ELEVEN

My Symptoms Are Not Under Control—Troubleshooting Your System

Although we hope everything has gone smoothly with your DBS procedure and programming, nothing ever goes perfectly. In this chapter, we go over cases where the symptoms are not under control. The first few cases go over situations where the symptoms were never helped even with the DBS surgery. The ones after that go over situations where the DBS was working for a while and then suddenly stopped working. We hope these examples help you understand potential problems with the DBS. The first people to ask if things are not going right are your DBS programmer and DBS neurologist. Although many of the examples relate to Parkinson’s disease, the same concepts can be applied to people with essential tremor and dystonia as well.

DBS NEVER HELPED SYMPTOMS IN THE FIRST PLACE

Poor DBS Candidate

A 68-year-old man had Parkinson’s symptoms for about 6 years prior to DBS surgery. When he first went to a neurologist, he was found to have a “stone face” and tremors of his hands (although they were noticeable only when he used his hands), but his most prominent problem was frequent falling and a shuffling gait with frequent episodes where he felt like he was “stuck in place.” His neurologist started carbidopa/levodopa with entacapone, and there was minimal change in his gait and no decrease in falls. He was tried on many other medications for Parkinson’s but had side effects with all of them. He needed to use a walker after 3 years and was wheelchair-bound after 6 years. Increasing the levodopa did not improve his walking ability, but he felt better on the medication. Five years into the course of his disease, he started developing speech problems as well. He was sent to a neurosurgeon who thought this individual might benefit from STN DBS. Unfortunately, he did not improve after turning the stimulators on, despite multiple DBS adjustments over a year.

Unfortunately, this person was not an appropriate DBS candidate in the first place. The first criterion for DBS surgery for someone living with Parkinson’s is a diagnosis of Parkinson’s without evidence of an atypical parkinsonian syndrome. This person’s clinical presentation and progression are atypical of Parkinson’s disease. Frequent falls are extremely rare within the first few years of a diagnosis of Parkinson’s disease. Although falling and balance problems can occur, they typically happen later in the course of Parkinson’s disease. This person also did not have the typical rest tremor that is seen in Parkinson’s disease. The second criterion for DBS surgery in an individual with Parkinson’s disease is a robust and sustained response to levodopa. This person did not have any clear response to levodopa. Remember, in Parkinson’s, DBS does not make you better than the medications. During this person’s best “on” time, he still needed a walker, so it was unrealistic to expect that his walking would improve with stimulation. Ultimately, the person found his way to a DBS center, and he was found to have eye movement problems that suggested a diagnosis of progressive supranuclear palsy, which is an atypical parkinsonian syndrome. The eye movement problems may not have been present at the time of surgery, which makes diagnosis of this condition difficult. Nevertheless, there were many other reasons to suspect that DBS would not be appropriate for this individual besides the incorrect diagnosis.

For this reason, we suggest that prior to considering DBS, you should be seen by a movement disorder specialist. Whether you have Parkinson’s disease, essential tremor, or dystonia, the movement disorder specialist evaluation is a way to confirm your diagnosis. DBS will not be successful if you have a diagnosis that will not respond to stimulation. Most DBS centers have a movement disorder neurologist who performs all of the screening evaluations. We believe that selection for DBS should involve an experienced multidisciplinary team that performs detailed preoperative assessments. If you are interested in DBS, please read Chapters 3 and 4 to get a better idea of the selection criteria for DBS and how to choose your DBS team. Deciding to undergo DBS is a big step, and you want to make sure that you have the best team in place to insure your success.

Poor Electrode Placement

This 65-year-old man was diagnosed with Parkinson’s disease 10 years prior to DBS surgery. He was maintained on carbidopa/levodopa for many years, but 3 years into the course of the disease, he started to experience wearing-off symptoms. Pramipexole and entacapone were added over the next few years and seemed to smooth out his motor function. He then started to develop dyskinesias with his medication regimen. When his medications worked, he was able to perform his daily activities without difficulty. When he wore off, he felt aching in his legs and had a freezing gait. He was deemed an appropriate candidate for DBS and underwent bilateral STN DBS surgery in 2007. A few days after being programmed, he started developing unusual behaviors such as placing a dining room chair on the front seat of the car to go to the grocery or put what was needed in the oven in the freezer and vice versa. These behaviors went away with programming, but this person never felt that the stimulation helped the motor symptoms of his Parkinson’s disease. He was programmed for a year before being sent to a specialized DBS center for evaluation. On imaging, one of his electrodes was found to be misplaced. His symptoms improved dramatically after replacing the electrode.

