Epileptic seizures and electroencephalographic findings in patients with mitochondrial myopathy encephalopathy, lactic acidosis and stroke-like episodes

Abstract

Objective To investigate the features of epileptic seizures and eletroencepalogram（EEG） in patients with mitochondrial myopathy encephalopathy, lactic acidosis and stroke-like episodes（MELAS）. Methods Forty-four patients with MELAS were diagnosed at the First Hospital of Peking University from November 2007 to August 2013. EEG and head MRI were performed on all patients. The types of epileptic seizure and EEG changes were compared between patients in and outside stroke-like episodes. Results Epileptic seizures occurred in 39 of 44 patients (88.6%) with MELAS, while multi-type epileptic seizures were presented in 26 cases (66.7%). In stroke-like episodes, 22 patients presented with partial seizures, 30 with generalized seizures and 17 with status epilepticus. In nonstroke-like episodes, 7 patients presented with partial seizures, 14 with generalized seizures and 2 with status epilepticus. The frequency of partial seizures, generalized tonic-clonic seizures, status epilepticus were 47.7%(21/44), 68.2%(30/44), 38.6%(17/44) in stroke-like episodes and 13.6%(6/44), 27.3%(12/44), 4.5%(2/44) in nonstroke-like episodes, which have statistical significance(χ2=12.022,14.758,15.103；P=0.001, 0.000， 0.000， respectively). Abnormal EEGs appeared in all patients. The rates of slow alpha frequency, diffuse δ or θ wave, epileptic discharges were 6.8%(3/44), 43.2%(19/44), 25.0%(11/44) in stroke-like episodes and 31.8%(14/44), 59.1%(26/44), 22.7%(10/44) in nonstroke-like episodes, respectively. Slow alpha frequency were significantly different between patients in and outside stroke-like episodes (χ2 =8.822, P=0.003). Conclusions Epileptic seizures with different types are more common during stroke-like episodes in patients with MELAS. While the rates of epileptic discharges are also common outside the stroke-like episodes. Key words: MELAS syndrome; Epilepsy; Electroencephalography