All seizures are not epilepsy: many have a cardiovascular cause

The aim of this study was to investigate the value of cardiovascular tests to diagnose convulsive syncope in children with apparent treatment-resistant epilepsy and to assess the extent of misdiagnosis of epilepsy in children.

Adult studies have shown that up to 35% of epileptics may have been misdiagnosed. These patients may have cardiovascular syncope, with abnormal movements due to cerebral hypoxia, which may be difficult to differentiate from epilepsy. Studies in children are lacking.

Thirty-one children (12 male, mean age 10.07 +/- 5 years [range 4 to 17]) who were previously diagnosed with epilepsy were studied. Inclusion criteria were continued attacks despite adequate anticonvulsant drug treatment (n = 17) or possible epilepsy on the basis of clinical grounds (n = 14). Each patient underwent a 12-lead electrocardiogram (ECG), an orthostatic test and carotid sinus massage during continuous ECG and blood pressure monitoring. Ten patients had Holter monitoring.

An alternative diagnosis was found in 19 patients (61.3%), including 8 (47%) of 17 patients taking anticonvulsant medications. Nine patients (29%) developed profound hypotension or bradycardia during orthostatic test, confirming the diagnosis of vasovagal syncope. Seven patients (22.5%) had long Q-T syndrome (LQTS). Two (6.4%) had significant ECG pauses during carotid sinus massage. In these two patients episodes of prolonged bradycardia correlated precisely with seizures by Holter recording, was noted. One patient (3.2%) developed psychogenic symptoms during the orthostatic test.

A simple, non-invasive cardiovascular evaluation may identify an alternative diagnosis in many children with apparent epilepsy and should be considered early in the management of children with convulsive episodes.