Objective/Rationale:
The stimulation frequency in subthalamic nucleus deep brain stimulation (STN DBS) has been found to affect the axial symptoms of freezing of gait (FOG) and speech in advanced Parkinson’s disease (PD) patients. The traditionally high stimulation frequency of 130 Hz worsens these symtpoms, while low frequency of 60 Hz improves them. The effect of stimulation frequency on another important axial symptom, swallowing dysfunction, has not been studied. We hypothesize that stimulation frequency could have similar effect on swallowing function.
Project Description:
Eight PD patients with STN DBS and FOG responsive to stimulation frequency changes will be enrolled. Each patient will be randomly assigned to one of three situations (Med on/DBS off, Med on/DBS 130 Hz, or Med on/DBS 60 Hz.) in a double-blinded manner each 30 minutes. The patients will be reassessed under the single best condition (likely Med on/DBS 60 Hz) after being on for six-eight weeks.
Relevance to Diagnosis/Treatment of Parkinson’s Disease:
This is the first study on the effect of the stimulation frequency on swallowing function in PD patients with STN DBS. Swallowing dysfunction is often difficult to treat pharmacologically and associated with increased morbidity and mortality. This study hence would have significant clinical implications in the management of swallowing dysfunction in these PD patients with STN DBS and could potentially decrease their morbidity and mortality.
Anticipated Outcome:
We anticipate the traditionally high frequency stimulation of 130 Hz would worsen while the low frequency stimulation of 60 Hz would improve the swallowing function. The response to stimulation frequency change in FOG might predict the response in swallowing function. We anticipate that the benefit of the swallowing function from 60 Hz low frequency stimulation persists in the six-to-eight-week period studied.
Final Outcome
Seven PD patients with STN DBS and freezing of gait responsive to stimulation frequency changes have completed the study. Each patient was randomly assigned to one of three situations (Med on/DBS off, Med on/DBS 130Hz, or Med on/DBS 60Hz.) in a double-blinded manner. The patients were reassessed under the single best condition (Med on/DBS 60Hz) after being on for six weeks on average. We found that, compared to the traditional high frequency stimulation of 130 Hz, the low frequency stimulation of 60 Hz improves the swallowing function and freezing of gait. The benefit of the swallowing function from 60Hz low frequency stimulation persists in the six-week period studied. This is the first study on the effect of the stimulation frequency on swallowing function in PD patients with STN DBS. This study has confirmed our hypothesis and would have significant clinical implications in the management of swallowing dysfunction and gait difficulty in these PD patients with STN DBS, and accordingly could potentially decrease their morbidity and mortality.
Presentations & Publications
Paper submitted to Neurology.
Abstract submitted to the annual PSG meeting to be held in September 2014.
June 2014