Bispectral Index Monitoring Does Not Improve Anesthesia Performance in Patients with Movement Disorders Undergoing Deep Brain Stimulating Electrode Implantation

Abstract

Deep brain stimulation (DBS) has emerged as a promising therapy for movement disorders. During the implantation procedure for the electrodes, the patient emerges from anesthesia repeatedly to facilitate neurological testing. We investigated whether Bispectral Index (BIS) monitoring would be beneficial in patients receiving "sleep-awake-sleep" anesthesia with respect to time of arousal, consumption of propofol, and cardiopulmonary stability (i.e., heart rate, arterial blood pressure, and end-tidal carbon dioxide). We investigated 21 patients scheduled for implantation of DBS electrodes. Depth of propofol anesthesia was controlled either with BIS guidance in 10 patients (BIS group) or without in 11 patients (non-BIS group). In the BIS group, a BIS score of 40-60 was targeted during sleep periods, whereas in the non-BIS group, a value of 1 (= no response to tactile stimulation [unconsciousness]) on the Observers' Assessment of Alertness/Sedation Scale was targeted. For analgesia, the sites for the burr holes and for the pins of the stereotactic ring were infiltrated with 2% lidocaine; no opioids were used. For periods during which an awake patient required neurological testing, propofol was discontinued. We found no difference between groups with respect to times of arousal, total amount of propofol consumption, and cardiopulmonary stability. However, significantly more propofol boluses had to be administered in the BIS group (30 +/- 11.6 vs 17 +/- 4.6) to maintain the BIS score within the target range (P < 0.05). BIS monitoring does not improve anesthesia management for DBS electrode implantation in patients with movement disorders.