What is deep brain stimulation

Deep brain stimulation (DBS) is a surgical procedure that implant electrodes within certain areas of your brain used to treat disabling symptoms of neurological disorders, including dystonia, epilepsy, essential tremor, and Parkinson’s disease. Deep brain stimulation uses a surgically implanted, battery-operated medical device called an implantable pulse generator, 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 impulses that cause symptoms. The electrical stimulation can affect certain cells and chemicals within the brain.

The amount of stimulation in deep brain stimulation is controlled by the implantable pulse generator placed under the skin in your upper chest. A wire that travels under your skin connects this device to the electrodes in your brain.

The deep brain stimulation system consists of three components: the lead, the extension, and the implantable pulse generator. The lead (also called an electrode) is a thin, insulated wire that 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 implantable pulse generator (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 implantable pulse generator 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.

Deep brain stimulation is approved by the US Food and Drug Administration (FDA) to treat a number of conditions, such as:

• Dystonia
• Epilepsy
• Essential tremor
• Obsessive-compulsive disorder
• Parkinson’s disease

Deep brain stimulation is also being studied as a potential treatment for:

• Addiction
• Chronic pain
• Cluster headache
• Dementia
• Depression (major)
• Huntington’s disease
• Multiple sclerosis
• Stroke recovery
• Tourette syndrome
• Traumatic brain injury

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

Although minimally invasive, deep brain stimulation 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 deep brain stimulation, 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.

Deep brain stimulation for dystonia

For individuals with dystonia, deep brain stimulation may reduce the disorder’s characteristic involuntary muscle contractions that cause such symptoms as abnormal posture, repetitive movements, or twisting. deep brain stimulation 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 deep brain stimulation than medication; therefore, deep brain stimulation 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). Deep brain stimulation 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.

Deep brain stimulation for dystonia specifically targets the globus pallidus interna (involved in the regulation of voluntary movement), while deep brain stimulation for essential tremor targets the thalamus.

Deep brain stimulation for essential tremor

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

Deep brain stimulation for 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.

Deep brain stimulation 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.

Deep brain stimulation for Parkinson’s disease

Deep brain stimulation is used to treat the most commonly debilitating motor symptoms of Parkinson’s disease 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 disease benefit from deep brain stimulation. A variety of conditions may mimic Parkinson’s disease but do not respond to medication or deep brain stimulation.

Deep brain stimulation 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).

Deep brain stimulation in Parkinson’s disease success rate

Most people with Parkinson’s disease still need to take medicine after undergoing deep brain stimulation, 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. Deep brain stimulation does not improve cognitive symptoms in Parkinson’s disease and may worsen them. Therefore, it is not generally used if there are signs of dementia. deep brain stimulation does not slow the progression of the neurodegeneration.

In a 2015 study by Timmermann et al. ¹ found participants’ movement symptoms had improved remarkably by an average by 62 percent in six months. Participants experienced 3.5 hours a day more of “on” time at the six-month evaluation compared to baseline. On average, participants also reduced their use of anti-parkinsonian drugs by half. A year after deep brain stimulation surgery, study participants maintained these improvements and reported an improved quality of life ¹.

New results published in 2018 issue of Neurology ² suggest that deep brain stimulation may slow the progression of tremor if performed early on in the Parkinson’s disease course. This data implies that deep brain stimulation may not just treat the symptoms of PD, but act to alter the course of the disease, by slowing down the progression of tremor.

Which parts of the brain are targeted using deep brain stimulation for movement disorders?

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, deep brain stimulation 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). Deep brain stimulation for dystonia specifically targets the globus pallidus interna (involved in the regulation of voluntary movement), while deep brain stimulation 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.

Deep brain stimulation surgery

Deep brain stimulation surgery preparation

First, weigh the pros and cons

Deep brain stimulation is a serious and potentially risky procedure. Even if you might be eligible for deep brain stimulation, you and your doctors must carefully weigh the risks and potential benefits of the procedure.

Next, preparing for the deep brain stimulation surgery

Before surgery, you’ll need medical tests to make sure that deep brain stimulation is a safe and appropriate option for you. You’ll also need brain-imaging studies, such as an MRI, before the surgery, to map the areas of your brain to implant the electrodes.

During the deep brain stimulation surgery

In general, here’s how surgery for deep brain stimulation works:

Brain surgery

For the brain surgery portion, your care team fits you with a special head frame to keep your head still during the procedure (stereotactic head frame). Then, team members use magnetic resonance imaging (MRI) to map your brain and identify the area in your brain where they’ll place the electrodes.

