In six patients in the active-treatment group, some of these deficits were present at 12 months.
The researchers noted that an approach that has been suggested to reduce the risk of dyskinesias has been to extend ablations dorsal to the subthalamic nucleus in order to interrupt the pallidothalamic-projecting neurons.
The study also showed a greater reduction in the use of dopaminergic medication in the active-treatment group versus the control group, but the researchers noted that the 95% confidence intervals for this and other secondary outcomes were not adjusted for multiple comparisons, so no definite conclusions can be drawn from these data.
They also pointed out that subthalamotomy was performed in one hemisphere, and the natural evolution of Parkinson’s disease eventually leads to motor impairment on both sides of the body in most patients.
“The likely need for an increase in the daily dose of levodopa equivalent to maintain function on the untreated side of the body could lead to the development of dyskinesias on the treated side. However, the few open-label studies of long-term (≥36 months) follow-up of radiofrequency subthalamotomy performed in one hemisphere do not provide support for this concern,” they said.
An important step, but improvements are needed
In an accompanying editorial, Joel S. Perlmutter, MD, and Mwiza Ushe, MD, Washington University, St. Louis, noted that surgical deep brain stimulation of the left and right subthalamic nuclei has shown a reduction in the severity of motor signs of 40%-60% and a reduction in medication use of up to 50%. But this technique involves a small craniotomy with implantation of stimulating electrodes, which has a 1%-5% risk of major adverse events such as hemorrhage, stroke, or infection.
Less severe complications include dystonia, dysarthria, gait impairment, dyskinesia, swallowing dysfunction, or change in verbal fluency; however, modification of the device programming may alleviate these effects. Nevertheless, some patients are wary of the implantation surgery and hardware and therefore decline to undergo deep-brain stimulation, the editorialists explained.
“The development of alternative procedures to deep-brain stimulation is important to the field of Parkinson’s disease treatment. The current trial begins the path to that goal, and improvements in targeting may improve the risk-benefit ratio and permit the use of lesions in both hemispheres, which would widen the population of eligible patients,” Dr. Perlmutter and Dr. Ushe wrote.
They pointed out that limiting the treatment to one side of the brain by ultrasound-produced lesioning constrains the application, since most patients with Parkinson’s disease have progression of symptoms on both sides of the body.
“The potential advantages and limitations of focused ultrasound–produced lesioning should be discussed with patients. We hope that improved technique will reduce the associated risks and increase the applicability of this provocative procedure,” the editorialists concluded.
This study was supported by Insightec, the Focused Ultrasound Foundation, Fundacion MAPFRE, Fundacion Hospitales de Madrid, and the University of Virginia Center of Excellence. Dr. Martinez-Fernandez reported receiving for consultancy fees for Insightec. Dr. Ushe reported non-financial support for Abbott outside the submitted work. Dr. Perlmutter disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.