Clinical features of mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes: an analysis of 190 cases

Objective To summarize the clinical features of Chinese patients with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS). Methods A total of 190 patients with MELAS who presented to Peking University First Hospital between 1997 and 2015 were recruited. Among 190 patients, 175 were identified carrying mitochondrial DNA mutations, and the remaining 15 patients were diagnosed by muscle biopsy. The clinical features, including predisposing factors of stroke-like episodes, the onset symptoms and frequencies of various manifestations were analyzed and reported. Results In our cohort of MELAS patients, the male-to-female ratio was 1.44∶1. The median age of onset was 14 years (from 7 months to 45 years). The peak onset ages were 8-12 years. The median onset age of the first stroke-like episode was 16 years (from 1 to 53 years). There were 66(46.15%) patients who had predisposing factors before the onset, and fatigue and upper respiratory tract infection were the most common predisposing factors of stroke-like episodes in these patients (37.88%, 25/66 and 34.85%, 23/66, respectively). Other predisposing factors included emotional agitation, drinking alcohol, trauma, withdrawal of antiepileptic drugs, being frightened, satiation and hunger. Stroke-like episodes appeared in 70.53% (134/190) patients as an onset symptom and developed in all patients with disease progression. The neurological manifestations included seizure (89.42%, 169/189), mental retardation or dementia (82.87%, 150/181), headache (74.30%, 133/179), hemianopia or cortical blindness (67.72%, 107/158), exercise intolerance (50.87%, 88/173), hemiplegia or hemianesthesia (47.44%, 74/156), sensorineural deafness (46.20%, 85/184), aphasia (39.47%, 60/152), behaviour disorder (17.71%, 31/175) and ophthalmoplegia (9.60%, 17/177). The manifestations of extra-nervous systems included hirsutism (67.57%, 100/148), vomiting (65.58%, 101/154), fever (62.07%, 90/145), short stature (45.32%, 63/139), diarrhea or constipation (43.48%, 70/161), low body mass index (26.62%, 37/139), diabetes mellitus (20.79%, 37/178) and kidney disease (3.16%, 6/190). Conclusions The majority of the patients in this study have the disease onset during childhood. There are more male MELAS patients than females. Most common clinical manifestations are seizure, mental retardation or dementia, headache, cortical blindness, hirsutism, vomiting and fever in this patient group. Key words: MELAS syndrome; Seizures; Stroke; Age of onset; Gender identity; Retrospective studies