Low-frequency stimulation of STN-DBS reduces aspiration and freezing of gait in patients with PD.

OBJECTIVES To study whether 60-Hz stimulation, compared with routine 130 Hz, improves swallowing function and freezing of gait (FOG) in patients with Parkinson disease (PD) who undergo bilateral subthalamic nucleus (STN) deep brain stimulation (DBS). METHODS We studied 7 patients with PD who experienced FOG that persisted despite routine 130-Hz stimulation and dopaminergic medication. Each patient received 3 modified barium swallow (MBS) studies in a single day under 3 DBS conditions in the medication-on state: 130 Hz, 60 Hz, or DBS off, in a randomized double-blind manner. The laryngeal penetration and aspiration events were cautiously assessed, and a swallowing questionnaire was completed. The Unified Parkinson's Disease Rating Scale, Part III motor score, axial subscore, tremor subscore, and FOG by a questionnaire and stand-walk-sit test were also assessed. The best DBS condition (60 Hz here) producing the least FOG was maintained for 3 to 8 weeks, and patients were assessed again. Changes in measurements between the 60 Hz and 130 Hz were analyzed using paired t test, with swallowing function as primary and the remainder as secondary outcomes. Changes between other DBS conditions were further explored with Bonferroni correction. RESULTS Compared with the routine 130 Hz, 60-Hz stimulation significantly reduced aspiration frequency by 57% on MBS study and perceived swallowing difficulty by 80% on questionnaire. It also significantly reduced FOG, and axial and parkinsonian symptoms. The benefits at 60-Hz stimulation persisted over the average 6-week assessment. CONCLUSIONS Compared with the routine 130 Hz, the 60-Hz stimulation significantly improved swallowing function, FOG, and axial and parkinsonian symptoms in patients with PD treated with bilateral STN-DBS, which persisted over the 6-week study period. CLASSIFICATION OF EVIDENCE This study provides Class IV evidence that for patients with PD who experience FOG, STN-DBS at 60 Hz decreases aspiration events observed during MBS compared with DBS at 130 Hz.