Diffusion tractography predicts Deep Brain Stimulation evoked potential amplitude and delay.

ObjectiveThis study investigated the relationship between DBS evoked potentials (EPs) and diffusion tensor imaging (DTI) in a group of patients with dystonia who underwent DBS treatment. EPs and DTI are both useful methods for studying neural connectivity in the brain but measure different aspects of brain function. EPs provide information on electrical connectivity, while DTI provides information on anatomical pathways connecting regions. MethodsThis study focused on the pallidum and motor thalamus nuclei, which are common targets for DBS in dystonia. Prior to DBS implantation, DTI images were acquired for each patient, and were processed to obtain DTI coefficients such as length (L), volume (V), and fractional anisotropy (FA) of the fiber tracts. The relationship between the fiber tracts and electrophysiology was examined using a generalized linear model (GLM). ResultsWe showed that the amplitude of EPs correlated with FA and tract volume, while delay correlated with tract length. These findings suggest that DBS signals travel across tracts to affect both local and distant brain regions, and the magnitude of the effect of DBS is determined by the integrity of the white matter tract, while DBS signal delay is affected by the tract length. Our results further suggest that the magnitude and delay of the spread of the DBS signal may be predicted by the DTI connectivity. This provides strong supporting evidence for other studies that have assumed, but have been unable to test, such a relationship. ConclusionOverall, this study suggests that the electrical effects of DBS can be at least partially predicted by noninvasive DTI imaging in patients with dystonia. By combining EPs with DTI, we could investigate the propagation of stimulation pulses through brain regions. While this relationship has been previously hypothesized by the neuroscience community, this is the first study in humans to demonstrate this relationship between DBS EPs and DTI, thereby advancing the field of human brain mapping and enhancing the precision of neurosurgical targeting.