Use of Combined Electroencephalography and Tilt Table Testing to Determine Etiology of Loss of Consciousness.

Tilt table testing is a common noninvasive diagnostic test performed to reproduce and evaluate syncope in a vulnerable patient and subsequently guide therapy. Electroencephalography (EEG) is typically useful for identifying interictal and ictal abnormalities within the context of epilepsy or suspected epilepsy. We report a series of patients who underwent simultaneous tilt table testing with EEG. Diagnostic benefits are not exclusively the verification of EEG correlates secondary to clinical and cardiovascular changes during syncope, but also confirmation of nonphysiological events, including psychogenic nonepileptic seizures and psychogenic pseudosyncope. Fifty tilt table studies were combined with EEG over a six-year period. Seven studies (14%) captured episodes of behavioral unresponsiveness with normal EEG and EKG patterns, diagnostic of psychogenic pseudosyncope. Whereas psychogenic nonepileptic events are well established in the literature, psychogenic pseudosyncope is probably underestimated and rarely evaluated outside of an epilepsy monitoring unit. This novel combined protocol should be considered for any patient with suspected psychogenic unresponsiveness.