Objective To evaluate the long-term effect of 60 Hz stimulation of the subthalamic nucleus (STN) on dysphagia, freezing of gait (FOG) and other motor symptoms in patients with Parkinson’s disease (PD) who have FOG at the usual 130 Hz stimulation.
Methods This is a prospective, sequence randomised, crossover, double-blind study. PD patients with medication refractory FOG at 130 Hz stimulation of the STN were randomised to the sequences of 130 Hz, 60 Hz or deep brain stimulation off to assess swallowing function (videofluoroscopic evaluation and swallowing questionnaire), FOG severity (stand–walk–sit test and FOG questionnaire) and motor function (Unified PD Rating Scale, Part III motor examination (UPDRS-III)) at initial visit (V1) and follow-up visit (V2, after being on 60 Hz stimulation for an average of 14.5 months), in their usual medications on state. The frequency of aspiration events, perceived swallowing difficulty and FOG severity at 60 Hz compared with 130 Hz stimulation at V2, and their corresponding changes at V2 compared with V1 at 60 Hz were set as primary outcomes, with similar comparisons in UPDRS-III and its subscores as secondary outcomes.
Results All 11 enrolled participants completed V1 and 10 completed V2. We found the benefits of 60 Hz stimulation compared with 130 Hz in reducing aspiration frequency, perceived swallowing difficulty, FOG severity, bradykinesia and overall axial and motor symptoms at V1 and persistent benefits on all of them except dysphagia at V2, with overall decreasing efficacy when comparing V2 to V1.
Conclusions The 60 Hz stimulation, when compared with 130 Hz, has long-term benefits on reducing FOG, bradykinesia and overall axial and motor symptoms except dysphagia, although the overall benefits decrease with long-term use.
Clinical trial registration NCT02549859;Pre-results.
- Parkinson’s disease
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Contributors TX: study concept and design, obtaining funding, supervision and execution, data analysis and interpretation, and drafting and revising the manuscript. LB, MP, EM, AD, JV and PW: data collection, analysis and interpretation, and revising the manuscript. BB: data collection and revising the manuscript. WK: statistical data analysis and interpretation, and revising the manuscript. DS, CZ, KM: data interpretation, and revising the manuscript. UJK: study design, data analysis and interpretation, and revising the manuscript.
Funding This study had a grant support by the Michael J. Fox Foundation for Parkinson’s Disease under the Rapid Response Innovation Award (extension) to TX.
Competing interests None declared.
Patient consent Not required.
Ethics approval The study protocol and ethics were approved by the institutional review board at the University of Chicago.
Provenance and peer review Not commissioned; externally peer reviewed.
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