The process involves placing a neurostimulator in the brain. This sends out electrical impulses to specific parts of the brain. The impulses can block abnormal signals that can underlie a range of neurological conditions.
Deep brain stimulation (DBS) is commonly used to treat essential tremor, Parkinson's disease, and dystonia, a movement disorder in which the muscles contract and spasm, and it has been studied as a possible treatment for Tourette syndrome and major depression.
What does deep brain stimulation involve?
Deep brain stimulation delivers electrical impulses to parts of the brain.
The DBS system involves three different components:
- An implanted pulse generator
- A lead
- An extension wire.
The lead, also called an electrode, is a thin, insulated wire. It is implanted in the target region of the brain.
The extension wire travels under the skin and connects the lead to the implanted pulse generator. It is this generator that sends out the electrical signals.
DBS changes brain activity in a controlled way, and its effects are reversible.
DBS is associated with an increased release of adenosine triphosphate (ATP), an energy-carrying molecule that is found in the cells of all living things. This release of ATP leads to a build-up of adenosine.
Activating the adenosine A1 receptor triggers a process that reduces both tremor and any adverse effects caused by DBS.
This is because it dampens excitatory transmission in the thalamus.
The procedure does not destroy any nerve cells or healthy brain tissue.
DBS is mainly carried out on patients whose symptoms have not responded well to medications. Most patients will continue taking medication following DBS, but many experience a significant reduction in their symptoms.
What happens in deep brain stimulation?
DBS normally involves two separate surgeries. These are done to implant the necessary equipment.
Brain surgery will be necessary to implant the electrodes in the brain. An MRI scan enables doctors to identify the appropriate location.
First, a stereotactic head frame is fixed, to ensure that the patient's head remains still during the procedure.
Local anesthesia is used to numb the scalp, and a thin wire with electrodes is implanted into the brain. After this, a neurostimulator is implanted near the collarbone.
Patients must be awake during the procedure, so that the neurologist and neurosurgeon can ask questions to make sure the correct areas of the brain are being stimulated.
One day later, the surgeon implants a pulse stimulator in the patient's chest during chest wall surgery.
A small opening is made behind the ear, and the extension wire passes under the skin and connects to the neurostimulator.
The stimulator is programmed to send electrical pulses to the brain.
How can deep brain stimulation help?
People with severe Parkinson's disease have symptoms that cannot be controlled by medications. Additional methods of alleviating symptoms, such as DBS, can help.
Results of a two-year clinical trial have found that DBS improves the overall quality of life and social functioning of patients in the earlier stages of Parkinson's disease.
DBS can also help to treat the symptoms of other conditions, including rigidity, difficulty walking, dystonia, and tremors.
A study of people with the most common form of hereditary dystonia has reported that DBS brought lasting benefits for patients. Although it appears to be more effective for some types of dystonia than for others, scientists note that more definitive research is still needed.
A team from the University of South Florida observed that, after using DBS, a significant number of patients were able to stop taking medications used to treat essential tremors within one year after surgery.
DBS is thought to help people with essential tremor.
People with Tourette syndrome who received treatment with DBS have experienced fewer tics, but there is some evidence that people with this condition may be at higher risk of complications following DBS. These could include psychiatric side effects.
In Canada, patients with treatment-resistant major depression experienced positive results after treatment with DBS. Research has tentatively suggested that as an emerging treatment, DBS could be useful for treating depression, but scientists also urge caution in using such treatment for patients with psychiatric needs.
Neurosurgeons have suggested that DBS could help some people with alcohol addiction by impacting the impacting the "addiction circuitry"of the brain. But further studies are recommended into the effect of DBS on eating patterns.
Risks and complications of deep brain stimulation
DBS is considered a safe procedure, but there is a small risk of a number of complications.
These include confusion and problems with co-ordination and concentration, allergic reactions, blurry vision, and tingling over the body.
More serious problems could include brain swelling, blood clots, stroke, infection, and breathing problems.
There is also a risk that the equipment could break.