Parkinson's Disease: Treatment by Deep Brain Stimulation

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Parkinson’s Disease: Treatment by Deep Brain Stimulation




Guest:  Vicky Salak – Neurology, MUSC

Host:  Dr. Linda Austin – Psychiatry, MUSC


Dr. Linda Austin:  I’m Dr. Linda Austin.  I’m interviewing Vicky Salak, who is a family nurse practitioner and Program Coordinator for the Deep Brain Stimulation Program for the treatment of Parkinson’s disease, here at the Medical University of South Carolina.  Vicky, certainly, Parkinson’s disease is a very common neurological problem, and I’m going to assume that folks know what some of the major symptoms are.  You might review those, just quickly, for us, and then I really want to focus on what deep stimulation is, and how it may or may not be effective for the treatment of Parkinson’s.


Vicky Salak:  Okay.  Parkinson’s disease is characterized by hallmark symptoms of resting tremor, slowness; or bradykinesia, and rigidity.


Dr. Linda Austin:  So, when you say resting tremor, what do you mean by that?


Vicky Salak:  When you’re hand is resting in your lap, it’s shaking.  You have tremor.  It’s not the tremor of essential tremor, like when people are eating.


Dr. Linda Austin:  Or, writing, for example.


Vicky Salak:  Or writing; correct.  So, it’s a resting tremor when it’s resting in your lap, or when you’re walking, you may notice resting tremor.


Dr. Linda Austin:  And, I think most people know that it can progress, and it can be quite severe.  What are some more severe symptoms, or a more severe clinical picture, of Parkinson’s?


Vicky Salak:  Some patients go on to develop some gait disorder, which can be very problematic.  There are also non-motor symptoms that go along with Parkinson’s disease, such as cognitive thinking changes, or sleep disturbances, things like that, that are non-motor.


Dr. Linda Austin:  Depression?


Vicky Salak:  Yes.


Dr. Linda Austin:  And, of course, there are a lot of different medications now that can be used to treat Parkinson’s disease.


Vicky Salak:  Yes.  And, wonderfully, there are new ones on the horizon.  So, we are developing quite a large arsenal of medications that can be used to treat Parkinson’s disease.


Dr. Linda Austin:  So then, why is there interest in deep brain stimulation?


Vicky Salak:  Because there are side effects to the medications.  And, as the disease progresses, you need to add additional medications.  And, as that goes on, patients have side effects; cognitive.  They can develop hallucinations.  They can develop impulsive behavior.  They can develop dyskinesia, such as with Michael J. Fox; the movement that he has.  So, with deep brain stimulation, we’re able to significantly reduce the medications and give them more on time.  As times goes on, they develop fluctuations where the medications work some of the time, and not other times, and the deep brain stimulation smoothes that out so they have more on time. 


Dr. Linda Austin:  So, what exactly is deep brain stimulation?


Vicky Salak:  Deep brain stimulation is an implantation of electrodes into the brain, into a very specific area.  We create an electrical field that seems to help the motor symptoms of Parkinson’s disease.  Deep brain stimulation specifically helps tremor, rigidity, and slowness.  It doesn’t address so much the gait disorders or some of the non-motor issues.


Dr. Linda Austin:  Such as the cognitive slowing; the intellectual slowing, or the depression?  Is that right?


Vicky Salak:  Correct. 


Dr. Linda Austin:  So, the shaking gets better, and the stiffness gets better?


Vicky Salak:  Correct.


Dr. Linda Austin:  The slowness gets better?


Vicky Salak:  Yes.


Dr. Linda Austin:  Well, that’s a lot though.  That’s very significant.


Vicky Salak:  With much less medication.  And, their on time is probably 90 percent of time, rather than the fluctuations that they normally have.


Dr. Linda Austin:  How long has deep brain stimulation been around?


Vicky Salak:  It started out with essential tremor, probably, 20 years ago, but the FDA approved it for Parkinson’s disease in 2002.  And we have been doing it here, at MUSC, since that time.


Dr. Linda Austin:  So, do you have any idea; can you give us any numbers, about how many patients have been treated with this, whether that’s in terms of here, at MUSC?  Or, is this a well-established treatment, or is it still kind of experimental, for example?


Vicky Salak:  No.  It’s a very well-established treatment.  And there are specific centers throughout the United States that do this.  It’s not available everywhere.  We are the only center in South Carolina that’s providing this service.  We have provided DBS to close to 100 patients for Parkinson’s disease.  We’ve done other patients for some of the essential tremor and dystonia as well.


Dr. Linda Austin:  Now, tell us some more about the process of implanting electrodes.  How big are these electrodes, and just how are they implanted?


Vicky Salak:  The electrode is about the size of a hair.  It’s very thin.  It’s implanted by a neurosurgeon.  They cut a small, quarter-size, burr hole in the skull and implant the electrode into the subthalamic nucleus, which is the area that seems to be most affected in Parkinson’s disease.


