title: Effects of ketamine and propofol on motor evoked potentials elicited by intracranial microstimulation during deep brain stimulation.
abstract: Few preclinical or clinical studies have evaluated the effect of anesthetics on motor evoked potentials (MEPs), either alone or in the presence of conditioning stimuli such as deep brain stimulation (DBS). In this study we evaluated the effects of two commonly used anesthetic agents, propofol and ketamine (KET), on MEPs elicited by intra-cortical microstimulation of the motor cortex in a rodent model with and without DBS of the dentatothalamocortical (DTC) pathway. The effects of propofol anesthesia on MEP amplitudes during DTC DBS were found to be highly dose dependent. Standard, but not high, dose propofol potentiated the facilitatory effects of 30 Hz DTC DBS on MEPs. This facilitation was sustained and phase-dependent indicating that, compared to high dose propofol, standard dose propofol has a beta-band excitatory effect on cortical networks. In contrast, KET anesthetic demonstrated a monotonic relationship with increasing frequencies of stimulation, such that the highest frequency of stimulation resulted in the greatest MEP amplitude. KET also showed phase dependency but less pronounced than standard dose propofol. The results underscore the importance of better understanding the complex effects of anesthetics on cortical networks and exogenous stimuli. Choice of anesthetic agents and dosing may significantly confound or even skew research outcomes, including experimentation in novel DBS indications and paradigms.
authors.affiliation: Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Cleveland, OH, USA.
authors.forename: Havan
authors.initials: H
authors.lastname: Furmaga
authors.affiliation: Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Cleveland, OH, USA.
authors.forename: Hyun-Joo
authors.initials: HJ
authors.lastname: Park
authors.affiliation: Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Cleveland, OH, USA ; Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic Cleveland, OH, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Cooperrider
authors.affiliation: Department of Neurology, University of Minnesota Minneapolis, MN, USA.
authors.forename: Kenneth B
authors.initials: KB
authors.lastname: Baker
authors.affiliation: Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Cleveland, OH, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Johnson
authors.affiliation: Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Cleveland, OH, USA ; Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic Cleveland, OH, USA.
authors.forename: John T
authors.initials: JT
authors.lastname: Gale
authors.affiliation: Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Cleveland, OH, USA ; Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic Cleveland, OH, USA.
authors.forename: Andre G
authors.initials: AG
authors.lastname: Machado
keywords: deep brain stimulation; excitability; ketamine; motor evoked potentials; propofol