Predictive factors of speech intelligibility following subthalamic nucleus stimulation in consecutive patients with Parkinson
Tripoliti E1, Limousin P, Foltynie T, Candelario J, Aviles-Olmos I, Hariz MI, Zrinzo L. Predictive factors of speech intelligibility following subthalamic nucleus stimulation in consecutive patients with Parkinson , Mov Disord. 2014 Apr;29(4):532-8. doi: 10.1002/mds.25816. Epub 2014 Feb 14.
Intro: People with Parkinson’s disease (PWP) can have changes in their speech due to the disease. Research has also shown that there are speech adverse effects from DBS therapy. The goal of this article was to evaluate various aspects of speech (“articulation, respiration, resonance, phonation, prosody, and rate”) before and after DBS and if there were any predictive factors to explain speech side effects.
Methods: Fifty four patients that had bilateral DBS STN were evaluated. Each patient was administered a speech assessment that was analyzed by a Speech Language Pathologist before surgery (off and on medication) and one year later (on meds/on stimulation and off meds/on stimulation).
Results: The authors found that speech deteriorated on average by 12-14% after one year of DBS STN. Almost all areas of speech showed decline except prosody and phonation. Predictive factors for those that had speech side effects included presurgical speech problems, disease duration, and left hemisphere medial STN placed contacts. Notably they found that even in those patients that did not have presurgical speech problems, the medially placed left hemisphere contact remained problematic with speech.
Conclusion: As in other studies, this study also found speech adverse effects from DBS STN. The study went a few steps further and discussed specific contact placement (left hemisphere medial STN) as a predictive factor as well as that the pattern of speech problems after DBS STN is different than those experienced from PD alone. Patient complaints, while taking medication and under stimulation conditions, included articulation problems, reduced lip and tongue movements, and hard to control voice volume. Presurgical predictors of speech difficulties after surgery included having speech difficulties prior to the surgery and those that had PD for longer periods of time. Surprisingly age was not a predictive factor in the face of those having PD for longer was a predictive factor. The authors suggest that more research needs to be done to continue to evaluate speech issues in PWP with and without DBS.