Safety and Feasibility of Low-Intensity Transcranial Focused Ultrasound Targeting the Anterior Thalamus: A Pilot Study for Chronic Central Neuropathic Pain.

Abstract

Low-intensity transcranial focused ultrasound (tFUS) is a novel noninvasive neuromodulation technique capable of reaching deep brain structures with high spatial precision. The anterior thalamus, a key relay in pain processing, is a promising target for modulating central pain networks. In this context, this study aims to assess the safety, feasibility, and preliminary effects of anterior thalamic low-intensity tFUS in patients with chronic Central Neuropathic Pain (CNP). In this prospective, open-label, single-arm pilot study, 5 adults with refractory central neuropathic pain underwent neuronavigated low-intensity transcranial focused ultrasound targeting the anterior thalamus contralateral to the pain-affected region. Each session consisted of two 10-minute stimulation blocks separated by 20 minutes. Pain intensity was assessed using the visual analog scale at baseline, immediately poststimulation, and also after 4 hours, 24 hours and 10 days after the intervention. Secondary outcomes included the Brief Pain Inventory, McGill Pain Questionnaire, Douleur Neuropatique 4, Hamilton Depression Rating Scale, Hamilton Anxiety Rating Scale, Patient Global Impression of Change and Clinical Global Impression of Change scale. The procedure demonstrated feasible with no serious adverse events. One participant experienced mild transient neck discomfort. No statistically significant improvements were observed in pain intensity or secondary outcomes at any time point compared with baseline. Overall, anterior thalamic low-intensity tFUS presented safe and feasible for patients with CNP but did not yield significant short-term analgesic effects. These findings support further controlled clinical trials with larger samples, optimized stimulation parameters and repeated sessions to better evaluate the therapeutic potential of low-intensity tFUS for chronic CNP.