Transcranial ultrasound stimulation may modulate acute heat pain perception

1. Primary somatosensory cortex stimulation lowered heat pain threshold and heat pain tolerance in the contralateral hand.

2. Both primary somatosensory cortex and ventral posterolateral thalamic stimulation reduced warm detection thresholds bilaterally.

Evidence Rating Level: 2 (Good)

In this double-blind, sham-controlled, within-subject experimental study, investigators examined whether transcranial ultrasound stimulation can modulate acute pain perception by targeting the left primary somatosensory cortex and the left ventral posterolateral nucleus of the thalamus. Twenty-five healthy participants underwent separate stimulation sessions for each target, with quantitative sensory testing performed before and after intervention. Outcomes included heat pain threshold, heat pain tolerance, warm detection threshold, mechanical detection threshold, and pressure pain threshold. Stimulation of the primary somatosensory cortex significantly reduced heat pain threshold and heat pain tolerance in the contralateral hand, suggesting increased sensitivity to noxious heat. The median change was −0.6°C for heat pain threshold and −0.2°C for heat pain tolerance. In addition, stimulation of both the primary somatosensory cortex and ventral posterolateral nucleus produced bilateral reductions in warm detection threshold, indicating modulation of nonpainful thermal sensory processing at both cortical and thalamic levels. No significant effects were observed for mechanical detection threshold or pressure pain threshold. Overall, these findings support a role for the primary somatosensory cortex in acute heat pain perception and suggest that transcranial ultrasound stimulation can influence sensory processing across multiple levels of the somatosensory pathway. Further work is needed to confirm reproducibility, clarify mechanisms, and refine protocols for translation into clinical pain applications.

Click here to read the study in Pain

Image: PD

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