Advances & Insights: Neurosciences
December 1, 2006
What the news means for you
A. Byron Young, MD
‘Brain pacemaker’ is useful for many neurological conditions
Deep brain stimulation (DBS) for depression is still in clinical trials, so it is not currently preformed at the University of Kentucky. However, UK surgeons do perform deep brain stimulation for movement disorders. Our surgeons average around 30 DBS operations a year and put in more than 200 electrodes. This is the most experienced, comprehensive program in Kentucky for DBS.
“Success of DBS is directly related to the surgeon finding the best location in the brain to deliver stimulation.”
Typically, two procedures are required for DBS, although it may not be performed exactly the same way in every hospital or for every disorder. First, a surgical procedure is done on the brain to implant electrodes. The patient is given local anesthetics to numb the area, but is kept awake so the surgeon can communicate with the patient and ensure the proper areas of the brain are being stimulated. Success of DBS is directly related to the surgeon finding the best location in the brain to deliver stimulation.
Following the first procedure, the patient is put under general anesthesia and a neurostimulator is implanted in the patient's chest. Wires leading from the electrodes in the brain to the neurotransmitter under the chest are placed under the skin. Once this procedure is complete the patient is discharged.
One to two weeks after implantation, the neurotransmitter is turned on and electrical stimulation is first delivered to the brain. The electrical pulse will be adjusted in the following weeks for optimal performance.
Effectiveness of DBS
DBS is very effective in regard to movement disorders. Approximately 60 percent of patients show improvements in Parkinson's disease, around 80 to 90 percent of essential tremor patients show improvement and around 50 to 60 percent of dystonia patients show improvement.
How DBS affects depression isn't clear. Researchers theorize there are chemical imbalances in the brain that cause hyperactivity. When an electrode is placed in that area and high frequency stimulation is applied, the patient has less depression. The trials show promising results; however, since research in this area is still relatively new, follow-up times are minimal. The national trial Medtronic is getting ready to start should lead to more concrete analysis of DBS as a treatment for depression.
As with any surgery, there are some risks to DBS. The biggest risk (1-2 %) is a hemorrhage caused from the electrode being placed in the brain. The other major risk is infection. Antibiotics are given during the procedure to help combat the risk of infection. The long-term risks of DBS for depression are not yet known.
As a result of the potential risks, all other therapies including medication, psychotherapy and electroconvulsive therapy should be rendered ineffective before DBS is considered.
Research in DBS is leading toward treatment of depression, obsessive compulsive disorder and other psychiatric illnesses. The surgical treatment of psychiatric disorders was once very invasive. Neurosurgeons would remove a part of the frontal lobe of the brain in a lobotomy procedure. Due to its invasive and irreversible nature, the operation became very controversial and the procedure was stopped.
DBS has proven in clinical trials to be a much less invasive surgery and it is completely reversible. An external source controls the voltage of the electrical stimulation. It can be turned off and the patient will return to his or her state before the operation. Additionally, electrical stimulation can also be increased or decreased as the patient's depression gets better or worse. These improvements have made DBS a more acceptable procedure than lobotomy and other invasive techniques.
There has also been some research in using DBS as a treatment for morbid obesity. It has been shown in a few patients that the brain can be stimulated to turn off appetite. The next few years should show more research in these areas.
Dr. Young is chief of neurological surgery at UK HealthCare and professor of surgery at UK College of Medicine.
Deep brain stimulation (DBS) shows promise for depression
Depression has become a major public health crisis in recent years. It is the most common of all psychiatric disorders and ranks among the top causes of worldwide disease burden. Studies show an estimated 9.5 percent of the population suffer from a depressive order each year.
“Surgical intervention with DBS may be an effective treatment option to ease major depression in cases where other therapies have failed.”
Most people who suffer from depression can be treated with antidepressant medication, psychotherapy or electroconvulsive therapy. However, approximately 20 percent of patients do not respond to these interventions. Recent research shows surgical intervention with deep brain stimulation (DBS) may be an effective treatment option to ease major depression in cases where other therapies have failed.
Deep brain stimulation
DBS is a surgical procedure that involves placing implantable battery-powered electrodes into a targeted area of the brain that is functioning abnormally. The medical device is also called a brain pacemaker. The electrode is connected to a battery-powered stimulator. It is used to deliver high frequency electrical stimulation to block abnormal nerve signals in the brain, which can cause pain, movement problems, obsessions and anxieties associated with psychiatric disorders.
DBS does not damage brain tissue and the procedure can be reversed. The neurostimulator can be adjusted if the patient's condition changes. Currently, the batteries used to emit the electrical currents typically last two or three years and are surgically replaced when depleted. However, rechargeable batteries that will not have to be replaced are being developed.
The latest research findings from the Cleveland Clinic and Brown University's Butler Hospital were presented at the American Association of Neurological Surgeons annual meeting in April 2006. Six patients were treated in this study: four women and two men. The patients had bilateral DBS leads implanted into the ventral anterior internal capsule. Each patient underwent standardized psychiatric, quality-of-life and neuropsychological tests throughout the trial.
A six-month followup showed four of the patients had a 50 percent or greater improvement on the Montogomery-Asberg Depression Rating Scale. Scales measuring quality-of-life also showed improvement. An immediate change in mood was witnessed during the trial. As a result of this trial and others, researchers believe DBS for depression is successful but caution that larger, long-term studies need to be conducted.
Clinical applications for DBS
A relatively new procedure, brain pacemakers were approved by the Food and Drug Administration (FDA) in 1997 as a treatment for Parkinson's disease and essential tremor. In 2003, the FDA also approved brain pacemakers as a treatment for primary dystonia. The FDA has not approved DBS for major depression but clinical trial results are promising.
Medtronic produces the only commercially available DBS system approved by the FDA. Since FDA approval in 1997, more than 14,000 people worldwide have undergone DBS therapy for essential tremor and Parkinson's disease by electrically stimulating the areas of the brain that control movement and muscle function. When used for tremor control, DBS works by delivering electrical stimulation to an area of the thalamus.
Because small clinical trials have suggested DBS may be beneficial in the treatment of depression, Medtronic has announced it will pursue a major national clinical trial using Activa® DBS technology for treatment of severe depression.
UK HealthCare Services - Kentucky Neuroscience Institute
For more information, or to make an appointment with a UK HealthCare physician, please call UK Health Connection at 1-800-333-8874.