Deep brain stimulation (DBS) was first developed as a treatment for Parkinson's disease to reduce tremor, stiffness, walking problems and uncontrollable movements. In DBS, a pair of electrodes is implanted in the brain and controlled by a generator that is implanted in the chest. Stimulation is continuous and its frequency and level are customized to the individual.

DBS has been studied as a treatment for depression or obsessive compulsive disorder (OCD). Currently, there is a Humanitarian Device Exemption for the use of DBS to treat OCD, but its use in depression remains only on an experimental basis. A review of all 22 published studies testing DBS for depression found that only three of them were of high quality because they not only had a treatment group but also a control group which did not receive DBS. The review found that across the studies, 40-50% of people showed receiving DBS greater than 50% improvement.

Deep brain stimulation (DBS) is a surgical procedure used to treat disabling symptoms of neurological disorders, including dystonia, epilepsy, essential tremor, and Parkinson’s disease. DBS uses a surgically implanted, battery-operated medical device called an implantable pulse generator (IPG)—similar to a heart pacemaker and approximately the size of a stopwatch—to deliver electrical stimulation to specific areas in the brain that control movement, which blocks the abnormal nerve signals that cause symptoms.

The DBS system consists of three components: the lead, the extension, and the IPG. The lead (also called an electrode)—a thin, insulated wire—is inserted through a small opening made in the skull and implanted in the brain. The tip of the electrode is positioned within a specific brain area, depending on the disorder. The extension is an insulated wire that is passed under the skin of the head, neck, and shoulder, connecting the lead to the implantable pulse generator. The IPG (the "battery pack") is usually implanted under the skin near the collarbone. In some cases, it may be implanted lower in the chest or under the skin over the abdomen.

Once the system is in place, and after a period of healing post-surgery, the device is programmed to sets of parameters that work best for each person, over several visits with a neurologist. The therapy works by delivering electrical pulses from the IPG along the extension wire and the lead and into the brain. These pulses change the brain’s electrical activity pattern at the target site to reduce motor symptoms.

What is deep brain stimulation?

Deep brain stimulation (DBS) is a surgical procedure used to treat several disabling neurological symptoms—most commonly the debilitating motor symptoms of Parkinson’s disease (PD), such as tremor, rigidity, stiffness, slowed movement, and walking problems. The procedure is also used to treat essential tremor, dystonia, and focal epilepsy (epilepsy that originates in just one part of the brain). At present, the procedure is used only for individuals whose symptoms cannot be adequately controlled with medications. However, only individuals who improve to some degree after taking medication for Parkinson’s benefit from DBS.

DBS uses a surgically implanted, battery-operated medical device called an implantable pulse generator (IPG)—similar to a heart pacemaker and approximately the size of a stopwatch to—deliver electrical stimulation to specific areas in the brain that control movement, thus blocking the abnormal nerve signals that cause symptoms. The DBS system consists of three components: the lead, the extension, and the IPG. The lead (also called an electrode)—a thin, insulated wire—is inserted through a small opening in the skull and implanted in the brain. The tip of the electrode is positioned within the specific brain area. The extension is an insulated wire that is passed under the skin of the head, neck, and shoulder, connecting the lead to the implantable pulse generator. The IPG (the "battery pack") is the third component and is usually implanted under the skin near the collarbone. In some cases it may be implanted lower in the chest or under the skin over the abdomen.

Before the procedure, a neurosurgeon uses magnetic resonance imaging or computed tomography scanning to identify and locate the exact target within the brain for surgical intervention. Generally, these areas are the thalamus, subthalamic nucleus, and globus pallidus.

Once the system is in place, electrical impulses are sent from the IPG up along the extension wire and the lead and into the brain. These impulses block abnormal electrical signals and alleviate motor symptoms.

Is there any treatment?

DBS uses electrical stimulation to regulate electrical signals in neural circuits to and from identified areas in the brain to improve movement symptoms. Thus, if DBS causes unwanted side effects or newer, more promising treatments develop in the future, the implantable pulse generator can be removed, and the DBS procedure can be halted. Also, stimulation from the IPG is easily adjustable—without further surgery—if the person’s condition changes. Some people describe the pulse generator adjustments as "programming."

DBS involves minimal permanent surgical change to the brain. Although minimally invasive, DBS is a surgical procedure that carries some associated risk. There is a low chance that placement of the stimulator may casue bleeding or infection in the brain. Complications may include bleeding and swelling of brain tissue, headaches, seizures, and temporary pain following the surgery.

