Abstracts

Rationale: Epileptic seizures in patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) are reportedly known for heterogeneity with no pathognomic features. We reviewed epilepsy characteristics and clinical outcome exclusively in a pediatric population. Methods: Twenty-two children and adolescents (13 males) with confirmative diagnosis of MELAS and epilepsy were recruited. Clinical data including seizure semiology, treatment response, neuroimaging findings, and electroencephalography (EEG) were analyzed. We also examined the impact of the age of seizure onset and initial symptoms on the clinical variables. Results: Twelve (54.5%) initially presented with seizure, and subsequently all subjects experienced seizures. Seizure semiology and EEG abnormalities showed no syndrome-specific findings. Focal seizures were seen in 21 of 22 (95.5%) while generalized seizures were seen in 7 of 22 (31.8%). All patients were treated with antiepileptic drugs. Twenty of 22 (90.9%) subjects achieved partial to complete reduction of clinical seizures for more than one year with combination of more than 2 antiepileptic drugs. The subgroup with earlier seizure onset presented significantly earlier (5.4 2.4 years versus 11.1 2.8 years, P < 0.001) and showed significantly higher rates of drug resistant epilepsy compared to the late onset group (83% versus 40%, P = 0.017), while there were no significant differences in the initial symptoms. The subjects with severe epileptic conditions tended to show more severe clinical status, as well as more severe organ involvement. Conclusions: Both focal seizures and primary generalized seizures were observed in pediatric MELAS patients. Epilepsy in this population is drug resistant, but a certain degree of clinical seizure reduction was achievable with antiepileptic drugs, with more favorable outcomes than historically expected. Close observation and active epilepsy treatment in pediatric patients with MELAS and earlier seizure onset would enable better prognoses. Funding: This research was supported by a faculty research grant from Yonsei University College of Medicine for 2010 (6-2010-0172), and Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (2015-31-0580), and by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI15C2578)."