Deep Brain Stimulation (DBS)
Overview
While medications, such as propranolol, primidone, levodopa, dopamine agonists, botulinum toxin, and other drugs are helpful, many patients with Parkinson’s disease (PD), tremor, dystonia and other movement disorders continue to experience embarrassing, troublesome or even disabling symptoms. Patients who do not obtain satisfactory response from optimal medical therapy may be considered candidates for surgical intervention. In the past, the neurosurgical treatments consisted chiefly of procedures that produced lesions to selected areas of the brain in order to control the movement disorder (“ablative surgery”). These procedures involve an incision in the scalp and drilling a hole through the skull. The surgeon than uses a “probe” (electrode) and advances it into the portion of the brain that is thought to be functioning abnormally. An electrical current is then used to heat the tip of the electrode which results in a lesion in the target brain area (nucleus). This is usually associated with a reduction of the abnormal or involuntary movement on the opposite side of the body. Although effective in most cases, there is a risk of stroke resulting in weakness on the opposite side of the body, numbness, incoordination, speech disturbance and other complications. These potential risks are compounded when the procedure is performed bilaterally (on both sides).
In the late 1980's it was discovered that tremor can be relieved not only by a destructive lesion, but also by a high frequency stimulation of certain brain structures. This technique, called deep brain stimulation (DBS), is gradually replacing the traditional ablative procedures, as the surgical treatment of choice for a variety of movement disorders such as Parkinson’s disease, tremors, dystonia, and tics. In this procedure, the DBS lead, which actually contains four electrodes, is surgically inserted into the desired target and fixed to the skull with a ring and cap. An extension wire passes from the scalp area under the skin to the chest and is connected to an implantable pulse generator (IPG), a pacemaker-like device, which can deliver pulses with a variety of parameters, modes, and polarities to the target brain area. The IPG is surgically implanted under the skin in the upper chest area near the collar bone. The patient can activate or deactivate the DBS system by placing a magnet over the chest area that contains the IPG. IPG is a metal "box" about two inches in diameter and about 1/2 inch thick, similar to a cardiac pacemaker. It contains a small battery and produces the electrical pulses needed for stimulation. The typical battery life is expected to be approximately 5 years, but this may vary depending on the individual settings and hours of use per day. The battery cannot be replaced without replacing the entire IPG. Replacing the IPG involves minor surgery. This needs to be done every 3-4 years.
The major advantage of DBS over the traditional ablative procedures is that the stimulating electrodes and parameters (frequency of stimulation, pulse width, and voltage) can be adjusted and “customized” to the needs of the individual patients. Potential risks, such as hemorrhage, stroke or infection, are rare, but should be considered when making a final decision about this treatment option. Side effects, if they occur, are usually reversible, but may include weakness, speech and swallowing difficulties, and abnormal sensations.
As a result of improved understanding of the anatomy and function of the basal ganglia, (the part of the brain involved in Parkinson’s disease and other movement disorders), coupled with refinements in imaging and surgical techniques, DBS is gaining wide acceptance as a chronic treatment of not only tremor, but also other symptoms of Parkinson’s disease, complications related to levodopa therapy, such as motor fluctuations and dyskinesias, and other movement disorders such as dystonia. DBS is currently being used in selected centers around the world, including at Baylor College of Medicine, to treat a variety of movement disorders. In collaboration with Dr. Simpson from the Department of Neurosurgery, The Methodist Hospital, we have implanted over 500 DBS devices.
Since the early 1990s, clinicians from around the world, including those at Baylor College of Medicine, began to explore different brain targets to control the various movement disorders. The current data, based on the extensive experience at Baylor and abroad, provide compelling evidence that chronic, high-frequency stimulation of the ventral intermediate (VIM) nucleus of the thalamus, subthalamic nucleus (STN) and globus pallidus (GPi) improves essential tremor and Parkinson’s disease. STN and GPi control not only tremor, but also motor slowness, rigidity, gait, and, most importantly, levodopa-related motor fluctuations and dyskinesias in patients with moderately advanced Parkinson’s disease.
The major advantage of DBS over ablative procedures is that the stimulating electrodes and parameters (frequency of stimulation, pulse width, and voltage) can be adjusted and “customized” to the needs of the individual patients. Furthermore, side effects, if they occur, are usually reversible, and bilateral stimulation is possible with minimal or no loss of speech volume. In some patients, ablative thalamotomy or pallidotomy on one side may be combined with or followed by DBS on the opposite side. Based on our experience and that of our European and American colleagues, we conclude that DBS is a safe and effective treatment of disabling tremors and other features of PD including levodopa-related motor complications.
Patients interested in being evaluated to determine whether they are candidates for VIM, STN, GPi DBS, or other surgical treatments, should contact the Parkinson’s Disease Center and Movement Disorders Clinic, Baylor College of Medicine, Department of Neurology (Tel: 713-798-7438). To further pursue one of the DBS procedures, patients may also make an appointment with Dr. Richard Simpson (713-798-4696), Department of Neurosurgery, for a consultation, more detailed discussion of the procedure, and to schedule the surgery. Dr. Simpson’s office also assists in arranging coverage with your insurance or Medicare for the hospitalization, surgery and DBS device. During the follow-up DBS visits, there will be a fee for the adjustment and reprogramming of pulse generator (CPT code 95971, 95974, 95975) for stimulator adjustment and for a routine follow-up visit. It is our policy that we require payment at the time of service (except for Medicare patients). We do, however, provide assistance in filing for Medicare/Third Party Payer reimbursement.
