Temporal excitation properties of paresthesias evoked by thalamic microstimulation.
OBJECTIVE
The neuronal elements mediating the effects of deep brain stimulation (DBS) are unknown. The objective was to determine the strength-duration properties of the neuronal elements that mediate paresthesias evoked by thalamic microstimulation.


METHODS
The strength-duration properties of the neuronal elements causing paresthesias were measured using intraoperative microstimulation of the human thalamus. The sample included both concordant (reported in the same region as the mapped sensory receptive fields) and discordant paresthesias (reported in a region different than the mapped sensory receptive fields).


RESULTS
There were no significant differences between the chronaxies of concordant and discordant paresthesias. There was no significant correlation between chronaxie and rheobase for concordant paresthesias, but a strong negative correlation existed for discordant paresthesias.


CONCLUSIONS
Chronaxies did not distinguish the neuronal elements mediating concordant and discordant paresthesias, but correlations between chronaxie and rheobase suggest that concordant paresthesias were produced by activation of local cells while discordant paresthesias were caused by activation of axons of passage.


CONCLUSIONS
The similarity between the strength-duration properties of paresthesias evoked by thalamic stimulation, tremor reduction evoked by thalamic DBS, and EMG responses to thalamic DBS does not mean that these effects are caused by the same neural elements.
Grill
Warren M
WM
Department of Biomedical Engineering, Duke University, Durham, NC 27708-0281, USA. warren.grill@duke.edu
Simmons
Adam M
AM
Cooper
Scott E
SE
Miocinovic
Svjetlana
S
Montgomery
Erwin B
EB
Baker
Kenneth B
KB
Rezai
Ali R
AR
D002907:Chronaxy / Q000502:physiology*; D046690:Deep Brain Stimulation; D004567:Electrodes, Implanted; D006801:Humans; D007432:Intraoperative Period; D008839:Microelectrodes; D008959:Models, Neurological; D010292:Paresthesia; D013788:Thalamus / Q000502:physiology*; D013997:Time Factors