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Dr. Okun

Post of the Week: STN DBS Worsens Language Function

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This recent study from the Vanderbilt COE revealed that STN DBS worsened motor aspects of language and grammatical function (but not the content of language). Patients seeking STN DBS should be aware of this potential impairment. The abstract is provided below:

 

PLoS One. 2012;7(8):e42829. Epub 2012 Aug 7.

Subthalamic nucleus deep brain stimulation impacts language in early Parkinson's disease.

Phillips L, Litcofsky KA, Pelster M, Gelfand M, Ullman MT, Charles PD.

 

Source

Department of Neurology, Vanderbilt University, Nashville, Tennessee, United States of America.

 

Abstract

Although deep brain stimulation (DBS) of the basal ganglia improves motor outcomes in Parkinson's disease (PD), its effects on cognition, including language, remain unclear. This study examined the impact of subthalamic nucleus (STN) DBS on two fundamental capacities of language, grammatical and lexical functions. These functions were tested with the production of regular and irregular past-tenses, which contrast aspects of grammatical (regulars) and lexical (irregulars) processing while controlling for multiple potentially confounding factors. Aspects of the motor system were tested by contrasting the naming of manipulated (motor) and non-manipulated (non-motor) objects. Performance was compared between healthy controls and early-stage PD patients treated with either DBS/medications or medications alone. Patients were assessed on and off treatment, with controls following a parallel testing schedule. STN-DBS improved naming of manipulated (motor) but not non-manipulated (non-motor) objects, as compared to both controls and patients with just medications, who did not differ from each other across assessment sessions. In contrast, STN-DBS led to worse performance at regulars (grammar) but not irregulars (lexicon), as compared to the other two subject groups, who again did not differ. The results suggest that STN-DBS negatively impacts language in early PD, but may be specific in depressing aspects of grammatical and not lexical processing. The finding that STN-DBS affects both motor and grammar (but not lexical) functions strengthens the view that both depend on basal ganglia circuitry, although the mechanisms for its differential impact on the two (improved motor, impaired grammar) remain to be elucidated.

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Is there anything that will improve  this deficit once the surgery is done? Is the cognitive deficit reversible ? Do "brain games" help?

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We don't actually know.  Some people think that cognitive games may help, and some people have used speech therapy and psychology to work on the verbal fluency issues.

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My husband was diagnosed a year ago. He is 39 years old. Recently we met a neurologist who told us about DBS for young patients, everything he said sound wonderful, but I have serious doubts about it. In your opinion is it a good option for a young patient even when meds are working well? Is there an important risk of impairment of cognitive functions such as executive functions? My husband works at an insurance company calculating the risk of accidents and things like that, and be able to judge, organize and plan are critical for the Job. He is really excited about DBS and the doctor talked about minimal risks, all of them reversible, but I have read some articles about serious consequences of DBS in very few cases or about using DBS for later stages of the disease. Wht do you think?

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In general if the medications are working well and there are no issues with tremor, on-off fluctuations, or dyskinesia I am cautious not to be too hasty to DBS.  It is not a risk free procedure and a complete interdisciplinary evaluation should be performed with a risk-benefit ratio.  If there are no issues and he is still working, I generally do not offer DBS and I watch conservatively and wait for a disabling symptom that would justify the risk-benefit ratio.  There is a study in NEJM on earlier DBS, but if there is no disabling symptom I think most people will not offer DBS.

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Dear Doctor,

The study talks about language difficulties after DBS for early PD patients. Does this mean that patients who had PD for more then 10 or 15 years are lets say less concerned about this problem after DBS.  To your knowledge is there any study in this area. Thanks.

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So far the concern has been the same for both earlier DBS or later DBS intervention (for speech problems); particularly when leads are implanted on both sides of the brain.

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Dear Doctor,

Thanks for the reply. Two more questions. Are the speech problems reversible? That is if the patient stops the stimulation do they go away? Secondly, you say in case of bilateral stimulation, are there PD patients with unilateral STN? Can any PD patient live for many years with unilateral STN? Thanks.

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It is totally possible and actually common to only get one STN or one GPi DBS.

 

The speech problems may be irreversible (getting words out of the moth) or reversible (slurring).  There are cases when they are not reversible by turning the DBS off.

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Are speech problems more common in bilateral STN DBS or bilateral GPi DBS? Does all, if not most, patients who undergo bilateral DBS report these problems with speech? How can this condition be mitigated for patient who underwent bilateral DBS?

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It is unknown if the speech problems are less with GPi DBS and some groups think so; most think they are less with one lead versus two.  Speech therapy can help post-DBS, but if not consistently applied patients report reverting back to their post-DBS poor speech (need consistency in the speech therapy).  I am unaware of a strategy to completely mitigate the problem.

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I've just had DBS, I think If I remember correctly, STN dbs. I do know it is bilateral. And I can report, at least in my case, having a harder time coming up with the "right word" than I had prior to DBS. I am currently off all meds at this point, and as far as PD symptoms, it has worked great. So far. (about 1 month from having it turned on right now).

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First, I am very sorry for the delay in response to your question.  The system underwent an upgrade and the software change captured some questions which we have now located. Please accept our sincerest apology.

The most common cognitive side effect of DBS is verbal fluency issues- problems getting words out of the mouth.  The St.Jude/Abbott study showed that the efffect is mostly surgical from the device implantation rather than stimulation induced (but stim can also effect this issue).  A soft voice is also a common side effect especially after bilateral leads.

Finally, be careful stopping all meds after DBS. Most people need a combination of medications and DBS to be successful.  Good luck.

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Thank you for your response, Dr. Okun.

Interestingly, the frequency of my difficulty finding the right words has become better in the last few months. IOW, I seem to have much fewer instances of it happening. From your description that this is more due to surgery than the stimulation, it would make sense that it could improve as brain swelling goes down. At any rate, what you said about having a soft voice is also a problem. But not much more than pre-DBS. I figured that was a PD symptom not affected by DBS. Sometimes it feels like I'm trying to talk through cobwebs in my throat. lol.

On the meds issue, I"ve been off of them since about five to six months ago when I had this turned on. The only other PD symptom that it doesn't seem to help is drooling. It isn't constant, but occasionally some escapes my mouth. I have been to a speech therapist and I do need to do more of the throat exercises she gave me to do that I'm sure would help. Anyway, thought you might appreciate the report, being this is about 5 months since I originally posted this.

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This is great feedback.  Many of my patients keep 1/2 tab of 25/100 sinemet every 4-5 hours after bilateral STN DBS and the drooling and other symptoms often improve without dyskinesia.  Something to consider with your doc for the future.

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As a contributıon to the subject, I have had PD for 21 years and still active and doing my researches on internet. However even after bilateral STN I  am having soft voice, articulation, drooling, difficulty in finding and pronouncing words, loss of short term memory, decrease in mental capacity and poor balance, and dry eyes and mouth. With LSVT I solve the voice and articulation side provided I do the daily exercises regularly. The memory problems  seem to be less with intensive training of the brain using certain proven software. For balance I  have had Posturography therapy which helped a lot. For dry eyes my ophthalmologist prescribed eye drops to be used daily.  I was not taking any serious medication, but the last time I consulted my doctor he prescribed Madopar a quarter every 4 hours. This improved the situation considerably. Finally I am still trying to live a normal life supported  by modern medical technology.

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This is a great post and illustrates the importance of not cutting back the medications too much after DBS.  It also shows how attention to each issue was helpful.  THANK YOU!

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