This was an appropriate candidate for DBS. He had a diagnosis of Parkinson’s disease with a progression in symptoms that was typical. He had a robust and sustained response to levodopa for many years, but started to have motor fluctuations despite optimal medication management. He also did not seem to have any significant memory problems or depression prior to surgery. However, he never really had a great response to stimulation, and in fact, he started to have unusual effects from the stimulation. In an appropriate candidate, the first step would be to obtain an imaging study of the head to look for a misplaced electrode.

There are two different ways to obtain brain imaging: magnetic resonance imaging (MRI) or computed tomography (CT) (please see Chapter 9 for more details). Please remember that if your physician orders an MRI to look for a misplaced lead, there are certain safety precautions that the MRI technician has to follow. In some centers, the radiology department or center will not perform MRI on anyone with a DBS system, so CTs are ordered. There are pluses and minuses to both techniques.

Sometimes a lead that is suboptimally placed can be overcome by DBS programming. This is why it is important to have not only a good neurosurgeon who can put the lead in the right place but also a good neurologist or nurse programmer who knows how to program the DBS device well. However, if the lead is way off target, replacement has to be considered. A study by two DBS centers has recently found that about half of their “DBS failures” were due to misplaced leads. While having to go through another surgery may seem horrible, at least lead misplacement could potentially be corrected, giving you a good chance at improving your symptoms.

Programming Problem

A 58-year-old man underwent bilateral STN DBS for Parkinson’s disease. His main symptom was a severe tremor, but he also had some slowness in movements. After surgery, his neurologist programmed him for 1 year. He had an improvement in his slowness but never noticed a significant improvement in his tremors. Brain imaging revealed that his electrodes were accurately placed. After referral to someone with more experience in programming DBS, he walked out of the office without a trace of tremor.

This person also seems like an appropriate candidate for DBS surgery. He has a diagnosis of Parkinson’s disease, but has tremor that is disabling despite being treated with medications. Remember that tremor is the one feature of Parkinson’s disease that may not respond to medications but could respond to stimulation. If an individual did not respond to stimulation, but seems like a candidate, the next step would be to check if the stimulators were placed appropriately. In this case, imaging confirmed good placement of the electrodes. After that, reprogramming would be the next step. This person’s neurologist had little experience programming stimulators, having only one other individual in his practice with this condition. An initial testing of the leads was never performed, so the optimal contact was not known. Remember that at the end of each lead, there are four different contacts where the stimulation comes out. For most cases, only one or two of these contacts are within the targeted structure (the thalamus, STN, or GPi). Therefore, testing should be done on all of the contacts to see which one helps the symptoms the most. This person was brought in, and each of the contacts on the left and right sides was tested. It was found that by changing to a different contact, the person had significant improvement in his tremors and walked out happy.

This case illustrates the need to have someone experienced with programming the DBS system. We suspect that many individuals may be told that the DBS was a failure, when, in fact, many could be turned into “successes” by referring them to a DBS center for evaluation.

Failure to Achieve Expectations

Case 1. A 73-year-old woman with a 12-year history of Parkinson’s disease underwent bilateral STN DBS surgery. Prior to surgery, she was responsive to levodopa, but her levodopa only worked about 50% of the waking day. When she was “off” medication, she needed assistance with all basic activities of daily living, and she could not walk at all. When she was “on” medication, she could dress and bathe independently, although slowly. She could walk in her “on” state but needed the help of a walker in order to walk without falling. Her main problems prior to surgery when “on” medications, however, were severe dyskinesias (involuntary movements) at the peak of her levodopa doses that were sometimes painful. After STN DBS surgery, her dyskinesias improved significantly, and she felt “on” for most of the day. She presented for a second opinion because the DBS was not helping her to walk independently.

Remember that for Parkinson’s disease, DBS does not make someone better than their best “on” medication state. This woman could not walk independently prior to surgery even with Parkinson’s disease medications. Thus, it is unrealistic to expect to walk independently after DBS surgery. By reducing dyskinesias and improving “off” time, this surgery should be considered a success. However, because it did not meet up her expectations, she thought it was a failure. While it is the job of the DBS team to let you know what the surgery will and will not improve for you specifically, it may not always be communicated to you clearly. We would recommend that you have an honest discussion with your neurologist and neurosurgeon about your own goals and expectations prior to surgery. Write these goals down on a piece of paper and ask your DBS team whether or not they are realistic. Your expectations can make a big difference in how you assess the success of your surgery.

Case 2. A 22-year-old man had generalized dystonia for most of his life. There was no injury at birth, but he developed dystonic postures of his body as he became older. Despite these problems, he was able to work and live independently, although he needed to put in extra effort sometimes in order to accomplish basic tasks that everyone else takes for granted. The most bothersome aspect of his dystonia was that he did not look “normal.” Also his speech was not always clear. He underwent GPi DBS with the hope that these symptoms would improve. Prior to surgery, he was counseled that the effect of stimulation likely would not improve his symptoms 100%, especially speech, and he appeared to understand. The DBS surgery improved his dystonia by approximately 50%, and he had a significantly easier time performing manual tasks. However, he was disappointed in the surgery and called his DBS a failure because he could not walk “normally.”

