Deep Brain Stimulation
Deep brain stimulation —sending electrical currents to specific sections of the brain—is an Food and Drug Administration-approved treatment that often brings significant benefits to people with neurological conditions such as essential tremor, Parkinson's disease, and dystonia. Yale Medicine currently offers all forms of deep brain stimulation (DBS) surgery, including asleep DBS.
What is deep brain stimulation and how does it work?
According to Yale Medicine neurosurgeon Jason Lee Gerrard, MD, PhD, deep brain stimulation is the process of “taking a circuit in the brain that has been thrown out of whack, and trying to return it to a normal state by modulating the activity of other neurons in the brain."
This is achieved by surgically implanting a three-part system into the patient.
First, one or two electrodes are placed in areas of the brain believed to be causing a patient difficulty. In the case of a patient with Parkinson’s disease, this could be the sub-thalamic nucleus—a part of the brain that controls motor skills.
A stimulator, which resembles a pacemaker, is then implanted in the patient’s upper chest and connected to the electrodes with a wire.
Programmed by a movement disorder expert working closely with the patient, the stimulator determines the frequency and intensity of electrical impulses to the patient’s brain. Though patients may not be able to feel, hear or see any evidence of these impulses, they help regulate the abnormal electrical activity that causes impaired motor functions or other neurological problems.
For patients with Parkinson’s-related tremors, results can be immediate and dramatic.
“The patient is able to turn the device on or off,” says Dr. Gerrard. “When they turn the device on, they often go from having quite marked tremor to, within several seconds, having almost no tremor. It’s amazing to see the difference.”
Who can be helped by deep brain stimulation?
Though deep brain stimulation isn't the right treatment for everyone, Dr. Gerrard says that it can be very helpful for those whose neurological conditions that are not being well regulated by medication at regular doses.
The therapy has proven especially helpful for people with Parkinson’s disease. It may be presented as an option to patients who've tried medications and are still experiencing a diminished quality of life, as well as those who cannot tolerate increasing dosages of their medications.
What is the surgical process for implanting deep brain electrodes?
Two separate surgeries are required to implant the entire deep brain stimulation system.
During the first procedure, the doctor will implant one or two electrodes into the brain. The electrodes must be placed in exactly the right portion of the brain in order to produce the desired effect. Therefore, the surgery is often done while patients are awake, under conscious sedation.
While doctors position the electrodes, they record brain functions and perform test stimulations, asking the patient for feedback to determine if the right areas of the brain are being targeted. Once the surgeon is confident that the electrodes are placed in the correct region of the brain, the electrode(s) are locked into position with a device that is mounted to the skull.
For patients who are unable to undergo this surgery awake, with conscious sedation, neurosurgeons are able implant the electrodes under general anesthesia.
Several days later, a second surgery will be performed to implant the stimulator—a small, battery-powered computer—into the upper chest.
Once all components of the deep brain stimulation system have been surgically implanted, several outpatient visits to the movement disorders specialists will follow. These visits are to “program” the stimulator and make sure the electrodes are working at the right intensity and frequency.
Why is deep brain stimulation prescribed for some Parkinson's patients?
Parkinson’s disease is a chronic, progressive movement disorder caused by the damage and loss of neurons in the portion of the brain called the substantia nigra. These neurons provide dopamine to the motor circuits of the brain, controlling movement, risk and reward assessment, and other functions.
Most medications for Parkinson’s work by increasing levels of dopamine. This helps, but as the condition progresses, many patients require higher and higher doses of medication, which can cause and intense, negative side effects. For people in this situation, deep brain stimulation may be an option. It has been shown to substantially relieve the motor side effects of the disease without damaging healthy brain tissue.
“When you have the right candidate, someone who is completely debilitated by Parkinson's disease, you can sometimes even see the changes that occur in the operating room, when you’re doing the test stimulation,” says Dr. Gerrard. “Their tremor will change instantaneously.”
What makes Yale Medicine's approach to deep brain stimulation unique?
The Yale Medicine Deep Brain Stimulation Program has grown rapidly over the last five years. Now it is one of the few that can offer all forms of DBS surgery, including both awake and asleep DBS.
“We strive to combine being on the cutting edge of technology and the latest clinical trials with having a very patient-centric, individual approach,” says Dr. Gerrard.