Impact of subthalamic nucleus stimulation did not differ on young-onset and older-onset Parkinson's disease: A three-year follow up

Highlights

• A three-year retrospective cohort study is conducted.

• The different impact of STN-DBS on YOPD and OOPD patients with an onset age cut-off of 50 years is first demonstrated.

• STN-DBS alleviates motor symptoms and improves quality of life equally in both YOPD and OOPD patients.

Abstract

Objective

To assess the role of onset age in the results of bilateral subthalamic nucleus deep brain stimulation (STN-DBS), we carried out a retrospective study of two groups of patients regarding age at disease onset.

Methods

We compared, up to 3 years after surgery, the clinical effects, quality of life and the levodopa equivalent daily dose (LEDD) in patients with young-onset Parkinson’s disease (onset age <50 years, YOPD) vs patients with older-onset Parkinson’s disease (onset age ≥50 years, OOPD).

Results

A dramatic improvement in motor symptoms was equally observed in both groups of patients after DBS. The improvements of the Unified Parkinson’s Disease Rating Scale part III motor scale (UPDRS-III) score, axial sub-score and non-axial sub-score from baseline gradually decreased over time. The benefit of STN-DBS for the axial symptoms decreased most rapidly, which directly resulted in a progressive decline in stimulation efficacy in both groups. Nevertheless, the improvement in non-axial symptoms after DBS was remarkable and long-lasting. The quality of life in both groups were also improved after DBS but were slightly decreased in the following years. The reduced LEDD were equivalent in both groups.

Conclusions

STN-DBS alleviates motor symptoms and improves quality of life equally in both YOPD and OOPD patients with similar LEDD. The initial therapeutic benefit of STN-DBS for PD gradually decreases over time, mainly due to the progression of PD and the rapid withdrawal of the benefit for axial symptoms.

Introduction

Parkinson's disease (PD) is a heterogeneous neurological disorder characterized by resting tremor, rigidity, bradykinesia, gait and postural disorders [1]. Based on the onset of the disease, PD can be classified into two subtypes: young-onset Parkinson's disease (YOPD) and older-onset Parkinson's disease (OOPD). YOPD has been typically defined as onset of PD signs between the ages of 21 and 40 [2]. For the present study, a somewhat less restrictive definition of YOPD was adopted; patients were considered eligible for study if they received a diagnosis of PD on or before the age of 50 [3,4].

Bilateral subthalamic nucleus deep brain stimulation (STN-DBS) is a well-recognized treatment for motor complications in advanced PD, with well-documented improvements in PD motor symptoms in the short- and long-term [[5], [6], [7]]. Nevertheless, there are few data focusing on the role of PD onset age on the outcome of patients treated with STN-DBS.

In 2010, Otaka and colleagues first reported the results of a short-term comparison between 15 YOPD (21–40 years of onset age) and 113 late-onset PD (LOPD) (>40 years of onset age) patients 6 months after STN-DBS surgery; the authors observed greater improvement in the UPDRS-III score in the YOPD group than in the LOPD group [8]. In the same year, Young Seok Park and colleagues also compared the differences in response between 18 YOPD (<40 years of onset age) and 15 LOPD (≥56 years of onset age) patients at six months postoperatively and found that the age of onset does not influence the response to STN-DBS in PD patients [9]. In 2012, a study by Merola et al showed that STN DBS-treated YOPD patients (<40 years of onset age) were associated with a medium to long term lower incidence of stimulation resistant symptoms [10].

The studies above used a cut-off onset age of 40 years for YOPD and resulted in conflicting conclusions. Nevertheless, differences in response to STN-DBS treatment between YOPD (onset age <50 years) and OOPD (onset age ≥50 years) patients have not been assessed. We therefore investigated the short- and long-term impact of bilateral DBS-STN on the patients with disease onset before the age of 50 years compared with those with older age of onset.