Deep Brain
Stimulation Program

DBS improves tremor and other involuntary movements such as dyskinesias and dystonic muscle contractions. In Parkinson's disease it also improves slowness and stiffness seen with motor fluctuations.

The effects of DBS are most prominent on the side of the body opposite to the side of stimulation. This means that for patients who have bothersome symptoms primarily on one side, one brain electrode is implanted. For example, to treat tremor in dominant hand.

For patients who have symptoms on both sides of the body (most patients with Parkinson's disease and dystonia), two brain electrodes (on one each side) are implanted.

Electrodes can also be implanted in a staged fashion meaning a second electrode can be added later on if necessary.

In experimental studies, DBS can also be used as a treatment for major depression, Tourette syndrome, chronic pain and several other conditions. In those cases an electrode is placed in a different brain target than for movement disorders.

Brain hemorrhage (a bleed or stroke) is the most serious potential risk occurring in approximately 1% of DBS patients. Most who experience a bleed, do not have permanent problems and only experience brief symptoms, if any. However, in more severe cases, hemorrhage can cause permanent weakness, speech difficulty, other symptoms of a stroke and even death.

Brain swelling, seizures and confusion can also happen during or shortly after the surgery, though these issues typically resolve while the patient is still in the hospital. Infection of the pulse generator or brain leads is more common, occurring in approximately 5% of DBS patients. This can initially be treated by oral antibiotics, but sometimes requires removal of the DBS equipment and IV antibiotics. The risk of infection is the highest in the first 3 months after the surgery, but it can happen at any time, including after battery replacements.

Stimulation itself may cause various side effects affecting motor function, speech, balance, sensory, visual, mood and cognitive systems. Adjustment of stimulation settings typically resolves or minimizes these problems.

Procedures such as gamma knife and focused ultrasound are sometimes advertised as 'non-invasive' because the high energy beams used for these methods pass through the skull without the need for drilling. However, these procedures create permanent lesions or holes in the brain itself, making them far from non-invasive.

These alternatives to DBS may be appropriate for certain patients so it is important to discuss all options.

Other methods that are less invasive — meaning they do not require incisions or lesions such as transcranial magnetic stimulation (TMS), transcranial current stimulation (tCS) and peripheral stimulation — have not yet shown to provide significant long-term benefits for movement disorders.

It’s important to remember that any intervention that directs stimulation or energy toward the body has the ability to affect its structure and function, both in desirable and undesirable ways.

Other advanced therapies for Parkinson's disease that do not involve brain surgery include levodopa gel intestinal infusion (such as Duopa pump). Delivery systems (such as pumps and patches) for continuous infusion of levodopa and dopamine agonists (such as apomorphine) are currently under development.

There are several brain regions (or nuclei) that are involved in motor function. The specific nucleus targeted during surgery will depend on a patient's specific symptoms.

For patients with essential and other forms of tremor, ventral intermediate nucleus of thalamus (ViM) is most commonly implanted.

For patients with dystonia, globus pallidus internus (GPi) is the most common target, but patients with dystonia who mainly have tremor may also benefit from ViM DBS.

With Parkinson's disease, the subthalamic nucleus (STN) and GPi are the most common targets, but ViM can also be used in certain cases.

STN and GPi stimulation have similar motor outcomes. STN stimulation, however, generally allows greater medication reduction, while GPi may be better for improving dyskinesias and dystonia. GPi may have fewer cognitive and mood side effects in individuals with already impaired cognition and/or mood disorders.

The optimal target is decided by a multidisciplinary team conference after reviewing results of patient's screening tests.

Horizontal (axial) cross-section of brain MRI showing DBS electrodes in subthalamic nucleus

Patients typically have two small bumps in the hairline above the forehead. For those who don't have hair in the front, these can be visible. The extension cable that runs from top of the head to the battery usually isn’t visible, but can be felt underneath the skin. The battery (pulse generator), similar to a heart pacemaker, is most often implanted in the upper chest underneath the clavicle, but it can also be placed in the abdomen. The battery will create a small visible bulge, which can be more prominent in thin individuals.

DBS pacemaker is typically implanted in the upper chest, below the clavicle.

<p>Lesioning surgery was the main surgical treatment for movement disorders before DBS was developed. It involves creating a small lesion or hole in the same motor area of the brain where DBS would be placed, providing similar clinical benefits. Lesioning can be done using a wire probe temporarily inserted in the brain, called radiofrequency (RF) ablation, or without opening the skull by using gamma knife or focused ultrasound technology.

<p>In some cases, a patient may decide to undergo a lesioning surgery instead of implanting the DBS system. The advantage of lesioning surgery over DBS is that it requires no hardware to be implanted, and no programming or battery replacements. The disadvantage is that the lesion, if too small, will not adequately control the movement disorder, and another surgery may be necessary. If the lesion is too large, it may cause permanent side effects such as weakness, numbness and difficulty speaking. Lesions are typically performed only on one side of the brain, so for patients who have symptoms on both sides of the body, only one side would be treated. In those cases, DBS can be placed on the other side.

Awake procedure:

Brain lead implantation has traditionally been done under light or moderate sedation in the operating room. That means the patient is asleep for any painful parts, such as cutting skin and drilling into skull, then awakened for brain activity recordings and test stimulation.

During brain activity recordings, the surgical team will move the awake patient's arm and leg to verify the electrode is in the motor area. The patient may be asked to make some simple movements such as opening and closing their hand. After the target is located, the DBS lead is implanted.

