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Parkinson’s Disease
Volume 2015, Article ID 382320, 7 pages
Clinical Study

Articulatory Changes in Vowel Production following STN DBS and Levodopa Intake in Parkinson’s Disease

1Centre Interdisciplinaire de Recherche en Réadaptation et en Intégration Sociale, Québec, QC, Canada G1M 2S8
2Centre Interdisciplinaire de Recherche sur les Activités Langagières, Université Laval, Québec, QC, Canada G1V 0A6
3Département des Sciences Neurologiques, CHU de Québec (Hôpital de l’Enfant-Jésus), Québec, QC, Canada G1J 1Z4
4Centre de Recherche, Institut Universitaire en Santé Mentale de Québec, Laboratoire Langage et Cognition, Québec, QC, Canada G1J 2G3

Received 7 July 2015; Revised 24 August 2015; Accepted 14 September 2015

Academic Editor: Huw R. Morris

Copyright © 2015 Vincent Martel Sauvageau et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Purpose. To investigate the impact of deep brain stimulation of the subthalamic nucleus (STN DBS) and levodopa intake on vowel articulation in dysarthric speakers with Parkinson’s disease (PD). Methods. Vowel articulation was assessed in seven Quebec French speakers diagnosed with idiopathic PD who underwent STN DBS. Assessments were conducted on- and off-medication, first prior to surgery and then 1 year later. All recordings were made on-stimulation. Vowel articulation was measured using acoustic vowel space and formant centralization ratio. Results. Compared to the period before surgery, vowel articulation was reduced after surgery when patients were off-medication, while it was better on-medication. The impact of levodopa intake on vowel articulation changed with STN DBS: before surgery, levodopa impaired articulation, while it no longer had a negative effect after surgery. Conclusions. These results indicate that while STN DBS could lead to a direct deterioration in articulation, it may indirectly improve it by reducing the levodopa dose required to manage motor symptoms. These findings suggest that, with respect to speech production, STN DBS and levodopa intake cannot be investigated separately because the two are intrinsically linked. Along with motor symptoms, speech production should be considered when optimizing therapeutic management of patients with PD.