[Criteria for differential diagnosis of epilepsy and long QT syndrome presenting with seizures and EEG abnormalities].

We report a 13-year-old girl with congenital long QT syndrome (LQTS) who developed a cluster of generalized tonic clonic seizures with post-ictal EEG abnormality. The provisional diagnosis was epilepsy. However, ECG monitoring showed torsade de pointes, and thus the final diagnosis was LQTS. Although LQTS can be potentially misdiagnosed as epilepsy when it presents with seizures, it is important to differentiate LQTS from epilepsy because patients with LQTS are at risk of sudden death. We reviewed 11 previously reported cases with LQTS and EEG abnormalities who were initially diagnosed as epilepsy. We emphasized the importance of the following five criteria in the differentiation of LQTS from epilepsy: 1) awareness that LQT2 and LQT3 can cause life-threatening arrhythmia at rest or during sleep, 2) examination of arterial pulse during seizures, 3) monitoring ECG during EEG recording, 4) careful establishment of the correct diagnosis taking into consideration the interictal EEG findings, and 5) reconsidering the possibility of cardiac origin when the attacks cannot be controlled even by therapeutic levels of antiepileptic drugs in the blood.