Surgery can be done under general anesthesia so that you’ll be unconscious. Or the procedure can be done with you awake and alert. If you’re awake for surgery, you’ll be given a local anesthetic to numb your scalp before the procedure, but you won’t need an anesthetic in your brain itself because the brain has no pain receptors.

Your surgeon implants a thin wire lead with a number of contacts (electrodes) at the tips into a specific area of your brain. Or one lead is implanted into each side of the brain (for a total of two leads). A wire runs under your skin to a pulse generator (neurostimulator) implanted near your collarbone.

During surgery, both the neurologist and surgeon carefully monitor your brain to help ensure correct electrode placement.

Chest wall surgery

During the second portion of the surgery, the surgeon implants the part of the device that contains the batteries (pulse generator) under the skin in your chest, near your collarbone.

General anesthesia is used during this procedure. Wires from the brain electrodes are placed under your skin and guided down to the battery-operated pulse generator.

The generator is programmed to send continuous electrical pulses to your brain. You control the generator, and you can turn it on or off using a special remote control.

After the deep brain stimulation surgery

A few weeks after surgery, the pulse generator in your chest is activated in your doctor’s office. The doctor can easily program your pulse generator from outside your body using a special remote control. The amount of stimulation is customized to your condition, and may take as long as four to six months to find the optimal setting.

Stimulation may be constant, 24 hours a day, or your doctor may advise you to turn your pulse generator off at night and back on in the morning, depending on your condition. You can turn stimulation on and off with a special remote control that you’ll take home with you. In some cases, your doctor may program the pulse generator to let you make minor adjustments at home.

The battery life of your generator varies with usage and settings. When the battery needs to be replaced, your surgeon will replace the generator during an outpatient procedure.

Deep brain stimulation results

Deep brain stimulation won’t cure your disease, but it may help lessen your symptoms. If deep brain stimulation works, your symptoms will improve significantly, but they usually don’t go away completely. In some cases, medications may still be needed for certain conditions.

Deep brain stimulation isn’t successful for everyone. There are a number of variables involved in the success of deep brain stimulation. It’s important to talk with your doctor before surgery about what type of improvement you can expect for your condition.

Deep brain stimulation side effects

Although deep brain stimulation is minimally invasive and considered safe, any type of surgery has the risk of complications. Also, the brain stimulation itself can cause side effects.

Surgery risks

Deep brain stimulation involves creating small holes in the skull to implant the electrodes, and surgery to implant the device that contains the batteries under the skin in the chest. Complications of surgery may include:

• Misplacement of lead
• Bleeding in the brain
• Stroke
• Infection
• Breathing problems
• Nausea
• Heart problems
• Seizure

Possible side effects after surgery

Side effects associated with deep brain stimulation may include:

• Seizure
• Infection
• Headache
• Confusion
• Difficulty concentrating
• Stroke
• Hardware complications, such as an eroded lead wire
• Temporary pain and swelling at the implantation site

A few weeks after the surgery, the device will be turned on and the process of finding the best settings for you begins. Some settings may cause side effects, but these often improve with further adjustments of your device.

Possible side effects of stimulation

• Numbness or tingling sensations
• Muscle tightness of the face or arm
• Speech problems
• Balance problems
• Lightheadedness
• Vision problems, such as double vision
• Unwanted mood changes, such as anger and depression

1. Timmerman L, Jain R, Chen L, Maarouf M, Barbe MT, Allert N, Brücke T, Kaiser I, Beirer S, Sejio F, Suarez E, Lozano B, Haegelen C, Vérin M, Porta M, Servello D, Gill S, Whone A, Van Dyck N, Alesch F. Multiple-source current steering in subthalamic nucleus deep brain stimulation for Parkinson’s disease (the VANTAGE study): a non-randomised, prospective, multicentre, open-label study. The Lancet Neurology (2015) 14:693–701. http://dx.doi.org/10.1016/S1474-4422(15)00087-3[↩][↩]
2. Effects of deep brain stimulation on rest tremor progression in early stage Parkinson disease. Mallory L. Hacker, Mahlon R. DeLong, Maxim Turchan, Lauren E. Heusinkveld, Jill L. Ostrem, Anna L. Molinari, Amanda D. Currie, Peter E. Konrad, Thomas L. Davis, Fenna T. Phibbs, Peter Hedera, Kevin R. Cannard, Lea T. Drye, Alice L. Sternberg, David M. Shade, James Tonascia, David Charles. Neurology Jul 2018, 91 (5) e463-e471; DOI: 10.1212/WNL.0000000000005903 https://n.neurology.org/content/91/5/e463.long[↩]