BJA Advance Access originally published online on November 9, 2006
British Journal of Anaesthesia 2007 98(1):100-104; doi:10.1093/bja/ael309
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Transient decreases in Bispectral Index without associated changes in the level of consciousness during photic stimulation in an epileptic patient
1 Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo Tokyo, Japan
2 Department of Neuropsychiatry, National Hospital Organization, Hanamaki Hospital, Iwate Tokyo, Japan
3 Department of Anesthesiology, Graduate School of Medicine, The University of Tokyo Tokyo, Japan
*Corresponding author: Surgical Center Research Hospital, The Institute of Medical Science, The University of Tokyo 4-6-1 Shiroganedai, Minato-ku, Tokyo, 108-8639 Japan. E-mail: hayashida-todai{at}umin.ac.jp
This case report describes a patient with a history of epileptic seizures who showed unusual decreases in the Bispectral Index (BIS) attributable to the induction of abnormal slow electroencephalographic (EEG) waves by photic stimulation, without any associated decrease in his level of consciousness. After starting anticonvulsive therapy, photic stimulation no longer induced abnormal EEG activity nor decreased BIS values. These findings suggest that BIS values may not accurately reflect a patient's actual level of consciousness in the presence of epilepsy-related abnormal EEG activity and that the BIS monitor may be able to track such EEG changes.