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

 -  PD patients with bilateral STN DBS placement and FOG at 130Hz even at usual medication
 "on" state.

 Exclusion Criteria:

 -  Known history of recent aspiration pneumonia