It has been consistently shown that deep brain stimulation (DBS) in combination with medication is superior to medication alone in mid- and advanced-stage Parkinson’s disease (PD).1 These findings also motivated researchers a few years ago to determine the effect of DBS in early-stage PD in a prospective, randomised clinical pilot trial.2 In this pilot study, 30 early‑stage PD patients were randomised 1:1 to receive either bilateral subthalamic nucleus (STN) DBS in addition to optimal drug therapy or optimal drug therapy only. Patients were evaluated over a period of two years.2 The primary safety endpoint at this timepoint was met, and the results provided class II evidence that STN DBS slows down the progression of rest tremors.3
Interest in long-term data
While these results led to the approval of a Phase 3 clinical trial to evaluate DBS in early-stage PD, Mallory Hacker (Department of Neurology, Vanderbilt University Medical Center, United States) and his colleagues focused on the long‑term results of the pilot trial.1 Until that point, there were no published reports of long-term follow-up of DBS in PD patients of any stage available. This type of data was of particular interest in early-stage PD patients due to the long duration of DBS they would be exposed to.
Benefit of DBS seen in 5-year follow-up
The recently published observational follow-up data from Dr Hacker and his team comprise reports from annual visits over five years.1 The data show that STN DBS plus medication led to a significantly lower chance of patients receiving several medications at 5 years compared with patients who only received medication. In addition, patients who received DBS had a significantly lower risk of having a worse rest tremor (P=<0.001), while the safety profile was comparable between the two groups.
Promising outcomes, more data to come
The published long-term data are promising but not enough to provide profound evidence. The results suggest that STN DBS is safe in early-stage PD patients, and that it has potential to provide a long-term and sustained motor benefit. In addition, it was shown that it reduces the need for antiparkinsonian medications. As mentioned previously, a Phase 3 trial following up on the results of the pilot study has already been approved, and Dr Hacker and his team will have to wait for the results to draw profound conclusions.