Scientists study ways the mind can heal itself

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BY JACOB GOLDSTEIN/Knight Ridder Newspapers

MIAMI — One day in March, Erin Smith, age 25, was learning how to walk.

She stood in a small, windowless room at the Miami Jewish Home and Hospital. Nine gauze pads stuck to her shin and calf, and spaghetti-like cables connected the pads to a computer called the "Neuroeducator." A monitor showed the electrical impulses sent by Smith's brain — badly damaged in a motorcycle accident six years ago — as she flexed her foot up and down. When she raised the foot, a blue line shot up like a stock chart on a good day.

As Smith watched the monitor, her brain was busy retraining itself to orchestrate the complex series of muscle movements required to walk. Standing in that windowless room, Smith was displaying one of the hottest buzzwords in neuroscience: plasticity.

[+]Enlarge

Dr. Bernard Brucker (right) has been working with Erin Smith, 25, who was in a coma after a car accident five years ago. Dr. Brucker has a lab at the Miami Jewish Home and Hospital that deals with teaching patients to walk with the help of biofeedback. (Raul Rubiera/Miami Herald)

Dr. Bernard Brucker (right) has been working with Erin Smith, 25, who was in a coma after a car accident five years ago. Dr. Brucker has a lab at the Miami Jewish Home and Hospital that deals with teaching patients to walk with the help of biofeedback. (Raul Rubiera/Miami Herald)

Plasticity means an injured brain can reroute signals through existing pathways and grow new connections between cells. It means the mind — in some cases, and given the right prompting — can begin to heal itself.

Traumatic brain injury is the leading cause of death and disability for adults in their 20s and 30s. Every year, some 80,000 people suffer serious damage from injuries like Smith's, largely the result of car and motorcycle accidents.

Yet for a variety of reasons, traumatic brain injury has long been overlooked in the medical community and the public at large. The Centers for Disease Control and Prevention has called it a "silent epidemic."

"It's a messy problem — it's not an easy injury to understand or to diagnose," says Dr. Ronald Hayes, director of the University of Florida's Center for Traumatic Brain Injury Studies. "Traumatic brain injury has been largely a neglected problem, medically and socially."

This neglect stemmed partly from the belief that little could be done for brain-injured patients because brain damage was irreparable.

"That's what I was taught: Once you're an adult, any damage to the adult brain, you're toast," says Dr. Donald Stein, an Emory University neuroscientist. "That's absolutely false."

But experts say the new understanding of plasticity has yet to move from the laboratory to rehabilitation centers, which often rely on the old wisdom that brain-injured patients can only improve for the first year or two after their injury.

"The most amazing thing from our data is how many people are out there with brain injuries who actually have surviving and repairing brain tissue that is never discovered by traditional diagnosis," says Dr. Bernard Brucker, the University of Miami psychologist who runs the lab where Smith has been learning to walk again. "And, more importantly, they never have an opportunity to use it."

Very slowly, that may be changing.

"The zeitgeist — the conceptual substance of the neurosciences — has become much more open to plasticity," says Dr. Paul Bach-y-Rita, a University of Wisconsin rehabilitation specialist. "Finally we are getting well-funded. People aren't laughing us out of the room."

Trauma to the head — slamming into a windshield at 50 mph, for example — damages brain cells in several ways.

The most direct is known as a coup-contrecoup injury. The "coup" occurs at the moment of impact, when the brain bangs up against the skull. The "contrecoup" occurs a moment later, when the brain bounces backward and bangs against the opposite side of the skull.

In many patients, the impact also causes damage throughout the brain to axons, the long nerve-cell tails that carry messages from one cell to the next.

In the days following the trauma, the brain swells against the skull, pinching off blood vessels and prompting further cell death. At the same time, a flood of chemicals released by the damaged axons go on to damage other cells.

"Brain injury is the equivalent of sprinkling meat tenderizer on your brain," says Hayes of the University of Florida. "Biochemical hell breaks loose because the cells begin to digest themselves. It's a very ugly scenario."

In the past decade, improved trauma care has increased the number of patients who survive serious head injuries, and new studies are examining ways to reduce cell death. In one study, patients are receiving estrogen — an experiment based on the observation that women survive injuries with more intact brain cells than men. Other studies are examining whether rapidly cooling the patient can reduce cell death by slowing metabolism.

But improvements in rehabilitation have been slower in coming, leaving thousands of families to contend with severely injured survivors — and, as often as not, a sense there's nowhere to turn.

"You're much better off having a heart attack than a head injury," Hayes says. "We have the ability to diagnose a heart attack and we have some reasonable therapies to manage cardiovascular disease. We have neither for traumatic brain injury."

A year after Smith's 1999 motorcycle accident, her doctors, who believed she would no longer improve, discharged her from the hospital.

"At the end of a year she was a zombie," her mother recalls. "They sent her home in a wheelchair slumped over and drooling on herself. They said, ‘There's nothing else we can do for her. Take her home.'"

Traumatic brain injury affects each patient differently, and there's no way to know precisely what a patient is up against. A revolution in brain imaging — CT scans, PET scans, MRIs — has yet to be translated into useful data for rehabilitation. This makes it difficult to develop rigorous, standardized treatments.

"For years what we have taught people is if you had right-sided weakness, just learn to write with your left hand," says Dr. Ross Zafonte, director of rehabilitation at the University of Pittsburgh. "This was probably the wrong thing to be teaching, because the brain is plastic — use facilitates recovery."

In a technique pioneered in stroke victims, patients struggle to use hands rendered nearly useless by brain damage.

Many of the stroke patients show marked improvement after just a few weeks — and scans show increased activity in brain regions surrounding areas affected by the stroke.

Researchers believe trying to use the weakened limbs creates new connections between existing cells. The training also may prompt the brain to recruit previously unused cells and pathways — a process neuroscientists call "unmasking."

"They're there already!" Bach-y-Rita says of the pathways. "The brain is incredibly plastic, but it doesn't happen unless you demand it."

Researchers are looking for other ways to encourage the brain to grow new connections and unmask unused pathways. Many believe drugs can amplify the effects of physical therapy. Others are examining whether powerful bursts of magnetic waves improve the brain's ability to reorganize itself.

In Brucker's Miami lab, when Smith lifts her foot, the Neuroeducator's screen shows her how many of her brain's foot-moving neurons are firing, a process known as biofeedback. Watching the screen helps her brain re-wire itself so she can walk again. Smith has been visiting Brucker's lab off and on for two years and working with a personal trainer between visits.

"We came in a wheelchair," her mother says of the first session. Now, with lumbering, stiff-legged steps, Smith walks in and out of the building on her own.

Prevalence of traumatic brain injury

Each year in this country:

-- 50,000 people die from traumatic brain injuries

-- 230,000 people are hospitalized and survive

-- 80,000 people suffer long-term disabilities

Source: Centers for Disease Control and Prevention

 

For more information

-- Brain Injury Association of America, www.biausa.org, (800) 444-6443

-- National Institute of Neurological Disorders and Stroke's traumatic brain injury page: http://www.ninds.nih.gov/disorders/tbi/tbi.htm