Usefulness of the head-up tilt test in distinguishing neurally mediated syncope and epilepsy in children aged 5-20 years old.

Many nonepileptic disorders may mimic epilepsy by history or clinical presentation. Neurally mediated syncope is one of the most important conditions that might be difficult to differentiate from epilepsy on clinical grounds. We investigated the value of the head-up tilt test (HUT) to diagnose syncope in epileptic children. We studied 40 patients (18 girls and 22 boys) between 5 and 20 years old (mean, 11.5 +/- 3.5) who had a previous diagnosis of epilepsy. All patients underwent a HUT test. The HUT test was positive in 26 patients (65%). No statistical difference was observed between the tilt positive and negative groups in sex, age, provocating factors, associated symptoms, family history of syncope and heart disease, findings in physical examination, and electroencephalogram result. There was a history in favor of true syncope in 58% of tilt positive patients compared to 14% of tilt negative patients (p < 0.05). Also, family history of seizure was more frequent in tilt positive patients (p < 0.05). After 18 +/- 6 months of follow-up, 18 of 26 patients with a positive tilt test were completely asymptomatic. Inadequate history taking and overemphasis on positive family history for seizures were important causes of misdiagnosis of epilepsy in our study. The HUT test is a simple, noninvasive diagnostic tool for distinguishing syncope and epilepsy in children and should be considered early in the diagnostic plan and for determining management of selected patients with a history of drop attack and loss of consciousness.