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Extraordinary People: Living with Half a Brain - Monday October 1
27 Sep five's blog | email this | 217 reads
extraordinary people: living with half a brain
21.00–22.00
Five’s acclaimed documentary strand continues with
another batch of absorbing programmes exploring
remarkable stories of human experience. Tonight’s
programme follows the stories of two young sufferers of
epilepsy as they undergo radical surgery to remove large
sections of their brains.
At the age of just three, six-year-old Cameron Mott
developed a devastating and progressive brain disorder
called Rasmussen’s encephalitis. This rare disease
attacks the right side of the sufferer’s brain, causing
a rapid decline in mental faculties and –if left
untreated –eventually leading to partial paralysis.
Cameron’s condition has left her with extreme epilepsy.
Her daily life is plagued by sudden and frequent fits
forcing her to wear a protective helmet at all times. She is
only free from the fits for a precious 30 minutes at the
beginning of every day, before she collapses and falls
victim once more to the relentless cycle of seizures.
This film follows the Mott family as they travel from their
home in North Carolina to the Johns Hopkins Medical
Institute in Baltimore for a radical treatment. Cameron is
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about to undergo a complex operation called a
hemispherectomy, which is the last resort for doctors
treating children with her condition.
During seven hours of surgery, led by Dr George Jallo,
chunks of the right side of Cameron’s brain are
painstakingly removed. Though the operation is incredibly
delicate and difficult, time is of the essence, since the
cavity left in Cameron’s head fills with cerebral-spinal fluid
at a rate of a teaspoonful every five minutes. Once
surgery is over, Cameron is immobilised –any movement
could dislodge the remaining half of her brain. For 48
hours, Shelley and Casey Mott cannot hold or hug their
little daughter.
Just eight days after her radical treatment, Cameron
pedals down the hospital corridor on a tricycle, laughing
as she cycles. Her parents believe it is nothing short of a
miracle and even her neurosurgeon is amazed by the little
girl’s rate of recovery. “I always think that these
children... are going to be dependent on their parents for
the rest of their lives,” admits Dr Jallo.
However, surviving the operation is only the first hurdle
for Cameron –her real challenge is yet to come. The
effects of the surgery are similar to the results of a major
stroke, so there is a chance that the entire left side of the
little girl’s body could be permanently paralysed.
Incredibly, it is also possible that Cameron will make an
almost complete recovery. At her age, the brain has a
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remarkable capacity to reorganise itself – with one
side of the brain effectively taking over the
functions of the other. All Cameron’s parents can do for
now is wait and hope, but they remain confident that their
daughter’s determination will see her through.
Elsewhere, in London’s Great Ormond Street Hospital, 14year-old epileptic Sean Goldthorpe has his brain
connected to a machine. As Sean reads aloud, neurologist
professor Helen Cross sends electric charges into the part
of his brain that controls language. Sean stumbles and is
unable to read further, becoming anxious and frustrated.
This disquieting session is part of an invasive monitoring
programme being used by Professor Cross to pinpoint the
part of Sean’s brain causing his fits. It is an exhausting
ordeal for Sean, but he is willing to go through with it if it
will give him an opportunity to be seizure-free.
Professor Cross eventually discovers that Sean’s fits are
emanating from his hippocampus – an area deep within
the brain responsible for emotion and memory. As he
grows older, the effects of Sean’s seizures are spreading
to the language area at the back of his brain via a lesion.
To stop his fits, Sean will need to have both of these areas
of his brain removed, but doctors will only go ahead with
the operation if they are certain that his memory and
speech will not be damaged irreversibly. Sean’s parents
now face an anxious wait as their son’s future lies in the
doctors’ hands.
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Hemispherectomy
From Wikipedia, the free encyclopedia
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Intervention:
Hemispherectomy
ICD-10 code:
ICD-9 code:
01.52
Other codes:
Hemispherectomy is a surgical procedure where one cerebral
hemisphere (half of the brain) is removed or disabled. This procedure is
used to treat a variety of seizure disorders where the source of the
epilepsy is localized to a broad area of a single hemisphere of the brain. It
is solely reserved for extreme cases in which the seizures have not
responded to medications and other less invasive surgeries.
Contents
[hide]
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1 History and changes
2 Results
3 In the Media
4 References
5 See Also
6 External links
7 Further reading
[edit] History and changes
Hemispherectomy was first tried on a dog in 1888 by Friedrich Goltz.
The first such operation on humans was done by Walter Dandy in 1923.
In the 1960s and early 1970s, hemispherectomy involved removing half
of the brain, but this resulted in unacceptable complications and side
effects in many cases, like filling of excessive body fluids in the skull and
pressuring the remaining lobe (known as hydrocephalus). Today, the
functional hemispherectomy has largely replaced this procedure, in which
only the temporal lobe is removed; a procedure known as corpus
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callosotomy is performed; and the frontal and occipital lobes
disconnected.
[edit] Results
All hemispherectomy patients suffer at least partial hemiplegia on the
side of the body opposite the removed or disabled portion, and may suffer
problems with their vision as well.
