Dexmedetomidine vs Propofol on the Recordings of Deep Brain Activity Measured Through Implanted Stimulators

Patients will receive a loading dose of 1 µg/kg in 10 min before starting the surgery. The maintenance dose will be 0.2-1 µg/kg/h for a Ramsey Sedation Score of 3-4 during the surgery´s preparation. It will be reduced to 0.2 µg/kg/h 15 min before starting the microelectrode recording for a Ramsey Sedation Score of 2. After the placement of the deep brain stimulator we will record the local field potentials activity. In addition, the subscales of rigidity, tremor and bradykinesia of the Unified Parkinson's Disease Rating Scale (UPDRS-III) score will be evaluated. Once the deep brain stimulator recording and neurologic exploration will be over patients will receive a maintenance dose 0.2-1 µg/kg/h until the end of the surgery. It will be stopped to transfer the patient to the ICU.

The target doses are 0.5, 1, 1.5, 2 and 2.5 µg/kg. For its administration we will use the TCI (target controlled infusion) system. After programming each dose we will wait until the plasma and brain concentration of propofol are stabilized in this target and then we will record the local field potentials activity through the DBS. In addition, the subscales of rigidity, tremor and bradykinesia of the UPDRS-III score will be evaluated.