Bis monitor findings during self-hypnosis

Objective: We describe BIS values for a patient undergoing breast surgery under self-hypnosis in order to access the value of global surface EEG measures occurring during this process. Methods: Following verbal consent, a BIS™ monitor (Aspect Medical, Newton MA) was placed and values measured while the patient performed self-hypnosis for a simple mastectomy and sentinel node biopsy. Results: Thirty-nine minutes after incision the BIS value decreased transiently to 72 followed by several other transient decreases, the lowest of which was 59. Values remained at approximately 90 throughout most of the operative period. The BIS value returned to baseline after completion of the operation. Conclusions: Our findings support the hypothesis that hypnosis is a dynamic cerebral process incorporating many changes within brain activation centers and one distinct from dissociative patterns seen under anesthesia. Current algorithms employed by the BIS™ monitor add little to the management of patients utilizing hypnosis for analgesia.