Focused Ultrasound Offers Sustained Relief from Chronic Neuropathic Pain

Key Points

• A clinical trial using focused ultrasound medial thalamotomy to treat patients with chronic pain showed sustained pain relief over time.
• The 55 participants enrolled presented with spinal cord injury, trigeminal neuralgia, post-discectomy radiculopathy, and other types of nerve-related pain.
• One year after treatment, half of the participants had stopped taking opioid pain relievers.

Magnetic Resonance–Guided Focused Ultrasound Central Lateral Thalamotomy Against Chronic and Therapy-Resistant Neuropathic Pain: Retrospective Long-Term Follow-Up Analysis of 63 Interventions

At SoniModul, the Center for Ultrasound Functional Neurosurgery in Switzerland, neurosurgeons Marc Gallay, MD, and Daniel Jeanmonod, MD, recently published a follow-up analysis of their safety and efficacy study using Insightec’s Exablate Neuro MR-guided focused ultrasound system to create a central lateral thalamotomy (CLT) in 55 patients with chronic and therapy-resistant neuropathic pain.

The clinical trial, which began in 2011, was a single-center, nonrandomized, retrospective cross-sectional analysis of 63 consecutive focused ultrasound CLTs performed in 55 patients with various types of chronic pain, including spinal cord injury, trigeminal neuralgia, and post-discectomy radiculopathy. Of the 55 patients, 48 received bilateral CLT, 7 received a CLT that was contralateral to the pain, and 8 underwent a repeat CLT intervention.

After a mean follow-up period of 55 months (4.6 years), more than half of the patients reported greater than or equal to a 50% reduction in pain (with a mean pain reduction of 42%). Remarkably, at the 1-year follow-up visit, half of the participants had stopped taking opioid pain relievers. The group with the highest mean pain relief were the patients with classical and idiopathic trigeminal neuralgia. Overall, the frequency of pain attacks was reduced by 92%, and sensitivity to touch was reduced or suppressed in 68% of patients (and never began after treatment). Importantly, these pain relief results were sustained over the follow-up period.

“The treatment of chronic neuropathic pain poses a major clinical challenge,” said Dr. Gallay. “Patients who come to us are often feeling exhausted and resigned after enduring many years of ineffective treatments. The publication of positive results, stable over time, provides strong motivation for our team to continue pursuing this approach.”

As a treatment for neuropathic (also called neurogenic) pain, the authors concluded that focused ultrasound CLT is safe and stable over time. The study period included only one serious adverse event, which was upper lip numbness.

“I believe this is the longest period of follow up for focused ultrasound treatment of neuropathic pain to date,” said Tim Meakem, MD, the Foundation’s chief medical officer. “The sustained pain relief and reduction in opioid use are incredibly impactful findings.”

The American Chronic Pain Association defines neuropathic (nerve) pain as complex chronic pain from damage or injury to the central nervous system, which includes the spinal cord and brain. Damaged nerves do not function properly at their origin, and they also send the wrong signals to the brain. It is estimated that as much as 10% of the population suffers from this condition. The SoniModul website lists the following examples of neuropathic pain: phantom limb pain after amputation, nerve compressions or sections, polyneuropathies, plexus avulsions, paraplegic pain, pain after brain infarct (thalamic syndrome), trigeminal neuralgia, post-herpetic pain (after zona infection), and pain after lumbar disc operations.

Funding for the first 11 patients treated in the study was provided by Insightec.

See the Journal of Neurosurgery (Open Access)