EIGHT

I Had the Surgery. Now What?

At this point, you have been through what most people consider the most nerve-wracking part of DBS. However, it is important to remember that the first few months after surgery are equally important. This is when your neurologist or DBS nurse programmer will turn on your stimulators and slowly adjust the settings to help your condition. In some cases, it will not take long to find settings that will help your symptoms; in other cases, it may take a while. We usually tell people that it may take 3–6 months to arrive at a setting that is optimal for them, although in many cases, it does not take as long. During this time period, it may be frustrating to have gone through the surgery and not see immediate results. Keep in mind all that you have been through, and it will be worth it in the end.

THE HONEYMOON PERIOD

The time period right after the leads are placed and before the day of initial programming is sometimes called “the honeymoon period.” This is because some people notice an improvement in their symptoms after the surgery with the stimulator turned off, and it may last from a couple of days to a couple of weeks. If you have essential tremor, you may notice that your tremor is less or even gone for this period of time before coming back. People living with Parkinson’s may notice less tremor and stiffness, and they are able to move around more fluidly. In medical terms, this is called a “microlesioning effect” and is believed to be due to swelling in the brain that comes from placing the lead. However, it is important to remember that as the swelling goes down and your brain returns to its baseline, the symptoms almost always come back. Because no one can predict how long the honeymoon period lasts, it is important not to stop your medications suddenly, or else you might crash when the effect wears off. Always call your DBS team or neurologist if you have questions about whether you should adjust your medications after surgery.

It is also important to remember that the microlesioning effect does not happen to everyone. Whether you have a microlesioning effect or not does not influence whether the stimulator will work for you when it is turned on. We have operated on many people who did not experience such an effect, but are completely happy with their symptom control from their device.

WHEN IS THE STIMULATOR TURNED ON?

A common question is when the device will be turned on. While the DBS lead in your brain may be tested in the operating room, the stimulator is typically not turned on for some time after the surgery. This practice varies worldwide, with some DBS centers starting programming the day after surgery, and some waiting as long as 60 days. A North American survey of DBS centers published in 2005 found that initial activation of the electrodes took place about 18 ± 12 days after the leads were placed.

Of course, part of this variation depends on how the leads are initially placed. For people with essential tremor who only have one lead placed, 2–4 weeks from lead placement is a good estimate of when the initial programming will start. However, for people with Parkinson’s and dystonia who typically have leads placed on both sides of the brain, the start of programming depends on whether the leads are placed simultaneously or whether the second lead is implanted some time after the first side. About half of DBS centers in North America place both leads at the same time. At DBS centers where the leads are placed in each side of the brain in separate surgeries, the second lead is placed about 3–4 months after the first side. Some centers may wait for both sides to be implanted before programming, whereas some centers may program the first side before implanting the second side. This will be something that you should check with your DBS team if you are considering surgery.

PREPARING FOR P-DAY (THE DAY OF PROGRAMMING)

The first thing to realize about the initial programming visit is that it will be long. Remember that each lead in the brain has four contacts near the tip. Stimulation can be delivered through any one of these four contacts. Although the contacts are very close to each other, chances are only one or two of these contacts are at or near the right spot that will help your symptoms. The purpose of the initial programming session is to test all four contacts and find out which one helps your symptoms best. The best contact is the one that helps your symptoms at the lowest setting and gives you side effects only with high settings. (This is somewhat similar to finding a good medication for you—the best one helps your symptoms at the lowest dosage without giving you too many side effects.)

For people living with Parkinson’s disease, the initial programming visit is done in the “off” medication state. That means you should not take any of your Parkinson’s medications for 12 hours prior to the appointment. Again, this applies only to your Parkinson’s medications. You will be allowed to take your other medications as usual. While this will likely make you uncomfortable, it is a necessary part of programming because if you are “on” your medications, your symptoms are likely to be masked, and the clinician who is turning on and adjusting the stimulator will not be able to tell if the stimulation is helping you. DBS centers often make the initial programming session the first appointment of the morning, so that most people do not have to go for too long without their medications. You should bring your Parkinson’s medications with you to the appointment, as you will have to take them as soon as the programming visit is over. If you live far away from the clinic that will be doing your initial programming, it may make sense to stay at a nearby hotel the night before the programming for your convenience. People with ET and dystonia typically undergo the procedure only if medications are not helpful, so being “off” medications is not an issue. However, it will still be a fairly long visit.

Someone should accompany you to your initial programming session, as you will not know how your body will respond to the stimulator. It is always helpful to have someone there for support even if things go smoothly. Furthermore, if you are “off” Parkinson’s medications, you will be exhausted by the end of the programming session and likely will not be in the mood to drive yourself home.

WHAT HAPPENS ON P-DAY?

