The effect of photic stimulation alone and in combination with sleep deprivation after a seizure-like event – reappraisal by using linear and nonlinear EEG methods

ABSTRACT

Objectives

The present study aimed to compare the effectiveness of different provocation tests used for the study of the ‘susceptibility to seizure’ by quantitative electroencephalography (EEG) analysis.

Methods

Eight subjects with a history of a seizure-like disturbed consciousness participated in this preliminary study. A routine EEG was carried out with photic stimulation (eyes closed and after eyes open) at the beginning of the investigation. Some days later, a sleep-deprived EEG was recorded with the same protocol. Selected epochs (in eyes closed condition) after the stimulations were analysed with Point(wise) Correlation Dimension (PD2i) and Synchronization Likelihood (SL) methods. The results were compared to those obtained by similar analysis of the resting state (control) epochs with Wilcoxon Signed Rank Test (p ≤ 0.05).

Results

In our study, significantly lower grand mean PD2i and higher delta SL values were found in sleep-deprived state after stimulation with eyes closed compared to the control. Our results indicated a lower-dimensional, hypersynchronous state of the brain as a consequence of these combined provocations.

Discussion

This may correspond to a possible ’preictal’ state of the brain. Accordingly, it is suggested that photic stimulation together with sleep deprivation seems to be more effective in provocation – especially when the stimulation was made with eyes closed.

KEYWORDS:

• Susceptibility to seizure
• electroencephalography
• photic stimulation
• sleep deprivation
• point correlation dimension
• synchronization likelihood

Acknowledgments

The authors wish to thank Professor James E Skinner and Professor Cornelis J Stam for providing the PD2i and SL programs for data-processing. We are grateful to Professor Márk Molnár for the critical reading of the manuscript. Our thanks are also due to all probands for their participation in the study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Due to the nature of this research, participants of this study did not agree for their data to be shared publicly, so supporting data is not available.

Authors’ contributions

AJ and TJ attended the conception and design of the work. AJ made the data collection and data analysis. AJ interpreted the data, and prepared the draft of the manuscript. TJ read critically the manuscript. AJ and TJ made the final approval of the version to be submitted.

Additional information

Funding

This work was not supported by any grant.

Notes on contributors

Anett Járdánházy

Anett Járdánházy She is a specialist in Neurology, she has a PhD degree in Experimental and Clinical Neurosciences. Tamás Járdánházy Professor Emeritus at Department of Neurology, University of Szeged, Hungary. He is a specialist in Neurology and Clinical Neurophysiology, has a PhD degree.

Tamás Járdánházy

Anett Járdánházy She is a specialist in Neurology, she has a PhD degree in Experimental and Clinical Neurosciences. Tamás Járdánházy Professor Emeritus at Department of Neurology, University of Szeged, Hungary. He is a specialist in Neurology and Clinical Neurophysiology, has a PhD degree.