DBS for Tremor

DBS is a treatment that involves electrical stimulation of the brain. It is done in two stages and is usually performed on one side of your body.

First, surgery is performed to place an electrode in a region of the brain called the thalamus. During parts of the surgery, you will be awake. The electrode stimulates the brain with low-level electricity in the operating room, and the doctor checks to see if the stimulation is helping your tremor. If so, the electrode is left in place. On rare occasions when the tremor fails to improve the electrode is removed because you probably would not benefit from undergoing DBS stimulation. The electrode-placement surgery requires a 1-2 night stay in the hospital.

After about one week, you will return to the hospital for day surgery in which a pulse generator, or "battery," is placed under the skin of the chest. This is done under general anesthesia. The pulse generator is connected to the brain electrode(s) by an extension wire that runs under the skin. If you have two electrodes placed in the brain (to treat tremor affecting both sides of your body) then you will have two pulse generators in your chest. Once the pulse generator is in place, the neurologist will turn it on in order to begin stimulation of your electrodes.

The implanted electrodes interrupt the jumbled messages in your brain that are causing your tremor. Exactly how this is achieved is not clear and is still a topic of research and debate. However, we do know that a low level of electricity delivered into the thalamus can suppress tremor to a significant degree. Once your electrodes are in place, a clinician can make adjustments from outside the body using a special programming device. The device can change settings such as the strength and frequency of your stimulation. Over time, as your tremor changes, the electrode settings can be modified to maintain tremor control.

You can also adjust aspects of the DBS system yourself. For example, many patients choose to turn their stimulation off at night to help conserve the battery. You will be given a device that you can hold over the battery in your chest, to turn your stimulator on or off. However, only your neurologist or someone on the neurologist's staff will be able to change the strength of the stimulation you receive.

• Patients with essential tremor that is not well controlled with prescription medications
• Patients who are able to travel to BIDMC for follow-up appointments
• Patients who are 30-80 years old

You may notice small bumps on either side of your head at the surgical sites. The stimulator batteries can be felt under the skin. A wire that connects the battery in the chest to the scalp can also be felt under the skin but is not visible. There is a small amount of discomfort just after these devices are placed in your body, which is controlled with mild pain medication. After a few days, there is no discomfort from either the brain electrodes or the electrical devices in the chest.

When the electrodes are first activated or are being adjusted, you may feel a tingling or pulling feeling in your legs, arms, or face. This sensation should subside within a few moments. If not, the settings of your electrodes will be changed to correct the sensation. Your electrodes continuously stimulate the targeted brain region; however once they are turned on and set correctly, you should not feel anything.

Thalamotomy is another surgical option for patients who have tremor that is not well controlled by medication. In this procedure, the tissue in the brain that is causing the tremor is identified and destroyed using a heated electrode. Thalamotomy is rarely done these days and can only be done safely on one side.

Focused ultrasound (FUS) is another surgical option for controlling tremor. The procedure involves focusing high energy ultrasound beams to thermally destroy targeted brain tissue, enabling tremor to be treated without creating holes in the skull and without needing placement of a battery pack. Currently, FUS procedure is a unilateral procedure, providing tremor relief on one side of the body.

Thalamic DBS has some advantages when compared to these procedures. DBS does not destroy brain tissue. Stimulation is a reversible procedure, and it can be customized to provide the best control for an individual patient. It can be done on one or both sides of the brain though usually only one side is performed at first followed by the other side several months later if necessary.

DBS has some disadvantages that are important to consider. The battery must be replaced as needed. Battery life varies considerably from patient to patient and is highly dependent upon your individual settings. There is risk of complications such as infection at incision sites, electrode breakage, and pulse generator failure. Other complications associated with this procedure are discussed later in this brochure.

Another disadvantage of DBS is the need to return to the outpatient clinic for re-programming. For some patients, who live a long distance from the medical center or have problems arranging transportation, return visits to the hospital may pose a problem. In this case, DBS is probably not the best treatment choice. Overall, thalamic DBS is preferred over thalamotomy because brain tissue is not destroyed, lowering the risk of surgery-related neurological complications.

Some patients experience what we call a "honeymoon period" immediately following surgery, even before the electrodes are turned on. This improvement is a temporary effect that is sometimes seen when the electrodes are placed in the brain. It leaves after several weeks, and symptoms return. Once the electrodes are turned on and adjusted properly, symptoms will improve again. Remember, this process can take several months.

Unfortunately, we do not yet have a way to cure or stop the progression of dystonia. Even if the treatment works well, you may continue to have good and bad days. Just as you have ups and downs with medications, you will have ups and downs with the functioning of your stimulator. We will work closely with you to help you get through rough periods if your symptoms reappear or worsen.

DBS is beneficial for treating both resting tremor (tremor that is present when the arms and hands are resting or being still) and action tremor (tremor that occurs while performing a task, such as bringing a cup of water to your mouth). It is most commonly done for essential or familial tremor but can also be used to treat other tremors. The surgery seems more helpful in controlling tremors affecting the arms as compared to those affecting the legs. Patients with bilateral stimulation may notice improved head and voice tremor if one is present.