This procedure is almost exclusively performed in children, since their
brains generally display more neuroplasticity, allowing neurons from
the remaining hemisphere to take over the tasks from the lost hemisphere.
This likely occurs by strengthening neural connections which already
exist on the unaffected side but which would have otherwise remained
small in a normally functioning, uninjured brain.[1] One case,
demonstrated by Smith & Sugar, 1975; A. Smith 1987, showed that one
patient with this procedure had completed college, had attended graduate
school and scored above average on intelligence tests. Studies have found
no significant long-term effects on memory, personality, or humour
after the procedure[2], and minimal changes in cognitive function
overall.[3]
[edit] In the Media
A hemispherectomy is performed on a patient played by Dave Matthews
in the Season 3 episode of House, M.D., "Half Wit." His right
hemisphere was severely damaged in a car accident when he was 10 years
old.
In the season 1 episode called "The Self-Destruct Button" on Grey's
Anatomy, Dr. Shepherd performs a hemispherectomy on a 3 year old girl
with a seizure disorder.
[edit] References
Why would you remove half a brain? The outcome of 58
children after hemispherectomy-the Johns Hopkins experience:
1968 to 1996.
Vining EP, Freeman JM, Pillas DJ, Uematsu S, Carson BS, Brandt
J, Boatman D, Pulsifer MB, Zuckerberg A.
Pediatric Epilepsy Center, Johns Hopkins Medical Institutions,
Baltimore, Maryland, USA.
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PURPOSE: To report the outcomes of the 58 hemispherectomies
performed at Johns Hopkins between 1968 and January 1996.
METHODS: Charts were reviewed of the 58 hemispherectomies
performed at Johns Hopkins Medical Institutions by the Pediatric
Epilepsy Group during the years 1968 to 1996. Twenty-seven
operations were done for Rasmussen's syndrome, 24 operations for
cortical dysplasias/hemimegalencephalies, and 7 for Sturge-Weber
syndrome or other congenital vascular problems. Seizure control
alone did not seem to adequately describe the outcomes of the
procedure. Therefore, a score was constructed that included seizure
frequency, motor disability, and intellectual handicap. This burden
of illness score better described the child's handicap before and
after surgery. RESULTS: Perioperative death occurred in 4 out of
58 children. Of the 54 surviving children, 54% (29/54) are seizurefree, 24% (13/54) have nonhandicapping seizures, and 23% (12/54)
have residual seizures that interfere to some extent with function.
Reduction in seizures was related to the etiology of the unilateral
epilepsy. Eighty-nine percent of children with Rasmussen's, 67%
of those with dysplasias, and 67% of the vascular group are
seizure-free, or have occasional, nonhandicapping seizures. All
operations were considered by the parents and the physicians to
have been successful in decreasing the burden of illness. In 44 the
procedure was very successful, in 7 it was moderately successful,
and in 3 it was minimally successful. Success was related to the
etiology, and early surgery was preferable. CONCLUSION:
Hemispherectomy can be a valuable procedure for relieving the
burden of seizures, the burden of medication, and the general
dysfunction in children with severe or progressive unilateral
cortical disease. Early hemispherectomy, although increasing the
hemiparesis in children with Rasmussen's syndrome, relieves the
burden of constant seizures and allows the child to return to a more
normal life. In children with dysplasias, early surgery can allow the
resumption of more normal development.
PMID: 9240794 [PubMed - indexed for MEDLINE
This is truly, truly amazing. I remember reading somewhere
before (in an article called “Is Your Brain Really Necessary” by
somebody I can’t remember) on the condition of hydrocephalia
which sometimes is discovered only late in life. Someteimes the
patients have less than half of their brain tissue left, the most
being taken over by brain fluid the uptake of which has for some
reason been blocked. Nevertheless, in some cases the patients
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have been living normal, happy lives, engaged in highly
intellectual and social activities.
And now there is this story. In some severe cases doctors have
found that the only cure is to surgically remove hal of the
patients brain, the left or the right hemisphere, as the case may
be. If this is done in early childhood, thge patients may make an
almost full recovery, both in terms of physical ability (therer may
be a period of left/right paralysis), linguistic skills (even if you
remove the right hemipshere) and social and cognitive abilities.
So what does this suggest to me? On one hand that that surgery is
an amazing handicraft. Or what do you make of the fact that one
surgeon performing the hemispheroctomies describes his
expertise in a tactile way: “sick brain feels like mushy apple,
healthy brain like very soft boiled egg”. On the other hand, that
despite all the extravagant claims made in terms of physical
correlates of consciousness or certain cognitive functions, we
actually do know very little. This is proven by the simple fact
that normally functioning hydrocephalics or patients after
hemispherectomies simply do not possess the parts of brain that
are supposed to be the “correlates” of this or that mental
function. We do know that you need to have a brain in order to
have a mind, but after that there is a long long stretch of
unknowledge, and the neuroscientific claims coming after that
immense unknowledge are not much better in illuminating
philosophical questions than LaMetrrie’s description of the brain
as a collection of self-winding springs in the 17th century.
http://www.newyorker.com/archive/2006/07/03/060703fa_fact?curren
tPage=2
The Deepest Cut
by Christine Kenneally
At nine o’clock on July 28th last year, Wendy Nissley carried her twoyear-old daughter, Lacy, into O.R. 12 at Johns Hopkins Hospital to have
half of her brain removed. Lacy suffers from a rare malformation of the
brain, known as hemimegalencephaly, in which one hemisphere grows
larger than the other. The condition causes seizures, and Lacy was having
so many—up to forty in a day—that, at an age when other toddlers were
trying out sentences, she could produce only a few language-like sounds.
