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Updated: Aug 22, 2026
Quantitative Autonomic Testing
Published on: July 19, 2011
Electroencephalographic findings during presyncope and syncope induced by tilt table testing
R S Sheldon1, M L Koshman, W F Murphy
1Cardiovascular Research Group, Faculty of Medicine, University of Calgary, Alberta. bsheldon@cvr.ucalgary.ca
Insights
Electroencephalogram (EEG) abnormalities occur during head-up tilt table testing-induced syncope. Abrupt EEG changes mark the transition from presyncope to syncope, indicating altered brain activity during these events.
Area of Science:
- Neuroscience
- Cardiology
- Clinical Neurophysiology
Background:
- Syncope, a transient loss of consciousness, is often diagnosed using head-up tilt table testing.
- Understanding the accompanying electroencephalogram (EEG) changes during syncope is crucial for diagnosis and management.
Purpose of the Study:
- To investigate electroencephalogram (EEG) alterations during syncope induced by head-up tilt table testing.
- To characterize the EEG patterns associated with presyncope and syncope.
Main Methods:
- A prospective observational study was conducted involving 18 patients with recurrent syncope.
- Continuous EEG monitoring was performed during isoproterenol-induced head-up tilt table testing.
- Hemodynamic parameters (blood pressure and heart rate) were recorded concurrently.
Main Results:
- EEG abnormalities were observed in 13/14 patients during presyncope and 18/18 patients during syncope.
- Theta and delta wave slowing, along with background suppression, were common EEG findings.
- Abrupt EEG rhythm changes occurred within 15 seconds of syncope onset in 14/18 patients.
Conclusions:
- Head-up tilt table testing-induced presyncope and syncope are consistently associated with EEG abnormalities.
- No single EEG pattern is uniquely diagnostic of presyncope or syncope.
- The transition to syncope is characterized by rapid and significant changes in EEG patterns.
Objective:
To determine electroencephalographic (EEG) changes occurring during syncope induced by headup tilt table testing.
Design:
Prospective observational study.
Setting:
Calgary General Hospital Syncope Clinic, Calgary, Alberta.
Patients:
Eighteen patients with a history of recurrent syncope who developed syncope while undergoing diagnostic isoproterenol tilt table testing.
Interventions:
Continuous EEGs were recorded in 18 sequentially consenting patients while they underwent diagnostic headup tilt table testing.
Main Results:
Patients developed presyncope after 2.6 +/- 2.4 mins and syncope after 3.7 +/- 2.5 minutes. Systolic blood pressure dropped from 117 +/- 17 mmHg to 65 +/- 9 mmHg, and heart rate dropped from 124 +/- 26 beats/min to 65 +/- 27 beats/min. Fourteen patients developed presyncope, while five developed syncope without appreciable presyncope. Abnormal EEGs were recorded in 13 of 14 patients during presyncope and in 18 of 18 patients during syncope. No patients developed EEG abnormalities before the onset of presyncope, and the proportion of patients with EEG abnormalities gradually increased throughout presyncope. During presyncope, theta and delta wave slowing, and background suppression were noted in eight of 14, nine of 14 and one of 14 patients, respectively. During syncope, theta and delta wave slowing, and background suppression were noted in nine of 18, 11 of 18 and six of 18 patients, respectively (not significant versus presyncope). There were strikingly abrupt changes in the EEG rhythm within 15 s of the transition to syncope in 14 of 18 patients. Six patients developed new theta wave slowing, 11 developed new delta wave slowing, and seven developed background suppression. No epileptiform activity was recorded.
Conclusions:
Both presyncope and syncope induced by tilt testing are associated with EEG abnormalities, and no single EEG pattern is pathognomonic of either. The transition from presyncope to syncope is marked by abrupt EEG changes.
