ABCD: Arquivos Brasileiros de Cirurgia Digestiva (Jun 2007)
Detecção da encefalopatia hepática subclínica por espectroscopia cerebral Detection of subclinical hepatic encephalopathy by magnetic resonance spectroscopy
Abstract
RACIONAL: A encefalopatia hepática é anormalidade neuropsiquiátrica comum em cirróticos e está associada com alterações típicas de determinados metabólitos cerebrais, como o decréscimo de mio-inositol e colina e o aumento de glutamina-glutamato, observadas na espectroscopia cerebral por ressonância magnética. OBJETIVO: Determinar os níveis dos metabólitos cerebrais em pacientes cirróticos para diagnóstico da encefalopatia hepática em estágios iniciais. MÉTODOS Foram estudados 25 pacientes com cirrose hepática, do Serviço de Transplante Hepático da Universidade Federal do Paraná, através de avaliação clínica (exame neurológico e testes neuropsicométricos) e espectroscopia por ressonância magnética cerebral. A área espectral estudada por ressonância magnética envolveu a região occipital (substância branca e cinzenta). Trinta voluntários sadios formaram o grupo controle. RESULTADOS: A encefalopatia hepática subclínica foi diagnosticada em 12 pacientes (48%). Reduções significativas nos índices de MI/Cr foram observadas nos pacientes com encefalopatia quando comparados aos controles (0,49±0,10 vs. 0,83±0,13; P BACKGROUND: Hepatic encephalopathy is a common neuro-psychiatric abnormality in liver cirrhosis associated with typical changes of cerebral metabolite pattern, such as a decrease of myo-inositol and cholina and increase of glutamine-glutamate, observed by magnetic resonance spectroscopy. AIM: To determine cerebral metabolite ratios in liver cirrhosis patients with early stages of hepatic encephalopathy. METHODS: Twenty-five patients with chronic hepatic failure from Liver Transplantation Unit of the Federal University of Paraná were studied with clinical evaluation and magnetic resonance spectroscopy. Localized magnetic resonance spectra were acquired in the occipital gray/white matter regions. Thirty healthy volunteers were also subjected to the same evaluations, making up the control group. RESULTS: Subclinical hepatic encephalopathy was diagnosed in 12 patients (48%). MI/Cr ratios were significantly reduced in cirrhotic patients with hepatic encephalopathy when compared to the control group (0,49±0,10 vs. 0,83±0,13; P < 0,0001). In addition, patients with encephalopathy, showed reduction of the Cho/Cr ratio (0,54±0,15 vs. 0,77±0,09; P = 0,0001) and an elevated Glx/Cr ratio (1,12±0,26 vs. 0,89±0,19; P = 0,0146). The Ross's quantitive criterions for spectroscopic diagnoses of hepatic encephalopathy (MI/Cr and Cho/Cr below than 2 SD of controls) demonstrated a sensibility of 61,54%, specificity of 91,67% and accuracy of 76%. Cho/Cr ratio was considered the best parameter. CONCLUSION: Cerebral metabolic alterations that occur at an early stage of hepatic encephalopathy may be demonstrated through magnetic resonance spectroscopy, allowing a precise diagnosis before the appearance of clinical signs and symptoms.
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