As long as Lacy’s malformed right hemisphere was attached to the rest of
her brain, it would prevent her left hemisphere from functioning
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normally. So Lacy’s parents had brought her to Johns Hopkins for a
hemispherectomy, which is probably the most radical procedure in
neurosurgery.
Wendy laid her daughter on the operating table. Because Lacy was so
small, it took the anesthesiologist almost ninety minutes to insert her
intravenous lines. George Jallo, the attending neurosurgeon, spent a long
time arranging her head on gel padding and then drew “Cut here”
markings on her shaved scalp. The rest of Lacy’s head, including her
face, was covered with a sterile drape. Jallo made one long cut across the
top of her head from the front to the back, and another at right angles to
the first, which started midway along it and stopped just in front of her
right ear. He folded back the scalp and made small holes in her skull with
a power drill, outlining a rough semicircle. Then he used the drill to
connect the dots and removed a portion of the skull. He cut another T in
the dura, a thin, leathery membrane covering the brain. Gently, he peeled
back two large flaps.
By half past one, Jallo and a resident had already removed the right
frontal lobe. David Lieberman, the pediatric neurologist who had
examined Lacy when she first came to Johns Hopkins, looked on, shaking
his head in wonderment. “It’s so open,” he said, turning to me.
“Normally, with brain surgery, you make a hole about this big”—he
curled his thumb and index finger into a circle.
After removing the frontal lobe, Jallo embarked on the parietal lobe. In
case complications put a sudden stop to the surgery, it was important to
take out the seizure hot spots first, gradually working through the
hemisphere in descending order of priority: after the parietal lobe would
come a small section of the occipital lobe, then the temporal lobe, then
the rest of the occipital. Finally, Jallo would cut the corpus callosum, the
bundle of fibres that connect the two hemispheres of the brain. The
surgeons slowly worked around each side of the parietal lobe, making
tiny pinches in the brain with electric cauterizing forceps. There was a
slight smell of burning in the bright, noisy operating room. As the cut
became deeper and wider, the tissue on either side browned and
blackened, and the lobe started to move back and forth. At the bottom of
the parietal wedge, the clean white of nerve fibres was visible; as the lobe
was severed, they came apart like string cheese. A surgical technician
bent toward Jallo with a small plastic bowl in his hands. Jallo picked the
lobe out of the skull—it was the size of an infant’s fist—and dropped it
into the container.
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As she led me out of the O.R., Eileen Vining, the attending neurologist,
said, “Did you see how rigid it was? Normal brain sags in your hands.”
Vining talked quickly, moving from one complicated idea to the next,
punctuating each with “O.K.?” and an expectant nod. She had been in and
out of the operating room all morning, and now she was off to find the
Nissleys and tell them how Lacy was doing.
Four hours later, Vining took me back into the O.R. Lacy’s right
hemisphere was gone, and her cranium looked like a wide, uneven bowl.
I could see the deep cavity where the frontal and parietal lobes had been,
and the white-pink color inside the base of the skull. In the middle of the
remaining brain was a shallow mound where Jallo had left a layer of
nerve fibres to protect the ventricle, a fluid-filled pocket that cushions the
brain and the spinal cord. The white matter there was now gray-black.
Jallo and his resident lightly touched their forceps to it, and the
cauterizers fizzed, sealing the brain to prevent microhemorrhages.
Hemorrhaging is a constant concern in brain surgery, and at one point in
the operation Jallo decided to leave in a small piece of the right occipital
lobe which threatened to bleed dangerously. Jallo glanced at Vining and
Lieberman, and the doctors stretched forward to look at the severed
corpus callosum. Over and over, the surgical technician poured in saline,
and Jallo and his resident drew it out again with a loud suction pump.
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When he had finished removing brain tissue, Jallo tipped in small packets
of Surgicel, a feathery white substance that helps blood to clot. It melted
onto the surface of the brain. “That was good. There was not a lot of
bleeding,” Vining said. “You never know what you are going to get until
you open it up. Sometimes you just go in there and you hold your breath
and pray.”
In the final hour, Jallo sutured Lacy’s dura, which had shrunk slightly
from dehydration, and filled the right side of her head with saline. The
technician then brought the missing section of the skull back to Jallo,
carrying it in a wide right angle over surgical carts rather than risk
moving it over the floor. Jallo reattached it, using four tiny dissolvable
plates made of a sugarlike substance. He then closed the scalp incision
with a staple gun, leaving seventy-eight aluminum staples in Lacy’s skin.
