Abstract
The effect of deep brain stimulation (DBS) of the subthalamic nucleus (STN) and caudal zona incerta (cZi) on speech articulation in patients with Parkinson’s disease (PD) was investigated. Read speech samples were collected from nine patients with STN-DBS and 10 with cZi-DBS. The recordings were made pre-operatively and 12 months post-operatively with stimulator on and off (on medication). Blinded, randomised, repeated perceptual assessments were performed on words and isolated fricatives extracted from the recordings to assess (1) overall articulatory quality ratings, (2) frequency of occurrence of misarticulation patterns and (3) fricative production. Statistically significant worsening of articulatory measures on- compared with off-stimulation occurred in the cZi-DBS group, with deteriorated articulatory precision ratings, increased presence of misarticulations (predominately altered realisations of plosives and fricatives) and a reduced accuracy in fricative production. A similar, but not significant, trend was found for the STN-DBS group.
Acknowledgements
We would like to thank neurosurgeon Professor Patric Blomstedt for providing details of the surgical procedures, DBS nurse specialist Anna Fredricks for assistance in providing patient information, and research engineer Anders Asplund for preparation of the speech recordings.
Declaration of interest
The authors report no conflicts of interest.
They also acknowledge the support of grants from the Swedish Research Council (Grant nrs 2009-946, 2011-2294), and the Faculty of Humanities at Umeå University (Grant nr 210-2554-12).