Effects of subthalamic stimulation on speech of consecutive patients with Parkinson disease

Neurology. 2011 Jan 4;76(1):80-6. doi: 10.1212/WNL.0b013e318203e7d0. Epub 2010 Nov 10.

Abstract

Objective: Subthalamic nucleus deep brain stimulation (STN-DBS) is an effective treatment for advanced Parkinson disease (PD). Following STN-DBS, speech intelligibility can deteriorate, limiting its beneficial effect. Here we prospectively examined the short- and long-term speech response to STN-DBS in a consecutive series of patients to identify clinical and surgical factors associated with speech change.

Methods: Thirty-two consecutive patients were assessed before surgery, then 1 month, 6 months, and 1 year after STN-DBS in 4 conditions on- and off-medication with on- and off-stimulation using established and validated speech and movement scales. Fifteen of these patients were followed up for 3 years. A control group of 12 patients with PD were followed up for 1 year.

Results: Within the surgical group, speech intelligibility significantly deteriorated by an average of 14.2%±20.15% off-medication and 16.9%±21.8% on-medication 1 year after STN-DBS. The medical group deteriorated by 3.6%±5.5% and 4.5%±8.8%, respectively. Seven patients showed speech amelioration after surgery. Loudness increased significantly in all tasks with stimulation. A less severe preoperative on-medication motor score was associated with a more favorable speech response to STN-DBS after 1 year. Medially located electrodes on the left STN were associated with a significantly higher risk of speech deterioration than electrodes within the nucleus. There was a strong relationship between high voltage in the left electrode and poor speech outcome at 1 year.

Conclusion: The effect of STN-DBS on speech is variable and multifactorial, with most patients exhibiting decline of speech intelligibility. Both medical and surgical issues contribute to deterioration of speech in STN-DBS patients.

Classification of evidence: This study provides Class III evidence that STN-DBS for PD results in deterioration in speech intelligibility in all combinations of medication and stimulation states at 1 month, 6 months, and 1 year compared to baseline and to control subjects treated with best medical therapy.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Deep Brain Stimulation / adverse effects*
  • Female
  • Fourier Analysis
  • Humans
  • Linear Models
  • Linguistics
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Movement / physiology
  • Parkinson Disease / complications*
  • Parkinson Disease / therapy
  • Retrospective Studies
  • Speech Disorders / etiology*
  • Speech Intelligibility / physiology*
  • Subthalamic Nucleus / physiology*
  • Time Factors