Risks and Benefits
Activa Parkinson’s Control Therapy: Patients should always discuss the potential risks and benefits with a physician.
Indications: Bilateral stimulation of the internal globus pallidus (GPi) or the subthalamic nucleus (STN) using Medtronic Activa Parkinson’s Control Therapy is indicated for adjunctive therapy in reducing some of the symptoms of advanced, levodopa-responsive Parkinson’s disease that are not adequately controlled with medication.
Contraindications: Contraindications include patients who will be exposed to MRI using a full body radio-frequency (RF) coil or a head transmit coil that extends over the chest area, patients for whom test stimulation is unsuccessful, or patients who are unable to properly operate the neurostimulator. Also, diathermy (e.g., shortwave diathermy, microwave diathermy or therapeutic ultrasound diathermy) is contraindicated because diathermy's energy can be transferred through the implanted system (or any of the separate implanted components), which can cause tissue damage and can result in severe injury or death. Diathermy can damage parts of the neurostimulation system.
Warnings/ Precautions/Adverse Events: There is a potential risk of tissue damage using stimulation parameter settings of high amplitudes and wide pulse widths. Extreme care should be used with lead implantation in patients with a heightened risk of intracranial hemorrhage. Do not place the lead-extension connector in the soft tissues of the neck. Placement in this location has been associated with an increased incidence of lead fracture. Theft detectors and security screening devices may cause stimulation to switch ON or OFF, and may cause some patients to experience a momentary increase in perceived stimulation. Although some MRI procedures can be performed safely with an implanted Activa System, clinicians should carefully weigh the decision to use MRI in patients with an implanted Activa System. MRI can cause induced voltages in the neurostimulator and/or lead possibly causing uncomfortable, jolting, or shocking levels of stimulation. MRI image quality may be reduced for patients who require the neurostimulator to control tremor, because the tremor may return when the neurostimulator is turned off.
Severe burns could result if the neurostimulator case is ruptured or pierced. The Activa System may be affected by or adversely affect medical equipment such as cardiac pacemakers or therapies, cardioverter/ defibrillators, external defibrillators, ultrasonic equipment, electrocautery, or radiation therapy. Safety and effectiveness has not been established for patients with neurological disease other than Parkinson’s disease, previous surgical ablation procedures, dementia, coagulopathies, or moderate to severe depression; or for patients who are pregnant, under 18 years or over 75 years of age. Adverse events related to the therapy, device, or procedure can include: stimulation not effective, cognitive disorders, pain, dyskinesia, dystonia, speech disorders including dysarthria, infection, paresthesia, intracranial hemorrhage, electromagnetic interference, cardiovascular events, visual disturbances, sensory disturbances, device migration, paresis/asthenia, abnormal gait, incoordination, headaches, lead repositioning, thinking abnormal, device explant, hemiplegia, lead fracture, seizures, respiratory events, and shocking or jolting stimulation.
Common Questions about DBS STN Surgery
1. Benefits of surgery
- What benefits should I expect from the surgery?
In general DBS helps about as much and in the same way as levodopa (or Sinemet). The best improvement in movement with your medications is what you can expect from the surgery. The benefits, however, should be more sustained throughout the day, with fewer fluctuations than seen with levodopa. This should result in increased amount of “on” time for patients (the time the medication is working to reduce motor symptoms) as well as much less severe “off” time. In addition, many patients do not have the opportunity to experience the maximum benefit medicines (specifically levodopa) can provide because they are limited by side-effects, particularly dyskinesias (involuntary movements). The goal of surgery is to achieve that maximal benefit without levodopa side-effects. DBS has been especially helpful in reducing tremor, slowness, stiffness, and especially dyskinesias. This is in part due to reduction in the amount of levodopa patients take, but some patients see a reduction in dyskinesias even without reducing levodopa.
- What benefits should I not expect from the surgery?
The surgery has not been shown to be helpful in improving problems with balance, voice or many of the “non-motor” complications of PD such as depression, problems with thinking, constipation, or pain. It is critical to discuss the expected benefits of the surgery with your neurologist so that you do not have unrealistic expectations. DBS is NOT a cure; it can, however, improve the motor symptoms of the disease.
2. What are the risks associated with the surgery?
There are risks associated with any brain surgery, including infection, stroke, hemorrhage, cerebrospinal fluid leaks, seizures, weakness, tingling, technical problems, wound healing problems, disfiguring scars, prolonged hospitality, and need for additional surgery. The percentage of patients who report these complications is low.
In addition, there are risks associated specifically with DBS, including speech difficulties, such as speaking softly and slurring of words, mood changes (especially depression), involuntary movement, difficulty with coordination, recurrence of symptoms, malfunction or breakage of device, device migration, and early removal of device. Adjustments of the stimulator and speech therapy sessions can help to reduce some of these difficulties.
