Deep Brain Stimulation
Deep Brain Stimulation (DBS) is a surgical option for patients with Parkinson's disease, Essential Tremor, dystonia, and other movement disorders that are not responding to the usual medications, or where those medications are causing unwanted side-effects. During DBS surgery electrodes are implanted within the brain to deliver electrical impulses. The stimulation offers patients relief from the tremors, rigidity, slowness of movement, and abnormal postures commonly seen in those conditions. Gait and balance problems may also improve. The stimulation can be adjusted as a patient's condition changes over time.
Deep brain stimulation is a new and improved variation of an old surgery. The old surgery involved destroying small parts of the brain within structures called the thalamus or globus pallidus. Today, it is no longer necessary to destroy even small parts of the brain.
Deep brain stimulation involves the implantation of a very thin lead containing four electrode contacts into a specific target area in the brain. The lead extends through a small opening in the skull and is connected to an extension wire. The extension wire is connected to an impulse generator or "pacemaker" which is implanted under the skin over the chest. Programming of the stimulation is easy and painless.
The surgeon is aided by computerized brain-mapping technology to find the precise location in the brain where nerve signals generate the tremors and other symptoms. Highly sophisticated imaging and recording equipment are used to map both the physical structure and the functioning of the brain.
The patient is awake during surgery to allow the surgical team to assess the patient's brain functions. While the electrode is being advanced through the brain, the patient does not feel any pain as the brain itself does not experience sensation. When the surgeon makes the small opening in the skull a local anesthetic is administered. The anesthetic used is similar to those used during a dental procedure to numb an area of the mouth.
Most patients are in the hospital for two to three days. A week or two later the stimulators are implanted below the collarbone. For this part of the procedure, the patient is placed under general anesthesia. The stimulators are turned on for the first time within a few weeks after implantation.
In properly selected patients, deep brain stimulation is remarkably safe and effective, although not completely without risk. Beneficial effects have been demonstrated to last for several years. Patients who initially responded well to medications, but over time have developed sides effects, can experience between 60 to 80 percent improvement in such symptoms as tremor and slowness of movement. Patients on average report a 50 percent improvement in their walking and balance. Similarly, patients with involuntary movements (dyskinesia) due to their medications, experience over 80 percent reduction in their involuntary movements. Most patients are able to significantly reduce their medications following deep brain stimulation.
Regarding Parkinson's disease in particular, an important indicator of the effectiveness of any treatment is the duration of "on-time" without dyskinesia. This means the patient is mobile, can perform everyday tasks without experiencing the involuntary movements. On average, deep brain stimulation doubles the amount of "on-time" without dyskinesia.
As with any surgery, the procedure is not entirely risk free. There is approximately a two to three percent chance of brain hemorrhage that may be of no significance, or may cause paralysis, stroke, speech impairment or other major problems. This means that for every 100 patients who undergo surgery, two or three will experience a permanent or severe complication. However, this also means that many patients will have no complications. There is a 15 percent chance of a minor or temporary problem. Rarely, infections can occur. While treatment of infection may require removal of the electrode, the infections themselves have not caused lasting damage.
The electrode that is implanted in the brain, and the electrical systems that provide stimulation, are generally very well tolerated with no significant changes in brain tissue around the electrodes.
Patients with Parkinson's Disease, essential tremor, dystonia or tremor due to multiple sclerosis, as well as other movement disorders with symptoms that cannot be controlled by medications can be evaluated as possible candidates for deep brain stimulation. In addition, patients who experience intolerable side effects from medication may also be candidates.
Deep brain stimulation has been successful in treating patients as young as 13 years of age. In general, surgery is performed on those under 75 years of age. However, each patient must be assessed individually concerning his or her stamina and overall health.