Deep Brain Stimulation
What is deep brain stimulation?
Deep brain stimulation (DBS) is a neurosurgical procedure that uses implanted electrodes and electrical stimulation to treat movement disorders associated with Parkinson’s disease (PD), essential tremor, dystonia and other neurological conditions.
Doctors may use DBS for movement disorders or neuropsychiatric conditions when medications have become less effective or if their side effects interfere with a person’s daily activities.
- Surgeons implant one or more small wires (called leads or electrodes) in the brain during a surgical procedure.
- The leads receive mild electrical stimulation from a small pulse generator implanted in the chest.
- Proper patient selection, precise placement of the electrodes and adjustment of the pulse generator are essential for successful DBS surgery.
- DBS does not fully resolve the symptoms of PD or other conditions, but it can decrease a patient’s need for medications and improve quality of life.
How does deep brain stimulation work?
Movement-related symptoms of Parkinson’s disease and other neurological conditions are caused by disorganized electrical signals in the areas of the brain that control movement. When successful, DBS interrupts the irregular signals that cause tremors and other movement symptoms.
After a series of tests that determines the optimal placement, neurosurgeons implant one or more wires, called “leads,” inside the brain. The leads are connected with an insulated wire extension to a very small neurostimulator (electrical generator) implanted under the person’s collarbone, similar to a heart pacemaker. Continuous pulses of electric current from the neurostimulator pass through the leads and into the brain.
A few weeks after the neurostimulator has been in place, the doctor programs it to deliver an electrical signal. This programming process may take more than one visit over a period of weeks or months to ensure the current is properly adjusted and providing effective results. In adjusting the device, the doctor seeks an optimal balance between improving symptom control and limiting side effects.
Who is a candidate for deep brain stimulation?
DBS is more than just a surgical procedure. It involves a series of evaluations, procedures, and consultations before and after the actual operation, so people interested in being treated with DBS should be prepared to commit time to the process.
For example, those who do not live close to a medical center that offers DBS surgery may need to spend significant time traveling back and forth to appointments.
The procedure, as well as the pre-operative evaluation and post-operative follow-up, can be expensive depending on the person’s insurance coverage. DBS surgery is an FDA-approved treatment for Parkinson’s disease, and Medicare and most private insurers cover the procedure, but the extent of coverage will depend on each person’s individual policy.
Prospective patients should have realistic expectations about DBS results. Although DBS can improve movement symptoms of Parkinson’s disease and greatly improve quality of life in properly selected patients, it is not likely to return anyone to perfect health.
Three types of PD patients typically benefit from DBS:
Patients with uncontrollable tremor for whom medications have not been effective.
Patients with symptoms that respond well to medications but who, when the drugs wear off, experience severe motor fluctuations and dyskinesias, despite medication adjustments.
Patients whose movement symptoms might respond to higher or more frequent medication doses, but who are limited to do so because of side effects.
Essential tremor is the most common movement disorder, and DBS can be an effective therapy, particularly in severe cases where the shaking can be disabling, limiting everyday tasks such as dressing, shaving, eating or drinking. Since tremor is the only symptom in essential tremor, DBS can improve life for people with the condition and help them function normally.
Dystonia is a relatively uncommon movement disorder, but its symptoms — abnormal postures and twisting movements — can respond to DBS when medications fail to provide adequate relief. An individual’s response to DBS depends on the underlying cause of the dystonia — genetic, drug-induced, or other factor. If the cause isn’t known, the doctor is likely to perform more tests as part of the DBS workup.
Some recent studies have suggested that people living with depression, obsessive-compulsive disorder (OCD) or Tourette disorder may benefit from DBS surgery. More research is needed to determine if DBS is effective in treating psychiatric disorders and if any benefits outweigh risks and side effects.
Choosing Deep Brain Stimulation Surgery
DBS surgery is not recommended for all people living with Parkinson’s disease or other movement disorders. Talking with a neurologist who specializes in movement disorders can determine if an individual is a good candidate for DBS.
Why a Doctor May (or May Not) Choose Deep Brain Stimulation
According to the National Parkinson Foundation, the ideal Parkinson’s disease candidate for DBS surgery has:
PD symptoms that interfere with activities of daily living.
