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Deep Brain Stimulation Surgery (DBS) a Treatment for Parkinson disease Frequently Asked Questions

By: Jason M. Schwalb, MD, Julia Wall, Neepa Patel, MD, and Ellen L. Air, MD, PhD

1. When is it time to consider DBS surgery?

Many people do well with medications and other approaches for their Parkinson’s Disease (PD). However, sometimes the medication does not work as well as the disease progresses: it doesn’t kick in reliably after taking it; it causes dyskinesias or other side effects. These problems make it difficult for people with PD to plan their activities in advance because they don’t know whether they are going to be frozen, dyskinetic or “on” and good.

DBS can help with many of these symptoms. DBS generally makes patients at their best “on-medication” all the time without medication-induced dyskinesias. Patients can plan their days without fear. In addition, DBS can help with tremor that does not respond to medication.

People should consider DBS if there are reasons they can’t take more dopaminergic medication and when they want help with the things for which DBS is effective.

Benefits to gait are unpredictable and are not maintained at 5 years after surgery. There is no clear benefit to non-motor symptoms, such as constipation, postural instability, decreased sense of smell, mood fluctuations or dementia.

DBS is not a cure for PD but can be a great tool to help manage the symptoms of PD.

2. What are the criteria for being accepted for DBS surgery?

We want to make sure we can help patients with their problems and are not exposing them to unnecessary risks.

• DBS is generally ineffective for Parkinson’s Plus syndromes (e.g., Multisystem Atrophy, Progressive Supranuclear Palsy). Therefore, we try to make sure that the patient has classic, idiopathic PD. One of the ways we do that is to make sure that they have had symptoms at least 4-5 years, take a history from the patient and family and perform a detailed neurologic exam.
• Since DBS is generally not better than their best “on” condition, we want to make sure that they get adequate benefit from dopaminergic medication.
• Since there is a risk to thinking processes with DBS electrodes placed in certain areas of the brain, we need to make sure that the patient has adequate cognitive reserve. For patients that have cognitive limitations or are at risk from being over 80 years old, we can still help with DBS for tremor using an alternate target that has lower cognitive risks.
• The patient has to be medically fit to undergo surgery
• Any blood thinners need to be able to be safely stopped around the time of surgery
• The patient has to be able to follow up for the programming of the system over the long term and have good caregiver support. Optimizing the DBS programming can take up to 4-6 months and often require frequent visits. Throughout the course of the disease the DBS may need further adjustment and maintenance which requires regular follow- up visits with your Neurologist.

3. What is the evaluation process?

The evaluation is structured to assess the issues addressed in the last question. Some of this may be done by the referring neurologist. This testing is not necessarily done in this set order.

• The patient comes into the office “off medication” (typically stopping the medication after midnight the night before), at which time a detailed neurologic exam is completed. The patient then receives a large dose of dopaminergic medication and undergoes another neurologic exam when the medication has fully kicked in as a “levodopa challenge.”
• An MRI (or CT for patients who can’t undergo an MRI) is performed for surgical planning and to rule out other causes of their parkinsonism
• Neuropsychological testing is performed by a licensed neuropsychologist to determine the patient’s cognitive risks of surgery. This is generally done on a separate day from the levodopa challenge so that the patient can be at their best on medication and not be too tired. It lasts 3-6 hours.
• If the patient is to have their postoperative DBS programing at our center, they will meet and be evaluated by the neurologist who will be doing the programming.
• The patient is evaluated and has an opportunity to ask questions to the neurosurgeon.

At our center, each and every patient is discussed in a Multidisciplinary Conference of neurologists, neurosurgeons, neuropsychologists and our DBS coordinator to determine if the patient is a good candidate for surgery.

Sometimes, other options besides surgery are recommended to be tried first. This does not rule out surgery in the future. The results of the discussion are then discussed with the patient.

4. After being accepted for surgery, how many appointments do I attend prior to surgery?

Really, none. However, we strongly encourage our patients and caregivers to attend an education class prior to surgery to learn what to expect from surgery and recovery and to ask whatever additional questions they may have since their prior visits with the surgical team. Patients are always encouraged to see their neurologist or neurosurgeon again prior to surgery if they have any questions or concerns.

5. What is the surgical process? Explain the two-part process.

• The surgery can be performed either awake or asleep. For awake placement, the patient must not take their Parkinson’s medication the night before and morning of surgery. A frame is placed on the patient's head while the patient is sedated. A CT is obtained to get coordinates for every point in the brain. The patient is brought to the OR and a hole the size of a nickel is drilled. A microelectrode is passed, and we determine that we are in the right place by waking the patient up and listening to the neurons at rest and their reactions to the patient moving. Once we are satisfied with the recordings, the DBS electrode is placed. Small amounts of electricity are sent through the electrode to make sure we are in the right place. The process is then repeated on the other side. Once we are satisfied with the electrode placement, the patient is sedated, the scalp is closed, and the frame is removed. The patient goes to the ICU overnight for observation. Most patients go home the day after surgery. At our center, the frame is generally placed at 7 AM. We are usually making incision by 9:30 and are done by 2 PM.
• Intraoperative MRI (iMRI) placement is done under general anesthesia, so the patient is asleep. It takes about the same amount of time. Although asleep DBS placement without electrophysiologic confirmation is not FDA- approved, the results are equivalent in those we have done. Our results were published in 2016 in the Journal of Neurology and are available online (PMID 27126457). The incisions are larger, and the patient occasionally stays in the hospital an extra day due to anesthesia.
• Some groups have also reported CT-guided DBS placement under general anesthesia with good results.
• The patient returns on a different day for placement of extension cords and the battery/pacemaker (internal pulse generator or IPG) under general anesthesia. We usually schedule this for 2 weeks after the first surgery so we can take any sutures or staples out with the patient asleep. This takes about 1 hour, and the patient goes home the same day. The sutures or staples from the second surgery are generally taken out 10-14 days later in the office

6. After the surgery is complete, when do I go back for programming?

This is usually done about a month after the initial surgery. Many patients have benefit just from insertion of the electrodes, called an “insertional effect” that makes programming difficult until after it has worn off.

