How Do You Stop Agonizing Pain In an Arm That No Longer Exists? A Scientist Does It With Mirrors
By SANDRA BLAKESLEE
Published: March 28, 1995
THE third time he lost his left arm, Derek Steen yelped with joy. He could not believe his good fortune.
The problem began 10 years ago when Mr. Steen crashed his motorcycle, tearing all the nerves that attached his left arm to his spine. The arm was hopelessly paralyzed, bound in a sling. He lost his arm a second time, so to speak, one year later when, deemed useless and getting in the way, the limb was amputated.
But Mr. Steen, now a 28-year-old part-time worker in San Diego, continued to suffer. His phantom arm felt paralyzed, pressed against his body, and it ached horribly for 10 years.
Then, late last year Mr. Steen was cured. After a simple, three-week treatment involving mirrors, his paralyzed phantom arm suddenly vanished, as did the gnawing pain in his phantom elbow. In its place, Mr. Smith says, he has a much reduced phantom limb composed of his lower left palm and all five fingers, which he can now "wiggle" freely from the stump below his shoulder.
He is ecstatic, said Dr. Vilayanus S. Ramachandran, a professor of neuroscience at the University of California at San Diego, who devised the treatment. Mr. Steen's "body image," as he puts it, has been profoundly altered, he said, much for the better.
Dr. Ramachandran described the finding -- a rare example of successful treatment for phantom limb pain -- at the second annual meeting of the Cognitive Neuroscience Society being held in San Francisco. The three-day meeting, which ends today, drew nearly 700 scientists who are engaged in basic research on the nervous system and how it leads to cognitive acts like learning, remembering, perceiving and consciousness.
Phantom limbs occur when the brain modifies its sensory maps after an amputation, he said. The brain region mapping an arm no longer gets input from the arm but it continues to be constantly stimulated by inputs from adjacent body parts. These stimuli fool the brain into thinking the arm itself is still there.
But sometimes, as in Mr. Steen's case, a phantom limb can be paralyzed. "The arm is in a fixed position, as if frozen in cement," Dr. Ramachandran said. "The patient can't generate the slightest flicker of movement, even though he can feel all the parts. I started thinking why."
The answer lies in the feedback loops in the brain that integrate vision, senses, body movements, body image and motor commands, Dr. Ramachandran said. In the first few weeks after the accident, Mr. Steen would try to move his injured arm, to no avail. His brain sent signals to his arm, commanding motion, but though his eyes confirmed the arm was there, it did not move.
In time, Dr. Ramachandran said, Mr. Steen developed "learned paralysis."
"His brain constantly got information that his arm was not moving," even though it was still there, Dr. Ramachandran said. After the amputation, he still felt it was there.
"Now if it's true paralysis can be learned, can you unlearn it?" Dr. Ramachandran said. "And how do you do that if you don't really have an arm?"
Simple. With mirrors. Dr. Ramachandran constructed a simple box without a lid and front and placed a vertical mirror in the middle. By placing his right arm into the box, Mr. Steen could see a mirror image of his missing left arm.
"I asked him to make symmetric movements with both hands, as if he were conducting an orchestra," Dr. Ramachandran said. "He started jumping up and down and said, 'Oh, my God, my wrist is moving, my elbow is moving!' I asked him to close his eyes. He groaned, 'Oh no, it's frozen again,' " the scientist said. "The box cost only $5, so I told him to take it home and play around with it."
Three weeks later, Dr. Ramachandran said, "he phones me, sounding agitated and excited." The conversation went like this:
"Doctor, it's gone!"
"My phantom arm is gone."
"All I have is fingers and a lower palm dangling from my shoulder."
"Does this bother you?"
"No," Mr. Steen replied. "The pain in my elbow is gone. I can move my fingers. But your box doesn't work anymore."
The telescoping of fingers is common in phantom limbs, Dr. Ramachandran said. "But nevertheless I couldn't help think that I had permanently altered someone's body image."
The reason the arm disappeared and the body image changed probably has to do with tremendous sensory conflict, Dr. Ramachandran said. "His vision was telling him that his arm had come back and was obeying his commands. But he was not getting feedback from the muscles in his arm. Faced with this type of conflict over a protracted period, the brain may simply gate the signals. It says: 'This doesn't make sense. I won't have anything to do with it.'
"In the process, the arm disappears and the elbow pain goes away," he said. "The reason the fingers survive and dangle from the shoulder is that they are overrepresented in the cortex, much more so than the rest of the arm. So there may be a kind of tip of the iceberg phenomenon going on here."
Dr. Ramachandran is now treating other kinds of phantom limb pain, including a clenching spasm of phantom hands. "People feel as if their fingernails are digging into their hands and say it is excruciatingly painful," he said. The mirror box has helped one such patient.
The new finding may also have relevance to stroke rehabilitation, Dr. Ramachandran said. In the early stages, some paralysis is due to swelling in the brain and learned paralysis could result. While destroyed tissue could not be revived, he said, other circuits might be re-established with the use of the mirrors.
These ideas remain highly speculative, Dr. Ramachandran said. Moreover, pain is notoriously susceptible to placebo effects, so it may be difficult to prove that these brain-based therapies are effective.
Nevertheless, striking results are being seen with some stroke patients who lose the ability to talk. At the University of Iowa, Dr. Antonio Damasio and his colleagues are teaching American Sign Language to patients whose primary language areas have been partly damaged but not destroyed. By learning a sign for a concept, he said, they are often able to reconnect with the word for that concept -- and in this way can learn how to speak once again.
Such plasticity or adaptability in the adult brain may be more common that most people realize, said Dr. Michael Gazzaniga, a neuroscientist who is an expert on split brain patients at the University of California at Davis.
An effective treatment for severe epilepsy is to cut the bundle of fibers that connect the left and right brain hemispheres. Each half brain is conscious but does not know what the other half sees or does.
In such patients, the left brain "wakes up and starts talking," Dr. Gazzaniga said. The right brain usually shows no sign of language comprehension and it certainly has no ability to talk -- until a patient named Joe stunned researchers by learning how to talk with his right brain. Joe was like other split brain patients for 13 years, Dr. Gazzaniga said. Then his right brain started recognizing and saying words independently of the left brain. Now, 15 years after surgery, Joe can name 60 percent of the stimuli presented to his right brain, Dr. Gazzaniga said.
"It could be that new connections have been made, or that others have been unrepressed," Dr. Gazzaniga said. "At this point we have no idea how or why it happens." But answers, should they be found, might be used for helping people overcome all sorts of brain injuries and neurodegenerative diseases.
Photo: Dr. Vilayanus S. Ramachandran of the University of California at San Diego demonstrates the principle behind a mirrored device he has designed to help amputees deal with pain in a phantom limb. (Associated Press for The New York Times)