Where are we with surgery for PD?
I have had the privilege to be involved in surgery to treat Parkinson’s disease (PD) for over 20 years. I still remember the first patients with severe advanced PD who had deep brain stimulation (DBS) surgery in the early 90’s. After a lot of suffering, these patients could have a decent life back: no more violent dyskinesia or very painful and disabling dystonia, no more horrible tremor and motor fluctuations. It really was like a miracle! I also still remember the hours spent in the operating room to test treatment efficacy and side-effects…. A great team effort, but so rewarding for everybody!
Nowadays, DBS is a well-recognized standard treatment for advanced PD. Since the first surgery in Grenoble (France) in 1987, more than 160,000 patients have benefitted from this therapy all over the world. We have learned so many things about DBS within these years. We have a better understanding of the pathophysiology of the basal ganglia, the motor and non-motor effects of surgical treatments, and the short and long-term effects of DBS. The DBS mechanisms of action are complex, but overall advantageous for the brain functions and functionality. Moreover, the success of DBS in movement disorders has been applied to several other neurological and psychiatric diseases. Advances in technology and competition between industries have allowed the introduction of more flexible and smaller devices to better adapt stimulation to the person with Parkinson’s needs. Leads allowing the device to steer current and shape the stimulation area, and closed-loop stimulation allowing the delivery of current on-demand, are likely only the beginning of a new technological era for neuromodulation. Moreover, other brain targets beside the thalamus, the subthalamic nucleus and the globus pallidum, have been investigated.
Yet, DBS is not a cure, but a symptomatic treatment of the relative advanced phases of PD. DBS candidates represent less than 10% of the overall PD population since surgical indications remain quite strict despite some recent changes within the last few years. Compared to the first DBS indications for PD, there has been a trend to operate earlier within the course of the disease. Indeed, several trials have shown that DBS could improve PD signs and quality of life better than the best medical treatment. Former absolute contraindications, like the presence of impulsive control disorders at time of surgery, are not valid nowadays and actually can be improved after DBS surgery. Nevertheless, the DBS journey requires a specialized multidisciplinary team to achieve satisfactory results.
Before the DBS era, lesions were applied to alleviate tremor (conventional thalamotomy), bradykinesia, rigidity and levodopa-induced dyskinesia (conventional pallidotomy). Although somewhat effective, lesions were mostly done unilaterally and were not very popular because of the risk of permanent side effects. Recently, lesions have been revamped by the use of MRI-focused ultrasound, a technology that allows making small deep brain lesions without opening the skull. Non-invasive surgical treatments are very appealing due to the reduced risks related to the DBS surgery and devices, and the easy post-operative management with immediate relief of the symptoms. However, small lesions might shortly lose the initial benefit and be linked to permanent side effects.
Overall, DBS surgery remains a very effective treatment for motor signs in advanced PD. Several non-motor signs can also be improved. DBS has several limits, mainly due to technological limits and the absence of clinical neuroprotective effects. MRI-focused ultrasound can be currently applied in selected people with Parkinson’s who have contraindication for DBS surgery and do not require bilateral procedures.
Will DBS surgery become obsolete soon? I do not believe so, at least not within the next fifteen years. Although several new drugs are under study and development for early (even prodromal) and advanced PD, DBS allows the person with Parkinson’s to have a more independent life compared to the other invasive treatments (apomorphine and intestinal levodopa pumps). Compared to the modern lesions, DBS has a safer and more solid effective profile as a bilateral intervention. DBS technology continues to advance, and new devices will permit better management by the person with Parkinson’s.
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Elena Moro, MD, PhD is a Professor of Neurology at Grenoble Alpes University in Grenoble, France. Elena Moro was a speaker at the 3rd World Parkinson Congress in Montreal, and she is a current member of the Program Committee for the 5th World Parkinson Congress in Kyoto, Japan.
Ideas and opinions expressed in this post reflect that of the author(s) solely. They do not necessarily reflect the opinions of the World Parkinson Coalition®