Predictive factors of speech intelligibility following subthalamic nucleus stimulation in consecutive patients with Parkinson's disease

Authors

  • Elina Tripoliti PhD, MRCSLT,

    Corresponding author
    1. Unit of Functional Neurosurgery, University College London (UCL) Institute of Neurology, London, United Kingdom
    • Corresponding author: Dr. Elina Tripoliti, Unit of Functional Neurosurgery, UCL Institute of Neurology, Box 146, Queen Square, London, WC1N 3BG, UK; e.tripoliti@ucl.ac.uk

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  • Patricia Limousin MD, PhD,

    1. Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom
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  • Tom Foltynie MB BS, PhD, MRCP,

    1. Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom
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  • Joseph Candelario BSc,

    1. Unit of Functional Neurosurgery, University College London (UCL) Institute of Neurology, London, United Kingdom
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  • Iciar Aviles-Olmos MD, PhD,

    1. Unit of Functional Neurosurgery, University College London (UCL) Institute of Neurology, London, United Kingdom
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  • Marwan I. Hariz MD, PhD,

    1. Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom
    2. National Hospital for Neurology and Neurosurgery, UCL Institute of Neurology, Queen Square, London, United Kingdom
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  • Ludvic Zrinzo MD, PhD, FRCS

    1. Unit of Functional Neurosurgery, University College London (UCL) Institute of Neurology, London, United Kingdom
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  • Funding agencies: The Unit of Functional Neurosurgery, UCL Institute of Neurology, is supported by the Sainsbury Monument Trust and Parkinson's Appeal for Deep Brain Stimulation.

  • Relevant conflicts of interest/financial disclosures: Nothing to report.

  • Full financial disclosures and author roles may be found in the online version of this article.

ABSTRACT

Speech changes after bilateral subthalamic nucleus deep brain stimulation (STN-DBS) can be variable, with the majority of patients experiencing speech deterioration over time. The aim of this study was to describe the perceptual characteristics of speech following chronic STN-DBS and to analyze clinical and surgical factors that could predict speech change. Fifty-four consecutive patients (34 men; mean age ± standard deviation (SD), 58.8 ± 6.3 years; mean ± SD disease duration, 12.5 ± 4.7 years; mean ± SD levodopa equivalent, 1556 ± 671 mg/day; mean ± SD Unified Parkinson's Disease Rating Scale motor part (UPDRS-III) off-medication score, 48.1 ± 17.9 [range, 20-89]; and mean ± SD UPDRS-III on-medication score, 12.4 ± 7.8 [range, 2-31]) participated in this study. They were assessed before and at 1 year after surgery using the Assessment of Intelligibility for the Dysarthric Speech, the perceptual scale from Darley et al., and the UPDRS-III. Speech intelligibility deteriorated on average by 14.4% (P = 0.0006) after 1 year of STN-DBS when off-medication and by 12.3% (P = 0.001) when on-medication. The effect on speech was not linked to age at surgery, unlike the effect on motor outcome. The most significant predictive factors for deterioration of speech intelligibility when patients were off-medication/on-stimulation were lower preoperative speech intelligibility on-medication, longer disease duration, and medially placed left hemisphere active electrode contact. Speech change after STN-DBS is variable and multifactorial. Consistent preoperative speech evaluation would help inform patients about the possible effects of surgery. Appropriate consideration of speech deficits might assist surgical targeting, particularly of the left electrode. © 2014 International Parkinson and Movement Disorder Society

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