7. What is involved in programming?

Generally, the patient comes in the morning off PD medications after midnight the previous evening and sees the Movement Disorders neurologist. Programming is performed with a computer tablet. For some systems, a wand is held up to the battery (a pacemaker-like device that is typically inserted in the chest) during programming. Your neurologist will try different settings on each electrode, documenting benefit and side effects to determine the optimal settings. Sometimes benefits are obvious immediately, but sometimes it may take hours or even days to see benefits for certain symptoms of PD. Patients should expect the initial visit to take 2-4 hours to find optimal settings with which to go home.

8. How many post-surgery appointments will I need before the programming is right?

It is somewhat variable, depending upon the symptoms that are being addressed with DBS. However, in general, most patients are at stable settings at 4-6 months. If DBS is not meeting expectations, imaging with CT or MRI should be considered to make sure the electrodes are in the right place.

9. How long will I see benefits from the surgery?

For the 2 main targets in the brain for PD, benefits in tremor, bradykinesia (slowness of movement), rigidity, on-off fluctuations, and levodopa-induced dyskinesias are maintained for at least 5 years. With one of the targets, the subthalamic nucleus (STN), we have good data that benefits are maintained at 10 years. However, patients still have PD, which can progress. Other non- motor symptoms, such as constipation, loss of volume in their voice, postural instability, decreased sense of smell, mood fluctuations or dementia may develop over time and these symptoms are not responsive to DBS.

10. How long does the battery last? What is involved if you must replace the battery?

It depends on the type of battery. Rechargeable IPGs last 9-15 years, as long as they are not allowed to run too low on their charge. Non-rechargeable IPG battery life will depend upon the settings programmed by the neurologist, but patients should expect the IPG to last 2-5 years.

Replacement of the IPG is a 20-minute surgical procedure performed as an outpatient. The chest incision over the IPG is opened. The wires are disconnected from the old IPG and connected to a new IPG. Usually it is done with local anesthesia with sedation.

11. Does the device “wear out”?

The implanted hardware is hearty and made to withstand daily activities over many years. On a rare occasion, a wire may break, requiring replacement.

12. What is the percentage for “re-do’s? We hear about patients having to have the surgery re-done because the leads were not in the correct place.

The revision rate is generally in the 1-3% range (Fenoy 2014; Stroupe 2019), although one study using national data reported a revision rate of almost 13% (Petraglia 2016). It is not clear what the general rate of revision amongst all patients who have had DBS. There may be lower rates of revision at higher volume centers. Like many other groups, we have seen patients implanted at

other centers who are told that DBS just didn’t work for them. If we find that the leads are not in good position and revise them, we generally get excellent results. Another important factor that contributes to revisions is the amount of time a patient has had the system. We find that in some patient who have had the system for >10 years the electrode may shift out of position if they have increased rates of falling or due to natural changes in brain structure related to age.

We are not perfect either, which is why we analyze electrode location on all of our patients after surgery and have a low threshold to repeat imaging to check electrode location for any patient who loses benefit.

13. Will I come away with deficits in other areas? Cognitive? Speech?

The great thing about DBS is that it is generally reversible. Unlike lesional procedures, like MR-guided focused ultrasound or stereotactic radiosurgery, you can turn the device off or make adjustments. Often, problems with speech or thinking can be reversed by changing the programming or moving an electrode. However, most studies show a decrease in verbal fluency, e.g., the ability to name as many animals as possible in a certain time period, after DBS (Cernera 2019). Several studies show that this is an insertional effect that resolves over time. Like many groups, we are still quite cautious and concerned about cognitive deficits after surgery, which is why patients undergo neuropsychological testing prior to surgery to evaluate their cognitive reserves. This is brain surgery and, very rarely, patients may have a sustained cognitive change that persists after surgery.

References:

Cernera S, Okun MS, Gunduz A. A Review of Cognitive Outcomes Across Movement Disorder Patients Undergoing Deep Brain Stimulation. Front Neurol. 2019 May 7;10:419.

Fenoy AJ, Simpson RK Jr. Risks of common complications in deep brain stimulation surgery: management and avoidance. J Neurosurg. 2014 Jan;120(1):132-9.

Petraglia FW 3rd, Farber SH, Han JL, Verla T, Gallis J, Lokhnygina Y, Parente B, Hickey P, Turner DA, Lad SP. Comparison of Bilateral vs. Staged Unilateral Deep Brain

Stimulation (DBS) in Parkinson's Disease in Patients Under 70 Years of Age. Neuromodulation. 2016 Jan;19(1):31-7.

Stroupe KT, Smith B, Weaver FM, Gonzalez B, Huo Z, Cao L, Ippolito D, Follett KA. Healthcare Utilization and Costs for Patients with Parkinson's Disease After Deep Brain Stimulation. Mov Disord Clin Pract. 2019 Apr 22;6(5):369-378.