The role of neuroimaging in the determination of brain death.

Brain death is the irreversible cessation of all brain function. Although protocols for its determination vary among countries, the concept of brain death is widely accepted, despite ethical and religious issues. The pathophysiology of brain death is related to hypoxia and ischemia in the setting of extensive brain injury. It is also related to the effects of brain edema, which increases intracranial pressure, leading to cerebral circulatory arrest. Although the diagnosis of brain death is based on clinical parameters, the use of neuroimaging to demonstrate diffuse brain injury as the cause of coma prior to definitive clinical examination is a prerequisite. Brain computed tomography (CT) and magnetic resonance imaging (MRI) demonstrate diffuse edema, as well as ventricular and sulcal effacement, together with brain herniation. Angiography (by CT or MRI) demonstrates the absence of intracranial arterial and venous flow. In some countries, electroencephalography, cerebral digital subtraction angiography, transcranial Doppler ultrasound, or scintigraphy/single-photon emission CT are currently used for the definitive diagnosis of brain death. Although the definition of brain death relies on clinical features, radiologists could play an important role in the early recognition of global hypoxic-ischemic injury and the absence of cerebral vascular perfusion.

A morte encefálica é a cessação irreversível de todas as funções cerebrais. Embora os protocolos para sua determinação variem entre os países, o conceito de morte encefálica é amplamente aceito, apesar de questões éticas e religiosas. A fisiopatologia da morte encefálica está relacionada a hipóxia e isquemia no cenário de uma lesão cerebral difusa. Também está relacionada aos efeitos do edema cerebral, que aumenta a pressão intracraniana, levando à parada da circulação cerebral. Embora o diagnóstico de morte encefálica seja baseado em parâmetros clínicos, o uso de neuroimagem para demonstrar lesão cerebral difusa como causa do coma antes do exame clínico definitivo é um pré-requisito. A tomografia computadorizada (TC) e a ressonância magnética (RM) de crânio demonstram edema difuso e apagamento de ventrículos e sulcos, associados a herniações transcompartimentais. A angio-TC e a angio-RM demonstram a ausência de fluxo arterial e venoso intracraniano. Em alguns países, a eletroencefalografia, a angiografia por subtração digital cerebral, a ultrassonografia transcraniana com Doppler ou a cintilografia/TC por emissão de fóton único são atualmente usadas para o diagnóstico definitivo de morte encefálica. Embora a definição de morte encefálica dependa de características clínicas, os radiologistas podem desempenhar papel importante no reconhecimento precoce da lesão hipóxico-isquêmica global e da ausência de perfusão vascular cerebral.

Clinical and magnetic resonance imaging patterns of extensive Chikungunya virus-associated myelitis.

Chikungunya fever is an arbovirus infection transmitted by the same mosquito vector of dengue and Zika virus. Besides high fever, common clinical symptoms include articular pain and general malaise. Neurological involvement is unusual, but some patients may develop peripheral and central nervous system involvement, including meningoencephalitis, myelitis, Guillain-Barré syndrome, and acute disseminated encephalomyelitis. We present three cases of Chikungunya fever complicated with extensive myelitis. The spinal cord magnetic resonance imaging (MRI) pattern is characterized by multiple dotted-like and longitudinal hyperintense lesions, with contrast enhancement, mostly distributed in the peripheral regions of the spinal cord. It seems that these lesions are mostly located in the perivascular spaces (PVS), related or not to virus attack. Involvement of brain PVS can also be demonstrated, as shown in two of the cases described. Considering the MRI pattern, extensive spinal cord lesion should include Chikungunya as a differential diagnosis, especially during an outbreak.

Proton magnetic resonance spectroscopy in children with fetal alcohol spectrum disorders.

