How is deep brain stimulation performed?
Before the actual procedure begins, for most patients, a head frame (stereotactic head frame) is positioned on your head, which keeps your head still during brain imaging and is used to deliver the electrode to the target in the brain. Surgical pins or screws are used to secure the frame to your head. Sedation is typically given during this portion of the procedure.
Your neurosurgeon will implant the deep brain stimulation system in one to three stages.
First, a small hole is made in the skull. The leads, which have electrodes at the ends, are passed through this hole and surgically implanted in the areas of the brain identified as the site(s) responsible for the movements caused by Parkinson’s disease.
Most people with Parkinson's disease will require one lead placed on each side of the brain unless symptoms are mostly one-sided (then only one lead on one side of the brain would be needed). Each side (hemisphere) of the brain controls the opposite side of the body, so each lead is inserted on the opposite side of where symptoms are occurring. Sometimes this procedure is done in stages; one lead is placed at one time followed by another surgery for the other side. In other patients, both leads are placed during the same operation. Many times patients are awake during lead insertion. An intraoperative MRI is also sometimes used to image the lead location.
In a separate operation approximately 1 week later, one or two battery-powered pulse generator devices (one per lead) are implanted just under the skin in your upper chest area below your collarbone. An extension wire is attached to the lead already positioned in the brain, then tunneled under your skin behind your ear and down your neck to the pulse generator device.
You will return for an office visit about 2 to 4 after the implant surgery. The implanted pulse generator is turned on by a hand-held device and the electrical pulses are adjusted until symptoms improve. (The device sends electric pulses to the brain through these leads.) The hand-held device can also check the battery level and can turn the device on and off.
Several follow-up programming visits will be needed to fine-tune the stimulation sent to the brain to best relieve symptoms. Then regularly scheduled longer-term follow-up visits will be needed to continue to check to make sure the system is working properly, adjust the stimulation as needed to continue to best control symptoms and to check the battery life of the device.
How does the neurosurgeon know where to place the electrodes in my brain?
Positioning the electrodes in the brain is the most critical step. The electrodes have to be placed in an exact location in the brain to improve symptoms. Computed tomography (CT) or magnetic resonance imaging (MRI) scans are taken before and/or during the procedure to pinpoint the exact areas to target and guide the lead and electrode placement. Many times an electrode may be used to record brain cell activity at the target site to improve lead placement.
Will I be asleep during the entire procedure?
You will be sedated or receive local anesthesia for part of the procedure, may or may not be awake for lead and electrode placement, and will be asleep when the impulse generator is implanted. To provide more details:
- A local anesthetic is applied to areas of the head where pins or screws are used to secure the head frame and sedation is given.
- You will be sedated during the beginning of the procedure, while the surgical team is opening the skin and drilling the opening in the skull for placement of the lead.
- Most patients will be awake for lead and electrode placement. This part of the procedure is not painful, as the brain does not feel pain. Being awake allows the surgical team to interact with you when testing the effects of the stimulation. However, some patients who cannot tolerate the procedure while awake can have the electrode and lead placed under general anesthesia. The lead placement is guided in real time by magnetic resonance imaging. The procedure is performed in a special MR-equipped operation room.
- Implantation of the pulse generator in the chest and connection of the leads from the device to the lead in the brain is usually done under general anesthesia.