Dexmedetomidine and arousal affect subthalamic neurons

Stereotactic neurosurgeons hesitate to employ sedation in cases requiring microelectrode recording (MER). We report our experience with dexmedetomidine during MER of subthalamic nucleus (STN). Eleven Parkinsonian patients received dexmedetomidine during deep brain stimulation surgery. Seven received continuous IV infusions during MER in the STN. The bispectral index (BIS) was used to estimate the level of consciousness. The quality of MER was evaluated as a function of BIS, clinical arousal, and dexmedetomidine dose. MER during wakefulness (BIS > 80; 0.1 to 0.4 mcg/kg/hr dexmedetomidine) was similar to the unmedicated state. Subthalamic MER was reduced when the patient was asleep or unarousable (BIS < 80). Anxiolysis persisted for hours. Arousal affects STN neurons. Dexmedetomidine "cooperative sedation," from which the patient is easily aroused, provides interpretable STN MER and prolonged anxiolysis. We suggest dexmedetomidine infusions without a loading dose, a relatively low infusion rate, and discontinuation after completion of the bur holes.