Fluctuations in mobility due to PD medications (“on-off” phenomenon) with or without dyskinesia (involuntary jerking motions, especially in the arms and head).
Continued good response to PD medications, even if the medication effects may wear off sooner than they have in the past.
A history of several different combinations of PD medications while under the supervision of a neurologist specializing in movement disorders.
These factors* may make a person a less than ideal candidate for DBS surgery:
Difficulty with balance, walking, or “freezing” as the main disabling symptom.
A primary symptom of speech difficulty.
Continuous confusion and problems with memory and thinking.
A psychiatric condition such as depression or anxiety that has not improved or stabilized with other treatment.
Another condition that increases the risk for surgery complications.
*Some of these factors may be treatable. Having one or more does not disqualify a person for future DBS surgery, but the doctor may recommend more aggressive therapy focused on these issues before surgery takes place.
Testing Before Deep Brain Stimulation
For patients with Parkinson’s disease, the doctor must confirm that the PD is levodopa-responsive and determine which symptoms are most likely to respond to DBS and discuss these with the patient.
To accomplish these two objectives, the movement disorders neurologist will examine the patient in the absence of his or her PD medications, then again after having taken them. Seeing the effect of PD medications on the movement and non-motor symptoms helps the physician and patient identify good target symptoms for DBS.
A cognitive assessment can help determine a person’s ability to participate in the procedure, which involves providing feedback to the doctor during surgery and throughout the neurostimulator adjustment process. This assessment also informs the team of the risk of having worsened confusion or cognitive problems following the procedure.
Some hospitals also perform an occupational therapy review or speech, language and swallowing assessment. A psychiatrist may examine the person to determine if a condition such as depression or anxiety requires treatment before the DBS procedure.
The Deep Brain Stimulation Procedure
In some cases the surgeon will insert both the lead and the neurostimulator; in other instances the two surgeries may be performed separately, with the neurostimulator implanted days or weeks after the lead is placed.
Stereotactic DBS vs. Interventional Image-Guided DBS
Stereotactic DBS surgery requires the patient to be off their medication. During the procedure, a frame stabilizes the head and provides coordinates to help the surgeons guide the lead to the correct location in the brain. The patient gets local anesthesia (numbing medicine) to keep them comfortable throughout each step along with a mild sedative to help them relax.
During image-guided DBS surgery, such as with interventional MRI (iMRI) or CT scan, the patient is often asleep under general anesthesia while the surgeon uses images of the brain to guide the lead to its target.
Some advanced centers offer both the stereotactic and iMRI-guided options for DBS surgery. In this case, the doctor and patient will discuss which procedure is better based on a number of factors.
For instance, the doctor may recommend an image-guided procedure for children, patients who have extreme symptoms, those who are especially anxious or fearful or those whose leads are going into certain parts of the brain.
Generally, DBS surgery follows this process:
The person removes clothing, jewelry or other objects that may interfere with the procedure.
After shaving a small amount of hair behind the hairline, the surgery team injects local anesthesia (numbing medication) into the scalp for placement of the head frame.
The head frame (or “halo”) will be attached to the skull with screws, and remains in place during the entire procedure to keep the head in the proper position.
Next, the team uses CT or MRI to pinpoint the target site in the brain where the lead will go.
After more numbing medication, the neurosurgeon drills a small hole in the skull to insert the lead.
The team records the process as the lead moves through the brain tissue to ensure accurate placement of the lead. The person may be asked to move the face, arm or leg at certain times while the recordings are being taken.
Once the lead is in position it is attached to an external neurostimulator. Electrical stimulation administered through the lead for a short period helps the doctors see if symptoms improve or if side effects (such as muscle contractions or visual phenomena) appear.
An extension wire is attached to the lead and placed under the scalp, connecting the lead to the neurostimulator.
The opening in the skull is closed with a plastic cap and stitches.
Microelectrode recording (MER) uses electrical current (5-100uA) at a very high frequency (300Hz) to precisely identify the surgical site for implantation of the deep brain stimulator (DBS). This technique was pioneered at Johns Hopkins, and is endorsed by the Task Force on Surgery for Parkinson's Disease of the American Academy of Neurology Therapeutic and Technology Assessment Committee.
