- Movement Disorders, Movement and Neuroperformance Center of Colorado, USA
- Department of Neurology, Swedish Hospital Medical Center, Englewood, Colorado 80113, USA
Movement Disorders, Movement and Neuroperformance Center of Colorado, USA
Department of Neurology, Swedish Hospital Medical Center, Englewood, Colorado 80113, USA
DOI:10.4103/2152-7806.112612Copyright: © 2013 Farris S This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: Farris S, Giroux M. Retrospective review of factors leading to dissatisfaction with subthalamic nucleus deep brain stimulation during long-term management. Surg Neurol Int 28-May-2013;4:69
How to cite this URL: Farris S, Giroux M. Retrospective review of factors leading to dissatisfaction with subthalamic nucleus deep brain stimulation during long-term management. Surg Neurol Int 28-May-2013;4:69. Available from: http://sni.wpengine.com/surgicalint_articles/retrospective-review-of-factors-leading-to-dissatisfaction-with-subthalamic-nucleus-deep-brain-stimulation-during-long-term-management/
Background:Subthalamic nucleus deep brain stimulation is effective in reducing motor symptoms in appropriately selected patients with Parkinson's disease. We identified factors that contribute to poor outcomes during early, middle and late stages of stimulation management in a series of patients that were referred for troubleshooting poor outcomes.
Methods:We performed a retrospective review of 50 patients with bilateral STN DBS seen in our movement disorders clinic with unsatisfactory clinical response and/or patient dissatisfaction with deep brain stimulation outcome. All patients underwent a systematic evaluation to assess the primary cause of suboptimal outcome including lead position, hardware integrity, patient selection, patient expectations, effective use of stimulation settings, and pre- and postoperative levodopa responsive symptoms. The data was also analyzed by duration of stimulation to determine if these factors varied by stage of DBS management.
Results:Our series included patients implanted 4-68 months. We identified the following primary factors impacting outcome: Suboptimal stimulation settings (52%), disease progression (16%), inappropriate patient selection (10%), hardware damage (8%), lead malposition (8%), met expected motor outcomes (6%). Lead revision surgery occurred in 14%. Reversible factors accounted for dissatisfaction in 74%. Suboptimal stimulation was the dominant factor affecting outcomes in early and long-term management phases.
Conclusion:STN DBS outcomes can be improved even years after implantation. Stimulation parameters warrant investigation throughout the continuum of DBS management as a reversible cause of poor outcomes.
Keywords: Deep brain stimulation, long-term management, outcomes, Parkinson's disease, subthalamic nucleus
Subthalamic nucleus (STN) deep brain stimulation (DBS) can improve Parkinson's disease (PD) tremor and motor complications such as fluctuations and dyskinesia robustly in the initial years postimplantation with sustained efficacy noted over 10 years.[
We performed a retrospective chart review of 50 consecutive PD patients with bilateral STN DBS evaluated due to patient or clinician dissatisfaction with DBS that prompted a referral.
Fifty patients were evaluated between 2007 and 2010 and are described in
The primary factors impacting outcome for the group were suboptimal stimulation settings in 52%, hardware damage in 24%, disease progression in 16%, lead malposition in 8%, and inappropriate presurgical patient selection in 10%. Six percent met the benchmarks for benefit,[
Stimulation optimization phase (up to 12 months postimplantation)
Fourteen patients had DBS for up to 1 year. Axial symptoms were the reason for referral in nine patients. Of the five patients deemed poor candidates, two had multisystem atrophy with symptom onset less than 5 years prior to surgery, one had dementia, and two had dopaminergic nonresponsive motor symptoms with severe gait freezing. Five patients had wire damage but only two required lead replacement as programming options remained for the remaining three patients. Stimulation adjustment in the remaining eight patients (including the patient with dementia) further improved mUPDRS. Off medication on stimulation mUPDRS scores improved from 26% to 48% after reprogramming. Of note, axial symptoms improved in five patients when stimulation side effects (presumably internal capsule) were eliminated.
