Drug therapy is the traditional treatment for tremor. Surgical methods that destroy a part of the brain also are sometimes used. Tremor Control Therapy utilizing the Activa™ System suppresses tremor through electrical stimulation delivered by an implanted device. If drug therapy is not effective in controlling your tremor, you may be a candidate for this therapy. Deep inside your brain is a walnut-sized structure called the thalamus, a Greek word meaning “inner room.” Through this “Room” pass most of the messages about body motion that your brain needs to control movement. In people with tremor, these messages are not working correctly. If these messages are interrupted by electrical stimulation, tremor may be suppressed. The Activa™ Tremor Control Systems delivers that electrical stimulation.



Activa™ Therapy partially or completely suppresses tremor in 80% of patients. Activa™ Therapy delivers electrical pulses to the brain. You can activate these electrical pulses when you wish, and your doctor can adjust them as an outpatient to meet your tremor’s severity. The Activa™ System is not implanted unless your tremor has been suppressed during test stimulation without undesirable side effects.

Activa™ Therapy helps control tremor, but it does not cure tremor. When activated, the Activa™ System markedly reduces tremor in the targeted area, resulting in improved use and function. Tremor will return when the system is turned OFF.
* Medtronic clinical studies.



Deep inside your brain is a dime-sized structure called the subthalamic nucleus. Through this nucleus pass most of the messages about body motion that your brain needs to control movement. In people with the general symptoms of Parkinson’s disease and movement disorders (above), these messages are not working correctly. If these messages are interrupted by electrical stimulation, stiffness and rigidity may be suppressed. The Activa™ Tremor Control Systems delivers that electrical stimulation.



The Activa™ System includes an insulated lead wire with four electrodes at the tip. The lead is implanted in the thalamus for tremor, or the subthalamic nucleus for the general symptoms of PD, where the electrodes deliver electrical stimulation.

The lead is connected to an extension, essentially another thin, insulated wire that connects to the pulse generator. This extension is threaded under the skin from the top of the skull to the chest area near your collarbone.

The pulse generator, like an advanced pacemaker, is a small, sealed, metal and plastic device with a battery. The pulse generator produces the electrical pulses needed for stimulation. It is connected to the extension and implanted in the chest area near your collarbone.

A small, hand-held magnet allows you to turn the system ON and OFF. Numerous parameters of the stimulator may be changed at the office using a special programmer.



All Activa™ components, with the exception of the hand-held magnet, are inside the body. The pulse generator may bulge slightly under your skin, but it isn’t noticeable under clothes. There also may be a slight bump on the top of your head, but it usually isn’t visible under your hair.


This illustration shows a complete system implanted on the left side of the body, which would control tremor on the right side of the body.



To help you decide if Activa™ Therapy is right for you, Dr. Duma provides a thorough assessment of your tremor, your general physical condition, and your neurological status. He will assess your tremor of general symptoms of PD through rating scales, handwriting samples, and possibly videotaping.

Activa™ Therapy requires you to assume certain responsibilities. These include responding to questions during the implant procedure, following precautions regarding use of the system, and being available for follow-up programming. You will have an opportunity to discuss the implant procedure with Dr. Duma who will perform the operation. He specializes in surgical procedures for the brain that require the use of a special apparatus called a stereotactic frame.

Be sure to ask Dr. Duma any and all questions that you may have so that he may answer your questions regarding safety, expected outcomes, risks, and side effects.



Consider talking with people who are already implanted with the Activa™ System to learn directly what the procedure is like and how the therapy has affected their lives. You also can talk with people for whom the therapy was not successful. Ask Dr. Duma for the names of patients willing to discuss their experiences with tremor control therapy.



  • Implanting the Activa™ Tremor Control Therapy System carries the same kinds of risks associated with any other stereotactic neurosurgery.
  • These risks include:
    • Bleeding inside the brain (2%)
    • Leakage of fluid surrounding the brain (1%)
    • Seizure (1%)
    • Infection (2%)

While these risks are quite low, they could be life-threatening. After surgery, you might be sleepy, and experience headaches. Discuss all of these risks with Dr. Duma so you are fully informed.



Side effects usually are mild, and go away when stimulation is turned OFF. Dr. Duma can also adjust the stimulation so the side effects are eliminated or lessened.

Side effects may include:

  • Tingling in the limbs or face (paresthesia)
  • Facial and limb muscle weakness or partial paralysis (paresis)
  • Speech problems (dysarthria)
  • Dizziness or lightheadedness
  • Movement problems or reduced coordination
  • Jolting or shocking sensation



If you decide that Activa™ Therapy is right for you and the implant is scheduled, Dr. Duma will give you instructions regarding taking your medications, bringing insurance forms to the hospital, etc.



Most likely you will arrive at Hoag Hospital on the morning of the surgery. You will be asked to sign a surgery consent form. Then, the first part of the procedure takes place.




Dr. Duma attaches a stereotactic frame, a halo-type device, to your head. This frame stabilizes your head and helps Dr. Duma to locate the target precisely. Although local anesthetic is used to numb the areas where the frame is secured, you may feel pressure and some discomfort as it is attached.



Once the stereotactic frame is in place, an image of your brain will be taken using magnetic resonance imaging (MRI) or computer assisted tomography (CT). From this image Dr. Duma will check the position of the frame and take measurements to locate the position of the thalamus.



The operating room is staffed by a team of highly skilled professionals. You will see Dr. Duma, who leads the team, surgical assistants, nurses, and the anesthesiologist, who gives you anesthesia or medication and monitors your vital signs. Other team members may include a neurologist and/or a neurophysiologist, who will be involved with the testing of stimulation.