During the test stimulation, the patient will be asked to report any side effects such as tingling, muscle contractions, muscle pulling or difficulty speaking. The patient is monitored for side effects and symptom improvement with the stimulation. The surgery team uses several different methods to verify correct electrode placement.

The entire procedure lasts about 3-4 hours per side with awake period being about 1-2 hours.

Patients with Parkinson's disease or essential tremor should NOT take their PD or tremor medications on the day of surgery so that motor symptoms are visible for testing.

Asleep procedure:

More recently, a new way of implanting the DBS electrode has been utilized at Emory whereby the patient is under general anesthesia for the entire procedure. This is because the entire procedure is done within the MRI scanner, which is sterilized like the operating room. There is no brain activity recording or test stimulation because the surgeon is able to use continuous image guidance to place the electrode.

The length of this procedure is similar to awake implantation.

Studies have shown that both methods are similarly accurate when performed by an experienced team. However, the 'asleep' method may be more appropriate for children and other patients who may not tolerate lying awake on the operating table (for example due to dystonia or chronic neck or back pain) or those who experience severe anxiety when off medications. And the ‘awake’ procedure must be used for patients with essential tremor, because test stimulation for tremor is necessary for optimal placement.

Implantable pulse generator (IPG or battery) is usually placed under general anesthesia, typically 2-weeks following brain lead placement.

As of early 2019, there are 3 FDA-approved manufacturers of DBS equipment in the United States; Medtronic, Abbott and Boston Scientific. All three DBS systems are fundamentally the same since they all use a thin electrode wire to send continuous electrical pulses into implanted brain areas. The differences are simply in each system’s features.

Medtronic, who developed the first DBS system in the late 1980s and manufactures the most widely implanted system, offers both rechargeable and non-rechargeable batteries.

Abbott (formerly St. Jude) was FDA-approved for U.S. market in 2017. They provide a segmented brain lead which means that current can be steered toward a preferred direction (for example away from areas causing side effects). They currently offer only non-rechargeable batteries.

Boston Scientific was FDA-approved for U.S. market in 2018. They provide a lead where the current can be fractionated across 8 contacts so stimulation volume can be shaped more precisely, including a segmented lead option They offer rechargeable and non-rechargeable batteries.

Available devices and features (including compatibility with MRI) may change, so check with your DBS provider for the latest update.

For 'awake' surgery in the operating room there are two ways to steer the electrode into the target: using a frame or frameless. If using a frame, which is a metal box or cage, surgeons will screw it into the patient's skull on the day of the surgery using local anesthesia. The frame is then fixed to the operating bed to hold the person's head in place. While this is the traditional methods, it can create some discomfort during surgery since the patient is unable to move their head or neck.

Frameless surgery involves placing screws (fiducial markers) into the patient’s skull 1-2 weeks before the surgery below the skin so they are barely visible. A custom aiming device is then built for each individual patient. The aiming device is attached to the skull screws during surgery to guide the electrode. In this case, patients can move their head during surgery resulting in more comfort. However, patients can have some discomfort in days preceding the surgery due to the screws being in place.

In both cases, only a small patch of hair is shaved on the day of surgery. 

Traditional surgical frame (pictured left) is attached to the head on the day of surgery. Frameless surgery (pictured right) consists of a custom aiming device that is attached to the head on the day of surgery, and anchoring screws are placed several days before. 

Patients can choose either a non-rechargeable battery that needs to be replaced every 3-5 years or a rechargeable battery that lasts 15 years, but needs to be charged once a week for 2-3 hours or 20 minutes daily.

Charging is done by placing a wireless charger over the area where the battery is implanted (typically upper chest, below the clavicle). For patients who use up their non-rechargeable battery quickly (less than 2 years), it can be switched to a rechargeable one at the next battery replacement (and vice versa for patients who have difficulty with charging).

Patients who will have two brain leads placed can choose to have one battery to power both leads (dual channel), or two batteries to power one lead on each side (single channel).

The advantage of the dual channel is that there is only one battery to replace or charge.

The advantage of two single channel batteries is that if there is an infection causing the need for a battery and lead to be removed, the patient will still receive partial therapy through the other side (until infected side heals and can be re-implanted). Since single channel batteries are slightly smaller, they may be more appropriate for thin individuals.

A patient’s mental (cognitive) abilities can be worsened by the surgery. This is generally temporary, but in rare cases may be permanent. It is widely believed that patients who already have problems with memory and thinking are at greatest risk for deterioration after surgery. If results of the neurocognitive tests are below normal, the risk of mental worsening rises, and the chances of a good physical outcome may fall. In general, older patients have a greater risk than younger patients for mental deterioration after surgery. Because of this potential risk, all patients undergo detailed neurocognitive testing as part of the DBS screening process.

Patients who need an MRI after DBS is placed, can usually undergo low-energy MRI available at specialized DBS centers. This may differ by DBS manufacturer so it is important to check before any MRI scans are administered. DBS will need to be turned off for the MRI scan, so it is important for patients to bring their home DBS programmer to the scan.

In addition to MRI, it is also necessary to turn off DBS for some routine medical testing such as EKG, EMG, and EEG.

Medical tests and screenings such as CT scans, X-rays and ultrasounds can be performed safely without turning off DBS device.

Patients should never undergo a procedure called "diathermy" offered by some dentists for the treatment of tooth disorders.

If undergoing another surgical procedure, and electrocautery is performed, the grounding pad should not be placed near the DBS.

If surgery is near DBS hardware (for example, a skin cancer on the scalp), your DBS surgeon should be notified prior to undergoing the procedure. Please be sure to keep every health care professional informed of your implanted device.