Early maintenance phase (second year postoperative)
Of the 12 patients in the early maintenance phase, 1 had multiple system atrophy (MSA) and not a surgical candidate, 3 had malpositioned leads, and 2 had hardware damage requiring surgical referral for revision. In total, five patients were referred to a surgeon for lead revision. Stimulation adjustment improved mUPDRS scores in the remaining seven patients. Off medication on stimulation mUPDRS scores improved from 24% to 51% after reprogramming. Of note, gait improved objectively in the patient with MSA through reduction in internal capsule stimulation affecting lower extremities.
Late maintenance phase (more than 2 years postoperative)
Twenty-four patients were evaluated in this phase. Twenty patients had a primary complaint of axial symptoms of which eight were diagnosed with disease progression as determined by the nonlevodopa responsive symptoms also unresponsive to stimulation. Reprogramming did improve mUPDRS scores in 11 patients. The off medication on stimulation mUPDRS scores improved from 22% to 54% after reprogramming. Four had hardware damage requiring lead replacement in two and frailty prevented lead replacement in the other two. The remaining three patients were meeting expectations at mUPDRS 52% when compared with benchmarks for motor outcomes in the literature[
There are marked differences in the cause for suboptimal DBS response in our series compared with prior reporting.[
Patients were further separated into three groups as defined by the duration of DBS stimulation to gain a better understanding of contributing factors over time. The definition of the groups was chosen by the authors to represent different stages of clinical management. The DBS optimization phase is defined as the first 12 months postsurgery as supported by DBS consensus[
Analyzing the patient data in this way revealed some important findings. As expected patient selection, lead malposition, and suboptimal stimulation settings were significant factors in the earliest phase and disease progression coupled with incongruent patient expectations more prevalent in later stages of management. Of interest, stimulation side effects and subtherapeutic settings were prevalent in each of the clinical management phases regardless of whether patient was in the optimization phase or maintenance phases.
Over half (N = 26) of the patients had DBS within 2 years when benefit is expected to be robust,[
The majority of our programming changes involved strategies to reduce the field of stimulation to avoid side effects of overstimulation. Internal capsule stimulation was a noted reversible cause of worsening axial symptoms (gait, balance, and speech) where reprogramming improved axial symptoms in patients (N = 22) reporting worsening gait, balance, and speech after DBS. This finding is important since the majority of patients were self-referred and dissatisfied with therapy due primarily to problems of gait freezing, imbalance, and speech. Axial symptoms are typically nonresponsive to medication or DBS therapy and thought to be a marker of irreversible disease progression in a DBS patient. Improved axial symptoms with reprogramming was noted in each of the clinical phases including the group with longest duration DBS stimulation, highlighting the importance of threshold testing and levodopa responsiveness as valuable data in guiding long-term management.
Although our analysis was not intended to identify the root cause of suboptimal programming, there are likely many reasons that suboptimal programming was found to be the most prevalent factor in early and long-term management. Patients’ high and evolving expectations for surgery, frustrations with disease progression and nonresponsive axial symptoms prompting changes in stimulation, tendency to continue to tweak and overstimulate over time and difficulty differentiating motor symptoms from internal capsule stimulation vs. disease progression can play a role. In addition, DBS therapy in itself is complex and represents only one of a multitude of treatment decisions required to tailor treatment to an individual that and must be coordinated with medication changes, rehabilitative services, and behavioral counseling.
These findings reflect the need for greater programming expertise, which will become even more important as the number and type of implanted devices increases, indications broaden, and patient implantation years increases.
Difficulties inherent to a retrospective chart review and population biases are clear limitations of this study. Nonetheless, our experience provides valuable information that can guide long-term DBS care and serve as a lens for further study.
The authors thank Jay Nutt, MD, Professor of Neurology at Oregon Health and Science University, Portland Oregon, for guidance and review of the original manuscript.
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