Low-intensity focused ultrasound to the posterior insula significantly reduced subjective pain ratings compared to sham stimulation (2.77 vs 3.39) in healthy volunteers.
RCT (n=23)
Double-blind
Pseudo-randomized
No
Does low-intensity focused ultrasound to the insula reduce pain ratings and alter heart-rate variability in healthy volunteers?
Noninvasive low-intensity focused ultrasound to the anterior insula can simultaneously reduce perceived pain and modulate autonomic reactivity (HRV).
Absolute Event Rate: 2.77% vs 3.39%
p-value: p=0.019
ABSTRACT: The insula is an intriguing target for pain modulation. Unfortunately, it lies deep to the cortex making spatially specific noninvasive access difficult. Here, we leverage the high spatial resolution and deep penetration depth of low-intensity focused ultrasound (LIFU) to nonsurgically modulate the anterior insula (AI) or posterior insula (PI) in humans for effect on subjective pain ratings, electroencephalographic (EEG) contact heat-evoked potentials, as well as autonomic measures including heart-rate variability (HRV). In a within-subjects, repeated-measures, pseudo-randomized trial design, 23 healthy volunteers received brief noxious heat pain stimuli to the dorsum of their right hand during continuous heart-rate, electrodermal, electrocardiography and EEG recording. Low-intensity focused ultrasound was delivered to the AI (anterior short gyrus), PI (posterior longus gyrus), or under an inert Sham condition. The primary outcome measure was pain rating. Low-intensity focused ultrasound to both AI and PI similarly reduced pain ratings but had differential effects on EEG activity. Low-intensity focused ultrasound to PI affected earlier EEG amplitudes, whereas LIFU to AI affected later EEG amplitudes. Only LIFU to the AI affected HRV as indexed by an increase in SD of N-N intervals and mean HRV low-frequency power. Taken together, LIFU is an effective noninvasive method to individually target subregions of the insula in humans for site-specific effects on brain biomarkers of pain processing and autonomic reactivity that translates to reduced perceived pain to a transient heat stimulus.
Legon et al. (Thu,) conducted a rct in Healthy volunteers (n=23). Low-intensity focused ultrasound (LIFU) to anterior or posterior insula vs. Sham was evaluated on Subjective pain rating (0-9 scale) (p=0.019). Low-intensity focused ultrasound to the posterior insula significantly reduced subjective pain ratings compared to sham stimulation (2.77 vs 3.39) in healthy volunteers.