Long-term Effect of Low Frequency Stimulation on Aspiration and Freezing of Gait in PD With STN DBS

University of Chicago11 enrolled

Overview

Our recent study (Xie et al, Neurology 2015; 84: 415-420) found that bilateral STN DBS of 60Hz, compared to the traditional 130Hz, decreased the aspiration frequency and swallowing difficulty, freezing of gait (FOG), and other axial symptoms and parkinsonism in Parkinson patients with FOG refractory to 130Hz and medications. The benefit of 60Hz stimulation persisted during the 6-week study period, but with worsening tremor in one patient. However, it remains unknown whether the benefit of 60Hz would persist on prolonged stimulation period, and whether there is carry-over effect across different conditions. Hence, the investigators would like to test the hypothesis that the 60Hz stimulation, compared to 130Hz might have persistent benefit over an extended period in reducing the swallowing dysfunction, FOG, and other axial symptoms in these PD patients even after correcting the potential carry-over effect.

The investigators will enroll 14 Parkinson patients with bilateral STN DBS and refractory FOG to 130Hz stimulation and dopaminergic medications for two visits of at least 6-month apart. The 6 patients remaining on 60Hz stimulation after our previous study consisting of 7 patients will be assessed once again as visit-2 after previous visit-1 of their last study. We anticipate to have 20 patents complete for visit-1 and at least 18 patients complete for visit-2 in this randomized double-blind prospective crossover study with their usual medication "on" state, with 6-7 patients on each starting condition (60Hz vs 130Hz vs DBS off). Swallowing function on modified barium swallowing test and swallowing questionnaire, FOG in stand-walk-sit test and questionnaire, and other axial and motor function on UPDRS-III will be assessed under each DBS condition. Changes in measurements between 60Hz and 130Hz at each visit and under 60Hz between two visits will be analyzed, with swallowing function and FOG as primary, and the rest as secondary outcomes, correcting for potential carryover effect. Changes between other DBS conditions might also be explored in this 2-year study. This would be the first study on the long-term effect of 60Hz stimulation on dysphagia, FOG and other axial and motor symptoms in Parkinson patients with bilateral STN DBS and FOG refractory to 130Hz stimulation and dopaminergic medications, which will have significant impact on the treatment of difficult axial symptoms of high morbidity and mortality.

Study Type

INTERVENTIONAL

Allocation

Outcomes

Primary Outcomes

Frequency of Aspiration Events on Videofluoroscopic Swallow Study at Visit 1

A speech pathologist used the Penetration-Aspiration Scale (PAS) to rate swallows captured by a radiologist during VFSS recording. PAS is an 8-point interval scale: a score of 0 indicates no penetration or aspiration \& a score of 6-8 indicates aspiration of increasing severity. For the purpose of this study, aspiration was dichotomized to "0" if PAS score was under 6 or "1" if PAS score was between 6-8. Frequency of aspiration events was calculated by adding number of aspiration events in VFSS under various liquid \& food textures. The maximum aspiration frequency was 12 if aspiration occurred on every texture after 2 trials. Lower aspiration frequency means better swallowing function.