovery sample, n = 332) and São Paulo (replication sample, n = 304), Brazil. Subjects underwent genotyping and 6-min resting state funcional magnetic resonance imaging. Connections between the local maxima of tau pathology networks were used as dependent variables. The AD-PRS was associated with the connectivity between the right precuneus and the right superior temporal gyrus (discovery sample: ß = 0.180, padjusted = 0.036; replication sample: ß = 0.202, p = 0.031). This connectivity was also associated with inhibitory control (ß = 0.157, padjusted = 0.035) and moderated the association between the AD-PRS and both immediate and delayed recall. These findings suggest the AD-PRS may affect brain connectivity in youth, which might impact memory performance and inhibitory control in early life.

Distortion Correction Protocol for 3T Stereotactic Magnetic Resonance Imaging: A Clinical Study.

BACKGROUND: With application of 3T magnetic resonance imaging (MRI) to functional neurosurgery procedures and given the inherent requirement of millimetric precision, the need to develop a method for correction of geometric image distortion emerged. The aim of this study was to demonstrate clinical safety and practical viability of a correction protocol in patients scheduled to undergo stereotactic procedures using 3T MRI. METHODS: This prospective study comprised 20 patients scheduled to undergo computed tomography (CT) stereotactic functional procedures or encephalic brain lesion biopsies. The CT images were references for MRI geometric accuracy calculations. For each scan, 2 images were obtained: normal and reversed images. Eight distinct points on CT and MRI were selected summing 152 points that were based on a power analysis calculation value >0.999. One patient was excluded because of the inability to find reliable common landmark points on CT and MRI. RESULTS: The distortion range was 0-5.6 mm and increased proportionally with stereotactic isocenter distance, meaning the distortion was greater in the periphery. After correction, the minimum and maximum distortion found was 0 mm and 3.5 mm, respectively. There was no significant difference between CT and MRI corrected x-coordinates (P > 0.05). CONCLUSIONS: The proposed method can satisfactorily correct geometric distortions in clinical 3T MRI studies. Clinical use of the technique can be practical and efficient after software automation of the process. The method can be applied to all spin-echo MRI sequences.

Fluid-Attenuated Inversion Recovery Vascular Hyperintensities in Patients with Transient Ischemic Attack.

BACKGROUND: Fluid-attenuated inversion recovery (FLAIR) vascular hyperintensities (FVHs) are common in patients with acute ischemic stroke, possibly representing impaired hemodynamics in the ischemic territory due to intracranial steno-occlusive disease. There are few reports on FVHs in patients with transient ischemic attack (TIA). AIMS: We investigated the prevalence of FVHs and its clinical correlations in patients with TIA. METHODS: We evaluated consecutive patients admitted with TIA from February 2009 to June 2012 who had undergone magnetic resonance imaging within 30 hours of symptoms onset and intracranial and extracranial vascular imaging. Two independent neuroradiologists determined the presence of FVHs. We assessed the relationship between FVHs, clinical presentation, vascular risk factors, neuroimaging characteristics, and the presence of large artery stenosis or occlusion. RESULTS: Seventy-two patients with TIA were evaluated. FVHs were present in 12 (16.7%) patients. The overall agreement between examiners was good (κ = .67). There were no differences in the frequency of intracranial or cervical arterial stenosis in patients with and without FVH. In a multivariate logistic regression analysis including atrial fibrillation (AF), congestive heart failure, and diabetes, only AF remained in the final model. CONCLUSIONS: FVH signals on FLAIR images occur in patients with TIA and might correlate with clinical variables like AF and not only with large vessel occlusion. The presence of FVH in patients with TIA and AF might be a surrogate marker for a large vessel occlusion spontaneously recanalized or for impaired autoregulation in a previously ischemic vascular territory.

Connectome hubs at resting state in children and adolescents: Reproducibility and psychopathological correlation.