Again, it is worth emphasizing that who does your programming is as important as who places the DBS. Many people only research the neurosurgeon, how many individuals he or she has operated on, and what his or her complication rate is. However, once the DBS system is in place, the neurosurgeon is out of the picture (unless there are surgical complications). The person who turns it on and sets the settings will be your friend and contact over the next 3–6 months. This person will work with you to find the settings that benefit you with the least amount of side effects. While the basic principles of programming are rooted in science, programming is also part art. A feel for how someone will tolerate programming is something that is only picked up after much experience.

Who Does the Programming?

The person who turns on your DBS system and finds the best settings is known as the programmer. In most DBS centers, this person is either a neurologist specializing in DBS or a nurse/nurse practitioner working with a neurologist. Occasionally, a neurosurgeon or a nurse working with the neurosurgeon will be the programmer. There is no official certification or minimum amount of training to become a programmer, but by this time, you have probably researched and picked your DBS team because they have a lot of experience with this already.

PROGRAMMING BASICS

Monopolar vs. Bipolar Stimulation

Again, there are four electrodes or contacts at the end of each DBS lead. Depending on the model of the lead placed in your brain, these contacts can be 0.5 or 1 mm apart from each other. If you chose a good neurosurgeon, at least one of those contacts will be in the right spot. Programmers can choose any one of those contacts as the active contact (which means the contact where the stimulation comes out) or cathode (negative electrode). Once the stimulation comes out of the contact, it searches for the anode (positive electrode) to complete an electrical circuit. Thus, the electrical field can be changed to help enhance effect or minimize side effects depending on what the programmer chooses as the cathode and anode.

The most common type of stimulation is called monopolar stimulation. This is where one of the contacts on the lead is the active contact or cathode. The battery in your chest serves as the anode. When stimulation comes out of the contact in monopolar stimulation, it spreads out to try and find the anode. If you were to visualize how the electrical stimulation comes out of the contact, picture dropping a pebble in a pond. Where the pebble hits the water would be where the active contact is. The act of dropping this pebble creates waves that go out from the pebble in a radial fashion. This is how stimulation using a monopolar configuration spreads in your brain. Most programmers will start with a monopolar configuration because it is most likely to stimulate the area needed to help your symptoms. However, the downside of monopolar stimulation is that even if it spreads to the correct area, it could spread to an area that you do not want, and thus you would get side effects. In Parkinson’s disease, if the lead is placed in the subthalmic nucleus (STN), the nerve fibers that control your face, arms, and legs run right next to the STN. If stimulation spreads beyond the STN and into these nerve fibers, you could get muscle spasms or contractions in these body parts.

Monopolar stimulation vs. bipolar stimulation

If your programmer finds that you get such side effects at low settings, he or she might switch to something called bipolar stimulation. This is where one of the contacts is the cathode or active contact. However, the anode is set at the contact right next to the active contact. This time, when the stimulation comes out of the active contact, it is drawn to the anode right next to it. Thus, the area of stimulation is reduced compared with that of monopolar stimulation, and you are less likely to have side effects. The downside of bipolar stimulation, however, is that you typically have to turn the stimulation to higher settings to get the same response as with monopolar stimulation at lower settings.

Voltage, Frequency, and Pulse Width

In addition to setting which contacts are positive or negative, there are three other variables that your programmer can adjust: voltage, frequency, and pulse width. The electrical stimulation that comes out of the contact can be visualized as a square wave. Each square wave is a pulse of stimulation, and stimulation is delivered constantly to the brain in frequent pulses.

Voltage is measured in volts and refers to how high the pulse gets. Obviously, the higher the voltage, the bigger the pulse. Voltage is the main thing that is adjusted over time because a small increase in voltage tends to give you the most effect on symptoms, whether it is tremor, stiffness, or slowness. Average voltages tend to range from 2 V to 4 V. The higher the voltage is, the more likely the stimulation is to spread to other structures and cause side effects.

Frequency is measured in hertz and refers to how many pulses are given in 1 s. For people with tremor, Parkinson’s disease, and dystonia, the frequency typically ranges from 130 to 185 Hz. Frequencies lower than 100 Hz tend not to be as beneficial, although for some people with dystonia, lower frequencies may be helpful. There was also a study that suggested that lower frequencies may be more likely to help freezing of gait than higher frequencies in Parkinson’s disease.

Electrical pulse stimulation parameters

Pulse width refers to the length of time each pulse lasts. It can be programmed from 60 to 450 µs. For Parkinson’s disease and essential tremor, standard pulse widths tend to be between 60 and 120 µs. People with dystonia tend to have much higher pulse widths, with many DBS centers starting at 210 µs. This is because the medical literature has shown that higher pulse widths tend to be more helpful for dystonia symptoms.

