Essential Tremor and Deep Brain Stimulation
Deep brain stimulation (DBS) is used to treat a number of movement disorders, including essential tremor. DBS is a way to inactivate the thalamus, a structure deep in the brain that coordinates and controls muscle activity. The true cause of essential tremor is still not understood, but it is thought that the abnormal brain activity that causes tremor is processed through the thalamus.
How Effective Is Deep Brain Stimulation?
Deep brain stimulation provides moderate relief for approximately 90% of patients with essential tremor.
How Does Deep Brain Stimulation Work?
To treat essential tremor with deep brain stimulation, electrodes are placed in the thalamus during surgery. The electrodes are connected by wires to a type of pacemaker device (called an impulse generator, or IPG) implanted under the skin of the chest, below the collarbone. Once activated, the device sends continuous (painless) electrical pulses to the thalamus, blocking the impulses that cause tremors. This has the same effect as thalamotomy without actually destroying parts of the brain.
The IPG can easily be programmed using a computer that sends radio signals to the IPG. Patients are given special magnets so they can externally turn the IPG on or off.
Depending on use, the stimulators may last three to five years. The IPG replacement procedure is relatively simple.
What Are the Pros and Cons of Deep Brain Stimulation?
Advantages of deep brain stimulation include:
- It doesn't destroy brain tissue and won't limit future treatment.
- The device can be removed at any time.
- It is adjustable.
- It may be more effective in controlling tremors than thalamotomy, or destruction of the thalamus.
Disadvantages of deep brain stimulation include:
- Increased risk of infection from the presence of a foreign object in the body
- Repeat surgery every three to five years in order to replace the battery in the device
- Uncomfortable sensations that may occur during stimulation
Who Should Consider Deep Brain Stimulation?
There are many important issues to be addressed when considering deep brain stimulation. These issues should be discussed with a movement disorders expert or a specially trained neurologist.
Before considering DBS, you should exhaust all medication options. Surgery is not recommended if medications can adequately control the disease.
What Happens During Deep Brain Stimulation Surgery?
Using CT or MRI scans, surgeons will target areas for placement of the electrodes. Some doctors may use an electrode-recording technique to map and target the specific areas in the brain they will need to reach.
Once the correct location is identified, the permanent electrodes are implanted in the brain. The loose ends are placed underneath the skin of the head and the incision is closed with sutures. The wires are attached to a small impulse generator, about the size of a pacemaker, that is placed under the skin on the upper chest. Two to four weeks later, the IPG is turned on and adjusted. It may take a few weeks until the stimulators and medications are adjusted before a person gets relief from symptoms.