Effect of bilateral deep-brain stimulation on oral control of patients with parkinsonism

We assessed the oral system of parkinsonian patients treated with bilateral chronic stimulation of the ventral intermediate nucleus of the thalamus (Vim), and of the subthalamic nucleus (STN) to compare the effects of these procedures on the articulatory organs. Force transducers were used to sample ramp-and-hold force contractions generated by the upper lip, lower lip and tongue at 1- and 2-newton target force levels, as well as maximal force. Fourteen healthy control subjects and 14 parkinsonian patients participated in this study. After an overnight fast the patients were evaluated under two conditions: during bilateral stimulation and 1 h after stopping stimulation. With Vim stimulation, dynamic and static control of the articulatory organs was worsened while with STN stimulation it was greatly improved. The target of stimulation differently influences the oral system and modulates neuronal structures involved in speech.