Subthalamic and nigral stimulation for freezing of gait in Parkinson's disease: Randomized pilot trial

Freezing of gait (FoG) is a debilitating symptom of Parkinson's disease (PD) with limited response to dopaminergic medication and subthalamic deep brain stimulation (STN-DBS). Substantia nigra pars reticulata (SNr) stimulation could improve FoG. To analyze the effect of combined STN-SNr stimulation at different frequencies on FoG. We performed a double-blind, cross-over, randomized pilot trial involving STN-DBS treated PD patients with FoG. Participants received: high-frequency (HF) STN-DBS (S), combined HF-STN and SNr stimulation (C1), and combined HF-STN and low-frequency (LF) SNr stimulation (C2), for one month each. The primary endpoint was the score change in the New-Freezing-of-Gait-Questionnaire (NFOG-Q). Secondary analyses were performed on motor complications, axial symptoms, daily living activities, psychiatric symptoms, sleep, and patient preference. Fifteen patients received at least one combined stimulation. No significant difference in NFOG-Q scores was found between S, C1, and C2; one-third of patients showed a clinically significant improvement (≥8 points) with combined stimulations. Motor complications improved significantly with C1 and C2 (C1-S: 3.6 ± 3.8 vs. 4.9 ± 3.8, p = 0.046; C2-S: 2.7 ± 3.1 vs. 4.9 ± 3.8, p = 0.005). 80% of patients preferred the combined STN-SNr stimulation while blinded. All adverse events were manageable. Our study did not prove a statistically significant improvement in NFOG-Q with STN-SNr stimulation; however, one-third of patients experienced a clinically meaningful FoG improvement, and the majority preferred to maintain STN-SNr stimulation. STN-SNr stimulation was both safe and effective in addressing motor complications and improving sleep quality, highlighting the importance of further exploration into the effects of combined STN-SNr stimulation.