Deep brain stimulation targeting the subthalamic nucleus versus the globus pallidus internus for tremor control in parkinson's disease: A systematic review and meta analysis.

Deep brain stimulation (DBS) is a well-established therapy for advanced Parkinson’s disease (PD). Among available targets, the subthalamic nucleus (STN) and the globus pallidus internus (GPi) are most frequently stimulated, yet their relative efficacy for tremor control remains uncertain. This systematic review and meta-analysis aimed to quantitatively compare tremor outcomes between STN-DBS and GPi-DBS in patients with PD. Following a prospectively registered protocol (PROSPERO CRD420251153336), comprehensive searches of PubMed, Embase, Scopus, Web of Science, and the Cochrane Database were performed. Randomized or controlled comparative studies reporting tremor outcomes under standardized medication/stimulation conditions were eligible. Change scores were converted to standardized mean differences (Hedges g) and pooled with a random-effects model. The primary endpoints were the magnitude of tremor improvement, heterogeneity indices (τ², Q, I²), and between-target differences. Certainty of evidence was rated according to the GRADE framework. Ten studies met inclusion criteria, of which three provided quantitative data for meta-analysis (Mann 2009; Nutt 2001; Zeng 2022). Both STN-DBS and GPi-DBS yielded marked tremor reduction ranging between approximately 65% and 90% from baseline in individual trials. Pooled analysis showed no significant long-term difference between targets (Hedges g = − 0.08; 95% CI − 0.53 to 0.38; p = 0.74; I² = 0%). Early postoperative data suggested a modest temporal advantage for STN-DBS, although long-term outcomes converged. Across studies, adverse events were mild and comparable, with transient dysarthria and behavioral changes slightly more frequent with STN stimulation. The overall certainty of evidence for tremor outcomes was low, mainly due to small sample size and variability in tremor assessment scales. In conclusion, both STN and GPi targets provide comparable and substantial tremor suppression in PD. The pooled analysis demonstrated statistical equivalence between targets with low heterogeneity and low certainty of evidence. While STN-DBS may offer slightly faster tremor relief and broader motor improvements, GPi-DBS remains equally effective for long-term tremor control and may better mitigate dyskinesias. Optimal target selection should therefore rely on individualized clinical profiles rather than presumed efficacy differences.