ABSTRACT
Objective To explore clinical features and misdiagnosis reasons in mitochondrial encephalomyopathy,lactic acidosis,and stroke-like episodes (MELAS) syndrome.Methods The results of clinical data,brain magnetic resonance imaging (MRI),and the course of diagnosis were analyzed in 6 patients with MELAS.Results (1) Clinical features:headache and vomiting were the starting symptoms in 4 of 6 cases,and developmental delay was initial symptoms in 2 of 6 cases.Marasmus occurred in 6 cases,seizure in 5 cases,fever in 3 cases,and hirsutism and visual impairment in 2 cases.(2) Experimental results:blood lactic acid was higher in 6 (4.28 ～ 10.3 mmol/L).(3) Brain MRI:6 patients had abnormal signals in parietal,occipital,temporal lobe,which were not in accordance with vascular distribution.(4) Molecular genetics:All the 6 patients had A3243G gene mutation.(5) Three patients were misdiagnosed for viral encephalitis,and 2 developmental retardation.Conclusions MELAS is characterized with developmental retardation,and repeated encephalitis attack.It is also misdiagnosed because of its variety of clinical features.If patients have high level of lactic acid and multiple MRI signal abnormalities of brain which are not in accordance with vascular distribution,MELAS should be suspected of.Genetic examination and muscle biopsy are especially important in the diagnosis of MELAS.