OBJECTIVE: To analyze the metabolic constitution of brain areas through proton magnetic resonance spectroscopy in children affected with fetal alcohol spectrum disorder compared with normal children. METHOD: The sample of this case-control study included eight boys with epidemiologic history of in utero exposure to alcohol (median age 13.6+/-3.8 years) who were diagnosed with fetal alcohol spectrum disorder, and eight controls (median age 12.1+/-3,4 years). An 8 cm(3) single voxel approach was used, with echo time 30 ms, repetition time 1500 ms, and 128 acquisitions in a 1.5T scanner, and four brain areas were analyzed: anterior cingulate, left frontal lobe, left striatum, and left cerebellar hemisphere. Peaks and ratios of metabolites N-acetylaspartate, choline, creatine, and myo-inositol were measured. RESULTS: Children with fetal alcohol spectrum disorder showed a decrease in choline/creatine ratio (p=0.020) in left striatum and an increase in myo-inositol/creatine ratio (p=0.048) in left cerebellum compared with controls. There was no statistically significant difference in all peaks and ratios from the anterior cingulate and frontal lobe between the two groups. CONCLUSION: This study found evidence that the left striatum and left cerebellum are affected by intrauterine exposure to alcohol. Additional studies with larger samples are necessary to expand our knowledge of the effects of fetal exposure to alcohol.

Potential role of diffusion tensor MRI in the differential diagnosis of mild cognitive impairment and Alzheimer's disease.

OBJECTIVE: The purpose of this study was to evaluate the fractional anisotropy values of several white matter tracts with the aim of differentiating a healthy population from persons with mild cognitive impairment or Alzheimer's disease. SUBJECTS AND METHODS: Seventy-nine patients with memory impairment and 16 volunteer controls participated in the study. MRI was performed with a 1.5-T system. Conventional MR images and diffusion tensor images were obtained for all participants. The diffusion tensor imaging data were postprocessed, and low b-value, fractional anisotropy, and fractional anisotropy color-coded maps were calculated. With the three maps as an anatomic reference, fractional anisotropy was measured for hippocampal formations, superior longitudinal fascicles, posterior cingulate gyri, and the splenium of the corpus callosum. Kruskal-Wallis and Steel-type multiple-comparison nonparametric tests were performed for the statistical analysis. RESULTS: The fractional anisotropy values for the splenium of the corpus callosum, bilateral posterior cingulate gyri, and bilateral superior longitudinal fascicles of patients with mild cognitive impairment and those with probable Alzheimer's disease were significantly lower than the values of controls. No differences were found in hippocampal formations in any group. No significant difference was found in fractional anisotropy values in comparisons of mild cognitive impairment versus possible Alzheimer's disease and probable Alzheimer's disease or comparisons of probable Alzheimer's disease and possible Alzheimer's disease. CONCLUSION: Diffusion tensor imaging is a promising technique for the evaluation of patients with probable mild cognitive impairment. Early detection of the disease expands the treatment options, increasing the likelihood of a good clinical response and enhancing the quality of life of patients and their relatives. Further studies with larger populations are needed to confirm the role of diffusion tensor imaging in the evaluation of memory impairment.

Proton magnetic resonance spectroscopy in school-aged autistic children.

PURPOSE: This study aims to assess cerebral metabolites in school-aged autistic patients through proton magnetic resonance spectroscopy. METHODS: This case-control study included 10 right-handed male children (median age, 9.53 years +/- 1.80) with autism according to DSM-IV criteria, and 10 healthy age- and sex-matched healthy controls (median age, 8.52 years +/- 1.42). Imaging was performed on a 1.5-T scanner utilizing a single voxel point-resolved spectroscopy (PRESS) technique (TR = 1,500 ms, TE = 30 ms). Four cerebral areas were evaluated: bilateral anterior cingulate, left striatum, left cerebellar hemisphere, and left frontal lobe. Peak areas and ratios to creatine (Cr) of N-acetylaspartate (NAA), choline (Cho), and myo-inositol (mI) were analyzed. RESULTS: Compared with controls, autistic children showed a significant increase in mI (P= .021) and Cho (P= .042) peak areas in anterior cingulate and in mI/Cr ratio in anterior cingulate (P= .037) and left striatum (P= .035). The remaining metabolites and ratios were not significantly different between the 2 groups. CONCLUSIONS: This study found a statistically significant increase in myo-inositol and choline in anterior cingulate and left striatum of autistic children compared with controls. In contrast to previous studies, NAA peak area and NAA/Cr and NAA/Cho ratios had no statistically significant decrease in any of the 4 brain regions.

Evaluation of white matter in patients with multiple sclerosis through diffusion tensor magnetic resonance imaging.

