Effect of bilateral subthalamic nucleus deep brain stimulation on postural adjustments during arm movement

Objective: Although it is well known that postural adjustment (PA) is impaired in advanced Parkinson's disease (PD), the potentially compensatory effects of bilateral subthalamic nucleus deep brain stimulation (STN DBS) in this respect are less clear.

Methods: While standing on a force platform and in the absence of antiparkinsonian medication, 10 patients performed voluntary, unilateral arm movements before surgery (the 'off stim' condition) and then afterwards (the 'on stim' condition). The patients' PAs were monitored by vertical torque (Tz) and compared with those recorded in control subjects.

Results: Patients with STN DBS and control subjects showed similar values for PA amplitude, duration and latency.

Conclusions: STN stimulation may induce better postural control during the movement preparation and execution phases. Our results argue in favour of a positive effect of STN DBS on PA.

Significance: The PA amplitude (provided by Tz) may be a strong marker reflecting the clinical improvement seen in stimulated PD patients.