Once your electrodes and pulse generators are in place, your system can be turned on. Usually stimulation will be started 2-3 weeks after the pulse generator is implanted, in an outpatient visit with your neurologist, who will check your DBS system to make sure it is working at its best. The neurologist will test several combinations of settings on each electrode to ensure that the best combination is being activated. Once optimal settings have been determined, you will be seen at least every 6 months to check how well your system is working and to make any necessary changes.

The treatment is generally not offered if any of the following exist:

• Significant dementia or confusion
• Active psychiatric problem such as depression
• Another significant brain disorder
• A medical condition that makes general anesthesia unsafe
• A medical condition that requires body MRI on a regular basis

Any surgical procedure carries some risk, and this is also true of STN DBS surgery as well. Your overall health will be evaluated carefully before you are recommended for this surgery to make sure the risk of problems is low. Fortunately, neurologic side effects of STN DBS have been very uncommon in our experience. The most potentially serious side effect is bleeding in the part of the brain where each electrode is inserted. Some bleeding in the brain occurs in 1-2% of procedures in which a needle, wire, or electrode is passed through the brain. Fortunately, the majority of such brain hemorrhages are small, produce little or no neurologic deficit, and are detected only by postoperative brain imaging, which is done the day after surgery. To help prevent bleeding, patients are instructed not to take any blood thinners such as warfarin (Coumadin), heparin, aspirin, anti-inflammatory drugs, or arthritis medications (all of which interfere with blood clotting mechanisms) for at least two weeks before surgery.

There are several possible problems related to equipment that may occur months to years after the system has been installed. These include breakage of the electrode wire under the skin in the scalp or neck and skin infection or skin breakdown in the scalp. With the exception of certain types of hardware breakage, these problems can usually be corrected without removal or replacement of the brain electrode. Your neurologist and neurosurgeon will speak with you in more detail concerning these possible complications and answer any questions you may have.

If MRI is needed for any reason after having DBS placed, you will need to let the radiologist know that you have a DBS system in place. Because MRI uses a powerful magnet to make images, care is needed to avoid damaging the hardware or any tissues that are in contact with the DBS. For this reason, head MRI may be done in a very limited fashion. MRI of other body parts may not be done safely at this time and CT scan is recommended. Other tests, like X-rays, ultrasound or CT scans, can be done safely.

Also, diathermy (e.g., shortwave diathermy, microwave diathermy or therapeutic ultrasound diathermy) is contraindicated because diathermy's energy can be transferred through the system, which can cause tissue damage and can result in injury or death.

If you and your doctor decide that you might be a good candidate for this surgery, we will ask you to meet with a number of specialists on our team and to undergo a series of examinations. Through this process, we will be better able to tell if there is a good chance the surgery will help you without posing any unusual risk. This process will include:

• Neuropsychological testing - You will meet with a neuropsychologist who will administer tests to evaluate how your brain functions in domains such as attention/concentration, processing speed, language processing, and executive functions.
• Meeting with the neurosurgeon - You will also meet with the neurosurgeon who will perform the operation. You will undergo a complete examination, and have a chance to talk about any questions or concerns you may have about the surgery. If needed, an MRI examination of the brain will be scheduled.

Once all these exams are complete, our team will look at the information and decide whether or not to recommend surgery. The DBS team at BIDMC is a multidisciplinary group of healthcare providers specializing in neurology, neurosurgery, social work and neuropsychology.  If our team feels that further treatment with medication is needed, these recommendations will be provided to you and your referring physician. If surgery is recommended, you will be scheduled for the procedure to take place within approximately one month. Once your surgery has been scheduled, you will be given more information about coming to the hospital for routine pre-operative tests.

First Stage

The first stage is implantation of an electrode on one side of the brain which is done after you undergo an MRI wearing a head frame on the morning of the operation. The operation is done under intravenous anesthesia so that you can be awakened during parts of the procedure so that we can judge your responses to brain stimulation during the operation. Medication for discomfort or anxiety will be given if needed. Electrical recording and stimulation of the brain is carried out by an electrophysiologist to precisely identify and map out the surgical target. You may be asked to perform some simple motor or cognitive tasks so that the best location for electrode placement can be identified. After mapping of the brain, a permanent stimulating electrode is placed within the thalamic nucleus. The procedure will take approximately 3 to 4 hours. After surgery your medication will be resumed and a CT or MRI scan will be done. You will be sent home after one or two nights in the hospital.

Second Stage

Both stages of DBS surgery may take place in one day. If the neurosurgeon decides to wait before proceeding with the second stage, you will return about 7 days later for the second stage. The pulse generator will be implanted under the skin just below or near the collar bone. This is done under general anesthesia and will take approximately 1 hour. These will be connected to the brain electrode by an extension wire running under the skin from the top of the head and behind the ear to the pulse generator which will not be visible. You will go home on the same day. Your first programming session will be scheduled for approximately 2-3 weeks after the second stage operation.