The hemispherectomy had taken nine hours. The resident bandaged
Lacy’s head, gently turned her onto her right side, and stuck a piece of
tape on her head that said “This side up.”
I first met the Nissleys three months before Lacy’s surgery, at their home
in Palmyra, Pennsylvania. As I drove up, I could see Lacy’s father, Mike,
dangling a leg over the edge of the front porch. He looked like a surfer,
with a goatee beard and gold-lens Oakleys pushed back on his head.
Wendy sat on a chair near the front door, and Lacy’s four-year-old sister,
Lily, flitted around the adults. Lacy, blond like her mother, lay across
Wendy’s lap. “She had a seizure just before you got here, so she’s
sleeping now,” Wendy said. They invited me inside.
Lacy had her first seizure on October 13, 2003, when she was four and a
half months old. Wendy had been doing laundry, and when she turned
around she saw that Lacy’s lips were blue and that she was shaking. She
called 911, but by the time the ambulance arrived the seizures had ended.
In the following month, the family went to the hospital many times, but,
on each occasion, by the time they got there the spell had ended and there
didn’t seem to be anything wrong. The doctors took an MRI but saw
nothing unexpected, and they suggested that Lacy might have acid reflux
or sleep apnea, or could even be doing it on purpose, out of anger. “But
she wasn’t angry,” Mike said. “She was sitting there happy, and all of a
sudden it hit her like a train.” One doctor put her on phenobarbital,
increasing the dose each time there was another seizure. “It made her
lethargic, like she was drunk,” Wendy said. That November, Lacy had a
terrible attack. “Her arm went up in the air,” Mike said, throwing his left
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arm straight up, stiff. “Her lips went blue. She was having them in a
row.” By the time the ambulance came, the seizures had subsided, but the
attendants advised the Nissleys to get in their car and take Lacy to Johns
Hopkins anyway. The drive took two hours, and, just as Mike and Wendy
walked over to the triage nurse, Lacy began another cluster of seizures.
The nurse said, “We’ve got to get you a room.”
At Johns Hopkins, David Lieberman ordered another MRI. The scan
seemed normal, and after a week of further testing Lacy was sent home
without a clear diagnosis. Lieberman, in consultation with Eileen Vining
and the Johns Hopkins epilepsy group, tried to control the convulsions
with medication. Lacy was weaned off the phenobarbital and put on
Dilantin and Ativan. They tried Diastat, Topamax, and, later, Tegretol
and Keppra. But the seizures continued. When they hit, Mike and Wendy
would lay Lacy on the floor and talk to her. “Every couple of minutes,
she would moan and groan like she’s in pain,” Wendy told me. Mike
nodded. “They said that seizures don’t hurt,” he said. “I don’t know that I
believe that.” As we spoke, Lacy sat up a few times and turned to look at
me. When I waved and said, “Hi,” she said, “Ba.” Twice, she smiled;
once she looked completely terrified. Each time, she turned her shaky
head toward her mother and nestled down.
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In April, 2004, Lacy returned to Johns Hopkins for four days of
continuous EEG monitoring, and again in November for another MRI.
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The scan showed that she had an enlarged right hemisphere. The bulge on
the right made the midline between the two lobes bow slightly toward the
smaller side, and there was a strange fogginess on the right side of the
scan, whereas the left was clear. Lieberman told the Nissleys about
hemimegalencephaly. “We had a diagnosis, finally, and we were happy
with that,” Mike said. “It’s not sleep apnea. It’s not acid reflux. It is
something. We didn’t know if she was going to die.” Diana Pillas, who
coördinates counselling at the Johns Hopkins epilepsy center, told Mike
and Wendy about various possible treatments. They could try a ketogenic
diet—which is ninety per cent fat and has been shown to stop convulsions
in some children—but Lacy would be restricted to a special liquid
formula for two years. She also told them about hemispherectomies. “I
couldn’t believe it. I didn’t know people could do that and be alive,”
Mike said. “The first question I had was ‘Well, what do they put in
there?’ ”
After the initial shock, Mike and Wendy decided that the surgery was the
best option. Lacy’s seizures had hindered her development to the point
where she couldn’t walk unless she was holding someone’s hand, and she
hadn’t learned how to chew. The seizures were also becoming more
frequent, and they knew that children with her condition tended to live
much shorter lives than their peers. The Nissleys were concerned about
the costs, though. Mike worked as a butcher at a local supermarket, and
Wendy, a doctor’s receptionist, had had to quit working in order to look
after Lacy; no day-care program would take her. Johns Hopkins put them
in touch with another family whose child had had the procedure, and who
told the Nissleys about the financial aid that was available. They finally
made a date.
I bumped into Mike and Wendy as I came out of the O.R. with Vining.
They were smiling but tense. “We were really stressed,” Mike said later.
“We were all wondering if it was the right thing to do. No one said it, but
we all knew what we were thinking.”
