Parkinson’s disease DBS: what, when, who and why? The time has come to tailor DBS targets.
Okun MS, Foote KD. Parkinson’s disease DBS: what, when, who and why? The time has come to tailor DBS targets. , Expert Rev Neurother. 2010 Dec; 10(12):1847-57
This article answers the questions of what, when, who, and why in regards to DBS for PD. The authors initially point out that all of the research so far on DBS for PD has shown that a single target and single approach to the surgery is not in the best interest of the patient or the field. Much of the research done to this point has shown that DBS needs to be tailored to each individual. The authors also highly recommend the use of an interdisciplinary approach ("neurosurgery, neurology, neuropsychology, and psychiatry") to screen individuals for such therapy in order to facilitate optimal surgical outcome.
- The authors recommended that the surgical target be selected based on all available information about the patient and their symptoms which should be collected by the interdisciplinary team.
- The topic of unilateral versus bilateral DBS was also discussed and the consensus was that there are still questions about which approach is best for various patients, and it may also depend upon the brain region targeted (e.g. GPi vs. STN). Research has shown that both the STN and GPi are effective targets to reduce motor symptoms. They recommended more studies look at this information.
- The article also discussed the pros and cons about simultaneous implantation of the DBS leads versus a staged approach over the course of days, weeks, or months. There is not a consensus about either strategy, and it depends on the comfort levels of the treating team as well as facility.
- The authors also discussed that the more "microelectrode passes" required in the surgery as well as poorer cognitive performance on a screening measure were indicators of likely longer stays within the hospital for various patients. They recommended more studies look at this information.
- In the research and clinical observations summarized to date, there have been positives and negatives to all of the targeted brain areas thus far.
- Due to the invasive nature of the surgery, most physicians make the determination for appropriateness of surgical intervention for PD patients after all medicinal therapies have failed and motor symptoms are difficult to manage. However, the authors also talk about questions and scenarios regarding patients that have not advanced to the point of medication failure and could possibly benefit from surgical therapy.
- They noted that surgery for the questionable cases described should be completed within a clinical research setting.
- One rationale for waiting on the surgery is the possibility that the condition is not truly Parkinson’s disease and may be another neurological condition that mimics PD early in the disease course.
- Studies to address this topic are ongoing, and the authors expect there to be continued debate on study outcomes, particularly as it relates to the studies’ research methodology.
- After a review of the larger studies on DBS the authors conclude that the most likely patient to benefit from DBS would be one that has a failed response to medications and poorly controlled on-off motor fluctuations.
- They noted that the most common cognitive difficulty that has occurred after DBS is a reduction in patient’s verbal fluency (e.g. ability to get words out quickly).
- The authors also discussed that depression has been shown to improve immediately after surgery but may worsen after a longer period of time. Anger was also found to be problematic. It is unclear whether or not these changes are due to the stimulation in and of itself or from the lesion created during the surgery.
- It is suggested that patient selection be done by a multidisciplinary or interdisciplinary team. Patient goals and expectations about the surgery should also be sought by the team and outcome measures need to be patient centered for motor and nonmotor symptoms.
- Surgical intervention can be very successful for appropriate PD candidates in the “moderate to advanced” stages.
- It was suggested that studies continue looking at other surgical treatment options compared to DBS to determine how effective those options are.
- The ultimate goal of DBS is to maximize therapeutic benefit in reducing specific motor symptoms; while at the same time minimizing risks for the patient (key areas were discussed in the article).
- Success also depends upon adequate programming of the device after the surgery.