Short-term neurochemical effects of transcutaneous trigeminal nerve stimulation using 7T magnetic resonance spectroscopy.

Abstract

The purpose was to explore the effects of transcutaneous trigeminal nerve stimulation (TNS) on neurochemical concentrations (brainstem, anterior cingulate cortex [ACC], dorsolateral prefrontal cortex [DLPFC], ventromedial prefrontal cortex [VMPFC], and the posterior cingulate cortex [PCC]) using ultrahigh-field magnetic resonance spectroscopy. This double-blinded study tested 32 healthy males (age: 25.4±7.3years) on two separate occasions where participants received either a 20-minute TNS or sham session. Participants were scanned at baseline and twice post-TNS/sham administration. There were no group differences in concentration changes of glutamate, gamma-aminobutyric acid, glutamine, myoinositol (mI), total N-acetylaspartate, total creatine (tCr), and total choline between the baseline scan and the first post-TNS/sham scan and between the first and second post-TNS/sham scan in the brainstem, ACC, DLPFC, VMPFC, and PCC. Between the baseline scan and the second post-TNS/sham scan, changes in tCr (mean difference=0.280mM [0.075 to 0.485], p=.026) and mI (mean difference=0.662mM [0.203 to 1.122], p=.026) in the DLPFC differed between groups. Post hoc analyses indicated that there was a decrease in tCr (mean change=-0.201mM [-0.335 to -0.067], p=.003) and no change in mI (mean change=-0.327mM [-0.737 to 0.083], p=.118) in the TNS group; conversely, there was no change in tCr (mean change=-0.100mM [-0.074 to 0.274], p=.259) and an increase in mI (mean change=0.347mM [0.106 to 0.588], p=.005) in the sham group. These data demonstrate that a single session of unilateral TNS slightly decreased tCr concentrations in the DLPFC region.