What is deep brain stimulation?
Deep brain stimulation is a method of treating seizures that involves the implantation of a device that sends electrical pulses to specific areas of the brain where the seizures are occurring.
How does deep brain stimulation prevent seizures from occurring?
When the brain is functioning normally, nerve cells carry chemical and electrical messages to and from parts of the body in a normal, orderly fashion. During a seizure, the nerve cells misfire, causing a burst of uncontrolled electrical activity in a particular area of the brain. This electrical storm causes a seizure. The electrical pulses from the deep brain stimulation system block signals from the nerve cells that trigger a seizure. The goal of deep brain stimulation is to reduce the number and severity of seizures.
Who is a candidate for deep brain stimulation therapy for epilepsy?
To be a candidate for deep brain stimulation, you must:
- Be at least 18 years of age
- Have partial-onset seizures (with or without generalization)
- Have tried three or more anti-seizure medications and have not experienced a reduction in seizures
- Have had an average of over six seizures per month for the last 3 months (with no more than 30 days between seizures)
How does deep brain stimulation system work?
The deep brain stimulation system consists of four parts:
- Leads (insulated wires) that end in electrodes that are implanted in the brain
- A small pacemaker-like device, called a neurostimulator, that generates the electrical pulses
- Leads that carry electrical pulses from the device and are attached to the leads implanted in the brain
- Hand-held programmer device that adjusts the device’s signals
Your neurosurgeon will implant the deep brain stimulation system in two stages.
First, a small hole is made in the skull. The electrodes that are attached to the leads are passed through this hole and surgically implanted in the areas of the brain identified as the site(s) of the seizures. In a separate operation approximately 1 week later, the battery-powered neurostimulator device is implanted just under the skin in your upper chest area below your collarbone. Leads run under your skin from the device up the neck, behind the ears and into the head and are attached to the leads already positioned in the brain. The device sends electric pulses to the brain through these leads.
You will return for an office visit about 10 to 14 days after the implant surgery. The implanted neurostimulator will be programmed using a hand-held device. The programmer adjusts the neurostimulator’s settings, can check the battery level, and can turn the device on and off. Several follow-up programming visits will be needed to fine-tune the strength of the electrical pulses and how often pulses are sent to the brain to best control seizures and prevent side effects.
Continued follow-up visits will be needed to check how well the deep brain stimulation system is working.
How does the neurosurgeon know where to place the electrodes in my brain?
Your surgical team will use MRI and CT scans to map your brain. They will create 3-D images to locate the exact areas to position the electrodes. More specifically, the electrodes are placed in the anterior nucleus of the thalamus on each side of the brain. This area of the brain is involved in the spreading of seizures. During surgery, an electroencephalograph (EEG) may be used to see how you respond and to make sure the electrodes have been placed correctly.
Will I be awake during the deep brain stimulation surgery?
You may or may not be awake while the electrodes are being positioned in your brain. Your brain does not feel pain. You and your doctor will decide the best approach for you. You will be put under general anesthesia during the implantation of the neurostimulator under your skin on your chest.
How long is the typical hospital stay?
The typical hospital stay is 1 to 2 days for the first stage of the procedure (implanting the electrodes). Usually, no overnight hospital stay is required after implanting the neurostimulator in the chest.
Risks / Benefits
What are the benefits of deep brain stimulation?
Unlike epilepsy surgery, no brain tissue is removed or separated.
The effects are reversible. No permanent brain damage results from use of the deep brain stimulation system. If the deep brain stimulation does not decrease the number of seizures or is otherwise not tolerated by the patient, the system can be turned off and the neurostimulator device and leads can be removed.
The pulse stimulation level can be adjusted to improve seizure control and reduce side effects if needed.
What are the risks of the deep brain stimulation therapy?
Any surgery carries risks, including the risks from anesthesia. The risks of deep brain stimulation surgery include but are not limited to coma, bleeding in the brain (hemorrhage), stroke, and infection.
