- One-year follow-up results from the first two participants treated in an epilepsy clinical trial have now been published.
- Unilateral anterior nucleus thalamus ablation was feasible and significantly reduced or stopped focal seizures.
- No serious adverse events were reported, but side effects included memory loss.
A Phase 1 Open-Label Trial Evaluating Focused Ultrasound Unilateral Anterior Thalamotomy for Focal Onset Epilepsy
One-year follow-up results from the first two participants enrolled in a clinical trial (NCT03417297) to assess the safety, feasibility, and preliminary efficacy of unilateral focused ultrasound ablation of the anterior nucleus thalamus (ANT) in adults with treatment-refractory, focal onset epilepsy have now been published.
Insightec’s Exablate Neuro focused ultrasound system was used in this open-label, single-center study designed to test safety and efficacy in patients with treatment-refractory focal or partial onset epilepsy with secondary generalization.
“The goal of this clinical trial is to test whether anterior nucleus ablation is safe and determine the initial efficacy,” said the principal investigator, Vibhor Krishna, MD, Associate Professor of Neurosurgery at the University of North Carolina (UNC) Chapel Hill. “We hope to offer a treatment option for patients who refuse epilepsy surgery or implanted hardware. Certainly, this is early, and we cannot make any conclusions about the efficacy without a control group, and seizure freedom or near seizure freedom is not expected in this patient population.”
Two neurologists, Nathan Fountain, MD, professor of neurology and director of the Comprehensive Epilepsy Program at the University of Virginia School of Medicine, and Robert Fisher, MD, PhD, Maslah Saul MD Professor and Director of the Stanford Epilepsy Center at Stanford University School of Medicine, are also leading this study.
“This novel study demonstrates that subcortical regions of the brain that are involved in seizures can be ablated by minimally invasive focused ultrasound,” said Dr. Fountain. “If this technique is ultimately shown to be safe and effective, then it would add an important tool to the armamentarium of treatments for medication-resistant focal epilepsy.”
Dr. Fisher commented that the procedure is being tested as a unilateral procedure because it poses some risk to memory. He added that the safety and efficacy of anterior thalamic ablation by focused ultrasound will only be proven by larger controlled clinical trials.
Assessing early safety, feasibility, and initial efficacy produced the following outcomes:
- This is primarily a safety study. Participants tolerated the procedure with no new neurological deficits or serious adverse events. One participant had a decline in fluency and memory but was able to fully return to work.
- Feasibility was defined as the ability to create a lesion in the ANT, and the procedure successfully created ANT lesions.
- Efficacy over time was defined as reduction in monthly seizure frequency from baseline to 12 months. One participant rapidly became seizure free, which lasted for the 12 month follow up period. The second participant’s seizures were reduced from 90 to 100 per month to 3 to 6 per month.
The study, which is funded by the Focused Ultrasound Foundation, will resume in May 2023.
According to the Epilepsy Foundation, focal onset seizures (“focal seizures”) are the most common type of seizure in people living with epilepsy. They begin in one region or on one side of the brain. The cause is often unknown, but focal seizures may be caused by a head injury, brain infection, stroke, or brain tumor. Medications do not control focal seizures in about 30% of people with epilepsy.