Different Causes of a Transient loss of Consciousness with Convulsions between Two Young Sisters: Epilepsy and Type-2 Long QT Syndrome

Abstract

A misdiagnosis of syncope as a seizure can lead to catastrophic outcomes, and thus should be avoided. We herein present the cases of two young sisters who experienced transient loss of consciousness with convulsions and were diagnosed with epilepsy. After discovering that their asymptomatic mother had type-2 long QT syndrome (LQT2), it was found that the younger sister had LQT2, while the older sister did not. Although the 12-lead ECG of the younger sister showed notched T-waves, the QTc interval (422 ms) was normal, which precluded a diagnosis of LQT2. These cases provide clues to distinguish between LQT2-related arrhythmic events and epileptic events.