This is not a comprehensive list of risks associated with DBS, please discuss the risks and benefits with your neurologist and neurosurgeon for further information.
3. How is it determined if I am a good candidate for the surgery?
There are several appointments that you will need to attend to determine if you are a good candidate for DBS. Please see the attached DBS Appointment Schedule Checklist for a listing of all appointments required for DBS STN surgery.
The Movement Disorders team meets once a month to discuss potential candidates for surgery. The neurologist will determine if you are a good candidate based on the difference between your examination (motor scores) “on” and “off” levodopa, the amount and severity of dyskinesias, your gait and balance, and the laterality of your symptoms. The neuropsychologist will determine if you are a good candidate based on your mental status and psychiatric profile. Other medical issues are also considered to determine if you are a good candidate for surgery in other, more general, ways.
4. How long will the surgery last?
If you are having DBS placed on both sides, you will undergo 2 surgeries approximately 10 days apart. The total time for the first day will last between six and eight hours. This includes placing the electrodes into the correct site in the brain, time getting your brain scan and time in the recovery room. The second surgery to place the batteries (10 days later) will last about two hours.
If you are having DBS placed on only one side, the entire procedure (electrode insertion and battery placement) will take between four and six hours on a single day.
5. How long do I have to wear the halo?
A halo (a metal stereotactic head frame that looks like a halo around your head) will be attached to your skull the morning of the surgery to help you remain still during the procedure. You will have to wear the halo for almost the entire time during the surgery.
6. Will I be awake for the surgery?
For most patients, you will be awake during the part where the electrodes are placed into the brain. This is necessary to ensure that they are in the best possible location. Dr. Simpson will ask you to perform simple motor tasks to assess the effect of the stimulator. You will be put asleep for the part where the battery is placed.
7. Does it hurt?
The brain is the only part of the body that has no sensation, so you will not feel the electrode being placed into the brain at all. Most people say that the most uncomfortable part is when the halo is placed tightly on their head. Often people have some soreness the following day from where the battery and wires are placed. You are asleep for that part of the surgery.
8. How long will I be in the hospital after the surgery?
The first night after the surgery will be spent in the neurosurgical intensive care unit (Methodist hospital Main building fourth floor). The family is not permitted to spend the night in the intensive care unit. Many patients will leave the hospital the next afternoon. However, if you are still not feeling well, you may stay one or two additional nights.
9. When do I return after surgery?
Before you leave the hospital you will have an appointment to see Dr. Simpson and/or Christina (Scurlock 9th floor) and your neurologist (Smith 18th floor) about 10-14 days after your final surgical procedure. The DBS will be activated and adjusted at that visit by the neurologist and his/her programmer, not at the time of surgery.
10. Will my medicines change when I leave the hospital?
Patients will usually be given an antibiotic after surgery. Unless you are told otherwise, continue your same medications until you return for the follow-up visit. DO NOT TAKE YOUR MEDICATIONS FOR PARKINSON’S, TREMOR, OR DYSTONIA ON THE DAY THAT YOU RETURN FOR YOUR FOLLOW-UP APOINTMENTS TO ACTIVATE OR PROGRAM THE DEVICE. WE WILL NOT BE ABLE TO ADJUST IT CORRECTLY IF YOU HAVE TAKEN YOUR MEDICATIONS THAT DAY.
11. Are there any restrictions after surgery?
Immediately following surgery, you are not allowed to get the surgical area wet until after the stitches are removed. You should avoid any heavy lifting or over strenuous activities.
At all times after implantation, you should be cautious around large magnets that can turn off your stimulator by accident. Examples are magnets inside the refrigerator door and airport security scanners. At the airport, notify the security officers that you have a pacemaker type device and will need a hand scan.
Please discuss all MRI scans with your doctor prior to making an appointment. Do not undergo diathermy after implantation.
12. How do I activate or adjust the device?
You cannot adjust the device settings at home. You will be given a remote control and two magnets so that you can turn the stimulator on and off. This will be demonstrated to you when the device is initially activated at the neurologist’s office.
13. How many programming sessions and follow-up appointments will I need?
At a minimum, you should expect to come in monthly for the first three months after surgery, then every three (3) months till one year after surgery, then annually. These visits will consist of evaluation of your condition, programming and adjusting medications. Your clinical condition is in a state of flux after your surgery and changes made in programming and medication may take several weeks to take full effect – both good and bad effects. Every patient is different – some require more frequent adjustments. In addition, a MRI will be scheduled about 6 months following surgery to confirm that the electrodes are in the proper position.
14. How do I contact individuals if I have questions?
- Drs. Jankovic, Ondo, Jimenez-Shahed - Neurology, Movement Disorder713-798-7438
- Scheduling Coordinator713-798-6337
- Mike Almaguer - Programming713-798-3474
- Dr. York - Neuropsychology713-798-5365
- Dr. Simpson - Neurosurgeon713-441-3800
For additional information visit http://www.bcm.edu/neurology/pdcmdc/