Dr. Duma makes a small hole, about the size of a dime, in your skull. This is done while you are under local anesthetic and mild sedation. Still, you may feel some pressure. Remember the surgical team wants you to be as comfortable as possible, so always let someone know if you are uncomfortable.

He then inserts the thin lead into the thalamus or subthalamic nucleus. Since brain tissue itself does not sense pain, you most likely will not feel any pain during this part of the procedure.



Dr. Duma uses microelectrode recording prior to implantation. Once the lead is in place, Dr. Duma connects it to an electrical stimulator. When the stimulator is turned ON, he and the other team members evaluate the lead location and stimulation strength by seeing how well you hold a cup, or stretch your arms out and bring your fingers together, or draw spirals. You also will be asked if you feel things like numbness and tingling, and your speech will be evaluated. Depending upon your responses, Dr. Duma will adjust the lead placement and the stimulation.

If tremor cannot be suppressed or rigidity relieved or if there are side effects that cannot be controlled adequately, the lead will be removed and the procedure will not continue.



If the therapy controls your tremor during intraoperative testing, the Activa™ System will be implanted – the lead, the extension, and the pulse generator. This may occur on the same day or some days later.

For this part of the operation, general anesthesia is typically used (you’ll be asleep). The lead is secured and the pulse generator is implanted in your chest near your collarbone. The two are connected by an extension, which is threaded under your skin from the top of your head to the pulse generator. The incision in your chest skin is then closed with staples, and you are prepared for the recovery room. The system may be left OFF until the next day.

The entire procedure (from the fitting of the frame to the time you go to the recovery room) may take 2-3 hours, and implanting of the stimulator (often done on a second visit) may take 1 hour as an outpatient.



Usually you need to stay in the hospital for only one night after the operation. The next day, a clinician will come to your hospital room, turn the Activa™ System ON, and program the pulse generator. Programming is done with a computer that communicates with the pulse generator through telemetry – a non-invasive, painless way of adjusting the stimulation. The clinician will find the best stimulation setting with the most symptom reduction and the fewest side effects. You also will be given an identification card that states you have a medical device. Be sure to keep this with you at all times!

Tremor doesn’t always return immediately after the procedure. In those cases, the clinician may decide to leave the system OFF until tremor returns.

You may feel some pain or discomfort after leaving the hospital, especially headache or neck pain. This may last several weeks. Dr. Duma can suggest medicine to make you more comfortable. Most patients, however, recover quickly and have minimal discomfort during this time.

Be sure to follow Dr. Duma’s instructions about self-care after the surgery.



  • Notify Dr. Duma of changes in side effects, such as tingling in the limbs or face, speech problems, or changes in symptom control.
  • Notify Dr. Duma if pain, swelling or redness occurs where the devices are implanted.
  • Notify Dr. Duma if you experience dizziness or lightheadedness.
  • Take medicines as prescribed by your doctor. If you have Parkinson’s disease, medicines may help you control symptoms other than tremor.
  • Notify Dr. Duma of persistent headache not relieved by medication.



When you leave the hospital, you will be scheduled for a follow-up visit with Dr. Duma, usually 7 to 14 days after the operation. Dr. Duma or the neurologist will schedule a follow-up visit to initiate the programming of your Activa™ System to adjust stimulation if it has already been started.

After that, you’ll visit once or twice a year for a check-up. The timing of these visits is set by the neurologist per Dr. Duma.



The pulse generator will last about 5 years at typical settings. Its longevity depends on how many hours a day it is used and how it is programmed. Your doctor can give you a better estimate of how long the battery will last once the pulse generator is programmed. To conserve the battery, turn OFF your pulse generator when you feel you don’t need it and at night if you can sleep comfortably without it.

During follow-up visits, your doctor will check the battery. If the battery is depleted, the pulse generator will be replaced. The lead in the brain is not replaced. Replacing the battery takes about an hour and is usually done as an outpatient procedure (you don’t have to stay in the hospital).



The Activa™ System is easy to turn ON or OFF with a control magnet. To turn it ON, grasp the magnet with the flat end away from you, as shown. Press the flat end of the magnet directly over and along the length of the pulse generator. Hold the magnet steady for two seconds. Then move the magnet away to turn the generator ON.

To turn the Activa™ System OFF, simply repeat the procedure. Keep the magnet away from the pulse generator when you are not using it. Also keep it away from credit cards or any other media including video and cassette tapes, computer disks, VCRs, televisions and cameras.

A small instruction card with complete directions and precautions will be given to you after the system is programmed.



You can use household appliances, computers, and cellular phones with the Activa™ System ON.

It is also safe for you to pass through metal detectors in airports. Your pulse generator may set them off, so always carry your identification card. You may want to request assistance to bypass the detectors.

Approach theft control devices in stores with caution. They may cause you to feel uncomfortable stimulation. Walk up to within a few feet of the theft detector. If you don’t feel anything unusual, walk directly through the theft detector area, keeping to the middle between the two pillars.

  • Avoid the following tests and equipment:
  • Magnetic resonance imaging (MRI)
  • Ultrasound, or diathermy (heat ultrasound treatments)
  • Electrocautery
  • Diathermy (deep heat therapy)

Tell your family physician and dentist that you have an implanted device. If you need a special medical test, be sure to tell the clinician about the system. Do not have medical tests without first checking with your doctor.


Christopher Duma, MD, FACS
3900 West Coast Highway, Suite 300
Newport Beach, CA 92663
Phone: 949-989-5894
Fax: 949.642.4833

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