Abstract: Objective To explore the clinical and electrophysiological characteristics of epileptic seizures in patients with mitochondrial encephalomyopathy with lactate acidosis and stroke-like episodes(MELAS). Methods The clinical data of 57 MELAS cases treated during Jan. 2009 and Jul. 2017 were retrospectively analyzed, including seizure semiology and electroencephalography(EEG)findings. In order to evaluate the relation between epileptic seizure and new stroke-like lesion, the patients were divided into two groups according to the results of cranial MRI: group with and without new stroke-like lesions. To study the relation between drug-resistant epilepsy and the first onset symptom and the first onset age, the patients were divided into four groups: group whose initial symptom was epileptic seizure, group whose initial symptom was not epileptic seizure, adult group(the first onset age ≥18 years), and non-adult group(the first onset age <18 years). Results The incidence of epileptic seizure was 82.5%. Of all patients, 35.1% had epileptic seizures as the onset symptom, and the most common type was tonic-clonic seizure(87.2%). Among the 22 patients who received EEG examination, 21(95.5%)showed unspecific EEG abnormalities and 15(68.2%)showed epileptiform discharges. The incidence of seizure was higher in patients with new stroke-like lesions than in those without 山 东 大 学 学 报 (医 学 版)56卷5期 -杨夏鑫,等.线粒体脑肌病伴高乳酸血症和卒中样发作中癫痫发作的临床特征 \=-(P=0.022). The incidence of drug-resistant epilepsy was higher in patients whose initial symptom was epileptic seizure, but there was no significant difference(P=0.545). The incidence of drug-resistant epilepsy was higher in the non-adult group than in the adult group(P=0.016). Conclusion Seizure is one of the common and the first onset symptoms in MELAS. The seizure semiology is various. The most common EEG characteristic is unspecific slow activity. New stroke-like lesions and the first onset age are important risk factors.

Key words: MELAS syndrome, Epilepsy, Electroencephalography, Stroke-like lesion, Drug-resistant epilepsy