by A groundbreaking study conducted by a team of physicians, neuroscientists, and engineers at Duke University has introduced two innovative strategies that utilize deep brain stimulation (DBS) to enhance the symptoms of Parkinson’s disease. By simultaneously targeting two crucial brain structures and employing a new self-adjusting device, the team has demonstrated the ability to effectively focus on and improve disruptive symptoms caused by this movement disorder. The findings of this research have been published online in the reputable medical journal Brain.
For the past two decades, DBS has been prescribed by physicians to alleviate the symptoms of advanced Parkinson’s disease when medications alone are no longer effective. This technique employs a device similar to a pacemaker to deliver electrical impulses to specific areas within the brain. This targeted stimulation successfully reduces tremors, stiffness, and involuntary movements that often occur after prolonged use of medications. However, while DBS has proven to be an efficient therapy, it still has limitations. Consequently, physicians and researchers are continuously exploring new approaches to enhance its effectiveness.
During DBS, physicians implant electrodes in either the subthalamic nucleus or the globus pallidus, two brain structures closely associated with movement. Senior author Dennis Turner, a professor of neurosurgery, neurobiology, and biomedical engineering at Duke University School of Medicine, states that although there are advantages to targeting either structure individually, there is the belief that utilizing electrodes in both locations could complement each other, reduce medication dosages and side effects, and introduce an entirely new approach to adaptive DBS.
In addition to wider stimulation coverage, the research team aimed to investigate whether employing adaptive DBS could enhance the efficiency of deep brain stimulation. In traditional DBS, physicians set specific electrical parameters, such as amplitude, pulse frequency, and pulse duration, to provide the best symptom relief while minimizing side effects. These parameters typically remain unchanged for extended periods, depending on the patient’s response. However, according to Warren Grill, a distinguished professor of biomedical engineering at Duke, these fixed parameters are far from optimal.
The required level of stimulation for individuals with Parkinson’s disease varies depending on factors such as medication use and activity levels. A patient may require more stimulation when participating in physically demanding activities compared to when they are at rest. An adaptive DBS system acts like a smart thermostat, making adjustments based on external factors such as temperature.
To implement this personalized approach, the research team collaborated with medical device company Medtronic to develop their own adaptive DBS techniques using experimental technology. By programming the device to detect and record key biomarkers and brain activity in patients, the researchers established a system that can automatically adjust stimulation parameters to provide optimal symptom relief throughout the day.
The team conducted a clinical trial at Duke University Medical Center involving six patients aged between 55 and 65, each with varying Parkinson’s disease symptoms. Initially, they spent two years observing and testing the effectiveness of stimulating both the subthalamic nucleus and the globus pallidus using the standard continuous DBS technique. The results were measured through patient feedback, tracking their ability to move without experiencing involuntary movements, and monitoring the reduction of medication needed to manage symptoms.
Simultaneously, the team conducted experiments to determine the parameters for an adaptive DBS system. They focused on studying a specific frequency of brain activity called beta oscillations in the subthalamic nucleus. Prior research has shown that high levels of beta oscillations are associated with the slow, halting movements characteristic of Parkinson’s disease. Stephen Schmidt, a research and development engineer in the Grill lab, explains that testing different levels of stimulation enabled them to identify optimal levels of beta oscillations for symptom improvement under various scenarios. Furthermore, this allowed them to compare the performance of adaptive and standard DBS in a home setting.
After two years of using the adaptive system, the team obtained promising results. Targeting both the subthalamic nucleus and globus pallidus simultaneously was found to improve motor symptoms more effectively than targeting either region alone. Furthermore, the adaptive DBS applied less stimulation but was equally effective as continuous DBS in clinical and home settings.
Assistant Professor of Neurology at Duke University School of Medicine, Kyle Mitchell, expressed his enthusiasm stating, “Clinically, the patients are doing phenomenally… We’re not only seeing excellent clinical responses to dual-target stimulation, but we’re also able to integrate this adaptive, smart tool into the brain that can at least match this clinical response.” Buoyed by the success of their initial research, the team plans to further optimize adaptive DBS and conduct additional testing in the next stage of clinical trials.
Warren Grill, the distinguished professor of biomedical engineering at Duke, highlights the immense potential of this breakthrough, describing it as a more tailored and elegant therapy for DBS. He acknowledges that this promising research could not have been accomplished without the six courageous participants who volunteered for this experimental work, as well as their families and caregivers. The team is grateful for their significant contributions to this effort, which has the potential to revolutionize the field of DBS.
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