Effect of bilateral subthalamic nucleus stimulation and dopatherapy on oral control in Parkinson's disease

This study focuses on the speech organs of a parkinsonian patient who initially had been treated with levodopa for 13 years, and had become severely disabled by motor fluctuations. This patient has been treated with bilateral chronic stimulation of the subthalamic nucleus (STN) for the last 2 years. Upper lip, lower lip and tongue force production were examined before surgery under off and on medication conditions, and 2 years after surgery under off and on stimulation conditions. We compared the effect of stimulation and dopatherapy on the speech organs. L-Dopa had a poor effect whereas bilateral stimulation improved oral control and speech intelligibility. These results suggest that STN stimulation influences speech organs in a different way from the dopaminergic system and similarly affects oral and limb motor systems.