Neurosurgery began with trepanation, the prehistoric practice of scraping,
sawing, or boring a hole in the skull. Trepanned skulls, some as old as ten
thousand years, have been unearthed in Europe, Africa, Asia, and the
Pacific Islands. Knowledge about the brain’s anatomy has accumulated
from the time of Galen, in the second century, but neurosurgery was not
recognized as a distinct specialty until the early twentieth century. Since
then, neurosurgeons have saved many brains by selectively destroying
some of their tissue. They’ve injected brains with pure alcohol,
electrocuted them, and inserted wire loops and metal probes and wiggled
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them about. They have frozen brain tissue, and they have burned it. But
no brain surgery is as dramatic as a hemispherectomy. “A
hemispherectomy is the opposite of everything you are taught in
neurosurgery,” Jallo told me. “You are told throughout your residency
training to preserve the brain, get what you have to get, do your work,
and leave, but with this you have to take out everything along the way.”
The first recorded hemispherectomy was performed, in 1888, on a dog by
Friedrich Goltz, a prominent German physiologist. (Apparently, the postop animal exhibited the same personality and a minimal reduction in
intelligence.) In humans, the operation was pioneered by Walter Dandy, a
Johns Hopkins neurosurgeon, who, in 1923, performed his first
hemispherectomy on a patient with an aggressive brain tumor in the right
hemisphere. The patient lived for three and a half years, until the cancer
invaded the remaining hemisphere. Dandy performed another four
hemispherectomies, all for patients who had brain cancer in their right
hemispheres. In 1938, the Canadian neurosurgeon Kenneth McKenzie
performed a hemispherectomy on a child suffering from seizures that
could not be controlled with drugs. The operation was a success, and
hemispherectomies came to be more popular as a treatment for chronic
seizures than for cancer. But eventually the operation fell out of favor.
Doctors found that, around ten years after the surgery, some patients
became paralyzed or comatose, and sometimes died. This was caused by
a buildup of cerebrospinal fluid, a saline-like substance that cushions the
brain. The fluid is produced at the rate of about one teaspoon per minute,
and in normal brains it is reabsorbed—the total supply of fluid renews
itself every five hours. But in some cases the trauma of the operation
seemed to prevent this, and the resultant pressure could distort the skull
and push the remaining brain to one side, a condition known as
hydrocephalus.
The hemispherectomy’s resurgence in popularity is largely the work of
John Freeman, a pediatric neurologist who has been at Johns Hopkins
nearly his entire career. Tall and charmingly gruff, Freeman is seventythree and semi-retired, though when I visited him before Lacy’s operation
he was still putting in forty hours a week in his cluttered office. “Semiretired for a workaholic,” he said. Freeman saw a few hemispherectomies
while on a training fellowship at Columbia, and started ordering them for
patients at Johns Hopkins in the early nineteen-seventies. By then,
hydrocephalus could be detected early, with scans, and the excess fluid
drained to other parts of the body, where it was reabsorbed naturally. In
the early nineteen-eighties, he proposed the treatment, for the first time,
for a patient with a diseased left hemisphere—a thirteen-year-old girl who
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suffered such uncontrollable seizures that she had spent several months in
the intensive-care unit. The prospect of removing a left hemisphere—
rather than a right one, as had been the case in previous operations—was
daunting. It is generally thought that language is situated in the left half of
the brain, and no one could say for certain what the effect of removing
that hemisphere would be. “We worried about that,” Freeman said. “What
would your life be like if you couldn’t talk, and you couldn’t understand,
and you were just there and aware?” While a number of the hospital’s
faculty approved the operation, an outraged senior physician vetoed it.
But the only alternative, Freeman observed, was for the girl to remain in
intensive care for the rest of her life, so the following week, when the
doctor in question was away, Freeman went ahead and arranged the
operation. “Can you imagine doing a hemispherectomy without the
assurance that the patient would talk?” he asked. The operation was a
success, and the girl recovered the ability to speak. “Now,” he said, “I can
tell the families: they all talk.”
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If Freeman revived the practice of hemispherectomies, their leading
practitioner has been Ben Carson, who joined Johns Hopkins in 1984 and,
at thirty-two, became the youngest head of pediatric neurosurgery in the
nation. A star in his field, Carson has written a book about his
transformation from angry teen-ager in Detroit to renowned
neurosurgeon. He did his first hemispherectomy a year after coming to
Johns Hopkins. The Washington Post wrote a story about it, and soon the
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hospital was getting calls from doctors all over the country saying that
they had patients with intractable seizures whom they wanted to send.
Carson has now performed more than a hundred hemispherectomies. One
of his oldest patients had the surgery in his thirties.