Unlike the individual in the first case, this person was counseled about realistic expectations prior to surgery, especially regarding the fact that he likely would still have some dystonia if the surgery was a success. The goal of the surgery according to the DBS team was to improve his symptoms so that he would have an easier time performing tasks. By doing so, his quality of life would also improve. They thought that this goal was communicated to him. However, in hindsight, the goal of the surgery in this man’s eyes was to make him “normal.” Because it did not accomplish that, the surgery was a failure. This case re-emphasizes the fact that you should write out your goals clearly prior to surgery and discuss them with your DBS team. If you have chosen a team that you trust, they should be willing to discuss these issues with you.

DBS WORKED AND SUDDENLY STOPPED WORKING

Infection

A 70-year-old man who underwent left Vim DBS for essential tremor had good control of his right-hand tremor after surgery. Approximately 2 months after surgery, he noticed a decrease in his tremor control, as well as scalp tenderness. He reported catching his comb on his surgery scar frequently over the past couple of weeks. Examination of the incision site on top of the head showed redness and swelling, suspicious for an infection. This individual eventually had to have his DBS system taken out and underwent a course of IV antibiotics. After his infection was treated, he opted to have his DBS lead replaced. After replacement, his tremor control was once again good.

Infections may be a complication of any surgery. An infection typically happens within the first few months of DBS placement and is likely due to poor wound care. Dirt or bacteria from hair, dirty hands scratching the incision site, soap, or shampoo could potentially get in a wound before it heals completely and lay the groundwork for an infection. That is why some DBS surgeons prefer shaving the entire head, so that there is less of a chance for these things to infect the wound. Others may not shave the head, but will restrict you from using shampoo and combs near the incision site until it is completely healed. In either case, it is important to keep the incision sites clean until they heal up properly. Once there is an infection, it can be difficult to treat. If the infection is small, a course of oral or IV antibiotics may be enough to treat the infection. However, often, the entire system has to be taken out, along with a course of IV antibiotics, before it is safe to put DBS hardware back in. It is important that you follow the directions of the neurosurgeon for the first few months after surgery to prevent infection.

Stimulator Off or at End of Life

Case 1. A 64-year-old man with Parkinson’s disease underwent DBS surgery and had marked improvement in symptoms for 6 months, and he was seen urgently because of recurring Parkinson’s disease symptoms over a 3-day period. He was given a device that allowed him to check whether his stimulator was on or off at the time of surgery, but did not know where he had placed it. In the clinic, the stimulator was checked, and it was discovered to be off. After turning the stimulator back on, his symptoms improved. The person had used a power saw in his shed a few days ago for the first time after surgery, which turned his stimulator off.

Case 2. A 24-year-old woman with generalized dystonia underwent bilateral GPi surgery 4 years ago with good benefit. She was seen urgently because of worsening dystonic symptoms over a period of 1 week. When the stimulator was checked in clinic, it would not respond to the controller, suggesting that the battery was at end-of-life. The woman’s battery was replaced, and she continued to experience a good benefit from stimulation.

Some people, specifically those with tremor, will notice almost immediately when their stimulators are turned off. That is because tremor seems to respond quickly (within minutes and sometimes within seconds) to electrical stimulation. For other symptoms such as bradykinesia and rigidity of Parkinson’s, the full effect of a change in stimulation may not be seen for days. With dystonia, the changes may take weeks to be seen. People living with essential tremor are often encouraged to turn their stimulators off at night and on in the morning, so if the tremor does not respond when they try to turn the stimulator on, it is likely at the end-of-life and needs to be changed. For those living with Parkinson’s disease, the stimulators are on 24 hours a day. For these people, we recommend that they check to see if their stimulator is on once a day. Nowadays, everyone should be given a device after surgery that allows them to check whether the stimulator is on, as well as allow them to turn the stimulator on or off. That way, if their stimulator is ever turned off for any reason, they can look back on their previous day to figure out what might have turned their stimulator off. Devices that generate strong magnetic fields, such as the refrigerator seal, mouthpiece of a phone, metal detectors, power tools, and even the remote of a Toyota Prius, have been reported to switch the DBS stimulators off. This seems to be less of a problem than several years ago, but if you notice that your symptom control changes suddenly or over a few days, you should first check your stimulator to see if it is on. If it is, you should then contact your DBS team to see if your stimulator battery has run out. Most stimulators can last anywhere from 3 to 5 years.

