Using case reports from their own experience and in the literature the authors illustrate the difficulty in distinguishing non-life threatening causes, including epilepsy, from a serious cardiac arrythmia when evaluating children with paroxysmal events. Focusing on long QT syndrome, they suggest an approach for the pediatric neurologist that utilizes the electrocardiogram recorded during the electroencephalogram--direct measurement of the corrected QT interval. This approach requires knowledge of the distribution of the corrected QT interval in long QT syndrome.