Carson’s office, like Freeman’s, is strewn with files, books, and X-rays,
and there is an abundance of photographs, cards, honorary Ph.D.s, and
gifts—a hanging plate painted with poetry, a framed sampler embroidered
with “Dr. Carson,” and, on the windowsill, a statuette of a handsome
black man in a white doctor’s coat who looks exactly like Carson. In
person, Carson is mild, tired, and friendly. He told me that when he
started doing hemispherectomies he would reach in and slice out an entire
hemisphere at once. But he modified this practice after one patient went
into a coma for a month. Carson believes that the patient’s brain stem was
moved about excessively during the procedure. “It’s too much like what
I’m doing right now,” he said, grappling with a plastic model of the brain
in an effort to pop out a recalcitrant lobe, which eventually shot off into
the mess on the floor. I asked him Mike’s question, about all that space
left by the missing lobes. In the past, he said, doctors worried about this
and tried to anchor the remaining brain by stitching it to the dura. They
would put all kinds of things in the cranial cavity—one surgeon used
sterile Ping-Pong balls. But, as Carson did more hemispherectomies, he
realized that the brain’s own drip of cerebrospinal fluid could adequately
fill the cavity. Sometimes the remaining brain moves during the weeks
following the surgery, but usually by less than an inch. “It doesn’t seem
to be a problem,” he said. Much of Carson’s method is intuitive. “You
develop a feel for the brain,” he said. “Normal brain feels like a very soft
boiled egg. A bad brain feels like a mushy apple.”
Freeman and Carson haven’t merely pioneered the surgery; with their
colleagues at Johns Hopkins, they have undertaken research into the
effects of hemispherectomy on behavior, language, and psychology. “We
as a group here in pediatric epilepsy have changed the way children are
handled,” Freeman told me. “It’s not just the surgery; it’s the network and
the contact. It’s the best thing I’ve ever done, and I don’t even do them.”
Freeman and Carson are in the process of handing the practice over to
Eileen Vining and George Jallo. Each doctor somehow resembles his
successor. Freeman and Vining are obsessive clinical researchers and
vigorous wranglers of surgeons, doctors, and patients. Jallo, like Carson,
has a quiet intensity and the gentlest of handshakes. When I asked the
surgeons how it’s possible for people with half a brain to live, let alone
have a life, each of them spoke about plasticity, flexibility, redundancy,
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and potential, and then they smiled and said the same thing: “We don’t
really know.”
“After I got this car, I noticed so many CR-Vs,” Christina Santhouse said.
“I guess you notice them after you get one.” Christina was driving a nice,
steady five miles per hour above the speed limit on the way to the Bristol
Pike Lanes bowling alley, in Croydon, Pennsylvania. She recently turned
eighteen and got her license on the second try. Her family outfitted her
Honda CR-V with an extra-long rearview mirror, additional side mirrors,
a knob on the wheel for steering, and a rod that brings control of the
indicator over to the right side. As an eight-year-old, Christina played
soccer, swam, and did karate. Then she contracted Rasmussen’s
encephalitis, a little-understood condition that causes chronic
inflammation of the brain. One day at the Jersey Shore, her foot started
twitching, and within a few months, as the right side of her brain
deteriorated, she was having hundreds of seizures a day. Christina
became Johns Hopkins hemispherectomy case No. 30—her surgery took
fourteen hours, one of the longest operations Carson has performed. The
alterations to Christina’s car are necessary, because she has impaired
motor function on her left side. (Each hemisphere of the brain primarily
controls the opposite side of the body.) She also lost sight on the left side
of each eye, and now wears prism glasses that bring the left field of
vision over to the center of the eye. When I met her, she had taken her
S.A.T.s and just finished high school, coming in seventy-sixth in a class
of two hundred and twenty-five. Last fall, Christina was a freshman at
College Misericordia, in Dallas, Pennsylvania, where she’s studying
speech pathology.
When we pulled into the parking lot of the bowling alley, she parked in
the same spot that she always used. She wore jeans, a college hoodie,
pink nail polish, and Skechers sneakers. A small brace beneath her jeans
kept her left leg straight, though she still had a slight limp, and her left
arm was partly paralyzed. “I can do this”—she shrugged her left
shoulder, moving it and the arm around. “I can’t do this”—she twinkled
the fingers of her right hand at me. Christina booked us a lane and we sat
down to put on our bowling shoes. She was on her high-school varsity
bowling team for four years, and in her final year she was captain. She
pulled a leather glove onto her right hand with her teeth and then insisted
that I go first.
17
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I knocked down eight pins, and Christina knocked down six. “I get really
nervous and my arm gets stiff,” she said. “Also, I haven’t practiced for a
month. And the finger holes in my ball are cold.” In the next round, I
knocked down seven pins, and Christina bowled a strike. As the game
continued, my score lagged, while Christina bowled spare after strike
after spare. Her ball weighed fourteen pounds. I’m at least seven inches
taller, so I started out with a sixteen-pound ball. After almost losing it on
the first backswing, I changed to a fourteen-pound ball. As my elbow
began to ache, I moved to a twelve, then a ten. Christina doesn’t have the
balance necessary to run and throw the ball, so she positions herself at the
bottom of the lane, crouching slightly and swinging it like an underhand
discus. I tried bowling like Christina. She coached me on where to stand
and what to aim for, but my first ball, deprived of the momentum that
comes from a running walk to the edge of the lane, dropped straight into
the gutter. The second time, I swung harder and my ball rolled just a little
farther before it hit the gutter. On the third try, I knocked down one pin.
