Over the last decades, neuromodulation has been evolving to treat Parkinson’s disease (PD). Deep brain stimulation (DBS) is now accepted as the gold standard of treatment for advanced PD motor features, improving quality of life in many patients worldwide. DBS is used in Parkinson’s to improve tremor, rigidity, bradykinesia, dyskinesia and motor fluctuations not sufficiently controlled by medication. Regulatory approval exists for DBS across the world but take-up remains limited to less than 5% of people with PD. This is in-part due to the cost and complexity of the surgical procedure to implant a DBS device.

During DBS, electrodes are implanted deep in the brain, a pulse generator is implanted in the right subclavicular chest wall, and an electric current is passed through a connected lead wire to stimulate the targeted deep brain tissue. In addition to the selection of the DBS target and the stimulation parameters, new technologies have enabled a personalized approach to PD. Regarding the brain targets, the subthalamic nucleus (STN) and globus pallidus internus (GPi) are commonly used for DBS in PD. Both have their own strengths, and previous studies have compared the therapeutic effects of DBS on motor and non-motor features in both targets. However, there are no clear criteria for the choice of DBS target for PD patients and this is often determined by the physician’s preference. STN-DBS is better from a cost point-of-view, as it allows a greater reduction in medication and less battery depletion, while GPi-DBS is superior for patients who have problems with mood, speech, or cognition.

The effects of targeting the post-subthalamic area, or caudal zona incerta (PSA/cZi) are also expected to be positive. Motor features of PD are bilateral in most cases and often have a right/left side dominance. The effectiveness of unilateral STN and GPi-DBS has indicated that unilateral DBS may be an option in cases with a strong left/right dominance. Additionally, stepped GPi and STN-DBS, which is initially unilateral and then contralateral, may offer an effective resolution for certain PD patients. It is also notable that the connectomic approach has focused on the identification of stimulation targets in individual cases, and this scientific advancement may also contribute to personalized DBS targeting.

In recent years, with the evolution of DBS technology, directional leads and adaptive DBS have been developed and made clinically offered. Directional leads can be particularly useful in optimizing DBS stimulation to expand therapeutic windows, to reach segmented areas within the nucleus and to avoid stimulation-induced side effects. Adaptative DBS is a technique that was developed to enable analysis of local field potentials from leads in STN and/or GPi, revealing that beta oscillations are associated with motor features of PD. It may speed programming sessions and lower battery consumption when compared to conventional DBS. Research in regulating the stimulation of DBS and specific areas surrounding the main nucleus has also progressed, for example, low-frequency stimulation has been reported to have favorable effects in patients with “freezing of gait”. In addition, a single trajectory multitargeting the GPi and the nucleus basalis of Meynert has resulted in motor and cognition improvement in Parkinson’s disease. With these new techniques and stimulus adjustments, further enhancement of motor and non-motor symptoms in PD patients is anticipated. Then, it is important for clinicians to comprehend the advantages of devices made by different companies.

Therefore, DBS may be the advanced treatment that is most appropriate to personalized medicine. Clinical teams should be conscious that selection of the optimal brain target, device, and the stimulation parameters are all important. It is necessary to decide the optimal indication for surgical treatment according to the timing of treatment and an individual’s unmet needs. Multidisciplinary team medical care is a major driver behind solving problems and helping in the decision of a personalized DBS targeting.

The exciting topic of “Personalized DBS targeting” will be covered at the workshop session on Friday, July 7, 2023 from 3:30 – 5PM at the 6th World Parkinson Congress in Barcelona, Spain. I am looking forward to meeting you all there.

Vanessa Milanese, MD, PhD currently works at the Functional Neurosurgeon at BP – A Beneficência Portuguesa de São Paulo and she is adjunct professor of Neurosurgery at Mayo Clinic Florida. Dr. Milanese was part of the WPC 2023 Program Committee and will be speaking at the WPC 2023 in Barcelona. View the Scientific Program here.

Ideas and opinions expressed in this post reflect that of the author(s) solely. They do not necessarily reflect the opinions or positions of the World Parkinson Coalition®