OBJECTIVE: To study the white matter of patients with multiple sclerosis (MS) with diffusion tensor magnetic resonance (MR) imaging (DTI). METHOD: Forty patients with clinical-laboratorial diagnosis of relapsing-remitting MS and 40 age- and sex-matched controls, who underwent conventional and functional (DTI) MR imaging, were included in the study. The DTI sequences resulted in maps of fractional anisotropy (FA) and regions of interest were placed on the plaques, peri-plaque regions, normal-appearing white matter (NAWM) around the plaques, contralateral normal white matter (CNWM) and normal white matter of the controls (WMC). The FA values were compared and the statistical treatment was performed with the Mann-Whitney U test. RESULTS: The mean FA in plaques was 0.268, in peri-plaque regions 0.365, in NAWM 0.509, in CNWM 0.552 and in WMC 0.573. Statistical significant differences in FA values were observed in plaques, peri-plaque regions and in NAWM around the plaques when compared to the white matter in the control group. There was no significant difference between the FA values of the CNWM of patients with MS and normal white matter of controls. CONCLUSION: Patients with MS show difference in the FA values of the plaques, peri-plaques and NAWM around the plaques when compared to the normal white matter of controls. As a result, DTI may be considered more efficient than conventional MR imaging for the study of patients with MS.

Meio diferencial para isolamento de Malassezia pachydermatis / Differential Media for isolation Malassezia pachydermatis

Desenvolvimento e teste de desempenho de um meio de cultivo diferencial destinado a facilitar a identificaçäo presuntiva, o mais precocemente possível, de Malassezia pachydermatis. Inicialmente experimentamos adicionar azul de bromotimol ao Sabouraud Dextrose Agar. Com um resultado considerado insatisfatório, procuramos formular um novo meio que, além do crescimento, nos permitisse aproveitar a capacidade de alcalinizaçäo dessa levedura. Finalmente comparamos o comportamento de M. pachydermatis com o de Candida albicans, C. tropicalis e C. parakrusei no novo meio visto que o gênero Candida é, também, freqüentemente encontrado nos materiais clínicos coletados para isolamento de Malassezia.

Case report of intraspinal paracoccidioidomycosis

Os autores registram um caso de paraplegia causada por uma lesao granulomatosa de PCM intramedular. O diagnostico clinico neurologico de uma lesao compressiva intramedular foi confirmado pelo exame de ressonancia nuclear magnetica da coluna, que mostrou lesao captante de contraste a nivel de T12. O paciente foi operado e a lesao totalmente retirada. O exame histopatologico da peca operatoria confirmou o diagnostico de PCM. O doente esta em uso de SMZ/TMP e fluconazol com boa recuperacao neurologica

Inhibition of fungal growth by extracts of Vernonia Scorpioides (Lam.) pers

As propriedades antifúngicas de extratos obtidos a partir de folhas e caules de Vernonia scorpioides (Lam.) Pers., foram testadas para Penicillium citrinum. Os extratos foram testados pelo método de difusäo em agar, nas concentraçöes de 1mg. 3mg e 5 mg para cada 100 ml de diluente, em poços escavados no centro de placas de Petri. Extratos clorofórmicos e hexâmicos obtidos a partr de caules foram extremamente eficientes, originando halos de inibiçäo com 40,0, 50,0 e 80,0mm, respectivamente. O desenvolvimento de hifas, na presença desses extratos mostrou-se incipiente. Os extratos de folhas verdes também apresentaram efeitos semelhantes, embora de menor intensidade, uma vez que originaram halos de inibiçäo entre 10 e 15mm de diâmetro para Aspergillus alutaceos (ochraceus) e entre 15 e 20mm de diâmetro para Penicillinium citrinum. Concluiu-se que que os extratos ativos de V. scorpioides exercem uma açäo fungicida, uma vez que näo se conseguiu, a partir dos tratamentos, realizar subcultivos em meio Czaoeck-Dox isento de inibidores. Através dos expectros no infravermelho dos extratos ativos, observou-se a existência de sinais, característicos do estiramento de carbonilas lactânicas (com absorçäo entre 1750cm e 1770cm) ativas, indicando a presença provável de lactonas sesquiterpênicas, possíveis responsáveis pela atividade observada