EFFECTS OF REDUCED DEEP BRAIN STIMULATION FREQUENCIES IN PARKINSON’S DISEASE

Abstract

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is widely used and proven to be highly effective in helping alleviate symptoms of Parkinson’s disease (PD). Nevertheless, although high‐frequency DBS (>120 Hz) is initially effective in improving patients’ motor symptoms (mainly bradykinesia and tremors), many patients still develop gait disturbances, such as freezing of gait (FOG). Recent studies have reported that stimulation of the STN with low frequencies produce positive effects on gait disorders and reduces the number of FOG events. As research is being done to investigate how reduced DBS frequencies will affect gait and balance control, it is also important to understand what effects reduced DBS stimulation will have on their PD symptoms. The aim of this study was to investigate the effects that reduced DBS frequencies have on the severity of PD patients’ symptoms. The effects were studied in twelve PD patients (receiving DBS treatment) after reducing their DBS frequency. The varied DBS frequencies included: their clinically determined stimulation setting (CDS), a low stimulation setting (30 Hz), and an intermediate stimulation frequency (80 Hz). Symptom severity was measured using the Unified Parkinson’s Disease Rating Scale (UPDRS‐III), and the Hoehn‐Yahr (HY) stage score. The results were supportive of what we expected; that as DBS frequencies are decreased from the patients’ clinically determined setting, the clinical symptoms worsened. This is an important observation which will allow the appropriate clinical decisions be made as we continue to investigate the effects of reduced frequency DBS on gait and posture control.