About deep brain stimulation

WHAT IS DEEP BRAIN STIMULATION?

Deep brain stimulation (DBS) is a surgery that is used to treat a number of disabling symptoms of neurologic diseases. These include symptoms of Parkinson disease (PD), essential tremor, dystonia, or obsessive-compulsive disorder. It has also been used in Tourette syndrome, neuropathic pain, and depression. A report of the first successful clinical use of DBS in PD was published in 1987 by Alim-Louis Benabid and his team from France.

Patients must be carefully studied and chosen for DBS. Patient selection for DBS is based on symptoms and medication response. The patient's major cognitive or emotional problems are also reviewed. DBS can be very beneficial for the treatment of symptoms that don't respond to standard medical treatments. Drugs should always be the first line of treatment, as they usually improve motor symptoms a lot, at least for some years. At some point, however, DBS could be the most effective therapy available for a number of persons with PD.

HOW IS DBS SURGERY PERFORMED?

During DBS, the patient will have one or more (typically 2) wires, also called “leads” or “electrodes,” placed into specific structures deep in the brain. An implantable pulse generator (“IPG” or “neurostimulator”) is also placed beneath the skin in the chest or abdomen. The location in the brain where the leads will be placed is based on the person's symptoms. That surgical target is carefully identified using sophisticated computer software and brain imaging such as MRI and CT. A frame, which is used to precisely guide the leads into the desired location within the brain, is attached to the patient's head after the skin has been numbed. Skin and bone are carefully cut open, allowing further lead positioning in the brain. The extension cables are then passed under the skin into the chest (outside the rib cage), where the IPG is positioned. These wires will connect the IPG to the leads. The IPG delivers electrical pulses to the deep brain structures where the leads are implanted. These pulses change nerve cell function to relieve symptoms. Doctors and nurses can regulate the IPG at any time using a special device that wirelessly “talks” to the IPG.

WHAT ARE THE BENEFITS OF DBS IN PD?

DBS is usually offered to patients with PD when the so-called motor complications have set in despite best medication treatment. These motor complications include peak-dose dyskinesias. These are excessive involuntary writhing movements caused by the action of PD drugs. Another motor complication is called delayed “on,” which is when there is an increasingly long interval between when a medicine is taken and when the symptom benefit is apparent. Sudden “off” periods, with rapid, sudden, and unpredictable loss of benefit from a given dose of medicine, may also be a problem.

In general, DBS can help symptoms that respond to medications such as levodopa, but it doesn't involve bothersome motor complications such as peak-dose dyskinesia. With DBS, patients will usually benefit from improved and more consistent mobility throughout the day, reduced tremor, and decreased motor fluctuations. There is growing evidence suggesting that DBS might also reduce a few nonmotor symptoms that improve with antiparkinsonian medication, such as anxiety and pain. In addition, after surgery many patients will be able to reduce the amount of medications taken.

WHAT ARE THE RISKS?

DBS should be carried out by an experienced team. This reduces the risk of complications. Postoperative infection of skin wounds is one of the most common serious complications, occurring in about 5%–10% of cases. It is usually not life-threatening, but the stimulation system may have to be removed. A repeat surgery is possible in many such cases. The most serious surgical complication is bleeding in the brain caused by lead placement. This occurs in 1% or less of patients treated in experienced centers. A number of other complications might occur, many of them temporary, and this issue should be discussed with the treating team before surgery. Very few patients experience speech, cognitive, or emotional problems, some temporary and others more lasting.

WHAT ELSE SHOULD PATIENTS KNOW?

The process of patient selection, surgical intervention, and postoperative DBS adjustment is difficult and takes time. Patients may need to be seen frequently in the clinic, especially in the first few months after surgery when stimulation and medication will be adjusted. Also, those considering the procedure should discuss expected benefits and risks with the treating team before deciding to have DBS so that expectations are clear.

FOR MORE INFORMATION

National Parkinson Foundation

http://www.parkinson.org/parkinson-s-disease/treatment/surgical-treatment-options/deep-brain-stimulation

Christensen, Jackie Hunt. Life With a Battery-Operated Brain: A Patient's Guide to Deep Brain Stimulation Surgery for Parkinson's Disease. Minneapolis, MN: Langdon Street Press; 2009.