Balance performance in people with Parkinson’s disease. Effects of subthalamic Deep Brain Stimulation

Abstract: The overall aims of this work were to investigate if Deep Brain Stimulation in the subthalamic nuclei (STN) affected balance, fear of falling and falls in people with Parkinson's disease. The effect of STN stimulation alone was investigated in Papers I, II and III. The participants were evaluated after an overnight withdrawal of anti-PD medication and with the STN stimulation turned off and on. Functional balance performance was evaluated by using the Berg balance scale (BBS: higher scores denote "better" balance). STN stimulation alone significantly increased the BBS-scores both at short and long-term follow-ups (3 years). There are thus no indices that STN stimulation by itself affects functional balance performance negatively as a side effect. Timed tests showed furthermore statistical improvements. The participants’ ratings showed an increased fall-related self-efficacy when the STN stimulation was turned on (Paper III). Force-plate measurements (posturography) were also conducted (Paper III). These results showed no statistical significant differences, which may be a consequence of the limited sample size. Three years after surgery, the dosage of anti-PD medication was reduced by approximately 50% (Paper II). The anti-PD medication further increased the BBS-scores. In Paper IV falls (fall-diary) were registered both before and after surgery. The rate of falls was not significantly different after surgery. Further and larger studies are warranted. One year after surgery, the participants’ ratings showed an increased fall-related self-efficacy during more complex activities and decreased activity avoidance due to the risk of falling. These findings indicate a positive effect on activities and participation.