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


CONCLUSIONS
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.


METHODS
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.
Sobell Department, Unit of Functional Neurosurgery, UCL Institute of Neurology, Box 146, Queen Square, London, WC1N 3BG, UK. e.tripoliti@ion.ucl.ac.uk
E
E
Tripoliti
L
L
Zrinzo
I
I
Martinez-Torres
E
E
Frost
S
S
Pinto
T
T
Foltynie
E
E
Holl
E
E
Petersen
M
M
Roughton
M I
MI
Hariz
P
P
Limousin
D000328:Adult; D000368:Aged; D046690:Deep Brain Stimulation / Q000009:adverse effects*; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D016014:Linear Models; D008037:Linguistics; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology; D010300:Parkinson Disease / Q000150:complications* / Q000628:therapy; D012189:Retrospective Studies; D013064:Speech Disorders / Q000209:etiology*; D013065:Speech Intelligibility / Q000502:physiology*; D020531:Subthalamic Nucleus / Q000502:physiology*; D013997:Time Factors