What is the prognosis?

Most individuals still need to take medication after undergoing DBS. Many people with Parkinson’s disease experience considerable reduction of their motor symptoms after DBS and are able to reduce their medications. People with dystonia may respond better to DBS than medications in reducing involuntary muscle contractions. DBS targeting the thalamus can improve involuntary movement of the hands, arms, and head that is associated with involuntary tremor. DBS for epilepsy may reduce the number of seizures over time. DBS does not improve cognitive symptoms in PD and indeed may worsen them, so it is not generally used if there are signs of dementia. DBS changes the brain firing pattern but does not slow the progression of the neurodegeneration.

Before the procedure, a neurosurgeon uses noninvasive diagnostic imaging—either magnetic resonance imaging (MRI) or computed tomography (CT) scanning—to identify and locate the exact target in the brain for the surgery. Most surgeons use microelectrode recording—which involves insertion of a tiny wire that monitors the activity of nerve cells—to more specifically identify the precise brain area that will be stimulated.

For treatment of Parkinson’s disease, DBS targets parts of the brain that play a role in the control of movement—the thalamus (which relays and integrates sensory and motor information), subthalamic nucleus (which helps direct movement preparation), or globus pallidus (which helps regulate intended movement). DBS for dystonia specifically targets the globus pallidus interna (involved in the regulation of voluntary movement), while DBS for essential tremor targets the thalamus. Different areas of the brain may be targeted for individuals with epilepsy who don’t respond well to other therapies.

Parkinson’s Disease

DBS is used to treat the most commonly debilitating motor symptoms of Parkinson’s disease (PD) such as rigidity, slowed movement, stiffness, tremor, and problems walking. It is used only for individuals whose symptoms cannot be adequately controlled with medication. However, only people who improve to some degree after taking medication for Parkinson’s benefit from DBS. A variety of conditions may mimic PD but do not respond to medication or DBS.

Most people with PD still need to take medicine after undergoing DBS, but many people experience considerable reduction of their motor symptoms and may be able to reduce their medications. The degree of reduction varies by individual but can lead to a significant improvement in side effects such as dyskinesia (involuntary movements caused by long-term use of levodopa). In some cases, the stimulation itself can suppress dyskinesia without a reduction in medication. DBS does not improve cognitive symptoms in PD and may worsen them. Therefore, it is not generally used if there are signs of dementia. DBS does not slow the progression of the neurodegeneration.

Dystonia

For individuals with dystonia, DBS may reduce the disorder’s characteristic involuntary muscle contractions that cause such symptoms as abnormal posture, repetitive movements, or twisting. DBS has been shown to reduce both the severity of symptoms caused by dystonia and the level of disability they may cause.

People with dystonia may respond better to DBS than medication; therefore, DBS may be an appropriate option for people who have found little or no improvement of symptoms after botulinum toxin injections (often the most effective treatment for some dystonia). DBS may be quicker to reduce symptoms of dystonia that migrates from place to place in the body than dystonia that remains fixed in a single body site, although both groups are likely to see improvement.

Essential Tremor

DBS targeting the thalamus can improve the involuntary movement of the arms, hands, and head that is associated with essential tremor.

Epilepsy

Brain stimulation for focal epilepsy (seizures that originate in just one part of the brain) may reduce the number of seizures over time. It is not a single therapy but is used along with anti-epileptic drugs.

DBS has been approved as add-on therapy for adults with focal epilepsy. Another form of treatment, called neurostimulation, uses an implanted monitor in the skull and tiny wires to give small pulses of stimulation to the brain when electrical activity in the brain looks like a seizure.

DBS involves minimal permanent surgical changes to the brain. If DBS causes unwanted side effects or more promising treatments develop in the future, the IPG can be removed and the DBS procedure can be halted. Also, stimulation from the IPG is easily adjustable—without further surgery—if the person’s condition changes. Some people describe the pulse generator adjustments as "programming."

Although minimally invasive, DBS is a surgical procedure and therefore carries some associated risk. There is a low chance that placement of the stimulator may cause bleeding or infection in the brain. Complications of DBS, such as bleeding and swelling of brain tissue, may result from mechanical stress from the device but are generally reversible. Other complications may include headache, seizures, and temporary pain following surgery. Also, the hardware may erode or break down with use, requiring surgery to replace parts of the device.

Side effects of the stimulation may include numbness or tingling sensations, behavioral changes, as well as balance or speech problems.