Finding the Sweet Spot

On the day of programming, your programmer will do a brief examination to see what your symptoms are. The object of programming is to find the best contact for you, which is the contact that gives you the best effect at the lowest settings. It is important to remember that not all symptoms respond in the same way to DBS. For example, tremor often responds within seconds to a minute after turning on or adjusting stimulation. For those with essential tremor and Parkinson’s disease with a noticeable tremor, you will be able to see the stimulator work for you immediately. For the parkinsonian symptoms of bradykinesia (slowness of movement) and rigidity (stiffness), you will have to wait longer before you will notice an improvement. Stiffness improves within minutes, whereas slowness may take minutes to hours before improvement is noticed. People with dystonia have to wait the longest of all. Dystonic symptoms may take weeks to months before getting better after an adjustment.

The stimulator is turned on using a handheld device. This handheld device has a screen that displays which contacts are set as cathodes or anodes, as well as the voltage, pulse width, and frequency. It also gives information as to how long the programmer has been on since the last visit as well as the battery life of your generator. The device uses radio waves to transmit information from the handheld device to the implanted generator in your chest. The radio waves can go through clothing and skin, and so are noninvasive.

Your programmer will turn on stimulation from each of the four contacts on the lead. The pulse width and frequency are typically set at standard parameters, and the voltage is adjusted. With each increase in voltage, you will be expected to report any improvement in symptoms or any side effects. It is important to report everything you feel, even if you do not think it is important. For each contact, your programmer will record the lowest setting where you noticed improvement in symptoms and the lowest setting where you noticed intolerable side effects. Some settings will bring out numbness, tingling, or an electrical shock. Some will bring out muscle spasms. Others will cause slurring of the speech, sweating, anxiety, lightheadedness, or even sadness. However, once the stimulator is programmed, the stimulator is left on, and there should not be any of these side effects. The exception is those individual with essential tremor who may feel a temporary tingling in their hand, arm, or face each time they turn on their stimulator.

After testing each contact, your programmer will select the best contact and put you on your initial settings of voltage, pulse width, and frequency. If you have Parkinson’s disease, you may then be asked to take your Parkinson’s medications and wait around in the lobby area for a while. Remember that the combination of new stimulation with medications may temporarily increase dyskinesias. Once your medications kick in, if there are too many dyskinesias, your programmer may elect to decrease the amount of stimulation before sending you home. If you have essential tremor or dystonia, you will also be asked to wait around in the lobby area for a while to monitor for side effects. If you do not experience any side effects after an hour or two, you likely will be able to go home.

FUTURE PROGRAMMING VISITS

The initial settings that are programmed at the first visit are rarely ideal. Your programmer will not want to set your stimulator at too high of a setting for fear of causing side effects. The full effects of stimulation sometimes are not seen until the evening or the day after your programming. Programmers who are too aggressive often get phone calls the next day from people because they cannot tolerate the settings. This is somewhat similar to starting medication. Sometimes if you take the highest dose suggested by the pharmacy, you may not be able to tolerate it. But if you start at the smallest possible dose and then increase it slowly over time, you might be able to tolerate your medication better. This “start low and go slow” approach is probably the best way to go about programming.

This means that you will likely have frequent visits over the first few months to have the stimulator adjusted. It is hard to give you an idea of how many programming visits you will need to optimize the settings because it varies widely from person to person. A North American survey of DBS centers reported that in the first month after initial programming, they averaged about 2 programming visits per person with DBS. In months 2–6, there were about 4 visits or 1 per month. In months 6–12, there was an average of 2 programming visits per person or 1 every 3 months. In months 12–24, there was an average of 2 programming visits per person or once every 6 months.

ADJUSTMENT OF MEDICATIONS

Because people with ET and dystonia have failed medications before getting DBS, they usually are not on medications for their condition after surgery. Therefore, this section really is focused toward those living with Parkinson’s.

You have to think of DBS as an electrical form of levodopa (the medication typically used for Parkinson’s). Levodopa can help tremor, slowness, and stiffness, and so can DBS. However, levodopa can also cause dyskinesias (abnormal involuntary fidgety type movements), and so can DBS. The dyskinesias caused by DBS are usually temporary and last for a few days before the brain adjusts to it.

We have already mentioned that people living with Parkinson’s disease can reduce their overall medication dose by about half. However, keep in mind that this is after medications and stimulation settings are optimized. It is unrealistic to think that you can reduce your medications by that much after the first session. More often, you might be able to reduce it only a little bit. Some people may not be able to even tolerate a dose reduction after the first visit. The key here is to remain patient. Some centers will tell you to try and reduce medications after the first programming visit, whereas others will tell you to not change medications. Although there is no standard guide to reducing medications, most people will get there eventually.

Some people may also want to be able to stop their Parkinson’s medications entirely. Although that may be possible, it occurs rarely. We like to compare adjusting stimulation and medications to making chili. Think of stimulation as chili powder and the other medications as other spices such as salt and pepper. Very few chilis will taste good with just chili powder alone. Most will need a combination of chili powder, salt, pepper, and other spices. Finding the right combination of spices is what adjusting stimulation and medication is all about. Although it may take some time to find just the right recipe, if you are patient, the end result will be sublime.