Transient decreases in Bispectral Index without associated changes in the level of consciousness during photic stimulation in an epileptic patient

• Published in: British journal of anaesthesia : BJA Vol. 98; no. 1; pp. 100 - 104
• Main Authors: Ohshima, N., Chinzei, M., Mizuno, K., Hayashida, M., Kitamura, T., Shibuya, H., Hanaoka, K.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2007; Oxford University Press; Oxford Publishing Limited (England)
• Subjects: Adult; Anesthesia; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; anticonvulsants; Anticonvulsants - therapeutic use; Biological and medical sciences; bispectral index; Consciousness; Electroencephalography; epilepsy; Epilepsy - drug therapy; Epilepsy - physiopathology; Humans; Male; Medical sciences; monitoring; monitoring, bispectral index; monitoring, electroencephalography; Photic Stimulation - methods; epilepsy; monitoring, bispectral index; monitoring, electroencephalography; anticonvulsants; Human; Nervous system diseases; bispectral index; monitoring; Epilepsy; Central nervous system disease; anticonvulsants; epilepsy; monitoring; Anesthesia; Anticonvulsant; Electroencephalography; Monitoring; Cerebral disorder
• ISSN: 0007-0912; 1471-6771
• DOI: 10.1093/bja/ael309

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.