DTI-ALPS index correlates with poor neuromodulation outcomes of bilateral STN-DBS in Parkinson’s disease patients: a prospective cohort study.

Publication date: Jul 07, 2026

This prospective study evaluated whether preoperative glymphatic magnetic resonance imaging (MRI) markers predict subthalamic nucleus deep brain stimulation (STN-DBS) outcomes in Parkinson’s disease (PD) and examined the mediating role of levodopa responsiveness. 111 patients with idiopathic PD scheduled for bilateral STN-DBS underwent multimodal preoperative MRI. Glymphatic indices-choroid plexus volume (CPV), diffusion tensor image analysis along the perivascular space (DTI-ALPS), periventricular diffusivity, perivascular space burden, choroid plexus free-water fraction, and global blood-oxygen-level-dependent cerebrospinal fluid coupling-were quantified. Patients were stratified by median postoperative motor improvement (52. 4%) into high- (n=55) and low-improvement (n=56) groups. The low-improvement group showed significantly larger total CPV (3353. 7 vs 3199. 4 mm^3, p=0. 039) and lower bilateral DTI-ALPS (1. 34 vs 1. 42, p=0. 004). DTI-ALPS correlated positively with both STN-DBS outcome (r=0. 246, p=0. 009) and levodopa challenge test (LCT) efficacy (r=0. 196, p=0. 039). Mediation analysis revealed that the DTI-ALPS effect on STN-DBS outcome was partially mediated by LCT (indirect effect 0. 096, 95% bootstrap CI 0. 013-0. 188), accounting for 50. 8% of the total effect. Other glymphatic markers showed no significant associations with DBS outcome. These findings indicate that glymphatic dysfunction, indexed by reduced DTI-ALPS, associates with poorer STN-DBS response in PD, acting partly through diminished dopaminergic reserve. DTI-ALPS may serve as an adjunctive preoperative marker to improve patient selection beyond conventional LCT.

Semantics

Original Article