Christina explained that you have to work out which side you’re stronger
on, and step to that side as you swing. Her final score was a hundred and
seventy.
Christina is a spectacular example of how well children can do after a
hemispherectomy, but she is no outlier. Many children who have had
hemispherectomies at Johns Hopkins are in high school, and one, a
college student, is on the dean’s list. The families of these children can
18
barely believe the transformation, and not so long ago neurologists and
neurosurgeons found it hard to believe as well. I asked Jallo if he
remembered his first hemispherectomy. “Yes and no,” he said. “I don’t
remember the patient. It was more of a ‘Wow.’ I was a resident in
training and I assisted in one of the operations. I didn’t realize you could
take out that much brain tissue and have someone be so functional and
useful in society. What amazes me is that, if someone all of a sudden
strokes out half of the brain, more likely than not they are not going to
survive. Yet a lot of these people develop their seizures when they’re
very young, or in utero, and when you take out half of their brain in one
sitting it’s as if they weren’t touched.”
There are wide variations in recovery, and any brain surgery carries grave
risks. Many factors affect how well a patient does—age at the time of a
condition’s onset, age at the time of the operation, the nature of the
condition itself, and the determination of parents and caregivers to
maintain an intense schedule of therapy before and afterward. Possibly
the greatest danger is posed by the brain’s veins and arteries, which are so
numerous and so wildly, individually arranged that they are impossible to
map and very hard to control. Excessive bleeding can send patients into
shock and then into comas from which they never return, or it can wipe
out most brain function. The other conflicting challenge of the surgery is
the necessity of making sure that enough tissue is removed. Freeman once
saw a small boy who made good progress for six months following a
hemispherectomy, after which he began to deteriorate. His doctors
discovered that they had left a small piece of the excised hemisphere in
the child’s head. It was, said Freeman, no larger than the top joint of his
thumb. But the electricity from that piece of neural tissue was enough to
compromise the remaining hemisphere. The boy had another operation, a
“redo,” as the doctors at Johns Hopkins informally call it, in which the
bad piece of brain was removed. After that, he had no more seizures.
The brain’s remarkable capacity for recovery has long fascinated
scientists. Bradley Schlaggar, a pediatric neurologist and a professor at
Washington University in St. Louis, told me about an experiment that he
conducted for his Ph.D. He transplanted the visual cortex from an
embryonic rat’s brain into the brain of a newborn rat, placing it in the
spot occupied by the somatosensory cortex, which is responsible for such
bodily sensations as pressure and temperature. Once the second rat had
grown up, Schlaggar took a look at its brain and discovered that the
transplanted chunk of visual cortex was functioning as a somatosensory
cortex. Such a basic architectural feature of the brain was thought to be
entirely hardwired, but Schlaggar showed that brain tissue could
19
reprogram itself to serve different purposes. In another experiment, Leah
Krubitzer, a professor of psychology at the University of California,
removed large pieces of the brains of newborn marsupials. Once the
marsupials became adult, she examined the brains again and found that
they had organized themselves in such a way that the visual, auditory, and
other somatosensory areas were all in the same relative positions that they
would occupy in a normal brain, but they were smaller, commensurate
with the total space available.
Schlaggar said that, in the mid-eighties, researchers invoked plasticity to
explain the brain’s ability to compensate for sudden damage—as when a
stroke victim relearns to walk or talk. Now, Schlaggar said, the concept is
used to describe a far more basic operation of the brain, including how it
develops from childhood to adulthood, and even how an adult brain
changes when a new skill is learned: “The idea is that when you talk
about plasticity you are talking about every bit of learning that we do.”
For a long time, the assumptions that neuroscientists made about what
was going on in a child’s brain were based on how the adult brain
worked. But now it seems that the brain’s internal configuration depends
on the age of the brain. If an eighteen-year-old’s brain sustained some
kind of damage, Schlaggar explained, it would occur in neural terrain that
is organized differently from, say, that of a two-year-old, even if the
injury was in the same spot. Children with damage to a particular area of
the brain often suffer losses that are different from those sustained by an
adult who experiences the same trauma.
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When Schlaggar lectures on plasticity, he shows slides of the construction
of the St. Louis Arch. “As the structure goes up, the relationship between
the scaffolding and the leading edge of the two sides of the arch change
as they rise up to meet in the middle,” he said. “The interaction between
the scaffold and the emerging mature structure is dynamic.” The ever
changing scaffolding of the developing brain, Schlaggar said, means that
the functional organization of the brains of children performing a task can
look quite different from that of adults engaged in the same task. If you
show seven-year-olds and thirty-year-olds a word and ask them to
generate a verb for that word, the two groups can do so with equal
accuracy and in the same amount of time, but they use slightly different
regions of the brain to arrive at their answers. Children, Schlaggar
explained, use extra regions of the brain during their development which,
like scaffolding that falls away, are no longer needed when the brain’s
architecture is mature.
