To update the long-term safety profile of MR-guided focused ultrasound (MRgFUS) for medication-refractory essential tremor (ET) and Parkinson’s disease (PD), incorporating clinical trial and real-world data sources.

MRgFUS is FDA-approved for the unilateral and staged, bilateral treatment of ET and PD. Over 25,000 procedures have been performed globally. Both clinical trial and real-world data demonstrate immediate and sustained symptom improvement, with most adverse events (AEs) being mild and transient.

Reviewed and compared long-term safety outcomes from pivotal clinical trials (ET thalamotomy [ET-T], recently published ET continued access study [ET-CA], ET staged, bilateral [ET-SB], Parkinson’s disease thalamotomy [PD-T], Parkinson’s disease pallidotomy [PD-P]) and real-world sources including published literature and post-market surveillance (PMS) data.

Across pivotal trials, most AEs were generally mild (74% ET-T; 85% ET-CA; 85% ET-SB; 72% PD-T; 75% PD-P). Related severe events were rare. The most common treatment-related AEs in thalamotomy procedures were paresthesias (38% ET-T; 34% ET-CA; 33% ET-SB; 25% PD-T) and gait disturbance (36% ET-T; 38% ET-CA; 24% ET-SB; 45% PD-T), with dysarthria more frequent after staged, bilateral MRgFUS (2% ET-T; 12% ET-CA; 24% ET-SB). In pallidotomy treatments, the most common AEs were dysarthria, gait disturbance, and loss of taste (2.9% each). Many AEs resolved within 6 months, and no new or worsening AEs were seen at longer-term follow-up. No declines in cognition have been reported in ET or PD. Literature indicates similar safety, with mostly mild and transient events; two recent case reports describe isolated and rare hemorrhages. The most recent PMS data indicate AEs were reported in 0.41% of 6997 clinical procedures.

Unilateral and staged, bilateral MRgFUS continues to demonstrate a favorable safety profile in ET and PD. Ongoing surveillance is essential to identify rare events, but overall, MRgFUS remains a safe and well-tolerated treatment option in clinical practice.