Because the structure of each person’s brain varies, the information obtained from MER gives an accurate target for final DBS placement. The microelectrode allows the surgical team to visualize and hear the neuronal activity from different areas of the brain to identify specific structures based on the unique patterns of neuronal activity. The patient needs to be awake (not under general anesthesia) in order for MER to yield high quality information.
Placement of the Neurostimulator
This procedure takes place under general anesthesia so that the person is asleep. The surgical team inserts the neurostimulator under the outer layers of skin, usually just under the collarbone, but sometimes in the chest or abdomen. The extension wire from the lead is attached to the neurostimulator.
After Deep Brain Stimulation Surgery
In the Hospital
In general, the hospital stay after DBS surgery is 24 hours but it may be longer depending on how quickly the patient recovers and is ready to go home. The doctor will visit, ensure the person is ready to leave and provide instructions for home care.
At home, it is important to keep the incisions clean and dry. The doctor will provide the patient with specifics on how to bathe while the surgical site heals. If there are stitches, these will be removed during a follow-up office visit. Adhesive strips, if present, should be kept dry and generally will fall off within a few days.
The patient will be given a magnet that can be used to turn the neurostimulator on or off under conditions prescribed by their doctor.
Programming the Neurostimulator
After the DBS lead(s) and neurostimulator are in place, the patient will return to the doctor to have the neurostimulator programmed for optimal electrical stimulation. Programming generally begins a few weeks after the DBS procedure, although some doctors activate the neurostimulator before the patient is discharged from the hospital after surgery.
Programming takes time, and may require several appointments for adjusting the neurostimulator settings. At the same time, the doctors will address the patient’s medications and dosages so that the medicines work effectively with the electrical stimulation to control symptoms.
Even after adjustment, the patient will need to return periodically for checkups. The doctor determines the frequency of follow-up appointments depending on each patient’s particular situation.
The neurostimulator runs on a battery that generally lasts three to five years. When the battery begins to wear out, doctors can replace the neurostimulator in an outpatient procedure. There are also rechargeable neurostimulators that last longer, but require regular recharging.
Long-Term Effects of Deep Brain Stimulation
DBS surgery can help people with Parkinson’s disease improve their symptoms of tremors, stiffness, slowness, and dyskinesias. It can also decrease the dose of medication the patient needs to manage their PD.
Researchers who have followed patients after DBS have found that many patients continue to have improvements in their symptoms for several years after the procedure and are able to eat, use the bathroom and feed themselves. Patients being treated with DBS for movement disorders may or may not experience changes in memory, thinking or mood.
At this time, Parkinson’s disease is a progressive disorder that cannot be halted entirely. Even while DBS continues to work on tremor, stiffness and slowness, other symptoms such as poor posture, speech impairment, gait freezing, balance problems and dementia may still appear.
Special Precautions After Deep Brain Stimulation
In general, people who have had DBS surgery should:
Always carry an ID card that states they have a DBS neurostimulator. In addition, they may want to wear a medical identification bracelet indicating this information.
People with a neurostimulator should let airport security screeners know before going through the airport detectors. Many airport detectors are safe for pacemakers, but the small amount of metal in the neurostimulator may set off the alarm. Patients selected for additional screening by hand-held detector devices should politely remind the screeners that the detector wand should not be held over the neurostimulator for longer than a few seconds, since these devices contain magnets that may affect the function or programming of the neurostimulator.
Patients with leads and neurostimulators may not have certain MRI procedures. Patients should always check with their physician before any type of MRI, though DBS can be compatible with MRI under certain circumstances. They should avoid places with large magnetic fields, such as power generators and automobile junkyards that use large magnets.
Patients who have had DBS surgery should avoid using heat in physical therapy to treat muscles.
They should also avoid high-voltage or radar machinery, such as radio or television transmitters, electric arc welders, high-tension wires, radar installations or smelting furnaces.
If patients are scheduled for a surgical procedure, they should tell their surgeon that they have a neurostimulator well in advance. It is important to ask for advice on special precautions before and during the surgery since equipment such as the electrocautery device that controls bleeding may interfere with the neurostimulator.
When participating in a physical, recreational or sporting activity, patients should protect the neurostimulator area from trauma. A blow to the chest near the pacemaker can affect its functioning and warrants a trip to the doctor.