• E Tripoliti, L Zrinzo, I Martinez-Torres, E Frost, S Pinto, T Foltynie, E Holl, E Petersen, M Roughton, M I Hariz, and P Limousin.
• Sobell Department, Unit of Functional Neurosurgery, UCL Institute of Neurology, Box 146, Queen Square, London, WC1N 3BG, UK. e.tripoliti@ion.ucl.ac.uk
• Neurology. 2011 Jan 4;76(1):80-6.

ObjectiveSubthalamic 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.MethodsThirty-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.ResultsWithin 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.ConclusionThe 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 EvidenceThis 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.

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