Brain power
With the right help and hard work, the mind can repair itself
 Samantha Para, 16, recently had brain surgery to remove portions of her brain. She remains amazingly active thanks to the brain's amazing powers to rewire itself. (Jonathan Wiggs / Globe Staff) |
When Samantha Para was born, the doctors told her mother that they did not know if she would ever walk or talk. Where the left side of Samantha's brain should have been, scans showed little but empty darkness, damage from a huge prenatal stroke. Take her home, they said, and do your best.
Now, at 16, Samantha not only walks, she water-skis. She shoots baskets. She toughs her way through algebra at Bourne High School on Cape Cod, likes to talk to friends, plays online Battleship and Spider Solitaire. Her charm and humor "dazzle" her neurosurgeon. Before a recent operation, she left him a pink Post-it note saying, "Good luck! Stay awake!"
When people meet her, they encounter a slight, creamy-skinned girl with golden hair who speaks with shy grace and seems no different from any other teen until she offers her left hand, instead of her weak right, to shake.
Samantha's excellent condition is a testament to years of her hard work and endurance, as her parents shuttled her to thousands of hours of doctors' appointments, speech lessons, and physical therapy.
It is also testament to the brain's amazing powers to rewire itself.
"What she is showing is that you can take an enormous neurological hit, and if you have the right opportunities and the skill and wit to use what you have left, you can lead a pretty normal existence," said Dr. Joseph Madsen, Samantha's neurosurgeon at Children's Hospital Boston.
Madsen's patients or their parents often mention to him the old saw that people only use 10 percent of their brain. Madsen doesn't believe that. In fact, modern brain science has not quantified how much of the brain is used, but cases like Samantha's raise the fascinating question of just how much we can get along without. Quite a lot, it turns out - if circumstances are right.
Samantha began with a gigantic advantage: Her stroke occurred while she was still in the womb, while her brain was still organizing itself and at its most "plastic," or changeable.
In brain recovery, timing is crucial. If a hemisphere is damaged well before a baby is born, for example, the nerves can likely rewire enough to allow both hands to function. But if the damage occurs after birth, the hand controlled by the damaged half of the brain will likely be curled in a useless fist, said Dr. Harry Chugani, a pediatric neurologist at Children's Hospital at Wayne State University. (Samantha has use of both hands, but the right is a "helper hand" that can do little on its own.)
Adults who have massive strokes that damage a whole hemisphere may find an entire half of their body paralyzed and have trouble speaking and seeing on the bad side. The adult brain can rewire itself, but not nearly as extensively as a child's.
Even with youth on her side, Samantha's brain faced a monumental task: Virtually all the functions of her damaged left hemisphere, including speech, some language, some vision and control of the right side of her body, had to be taken over by the healthy right hemisphere.
The transfer wasn't fully complete - the right side of her body remains a fraction smaller than her left, for example, and she walks with a slight limp - but a great deal did cross. "For what she had, it's remarkable what she's doing," said her mother, Annie Para.
What exactly happens when a brain remodels itself this radically is still largely a mystery. Some day, unraveling that mystery may help not only people with brain damage, but also help older people learn as fluidly as the young.
Brain plasticity works in various ways, said Dr. Jordan Grafman, chief of cognitive neuroscience at the National Institute of Neurological Disorders and Stroke, who has studied several patients like Samantha and is putting together a research plan to study more.
When damage occurs early, as it did with Samantha, sometimes a brain function - such as language - can cross from one hemisphere to the same position on the opposite side.
Such flexibility may come with a price, however. The good side of the brain may become "crowded," Grafman said.
For example, in a 2000 paper, he wrote about a patient with a damaged right hemisphere who had terrible trouble learning math. It could be, he said, that the left brain area that would normally deal with math had already been occupied by spatial relations, a function that had lost its usual spot in the right brain and migrated to the left.
For Samantha, schoolwork sometimes comes hard.
"I have to work more to do things that other kids can do more easily," she said, sipping hot chocolate recently in her family's tidy Colonial, heavily decked these days in Christmas candles and evergreen branches.
Even more problematic for Samantha: The damaged side of her brain was triggering epileptic seizures. They came unpredictably, sometimes two in a week, sometimes 20. She would feel her heart race and her hands grow sweaty. Afterward, a horrible headache would hit, and she could not concentrate.
Medication failed to stop them. Finally, despite the risks, she and her parents decided on the radical step of a hemispherectomy, a rare operation that either removes the whole damaged hemisphere or cuts its connections to the brain's good half. Nationwide, a few dozen are performed each year, and Children's Hospital Boston is one of the few centers that does them.
As the surgery approached, she became a celebrity at school; even kids she barely knew wished her luck. On Sept. 26, the day of her operation, many of Samantha's Bourne schoolmates wore pink or purple - her favorite colors - to show their support.
In a high-tech operating room, Madsen's surgical team drilled into Samantha's skull and removed a piece of it about the size and shape of an oyster shell.
They cut off the tip of her temporal lobe, a chunk about the size of a thumb that includes regions typically involved in memory and emotion. They left most of the left hemisphere in place but severed all its neural connections to the rest of the brain, reasoning that the less empty space left behind, the better.
Samantha's recovery was longer and harder than expected; for nearly a week, her oxygen level and heart rate ran low, and she remained in the intensive care unit. She briefly needed a shunt to drain extra fluid from her brain. Brutal headaches lasted for days.
But in the nearly three months since the operation, she has not had a single seizure. Her head still aches dully and she has lost a bit of short-term memory, but it seems to be coming back, she said. She is already doing schoolwork at home with a tutor, and expects to go back to school after Christmas break - and back to waterskiing next summer.
Carey Goldberg can be reached at goldberg@globe.com.
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