Abstract| Volume 14, ISSUE 6, P1665-1666, November 2021

Diffusional kurtosis imaging reveals taVNS facilitates microstructural changes in the developing neonatal brain

      Background: Transcutaneous auricular vagus nerve stimulation (taVNS) is a novel therapy that may enhance neuroplasticity for infants failing oromotor feeding. Diffusion MRI measures stochastic water movements to indirectly assesses white matter (WM) microstructural integrity. We employed diffusional kurtosis imaging (DKI) to determine whether taVNS alters WM microstructure using tensor-derived diffusivity and kurtosis metrics.
      Methods: We gathered DKI from 20 infants enrolled in our open-label pilot study of taVNS paired with feeding using 3T MRI before and after 2-3 weeks of taVNS treatment. These data consist of 9 responders to taVNS treatment and 11 non-responders. One responder and 6 non-responders were infants of diabetic mothers (IDM). Logistic regression and paired t-tests modeled response to treatment and WM diffusion changes, respectively. Multiple comparison correction was not performed for these exploratory analyses.
      Results: Logistic regression found pre-treatment mean kurtosis in the cortical spinal tract left (p = 0.0280) and right (p = 0.0273) predicted response to treatment while adjusting for IDM (p = 0.0251). Following taVNS, fractional anisotropy in the right superior longitudinal fasciculus (p = 0.050) and radial kurtosis in the right lower cortical spinal tract (p = 0.044), near the cerebellar peduncle, increased more per week in responders compared to non-responders.
      Conclusions: taVNS affects measures of microstructural integrity and neural plasticity in specific WM tracts differently depending on whether infants attained full oral feeds or received a G-tube. WM assessment with sensitive kurtosis imaging could be both a valuable means of assessing microstructural changes attributable to taVNS treatment and a biomarker for predicting response to treatment while taking IDM status into account.
      Funding Sources: NIH/NICHD P2CHD086844; COBRE in Stroke Recovery, P20GM109040; NIH/NINDS F31NS108623.
      Conflicts: BW Badran, MS George and DD Jenkins are named inventors on pending patents related to this work assigned to the Medical University of South Carolina.
      Keywords: diffusional kurtosis imaging, transcutaneous auricular vagas nerve stimulation, diffusion MRI, white matter;