Functional brain hubs are key integrative regions in brain networks. Recently, brain hubs identified through resting-state fMRI have emerged as interesting targets to increase understanding of the relationships between large-scale functional networks and psychopathology. However, few studies have directly addressed the replicability and consistency of the hub regions identified and their association with symptoms. Here, we used the eigenvector centrality (EVC) measure obtained from graph analysis of two large, independent population-based samples of children and adolescents (7-15 years old; total N=652; 341 subjects for site 1 and 311 for site 2) to evaluate the replicability of hub identification. Subsequently, we tested the association between replicable hub regions and psychiatric symptoms. We identified a set of hubs consisting of the anterior medial prefrontal cortex and inferior parietal lobule/intraparietal sulcus (IPL/IPS). Moreover, lower EVC values in the right IPS were associated with psychiatric symptoms in both samples. Thus, low centrality of the IPS was a replicable sign of potential vulnerability to mental disorders in children. The identification of critical and replicable hubs in functional cortical networks in children and adolescents can foster understanding of the mechanisms underlying mental disorders.

Estimation of post mortem interval by tomographic images of intra-cardiac hypostasis.

The determination of the post mortem interval (PMI) is important in many instances, especially in criminal investigations. So, we consider post mortem tomographic evaluation of intra-cardiac hypostasis as an additional method for such purpose. Tomographic images of the thoraces of the corpses of 23 patients who died in a hospital were obtained sequentially at one hour intervals to allow the analysis of changes in density due to hypostasis over time. The right and left atria, which appear in the mediastinal window, were selected for measurements of the average organ density. An exponential model was used to relate the difference between the attenuation coefficients of the anterior segment of the right atrium and the posterior segment of the left atrium to the PMI. In spite of the large variability of the data from this observational study, PMI estimates during the first 12 h after death can be estimated with a margin of error smaller than two hours. The results suggest that the difference between the attenuation coefficients stabilizes around 12 h post mortem and may be used as an additional method to estimate the PMI.

Right inferior frontal gyrus activation is associated with memory improvement in patients with left frontal low-grade glioma resection.

Patients with low-grade glioma (LGG) have been studied as a model of functional brain reorganization due to their slow-growing nature. However, there is no information regarding which brain areas are involved during verbal memory encoding after extensive left frontal LGG resection. In addition, it remains unknown whether these patients can improve their memory performance after instructions to apply efficient strategies. The neural correlates of verbal memory encoding were investigated in patients who had undergone extensive left frontal lobe (LFL) LGG resections and healthy controls using fMRI both before and after directed instructions were given for semantic organizational strategies. Participants were scanned during the encoding of word lists under three different conditions before and after a brief period of practice. The conditions included semantically unrelated (UR), related-non-structured (RNS), and related-structured words (RS), allowing for different levels of semantic organization. All participants improved on memory recall and semantic strategy application after the instructions for the RNS condition. Healthy subjects showed increased activation in the left inferior frontal gyrus (IFG) and middle frontal gyrus (MFG) during encoding for the RNS condition after the instructions. Patients with LFL excisions demonstrated increased activation in the right IFG for the RNS condition after instructions were given for the semantic strategies. Despite extensive damage in relevant areas that support verbal memory encoding and semantic strategy applications, patients that had undergone resections for LFL tumor could recruit the right-sided contralateral homologous areas after instructions were given and semantic strategies were practiced. These results provide insights into changes in brain activation areas typically implicated in verbal memory encoding and semantic processing.

A method to produce evolving functional connectivity maps during the course of an fMRI experiment using wavelet-based time-varying Granger causality.

Functional magnetic resonance imaging (fMRI) is widely used to identify neural correlates of cognitive tasks. However, the analysis of functional connectivity is crucial to understanding neural dynamics. Although many studies of cerebral circuitry have revealed adaptative behavior, which can change during the course of the experiment, most of contemporary connectivity studies are based on correlational analysis or structural equations analysis, assuming a time-invariant connectivity structure. In this paper, a novel method of continuous time-varying connectivity analysis is proposed, based on the wavelet expansion of functions and vector autoregressive model (wavelet dynamic vector autoregressive-DVAR). The model also allows identification of the direction of information flow between brain areas, extending the Granger causality concept to locally stationary processes. Simulation results show a good performance of this approach even using short time intervals. The application of this new approach is illustrated with fMRI data from a simple AB motor task experiment.