Dr. Linda Austin:  So, it’s a structure kind of deep within the brain?  Is that right?


Vicky Salak:  Yes.


Dr. Linda Austin:  Now, in order to implant that, do they kind of thread it down, as opposed to cutting brain tissue?  How does that happen?


Vicky Salak:  Right.  It’s threaded down.  Prior to the surgery, they do CT scans, MRI scans, so they have the targeting of where that particular patient’s structure is.


Dr. Linda Austin:  So, they’ve been able to map out the coordinates, in essence, and then they just zero right in on those coordinates with those tiny electrodes?


Vicky Salak:  Yes.  All of the hardware is under the skin, so it’s not visible.  The wire comes out, runs behind the ear, and then there’s a generator implanted under the clavicle; similar to a pacemaker.


Dr. Linda Austin:  The clavicle is?


Vicky Salak:  The collar bone.


Dr. Linda Austin:  Under the skin, though?


Vicky Salak:  Everything is under the skin, so it’s not visible.  The nice thing about the surgery is that it doesn’t destroy any brain tissue, as some of the previous surgeries have.  Therefore, if a treatment comes along that’s better, you can just remove them [the electrodes] or turn them off, and that patient can participate in whatever treatment may be available in the future.  As the disease continues to progress; because this is not a cure for Parkinson’s disease, it’s to relieve the symptoms, we’re able to adjust the stimulation to keep up with the progression of the disease.  So, it’s a nice bridge until a cure comes along.


Dr. Linda Austin:  That’s very exciting.  How long does it take, actually, to implant the electrodes?  How long is that surgical procedure?


Vicky Salak:  Generally, they do both sides.  We tend to do bilaterals, even if one side is not as affected, because it seems to work better with the medication reduction.  The surgery itself takes about four hours and the patient will return in about seven to ten days for the generator implantation under the clavicles.


Dr. Linda Austin:  And, those four hours, it’s under general anesthesia, correct?


Vicky Salak:  No.


Dr. Linda Austin:  It’s not under general anesthesia?


Vicky Salak:  Not necessarily.  They prefer to make the patient comfortable with some light sedation, but the patient is generally awake.  They’d like for them to be able to respond to certain stimulation to make sure they’ve exacted the target that they’re looking for. 


Dr. Linda Austin:  Is it fair to say that it’s painless?


Vicky Salak:  Yes.  They’re more anxious about the frame that they’re connected to for the surgery.  Some patients can become anxious, and sometimes cannot tolerate being awake.  So, they can do general anesthesia, but they prefer to do light sedation to make the patient comfortable.


Dr. Linda Austin:  I see.  And, of course, one has to remember that having Parkinson’s is uncomfortable every single day.  So, I guess what you’re saying is that it’s, obviously, an unusual thing and, therefore, can be scary for a patient to have to go through a procedure like that.  But that’s the nature of the discomfort.


Vicky Salak:  But they’re very excited about looking forward to an improved quality of life.


Dr. Linda Austin:  I bet!  I bet.  It must be very exciting.  How long do they stay in the hospital? 


Vicky Salak:  If there are no problems, generally overnight, and will go home; not the following day, the day after.


Dr. Linda Austin:  And how long does it take before one sees improvement?


Vicky Salak:  They can have what we call subthalomotomy effect just from the surgery itself, meaning that their Parkinson’s symptoms will get somewhat better.  That generally wears off over a seven to ten-day period, and then they’ll return to the way they were.  But, by that time, they’re putting in the generators, which is a procedure that’s done under general anesthesia.  They’ll be programmed about two weeks after that.  So, we start turning on the generators and doing the programming, and getting their Parkinson’s symptoms under control.


Dr. Linda Austin:  And, how big is the generator?


Vicky Salak:  It’s probably about two inches wide and, maybe, quarter of an inch thick.


Dr. Linda Austin:  I see.  Now, when you say turn on the generator, how does one turn on a generator?


Vicky Salak:  That’s my job.  I manage the patients after surgery.  The generators are turned on approximately 7 to 10 days after they’re implanted.  We have a computer that has a magnet attached to it.  Using the magnet, I’m able to change parameters.  There are about 25,000 combinations to find the correct settings for that particular patient, to improve their symptoms.


Dr. Linda Austin:  And, how much better, on average, do patients get?  Do all get patients get better?  What percentage gets better?


Vicky Salak:  DBS takes care of tremor, rigidity, and slowness.  It does not take care of gait problems.  Some patients do have gait problems, including freezing; which is not helped by the procedure.  But, with careful selection; which is done by our neurologist, our movement disorder specialist, as well as the neurosurgeon, we’ve had great success with our patients.  I’d say approximately 90 percent of them do improve.


Dr. Linda Austin:  That must be very thrilling to see.  Vicky, thanks so much for talking with us.


Vicky Salak:  Okay.


If you have any questions about the services or programs offered at the Medical University of South Carolina, or if you’d like to schedule an appointment with one of our physicians, please call MUSC Health Connection at:  (843) 792-1414.

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