Affiliations: [a] Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
| [b] Department of Neurosurgery, Nagoya University Graduate School of Medicine, Japan
| [c] Department of Otorhinolaryngology, Nagoya University Graduate School of Medicine, Japan
| [d] Department of Health Science, Aichi Gakuin University, Nisshin-city, Aichi, Japan
| [e] Research Division of Dementia and Neurodegenerative Disease, Nagoya University Graduate School of Medicine, Japan
Correspondence to: Hirohisa Watanabe and Gen Sobue, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8560,
Japan. Fax: +81 52 744 2943; E-mails: [email protected] (Hirohisa Watanabe); [email protected] (Gen Sobue).
Abstract: Background: Voice and speech disorders are one of the most important issues after subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson’s disease (PD) patients. However, articulation features in this patient population remain unclear. Objective: We studied the articulation features of PD patients with STN-DBS. Methods: Participants were 56 PD patients treated with STN-DBS (STN-DBS group) and 41 patients treated only with medical therapy (medical-therapy-alone group). Articulation function was evaluated with acoustic and auditory-perceptual analyses. The vowel space area (VSA) was calculated using the formant frequency data of three vowels (/a/, /i/, and /u/) from sustained phonation task. The VSA reportedly reflects the distance of mouth/jaw and tongue movements during speech and phonation. Correlations between acoustic and auditory-perceptual measurements were also assessed. Results: The VSA did not significantly differ between the medical-therapy-alone group and the STN-DBS group in the off-stimulation condition. In the STN-DBS group, the VSA was larger in the on-stimulation condition than in the off-stimulation condition. However, individual analysis showed the VSA changes after stopping stimulation were heterogeneous. In total, 89.8% of the STN-DBS group showed a large VSA size in the on- than in the off-stimulation condition. In contrast, the VSA of the remaining patients in that group was smaller in the on- than the off-stimulation condition. Conclusions: STN-DBS may resolve hypokinesia of the articulation structures, including the mouth/jaw and tongue, and improve maximal vowel articulation. However, in the on-stimulation condition, the VSA was not significantly correlated with speech intelligibility. This may be because STN-DBS potentially affects other speech processes such as voice and/or respiratory process.