To determine the one-year effects of Globus Pallidus Internus (GPi) deep brain stimulation (DBS) on freezing of gait (FOG) in Parkinson's disease (PD) using motor examination and patient-reported outcomes.

FOG has been well-studied in the context of subthalamic nucleus (STN) DBS; however, the effects of GPi DBS on FOG are not as well established.

We retrospectively analyzed PD patients from Emory clinical database who received bilateral GPi DBS (2017–2022) and had MDS-UPDRS Parts 2 and 3 at baseline and approximately 12 months post-DBS. Parts 2 (patient-reported) and 3 (examination) include items assessing freezing (2.13, 3.11). MDS-UPDRS scores were compared between med-off at baseline and med-off/stim-on at follow-up, and between med-on at baseline and med-on/stim-on at follow-up using paired t-tests.

Twenty-nine patients (11 females, mean age 65.7 ± 5.4 years, disease duration 13.6 ± 5.3 years) were followed for 13.7 ± 1.8 months post-DBS.

The MDS-UPDRS Part 2 total score decreased significantly at 12 months post-DBS (18.2 vs. 14.6; p = 0.04, n = 20), but there was no significant difference in the Part 2 freezing score (1.0 vs. 1.1; p = 0.83, n=20).

The MDS-UPDRS Part 3 total score improved significantly with GPi DBS in both med-off (45.8 vs. 23.1; p < 0.01, n = 29) and med-on conditions (18.4 vs. 12.8; p < 0.01, n = 20). The Part 3 freezing exam score was significantly reduced in the med-off condition (0.8 vs. 0.3; p = 0.01, n = 29), while no significant difference was observed in the med-on condition (0.1 vs. 0.3; p = 0.33, n = 20).

GPi DBS improves FOG in the short-term follow-up (~1 year) during the med-off state. However, this improvement is not observed in the med-on state or in patient-reported outcomes despite overall improvement in motor function.