Which target is best for patients with Parkinson's disease? A meta-analysis of pallidal and subthalamic stimulation

There is a growing body of evidence demonstrating that deep brain stimulation (DBS) of globus pallidus internus (GPi DBS) and subthalamic nucleus (STN DBS) are effective treatment for patients with Parkinson's disease (PD). However, it remains controversial whether the best stimulation target for a PD patient is GPi or STN.

A computer literature search of PubMed was carried out. We included randomised studies with direct comparison between targets. The outcome of unified PD rating scale (UPDRS) III was expressed as the standardised mean difference (SMD) between targets in baseline to endpoint change. Pooled risk ratio (RR) between targets was also used to assess adverse events.

Four studies, comprising a total sample size of 502 PD patients (254 GPi DBS, 248 STN DBS), were included in this meta-analysis. The overall effect of GPi DBS on UPDRS III was not significantly different from STN DBS (SMD=0.19, 95% CI -0.2 to 0.58, p=0.34, four studies, n=448). This result was heterogeneous (p=0.03, I(2)=66%). In terms of adverse events, depression was significantly less frequent in patients with GPi DBS than STN DBS with homogeneous studies (pooled RR=0.53, 95% CI 0.31 to 0.90, p=0.02, three studies, n=479, I(2)=48%).

The effect of GPi DBS was similar to STN DBS except for depression, however, only three studies described depression as adverse events. We need additional randomised trials with direct comparison between targets based on unified scoring of adverse events.