Cerebrospinal fluid lactate: a differential biomarker for bacterial and viral meningitis in children / Lactato no líquido cefalorraquidiano: um marcador diferencial para meningite bacteriana e meningite viral em crianças

Abstract Objective: To assess the performance of cerebrospinal fluid (CSF) lactate as a biomarker to differentiate bacterial meningitis from viral meningitis in children, and to define an optimal CSF lactate concentration that can be called significant for the differentiation. Methods: Children with clinical findings compatible with meningitis were studied. CSF lactate and other conventional CSF parameters were recorded. Results: At a cut-off value of 3 mmol/L, CSF lactate had a sensitivity of 0.90, specificity of 1.0, positive predictive value of 1.0, and negative predictive value of 0.963, with an accuracy of 0.972. The positive and negative likelihood ratios were 23.6 and 0.1, respectively. When comparing between bacterial and viral meningitis, the area under the curve for CSF lactate was 0.979. Conclusions: The authors concluded that CSF lactate has high sensitivity and specificity in differentiating bacterial from viral meningitis. While at a cut-off value of 3 mmol/L, CSF lactate has high diagnostic accuracy for bacterial meningitis, mean levels in viral meningitis remain essentially below 2 mmol/L.

Resumo Objetivo: Estudar o desempenho do lactato no líquido cefalorraquidiano como biomarcador para diferenciar a meningite bacteriana da meningite viral em crianças, e definir uma concentração de lactato ótima no líquido cefalorraquidiano que possa ser significativa para a diferenciação. Métodos: Foram estudadas crianças com achados clínicos compatíveis com meningite. O nível de lactato no líquido cefalorraquidiano e outros parâmetros convencionais do líquido cefalorraquidiano foram registrados. Resultados: Em um valor de corte de 3 mmol/L, o lactato no líquido cefalorraquidiano apresentou uma sensibilidade de 0,90, especificidade de 1,0, valor preditivo positivo de 1,0, valor preditivo negativo de 0,963, com uma precisão de 0,972. Os índices de probabilidade positivo e negativo foram 23,6 e 0,1, respectivamente. Para comparação entre a meningite bacteriana e viral, a área abaixo da curva do lactato no líquido cefalorraquidiano foi 0,979. Conclusões: Concluímos que o lactato no líquido cefalorraquidiano possui alta sensibilidade e especificidade na diferenciação da meningite bacteriana da meningite viral. Embora em um valor de corte de 3 mmol/L o lactato no líquido cefalorraquidiano possua alta precisão de diagnóstico da meningite bacteriana, os níveis médios na meningite viral permanecem basicamente abaixo de 2 mmol/L.

Current Challenges for the Early Detection of Alzheimer's Disease: Brain Imaging and CSF Studies

The development of prevention therapies for Alzheimer's disease (AD) would greatly benefit from biomarkers that are sensitive to the subtle brain changes that occur in the preclinical stage of the disease. Reductions in the cerebral metabolic rate of glucose (CMRglc), a measure of neuronal function, have proven to be a promising tool in the early diagnosis of AD. In vivo brain 2-[18F]fluoro-2-Deoxy-D-glucose-positron emission tomography (FDG-PET) imaging demonstrates consistent and progressive CMRglc reductions in AD patients, the extent and topography of which correlate with symptom severity. There is increasing evidence that hypometabolism appears during the preclinical stages of AD and can predict decline years before the onset of symptoms. This review will give an overview of FDG-PET results in individuals at risk for developing dementia, including: presymptomatic individuals carrying mutations responsible for early-onset familial AD; patients with Mild Cognitive Impairment (MCI), often a prodrome to late-onset sporadic AD; non-demented carriers of the Apolipoprotein E (ApoE) epsilon4 allele, a strong genetic risk factor for late-onset AD; cognitively normal subjects with a family history of AD; subjects with subjective memory complaints; and normal elderly followed longitudinally until they expressed the clinical symptoms and received post-mortem confirmation of AD. Finally, we will discuss the potential to combine different PET tracers and CSF markers of pathology to improve the early detection of AD.