Clinical spectrum and prevalence of neurologic events provoked by tilt table testing

Background: Motor activity occurring during neurocardiogenic syncope can mimic true neurologic events. Objective: To assess the prevalence and type of apparent neurologic events associated with tilt table testing. Methods: The records of consecutive patients undergoing tilt table testing for the evaluation of syncope were reviewed. Patients underwent a 70° upright tilt for 40 minutes, followed by a 20-minute tilt while receiving isoproterenol hydrochloride. The results of tilt table tests were considered positive when clinical symptoms were reproduced in association with a decline in blood pressure. Clinical variables and neurologic events were analyzed. Results: Tilt table tests were performed on 694 patients during the study period, and the results were positive in 222 of them. Eighteen patients (8%) had apparent neurologic events during tilt table testing. Eleven patients (5%) had apparent tonic-clonic seizure-like activity, and 7 patients (3%) had non-tonic-clonic neurologic events, including focal seizures (n=3), dysarthria or aphasia (n=2), unilateral extremity dysesthesia (n=1), and reproduction of temporal lobe epilepsy symptoms (n=1). The patients with tonic-clonic seizure-like activity had a significantly lower systolic blood pressure reading at the termination of tilt table testing than all other patients whose tilt table test results were positive (P=.04). The heart rate at the time of test termination was significantly lower in the patients with tonic-clonic seizure-like activity and non-tonic-clonic neurologic events (P<.01) than in those with positive test results and no provoked neurologic events, and asystole was provoked more frequently in these 2 patient populations (P=.03). Conclusions: Neurologic events are common during episodes of neurocardiogenic syncope, and this diagnosis should be considered in the evaluation of unexplained seizurelike activity.