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

Motor activity occurring during neurocardiogenic syncope can mimic true neurologic events.

To assess the prevalence and type of apparent neurologic events associated with tilt table testing.

The records of consecutive patients undergoing tilt table testing for the evaluation of syncope were reviewed. Patients underwent a 70 degrees 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.

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).

Neurologic events are common during episodes of neurocardiogenic syncope, and this diagnosis should be considered in the evaluation of unexplained seizure-like activity.