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Boosting the Brain
Implants. Among the most amazing new medical devices are those that stimulate nerves electrically. "Virtually every function in the body is controlled by electrical signals from the nervous system, so neural stimulation is potentially able to influence a huge range of functions," says Gerald Loeb, MD, professor of biomedical engineering at the University of Southern California.Jackie Brown can attest to the power of electricity. Brown, 50, of Duncanville, Texas, a suburb of Dallas, suffers from Parkinson's disease. A drug called Sinemet helped control her symptoms: tremors, impaired balance, slow and stiff movements. But each night, when the medication wore off, the tremors would start. As she lay on her bed, her husband, Guy Brown, a six-foot-four, 230-pound former linebacker for the Dallas Cowboys, would sometimes lie on top of her legs to keep her from helplessly thrashing about. "I could push him off the bed," she recalls. "It would cramp and shake that bad."
In March 2004, doctors drilled two symmetrical nickel-sized holes on each side of Brown's skull. In each, they inserted a thin electrode into a pea-sized structure called the subthalamic nucleus, deep in each hemisphere of the brain. Then they surgically threaded its wires under the skin of Brown's head and neck to an implanted, matchbook-sized pacemaker in her chest, much as electricians run wiring inside a wall. They spent two weeks programming the device, and weaned her off much of the Sinemet. Brown now does t'ai chi, lifts weights, drives her car and goes to bed like everyone else. "It's a miracle," she says.
Deep brain stimulation (DBS) "is an opportunity to help give people back their dignity, their control, their hope," says Malcolm Stewart, MD, the John and Patricia Fox chair of neurology at Presbyterian Hospital of Dallas, who was part of a three-doctor team that treated Brown. A clinical trial published in 2003 in the New England Journal of Medicine shows that DBS alleviates symptoms five years after it's implanted. But it takes $100,000 and an expert team of doctors to install a DBS system and program it, and brain surgery can lead to infection, stroke or seizure. What's more, the disease continues to damage the brain, Stewart says. Still, neural stimulators akin to Brown's are being used or tested to ease symptoms of an astonishing array of illnesses, including migraines, obesity, epilepsy, Tourette's syndrome and severe depression.
Neural prosthetics. Other new-generation neural devices are true prosthetics -- they carry out a brain or neural function lost to disease or injury. Cochlear implants, the first brain prosthetics, have given deaf people back the ability to understand speech and are now used by 60,000 deaf and hearing-impaired people worldwide. A retinal prosthetic developed at the University of Southern California has restored rudimentary vision, including, for several blind people, an ability to see light and distinguish between a cup, a plate and a knife. Loeb's team is testing remote-controlled injectable muscle implants the size of long-grain rice that impel flaccid, paralyzed muscle to move. So far, in a small trial, the device, called a BION (short for bionic neuron), has spurred paralyzed shoulder muscles to contract in stroke patients. It holds paralyzed arms in their sockets, reverses shoulder pain, and could keep muscles working until the stroke victim regains his ability to direct his arm, says Loeb. If used soon after a stroke, the BION could also prevent muscle atrophy in the first place.
Loeb emphasizes that no matter how promising such a device is, it will be widely used only if a medical device company commits to producing it, insurance companies agree to pay for it, and doctors get comfortable prescribing it. That took 20 years for cochlear implants, he says, so be patient.
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