Quantitative EEG-reactivity to different stimulation methods in comatose patients

Abstract

Objective This study investigates quantitative EEG-reactivity (EEG-R) as a tool for comparison of the efficiency of different clinical stimulation methods. Methods Standardized pain (right and left arm, one leg and sternal massage), auditory and visual stimulation in 30-second epochs were performed during EEG-monitoring of 31 comatose neurosurgical patients. The logarithm to the ratio between the power in a stimulation epoch and the power in the 30-second epoch of rest immediately before was used as a measure of EEG-R in the delta, theta, alpha and beta frequency bands. Results As muscle artifacts contributed to the power in the beta band, this was not used for further analyses. All four pain stimulation methods showed an increase in alpha activity compared to the auditory and visual stimulation methods. There were no differences between the four pain stimulation methods, except for increased delta activity during sternal massage compared to stimulation of the left hand. Conclusions It is possible to use quantitative EEG-R in the assessment of different stimulation methods. Pain stimulation provoked more EEG-R than auditory or visual stimulation. Key message Quantitative EEG-R was used to show that pain stimulation might be more effective than auditory and visual stimulation in comatose patients.