Deep brain stimulation may improve quality of life in Parkinsons disease

By Dr. Liji Thomas, MDJan 22 2024Reviewed by Benedette Cuffari, M.Sc.

A new study published in JAMA Network Open Neurology reports on a five-year follow-up of Parkinson disease (PD) patients treated with either medication alone or deep brain stimulation (DBS) of the subthalamic nuclei (STN).

Study: Neurostimulation for Advanced Parkinson Disease and Quality of Life at 5 Years: A Nonrandomized Controlled Trial. Image Credit: Pavlova Yulia / Shutterstock.com

What is DBS?

PD is among the most common and tragically disabling neurological conditions in older adults. DBS-STN has been shown to help patients suffering from advanced stages of PD; however, there is little data to support the effectiveness of this treatment over the long term.

Prior research revealed that DBS-STN helped PD patients regain some of their quality of life (QOL) and relieved some symptoms both related and not related to movement. The effects of this therapy on motor symptoms have been demonstrated in long-term studies with over five years of follow-up; however, these studies did not report similar benefits associated with improved QOL.

This led to more recent meta-analyses of the literature on DBS-STN patients, which claimed better QOL for up to three years following surgery and subsequently returning to baseline at five years. However, all PD patients exhibit declining QOL on standard medical care.

About the study

The current study compared QOL between patients treated with either standard medication (MED) or DBS-STN for three years or more.

The assumption was that at five years, patients with advanced PD would not exhibit a significant change in their QOL as compared to deterioration observed in patients on MED. This would lead to better outcomes with DBS-STN, as demonstrated by a reduced need for medication or improved motor symptoms, as well as higher QOL. The researchers also investigated links between altered QOL and other outcomes.

The current observational study included multiple centers as part of the ongoing prospective Non-Motor International Longitudinal Study (NILS) study. A total of 108 patients participated in the study, 46 and 62 of whom were treated with MED and DBS-STN, respectively.

Both groups were comparable in terms of advanced motor and non-motor symptoms, especially dyskinesia, tremor resistant to medication, and on/off states. Both patients were prescribed oral or transdermal drugs.

The median duration of PD in the study cohort was 7.7 years; however, the DBS-STN group had a longer median duration. At baseline, QOL in the DBS-STN group was lower and their motor symptoms were worse than those in the MED group.

What did the study show?

A 50% decline in QOL was observed in the MED group by five years, whereas a stable trend was observed in the DBS group. The difference between the QOL scores at baseline was 6.6 points favoring the DBS group.

In the MED group, total mobility scores declined by 4.5 points. Comparatively, DBS-STN led to an initial improvement in mobility scores, which eventually waned and returned to baseline.

The greatest improvement was in mobility at five years in the DBS-STN group as compared to the MED group, with overall mobility scores greater by one point in the former.

The decline in total mobility score in the MED group was attributed to worsening of activities of daily living (ADL) scores by 25% and motor complications by over 27%. Conversely, the DBS group exhibited 47% improvement in motor symptoms.

QOL remained higher in the DBS-STN group, mainly because of the increased mobility. Moreover, this group enjoyed better support from their social contacts, were better able to perform their ADL, had less discomfort, and felt less stigma. This underlines the benefits of using DBS in terms of better motor responses.

However, the MED group exhibited better communication ability, as expected from earlier studies revealing that speech intelligibility suffered over time with DBS-STN.

The DBS group had a 62% reduction in their requirement for levodopa equivalent daily dose (LEDD). Comparatively, the MED group registered an increase of 17% for LEDD.

The total electrical energy delivered (TEED) increased by 90% from the one-year to the five-year follow-up time point.

Adverse effects (AEs) occurred at a significantly high rate in the study, as reported in earlier studies, which reflects the need for proper evaluation of the patient for risk-benefit scores prior to surgery. None of the reported AEs were life-threatening and a third were related to the device or surgical procedure. Psychiatric and neurological AEs were also frequently reported.

What are the implications?

The study findings demonstrate that DBS-STN improves QOL in patients with advanced PD, mainly by promoting their mobility. This clinically relevant difference was not observed in DBS patients being treated for very early PD without motor complications or dyskinesia.

The higher QOL was associated with better scores for ADL, though not for other symptoms. Thus, ADL should be discussed when exploring long-term outcomes of DBS-STN in PD patients. Moreover, further research is needed to identify pre-surgical risk factors for poor QOL outcomes in these patients.

Motor symptoms and requirements for PD medications were followed up for five years for the first time in this study. Similar to prior studies, the researchers observed that motor symptoms significantly improved at this time point in the DBS group but only at one year in the MED group.

The one-year improvement in the MED group is attributed to medication protocols being optimized during the start of the study. However, this was followed by dyskinesia and greater fluctuation in motor symptoms until returning to baseline. This could be the result of disease progression or complications from long-term dopamine agonist therapy.

The association between changes in QOL and ADL highlights the relative importance of ADL outcomes for long-term DBS assessments.”

The improvement in QOL was limited to advanced PD cases and motor symptoms but not communication outcomes. Taken together, the study findings should help counsel patients eligible for DBS-STN and how they are monitored post-operatively.