How Deep Brain Stimulation is Done
Implanting a deep brain stimulator
The DBS electrode has four contact points that generally span 10.5 mm. Depending on the disorder and/or the target; one may use variable sized contacts with different spacing arrangements.
Each contact can be activated and multiple settings can be adjusted for individual patient needs. These settings include the pulse width (how long the stimulation is), frequency (how often the stimulation is delivered), and amplitude (the strength or force) of stimulation.
The DBS lead is surgically placed into a brain area and is attached to an extension wire and a programmable pulse generator, generally in two separate surgeries. For implantation of the electrode, the patient has a stereotactic frame placed on the morning of surgery with local anesthetic.
A CT is performed to help the surgeon pinpoint the exact target locations in the brain. The patient is brought to the operating room, where microelectrode recording is done to confirm appropriate placement of the DBS electrode.
By listening to the brain cells through an amplifier, the surgeon and electrophysiologist can tell whether they are in the right place.
In addition, electricity can be delivered through the electrode to look for desired effects and side effects. Once the testing is completed, the patient is sedated. The skin is closed and the frame is removed.
Patients are monitored closely overnight to make sure there is no bleeding around the electrode. CT or MRI is performed to make sure the electrode is in the right place. Most patients go home the day after surgery.
For patients who are unable to tolerate or do not want to undergo awake surgery, electrode placement can be performed in a special operating room with an MRI with the patient asleep under general anaesthesia. iMRI allows real time monitoring of electrode placement to make sure the electrode ends up in the right location.
After the surgery
Approximately two weeks later, a second operation is performed to place the pulse generator (or IPG) below the clavicle (collar bone). The pulse generator is connected to the DBS lead by the extension wire that travels behind the ear. The patient is asleep under general anesthesia for this procedure. All patients go home the same day.
The system is turned on and off with a small, hand-held magnet. Once the DBS system has been activated, symptom reduction may occur within seconds to minutes.
The benefits can be maximized through simple adjustments to the DBS system made by the movement disorder specialist during office visits. The patient also receives a patient controller to turn the system on and off. The batteries tend to last approximately five years and can be changed as an outpatient procedure.