May 2, 2014

Deep Brain Stimulation: Progress Today, Questions Tomorrow

The May 2014 issue of Smithsonian magazine includes a fascinating article by David Noonan about the current state of deep brain stimulation (DBS). It’s titled “Mind craft: The most futuristic medical treatment ever imagined is now a reality. But it won’t be long before brain implants are even more amazing – and troubling.”

The surgery involves strategically implanting electrodes in a patient’s brain. Those electrodes are powered by a battery pack sewn into the patient’s chest. By delivering a weak, steady electric current to the exact area of the brain, they reduce or eliminate the patient’s troubling symptoms. A century ago, the surgery would have seemed like bizarre science fiction . . . like wirelessly transmitting sounds and images through the air or landing a man on the moon.

DBS, of course, is of particular interest because of its growing – and successful – use as a treatment for people with Parkinson’s (PWPs) for whom disabling symptoms of the disease cannot be adequately managed with medication.

A Treatment for Many Ills
DBS gained approval in the 1980s as a treatment for movement disorders, like PD, essential tremor, and dystonia – involuntary muscle contractions. Estimates suggest about 100,000 people worldwide have undergone the surgery.

Now, DBS is showing promise as a treatment for Tourette’s syndrome, obsessive-compulsive behavior, post-traumatic stress disorder and other neuropsychiatric conditions. It may even help improve memory for Alzheimer’s patients. (So far, treatment remains elusive for multiple sclerosis, Lou Gehrig's disease, and myasthenia gravis.)

Dr. Michael Okum, a neurologist whose practice with neurosurgeon Dr. Kelly Foote is profiled in the Smithsonian article, reports that over 90 percent of their patients rate themselves as “much improved” or “very much improved” on standard post-operative scales.

The doctors’ challenge is to find that EXACT location in a patient’s brain (“amid the cacophony of a hundred billion chattering neurons,” as Noonan writes) where the circuitry is most disrupted, and thus where the new stimulant of electric current can bring the greatest benefit.

Patient as Operating Room Collaborator
They have the best tool for that purpose at their disposal: a totally awake, alert patient who – by talking or moving his arms or drawing spirals on a clear plastic clipboard – can help the doctors pinpoint the spot(s) that work best. No matter that the patient now has a dime-sized hole bored into his skull, or that his surgeon is sticking probes four inches down into his gray matter.

While Foote is manipulating initial probes (not the eventual electrodes) that act like radio receivers, picking up and amplifying the sounds of individual neurons in his patient’s brain, Okum is listening carefully. He can differentiate between the sounds of normal neural activity and sounds that are not normal.

When Foote’s probe enters that abnormal territory – the place where circuits are misfiring – Okum asks the patient to draw another spiral on the clipboard. This time, the design is smooth and even, not rough and jagged like before. Bingo. That’s the spot where Foote will place the permanent electrode.

Brave New World
Okum and Foote have seen how their electrical probing affects mode, too. Just one example: While performing DBS on a woman with debilitating obsessive-compulsive disorder, Foote’s initial probe hit a spot in the patient’s nucleus accumbens, a brain region that’s associated with pleasure, reward, and motivation. When he did, the woman laughed and smiled joyfully.

The neurologist and the neurosurgeon wonder, with some anxiety, if people in time will look to DBS for a happiness fix, or a personality adjustment. In many ways, the same concerns arose with the proliferation of Prozac use two decades ago, when people wondered about the morality of resetting disposition or temperament will a pill. To treat disease, yes. But “persona” or “character” issues? Was that OK, too?

Will DBS go the way of plastic surgery? In the middle of the last century, the practice -- very technically challenging -- dealt with treating patients with facial trauma or disfigurement. These days, of course, plastic surgery is commonplace. Men and women think nothing of having multiple procedures to lift a brow, tighten a face, resculpt the buttocks, enlarge or reduce the chest.

DBS is now in a time of incredible advancement, as science uncovers more and more mysteries of the brain. The technique is making very real and important improvements in people’s lives, a trend that can only continue. Foote and Okum feel privileged to be at work in the field right now.

But they have to wonder: Where will DBS take us in the years ahead?

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Internet searches on "deep brain stimulation" yield hundreds of links. Here's just one, from the Michael J. Fox Foundation. The page also offers several brief, interesting podcasts:
  • How DBS works
  • What to expect, and new surgical directions
  • Comments from PD patients who have undergone the procedure  

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