STN vs. GPi Deep Brain Stimulation: Translating the Rematch into Clinical Practice
Williams NR, Foote KD, Okun MS. STN vs. GPi Deep Brain Stimulation: Translating the Rematch into Clinical Practice , 2014 Apr 1;1(1):24-35
Intro: There are multitudes of studies that have shown DBS’s efficacy in treating motor symptoms in people with Parkinson’s disease (PWP). Typically, the treatment is implemented for advanced stages of PD but there is some literature suggesting the treatment may also benefit PWP earlier in the disease course. Throughout the past couple of decades there has been changing opinions about the best surgical site for DBS (globus pallidus internus-GPi or subthalamic nucleus-STN). This article reviewed the evidence for and against the different sites for DBS, motor and nonmotor symptoms, adverse events, as well as how best to optimize this treatment for PWP.
DBS vs. Medications: DBS has shown to be a better therapy than medications only for advanced stages of PD. The jury is still out regarding using the surgical treatment with known surgical risks as an earlier treatment.
Surgical Candidacy: Selection of good surgical candidates is very important for PWP to insure that the person will have good effects from the treatment. Notably, not everyone will benefit from this therapy and the decision regarding candidacy, follow up care, and surgical site should be made by a multidisciplinary team (neurology, neurosurgery, neuropsychology, psychiatry, and rehabilitation specialist). This team should meet with each PWP individually and discuss the best approach to treat motor and nonmotor symptoms. Preexisting behavioral difficulties should attempt to be stabilized before the PWP undergoes treatment and monitoring of depression and suicidality should be monitored after DBS regardless of surgical site.
Surgical Site: Review of the recent literature that directly compared STN to GPi found that both were effective in treating PD but each had different strengths and weaknesses. Table 1 in the article went through multiple points and specifically identified superiority of the treatment in defined areas. Generally, they found no differences between GPi and STN regarding tremor, rigidity, or off-time motor symptoms.
STN showed superiority for bradykinesia, ability to reduce L-dopa after surgery that may reduce overall treatment costs, and longer battery life. Weaknesses of the STN included the size of the surgical target being small and more prone to adverse events due to erroneous spread of current from the stimulator. Additionally speech and swallowing abilities were affected.
GPi showed superiority for gait and balance outcomes, suppression of dyskinesias, less cognitive adverse events, more flexibility to make L-dopa medication adjustments after stimulation, easier programming settings and maintenance options, unilateral DBS placement leading to motor and quality of life improvements, and mood outcomes. A weakness of the GPi included more battery usage due to the larger size target of the GPi, which resulted in increased cost of treatment.
Conclusion: The authors note that there is not a one size fits all approach to DBS for PD. They encourage tailoring the surgical site to each patient based on all of the above information as well as based on the strengths and challenges of the PWP. Much has been learned over the past couple of decades about DBS and more knowledge will be gained with improvements in imaging, surgical techniques, technology, and other possible targets related to the multiple symptoms of PD.