Research Insights

Efficacies of globus pallidus stimulation and subthalamic nucleus stimulation for advanced Parkinson

Clinical interventions in aging

Tan ZG, Zhou Q, Huang T, Jiang Y. Clin Efficacies of globus pallidus stimulation and subthalamic nucleus stimulation for advanced Parkinson Clinical interventions in aging, 2016 Jun 21;11:777-86. doi: 10.2147/CIA.S105505. eCollection 2016.

Introduction:   Parkinson’s disease (PD) is a common neurological condition that is initially treated with levodopa to control the motor symptoms.  The medications are frequently effective but as the disease progresses the medications are frequently not as effective and can cause adverse motor side effects (e.g. freezing and dyskinesias) for People with Parkinson’s disease (PWP).  Additional therapies were created, deep brain stimulation (DBS), in the 1990’s and have consistently shown efficacy in controlling motor symptoms for PWP.  Much of the earlier research focused on the motor control and did not pay as close attention to the nonmotor symptoms which can also be very disabling.  Recent research has focused on neurocognitive outcomes and these authors conducted a meta-analysis to review such studies.  

Method:  After establishing multiple exclusion and inclusion criteria, a review of the literature was completed and ten randomized clinical trials (9 bilateral STN or Gpi, 1 unilateral) were analyzed.  The trials had evaluations at a variety of times including 6, 12, and 24 months postsurgery.

Results:  

      Motor: The results were slightly mixed before 24 months but at the 24 month mark the DBS STN group had more motor improvement. Notably the score difference was only a few points which showed to be statistically significant but likely was not clinically noticeable.  

      Medications: Results showed that more medication was needed after DBS GPi.
 
      Mood: The results showed that the DBS STN group had statistically significant lower mean depression scores but only by a few points.  Notably both groups had clinically meaningful depression mean scores with variability within each group.
 
      Cognition: A variety of cognitive domains were evaluated including language (fluency and naming), processing speed, executive functioning, and a broad screening measure.  Most of the cognitive measures showed no difference between groups but the DBS STN group had lower scores on the fluency measures and one task of executive functioning.  Mean test scores were not provided so it was unclear to what level each group was experiencing cognitive changes in general.
 
      Quality of Life (QoL): QoL was measured by the PDQ-39 which is a self-report measure looking at multiple dimensions of QoL (scales: mobility, activities of daily living; ADLs, emotions, stigma, social support, cognitions, communication, body pain, and an overall score). The DBS GPi group had higher scores in all areas but stigma which still tended towards the GPi group.  

Conclusion:  The authors concluded that both groups had improvement in motor functioning after DBS regardless of the target site and the minimal findings between the two were clinically insignificant.  They suggested that the choice for surgical intervention may be better suggested by the medicinal needs and nonmotor symptoms present prior to surgery.  As an example, they noted that DBS STN may be a better option for a PWP that had more levodopa induced dyskinesias prior to surgery as they likely would have a lower dose of levodopa after DBS which may minimize that adverse event.  They note that it is important to monitor depression symptoms in all PWP undergoing DBS.  The neurocognitive findings also noted that the DBS STN had more cognitive challenges on three specific measures that may have been due to surgical effect as the challenges remained even when the DBS was off.  Interestingly the DBS GPi group had higher QoL in most areas but was based on limited data with some possible presurgical differences as well.   This meta-analysis is a great first approach in looking at the nonmotor symptoms of DBS treatment for PWP.  These findings continue to suggest that the best approach to choosing the appropriate target for DBS should be based on the individual PWP after evaluation by a multidisciplinary team.

(The full article was available free online at the time of this writing through the pubmed link below. Click on the button in the top right area of the screen. 

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Click on either link and it should take you to the article and you can click on the PDF or HTML option to read or access the article.)

Click here to read the abstract.

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