Objectives: To establish the main clinical characteristics of convulsive syncope and the usefulness of the tilt test in its diagnosis.
Methods: A total of 317 patients (aged 5-18 years old) under clinical suspicion of neurocardiogenic syncope underwent a multiparametric tilt test. Our tilt test protocol includes continuous noninvasive measurement of heart rate, blood pressure, and arterial oxygen saturation, as well as continuous noninvasive measurement of cerebral oxygen saturation by near-infrared spectrophotometry. In selected patients, simultaneous electroencephalogram (EEG) was performed.
Results: The tilt test was positive in 216 patients (68.1 %). Of these, 25 (11.6 %) showed seizures during the test (convulsive syncope). Convulsions were asymmetric-tonic in 15 patients (60 %), generalized tonic in 5 (20 %), and tonic-clonic in 5 (20 %). In all patients, convulsive episodes lasted less than 30 seconds and spontaneously ceased upon placing the patient in a horizontal or Trendelenburg position. When simultaneous EEG was performed, diffuse brain wave slowing was observed, without paroxysmal activity.
Conclusions: Convulsive syncope is not an uncommon event in children and is easily elicited by means of the tilt test. Pediatricians should be aware of this finding in order to avoid the frequently established unidirectional association between seizures and epileptic disorders. Consequently, the tilt test should be considered an essential tool in the differential diagnosis between convulsive syncope and epilepsy.