Deep Brain Stimulation
How is deep brain stimulation (DBS) surgery performed?
This surgery is performed through a small skull opening (burr hole) with the patient awake, using only local anesthetic and light intravenous sedation. Surgery is guided by stereotaxis, a method used for approaching deep brain targets through a small incision and skull opening. With stereotaxis, a rigid frame is attached to the patient’s head just before surgery, and a brain imaging study (usually an MRI) is obtained with the frame in place. The images of the brain and frame are used to calculate the position of the desired brain target and guide instruments to that target with minimal trauma.
To maximize the precision of the surgery, most surgeons use the electrical activity of the brain to guide the procedure. The surgeon records brain cell activity to check neurological response to electrical stimulation in order to confirm the correct location before implanting the electrode. The neurological status of the patient (such as vision, strength, reduction of tremor and/or appropriate relaxation of muscles) is monitored frequently during the operation. For implanting a single brain electrode, two to three hours of awake surgery is required. While pain can be eliminated, the discomfort of having an awake procedure with one’s head immobilized may be significant for some patients.
When the electrode has been implanted, a thin wire is “tunneled” under the skin (under full sedation) of the neck to the collarbone, where a battery called a “neurostimulator” is implanted to control the electrical impulses sent to the electrode in the brain. Dystonia and Parkinson’s patients whose symptoms are significant on both sides of the body, will usually require electrode placement on both sides of the brain. Dr. Fineman normally performs the two implants in two separate surgical procedures, spaced one to two months apart.
What are the risks of deep brain stimulation (DBS)?
The most serious risk of DBS is bleeding in the brain, potentially — but not always — resulting in a stroke. This risk varies from patient to patient, depending on other medical factors, but generally ranges from 1-3%. If stroke occurs, it usually occurs during or within a few hours after surgery. Another risk is infection, typically at the burr hole or at the site of the neurostimulator implant. Infection occurs in 4-5% of patients and is very rarely life threatening, although infection can require removal of all or part of the DBS system.
What are the benefits of deep brain stimulation (DBS)?
DBS surgery does not cure disease in Parkinson’s, essential tremor or dystonia, though it can significantly reduce symptoms in some patients. When the stimulator is turned off, or if it malfunctions, symptoms return. DBS can decrease abnormal movements, rigidity, tremor, abnormal postures (e.g. dystonia) and other symptoms, but usually does not totally eliminate them. The degree of benefit varies — in dystonia — with the type of disease, duration of symptoms and age of the patient. Adolescents and young adults with inherited forms of dystonia appear to get very significant benefit, while patients with dystonia due to stroke or head trauma may improve only slightly. Adults who have had dystonia for many years generally improve less than those with recent symptom onset. People with essential tremor are generally strongly benefited by DBS while, in Parkinson’s and dystonia patients, a number of factors interact to determine degree of benefit. Any patient considering DBS should have a frank and comprehensive discussion with their neurosurgeon to determine possible benefits and risks based on their unique history.