Other Hardware Malfunction

A 54-year-old woman with essential tremor underwent left Vim DBS and had significant improvement in her right-hand tremor for 2 years. However, she reported that her tremor control deteriorated suddenly 1 week prior to her clinic visit. When the stimulator was checked, it was turned on, and the battery was not close to end-of-life. Checking other stimulation parameters demonstrated a high impedance and low current, suggesting an open circuit. X-rays of the head and neck revealed that the extension wire from the stimulator to the lead was kinked. This person had a lead fracture, and tremor control was regained after replacing the extension.

There are other hardware problems that can result in a relatively rapid loss of symptom control. One such problem is a lead fracture. If your DBS programmer suspects a lead fracture, they will often order an X-ray of the head and chest to identify it. The reasons for a lead fracture are unclear, and although sudden and violent movements potentially could result in lead fractures, they often happen without a past history of trauma or sudden movement. Again, if you experience a sudden loss in symptom control, you should first check to see if your stimulator is still on. If it is, then you should make an appointment with your DBS programmer to check if the battery is still working and to check if you could have a possible lead fracture.

DBS SLOWLY STOPPED WORKING OVER TIME

Lead Migration

This 35-year-old woman underwent bilateral GPi DBS for generalized dystonia. She had a good response after about 6 months of stimulation, with about a 70% reduction in severity. About 9 months after her surgery, she presented for a regular follow-up in the DBS clinic and reported that her dystonia had gradually worsened over the past 2–3 months. She checked her stimulator religiously every day and reported that it had never been turned off. Her stimulation parameters were checked and did not show any abnormalities. Upon reimaging her electrodes, it was found that the right electrode had moved approximately 1 cm from previous imaging studies. Her electrode was repositioned in the proper spot without complications, and she again was able to report a 50% reduction in dystonic symptoms compared with before surgery.

Lead migration is not common, but it certainly does happen. If there is worsening of symptoms, lead migration should be one of the considerations. An imaging study compared with one taken immediately after the surgery should show if the electrode had moved. It is unclear why the leads should move over time, although anchoring devices sometimes have been blamed. These anchoring devices are basically plastic caps that fit in the hole that was drilled in your skull at the time of surgery. They are supposed to keep the lead in place, but sometimes they malfunction or the lead is not secured well before the surgeon closes the scalp. Children who often have DBS placed for dystonia and then grow may also be more likely to have lead migration. In the case described above, the lead had to be repositioned, but in some cases, the stimulator can be reprogrammed successfully by switching to an alternate DBS contact.

Disease Progression

This 73-year-old man with Parkinson’s disease has had STN DBS for 5 years. He had good control of tremor after surgery and had an improvement in his medication “on” time after surgery. He was happy with control of his motor symptoms for 4 years after surgery, but at that point, he started to notice problems with his balance. Over the past year, he has progressed from walking independently to needing a walker. He has developed freezing episodes that occur at any time throughout the day and do not correlate with when he needs to take his medications. Increasing his levodopa did not help his freezing, neither did increasing or decreasing his stimulation parameters. Brain imaging showed that the leads were in the right place and had not migrated.

Sometimes when a symptom is not optimally controlled, it may be due to progression or worsening of the Parkinson’s disease, essential tremor, or dystonia, even in cases with an optimally placed electrode that has been working well for a long period of time. Of course, all effort should be made to identify a correctable cause for inadequate symptom control, such as the stimulator being turned off, battery end-of-life, lead fracture, and lead migration. After that, the stimulators should be adjusted to see if the individual simply needs more stimulation. However, if increasing stimulation does not help, progression of disease is certainly a high possibility. Remember that DBS is not a cure. In this case, it has been well established that freezing and other symptoms that do not respond well to levodopa also do not respond well to stimulation, with the exception of tremor.

Tolerance/Habituation

This 58-year-old woman with essential tremor had excellent control of her hand tremor for 5 years after DBS surgery. After that, her tremor control seemed to decline. Now 7 years after surgery, she still has an improvement in tremor when she turns her stimulator on, but it is still noticeable. For the first 5 years after surgery, the tremor used to disappear with the stimulator turned on. Imaging has shown that the lead has not migrated and is optimally placed. Increasing the stimulator over the years improved the tremor minimally, and now will cause sustained tingling of the right side of the face and arm if turned up any higher. Multiple trials of DBS adjustments, including trying other contacts and parameters, failed to improve the tremor further.

DBS tolerance seems to happen to individuals with essential tremor, but not dystonia or Parkinson’s disease. In such cases, tremor is controlled over a long period of time (more than 1 year, but often for many years), and then this benefit is lost. It cannot be explained by lead migration or other hardware malfunction or improper programming. It also cannot be explained by disease progression because the loss of symptom control occurs over a relatively short period of time. It is unknown why tolerance occurs. When this happens, some DBS centers may offer an ablative procedure such as a thalamotomy. This involves lesioning the thalamus (i.e., killing the cells) and can be effective for tremor, although it is an irreversible procedure.