Developments in electrical stimulation treatment for the brain may offer hope to people suffering from a variety of disorders.
The technique can ease symptoms of depression, epilepsy, obsessive-compulsive disorder, headaches, chronic pain and stroke that have not responded well to other treatments, according to new and increasing research.
"Deep brain stimulation" – a surgical process that uses implanted electrodes to stimulate specific parts of the brain affected by a disorder – has already improved the lives of tens of thousands of people with motor disorders, including Parkinson's disease and tremors. The FDA approved the treatment for these conditions several years ago.
Now a growing body of research indicates this same technique may have the potential to treat an increasing list of other disorders. For these, people in the United States can currently only receive the treatment as participants in numerous FDA-approved studies.
“The brain controls the body, so if you can control the brain then you can control the body,” said Dr. Roy Bakay, professor of neurosurgery at the Rush University Medical Center in Chicago. Bakay was one of about 60 researchers involved in the first large, randomized deep brain stimulation (DBS) study on epilepsy. The “very promising” results are being published in a medical journal later this year, Bakay said.
“Participants in the study who received deep brain stimulation showed a significant reduction in seizures,” Bakay said. All of the participants suffered from refractory epilepsy, a form of the condition that does not respond well to anti-seizure medications. The treatment targeted the brain’s anterior thalamus, part of a limbic circuit that incorporates a lot of epileptic processes.
Another study published Tuesday in the medical journal Biological Psychology found that one year of the treatment significantly improved the symptoms for over half the participants, who suffered from severe, long-term depression.The researchers, from the University of Bonn in Germany, targeted the electric impulses on the nucleus accumbens, the so-called “pleasure center” of the brain tied to reward and motivation in human behavior.
“DBS is still in the formative stage with depression,” Bakay said. “It needs a big, multi-center study, and we’re on the cusp of that right now – maybe this summer.”
The two medical device companies behind the deep brain stimulation technology – Medtronic, Inc., and St. Jude Medical, Inc. – fund a large percentage of these multiple ongoing DBS studies.
The positive results of early research continue to thrust this experimental technology toward widespread applications. In order to cross this threshold, though, several larger studies showing significant results from treatment are needed, said Bakay.
Nonetheless, the potential of the treatment is, well, stimulating.
“The field is wide open,” said Dr. Manjit Sanghera, director of neurophysiology for the Neuroscience Institute at the Scott & White Health Hospital in Temple, Texas. “I’m sure within the next decade we’ll be seeing DBS approved for use in OCD, Tourette’s, epilepsy, depression. It might even work for obesity and Alzheimer’s one day.”
Sanghera’s hospital recently started a study to investigate the effects of deep brain stimulation treatment for the many non-motor symptoms of Parkinson’s disease, which include hallucinations, dementia and depression.
“If the target site of a disorder is discrete and one can get a probe in that area, it has potential,” Sanghera said, noting that neuroscientists must first pinpoint the affected brain region. “Deep brain stimulation really, really works.”
Patients undergoing DBS treatment must first have electrodes surgically implanted on to a highly specific part of the brain (usually no bigger than a thumbnail) affected by the disorder. The electrodes, wired to a pacemaker implanted near the collarbone, then provide an ongoing, externally adjustable electrical current to the brain region for a period ranging from a few months to several years. The continued stimulation of the malfunctioning brain region modifies brain circuitry and stabilizes the affected region, experts believe.
“The brain uses electricity to function; it is an intricate electrical system. DBS is a manual electrical system that can control the brain’s electrical system. It’s not as though this is some strange and sundry phenomenon: It makes sense,” Bakay added.
As with any major surgical procedure, there are risks and limitations.
The two biggest risks are hemorrhaging during the surgery (less than 1 percent of cases) and infection from plastic and metal materials in the body (about 2-5 percent of cases). Over a longer term, mechanical problems will eventually occur: The implanted battery will die; materials may move or malfunction.
“It’s a very safe procedure for most people,” Bakay said.
The major limitations of DBS include its enormous cost [about $150,000 for surgery and treatment], social stigmas and the need for FDA approval. The FDA supports studies of DBS treatment but requires a substantial amount of evidence to approve the procedure for wider use.