In addition to these surgical risks, other risks may arise from the device itself. The device may fail due to a mechanical or electrical problem, leads and/or the extension connector may move or not be placed within the target area, parts may wear through the skin, the implanted device may become infected and hardware erosion can occur.
According to the 110-patient trial upon which the device was approved by the Food and Drug Administration (FDA), the top complications were:
- Device implant site pain in 31 percent of patients
- Paresthesia (sensation of burning, prickling, tingling or numbness in parts of the body) in 24 percent of patients
- Leads not within the target and requiring replacement in 8 percent
- Implant site infection in 11 percent
Deep brain stimulation may also cause or worsen existing memory problems and depression.
Deep brain stimulation may not help a small number of patients. In approximately eight percent of patients, there can be a 50 percent increase in seizures over long-term follow-up.
Are there any side effects that occur during the programming stage when the neurostimulator is first turned on?
Yes, turning on the neurostimulator and beginning to send electrical pulses to the brain can cause some temporary side effects. These may include:
- Sensation of numbness and tingling
- Tightening on muscles in face or arm
- Balance problems
- Speech problems
Recovery and Outlook
How successful is deep brain stimulation therapy?
According to the results of the pivotal 110-patient study, deep brain stimulation was able to reduce seizure frequency and the results improved over time.
In this study, patients were implanted with the deep brain stimulation device and followed for 7 years. (Patients met the same study entry criteria as listed under the question, “who is a candidate for deep brain stimulation therapy.”) The results were as follows:
- After 7 years, patients experienced a median 75 percent reduction in seizure frequency from baseline.
- After 7 years, 20 patients (18 percent) reported a seizure-free interval of at least 6 months.
- The percentage of patients who achieved a 50 percent or greater reduction in seizures increased from 43 percent at 1 year to 74 percent at 7 years.
In addition to these clinical results, after 7 years:
- 43 percent of patients said their quality of life had improved
- 84 percent reported that they were satisfied or greatly satisfied with the results
Will I still need to take anti-seizure medications?
Yes, you will still need to take anti-seizure medications. You and your doctor will discuss your medications and any change in dosage.
When to Call the Doctor
Call your doctor:
- If you have any new symptoms or changes in the pattern of your seizures
Never hesitate to call your doctor if you have any questions or concerns about the deep brain stimulator system and your health.
Does having a deep brain stimulation system interfere with having certain medical screening tests or diagnostic procedures?
Patients with the deep brain stimulating system should not have the following procedures:
- Magnetic resonance imaging (MRI) except under special circumstances (see below)
- Transcranial magnetic stimulation (TMS)
- Diathermy procedures
The energy generated from these procedures can be sent through the neurostimulator – even if turned off – and can cause burns in the skin near the electrodes or leads or damage to brain tissue.
Talk to your doctor about these risks. It might be possible to have a brain scan with MRI if a specific strength setting is used. X-rays and CT scans do not affect the neurostimulator. However, it is recommended that the device be turned off during these procedures.
Make sure all healthcare professionals know you have a deep brain stimulator system before undergoing any scanning procedures.
How long does the battery in the neurostimulator device last?
Batteries can last 3 to 5 years in non-rechargeable devices and up to 9 years in rechargeable battery devices. However, these times may vary significantly. A simple battery replacement surgery is needed to replace the battery. Rechargeable battery devices can be charged daily (for about 30 minutes) or every 10 to 14 days (for about 4 hours). Your doctor will discuss how often you should recharge your battery based on your therapy settings.
What else do I need to know about my deep brain stimulator system?
- You will take home the hand-held programmer device. This device allows you to turn the neurostimulator on and off, check the battery level, and adjust the strength of the neurostimulator’s signal by selecting one of the programs your doctor has preprogrammed.
- Carry your “Implanted Device Identification” card with you if traveling by plane. The neurostimulator will be detected by airport security scanning machines.
- Other devices – cell phones, microwaves, security systems, anti-theft devices – do not interfere with the function of the deep brain stimulator system.