Effects of contact location and voltage amplitude on speech and movement in bilateral subthalamic nucleus deep brain stimulation

Mov Disord. 2008 Dec 15;23(16):2377-83. doi: 10.1002/mds.22296.


Subthalamic nucleus deep brain stimulation (STN-DBS) is particularly effective in improving limb symptoms in Parkinson's disease. However, speech shows a variable response. Contact site and amplitude of stimulation have been suggested as possible factors influencing speech. In this double blind study, we assessed 14 patients post bilateral STN-DBS, without medication. Six conditions were studied in random order as follows: stimulation inside the STN at low voltage (2 V) and at high voltage (4 V); above the STN at 2 V and at 4 V, at usual clinical parameters, and off-stimulation. The site of stimulation was defined on the postoperative stereotactic MRI data. Speech protocol consisted of the assessment of intelligibility of the dysarthric speech, maximum sustained phonation, and a 1-minute monologue. Movement was assessed using the UPDRS-III. Stimulation at 4 V significantly reduced the speech intelligibility (P = 0.004) independently from the site of stimulation. Stimulation at 4 V significantly improved the motor function. Stimulation inside the nucleus was significantly more effective than outside the nucleus (P = 0.0006). The significant improvement in movement coupled with significant deterioration in speech intelligibility when patients are stimulated inside the nucleus at high voltage indicates a critical role for electrical stimulation parameters in speech motor control.

Publication types

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

MeSH terms

  • Acoustics
  • Aged
  • Analysis of Variance
  • Antibodies, Monoclonal
  • Basiliximab
  • Biophysical Phenomena
  • Deep Brain Stimulation / methods*
  • Female
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Movement / physiology*
  • Neurologic Examination
  • Neuropsychological Tests
  • Parkinson Disease / physiopathology*
  • Parkinson Disease / therapy
  • Recombinant Fusion Proteins
  • Severity of Illness Index
  • Speech / physiology*
  • Subthalamic Nucleus / physiology*


  • Antibodies, Monoclonal
  • Recombinant Fusion Proteins
  • Basiliximab