In Challenge To Preferred Target Of Deep Brain Stimulation For Parkinson’s, A Call For More Research
When a neurologist and neurosurgeon believe deep brain stimulation may help a patient suffering from Parkinson’s disease they target either of two structures – the internal globus pallidus or the subthalamic nucleus – in an area of the brain that controls voluntary muscle movements.
While stimulating the subthalamic nucleus (STN) generally has been the therapy of choice, new research published in the June 20, 2012, issue of Neurology®, the medical journal of the American Academy of Neurology, challenges that preferred status, finding that stimulating the internal globus pallidus (GPi) may provide some long-term advantages.
The subthalamic nucleus has been regarded as the preferred target since 2002, when the Food and Drug Administration approved the therapy for Parkinson’s disease. Many physicians made this therapeutic choice because stimulation of the subthalamic nucleus often enabled patients to reduce their drugs, such as levodopa; the choice of target was left to doctors because no major clinical trial had shown that one target provides better results than the other.
The largest randomized trial, published in 2010, found “motor” outcomes – movement control – fared equally, regardless of target. That study and others also showed that while stimulation can improve motor skills, it does not stop cognitive, mood or behavioral declines.
The new study, based on outcomes in 159 patients from the 2010 trial, challenges the preferred targeting, finding that stimulating the internal globus pallidus may provide long-term advantages in both motor skills and cognitive function.
In his editorial, Tagliati says these and other findings warrant more research to answer questions such as: “Is it important or even desirable to reduce medications over the long term? Do medication and stimulation have a complementary or alternative role? Is GPi stimulation more compatible with long-term medical therapy? Is chronic STN stimulation interfering with dopaminergic stimulation?”
“If the art of making medical decisions reflects a continuous struggle between evidence- and preference-based practices, this study will inject more reliable evidence in delicate long-term decisions, based until now almost exclusively on the preference and personal experience of the DBS provider,” he concludes.
“Turning Tables: Should GPi become the preferred DBS target for Parkinson’s Disease?” (editorial),
published online in Neurology June 20, 2012, in print July 3, 2012