Although the plasticity of Christina’s brain in the years following surgery
has enabled her to live a remarkably normal life, other aspects of her
experience have been hard. When we were alone in the car, Christina told
me about years of social difficulties. “I didn’t tell many people at high
school, but it kind of got out,” she said. She didn’t make friends until
junior high. A few years after the operation, one of her mother’s relatives
phoned to say that there was a photograph of Christina in The National
Enquirer. Before going to Misericordia, Christina hoped for a fresh start,
but when she spent an introductory night there her roommate showed her
a photocopied article about her hemispherectomy. A psychology
professor had handed them out to her class.
After bowling, Christina drove me to her home and I spoke to her mother,
Lynne, and her grandmother Mary Lou. We looked at photographs taken
the day of the hemispherectomy, and we watched a video of Christina at
Johns Hopkins before the surgery. She is sitting on a bed, and her foot
begins to twitch. Within seconds, the twitches multiply and cascade
through her body, and she falls back onto the bed completely helpless. In
another video, Carson strides from the O.R. after Christina’s
hemispherectomy. He looks utterly invigorated. Lynne, waiting outside,
clasps his hands and then crumples before him in tears.
The day after Lacy’s surgery, Jallo came by early to visit her. She was
moving her right arm and leg weakly, and her color was good. The next
day, she started to run a fever, and then she had the worst seizures she’s
21
ever had—three in a row, each ten minutes long. This was not unusual—
most practitioners think it’s caused by the trauma of the operation—but it
wasn’t good. The doctors adjusted her medication, and over the next few
days she improved. When I phoned Mike, he said that, four days after the
surgery, she had been out of bed a few times to be held in her mother’s
lap. “She’s not doing much of anything on the left side,” he said. The left
side of Lacy’s body had always been weak, because it was controlled by
the damaged right hemisphere. With that hemisphere gone, Lacy would
need a year’s intensive therapy to remind her brain of the existence of her
left arm and leg. Three weeks after the surgery, Lacy’s staples were
removed and she was released from the hospital.
On a wet October day more than two months after the operation, I drove
back to Palmyra. As I pulled up to the house, I could see two small heads
at the front window. Lily and Lacy were standing side by side on the
couch, peering out. The doctors had told Mike and Wendy that it could
take Lacy six to twelve months to get back to where she had been before
the operation, but since July she had made extraordinary progress. “We
thought she’d be a blob for a few months,” Mike said. “But once she
started eating and got her strength back she was straight at it.”
We sat again in the living room. Lacy was pale and skinny, and her
white-blond hair was an inch long. The scar underneath was barely
visible. She was in constant motion, crawling and walking about on her
knees. Sometimes, when she crawled, she dragged the knuckles of her left
hand on the floor. She babbled and squealed, and she said “Yeah” when I
asked her how she was. She helped herself to a bottle of milk and drank
from it while she idled on her knees. She surfed around the furniture and
stood at an activity table in front of me. When I held out my right hand to
her, she wobbled for a second and then grabbed it with her left hand. She
swung her right hand around, placed it on top, paused, and was off again.
Then she sat with her back to me. She kept looking over her right
shoulder to see if I was still there, then looking away. “She’s really silly
all the time,” Mike said.
A month after the operation, Lacy began seeing a physical therapist, an
occupational therapist, and a speech therapist on a regular schedule. The
speech therapist would talk with her face right up against Lacy’s, and
after a few sessions Lacy began moving her mouth to mimic the therapist.
She learned some sign language, and used the sign for “more” a lot at the
dinner table, where she could now eat the same food as her family. She
still had to take the anti-convulsants Tegretol and Keppra twice a day,
and the doctors thought that it would be a year before she could stop. But
22
there had been no more seizures, and, the week before I visited the
Nissleys, Lacy had taken three steps by herself for the first time.
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By early December, Lacy was walking everywhere, and in January the
family returned to Johns Hopkins for a scheduled checkup. In Jallo’s
report, he wrote that Lacy had done beautifully. She had had no seizures,
and she was babbling and walking independently. She was “a happy
child.” Lacy still showed a clear preference for her right side, but he
wrote that he hoped for an improvement in tone and a loosening up on the
left side.
For two months after that, Lacy walked and played, but in March she had
a setback. Wendy put her down for an afternoon nap, and about fifteen
minutes later she had a seizure. Wendy said, “She just woke up, instantly,
with her eyes bulging out.” The seizure lasted a few seconds, and
afterward Lacy rolled over and went to sleep. She woke up happy.
Everything was fine for a few days, but then she had another seizure,
again about fifteen minutes after she had fallen asleep. “We were
shocked,” Wendy said. “Lacy went about seven months without any
seizures. It is disappointing.” The seizures increased steadily—after about
a month, there were a few every day, each lasting five or six seconds.
According to Wendy, Lacy didn’t appear particularly distressed by them,
though occasionally they made her more tired. “We are not sure what the
next step will be,” Wendy said, but she and Mike remained optimistic.
23
For Lacy’s third birthday, they had a big cookout in a rented pavilion at a
local park beside a lake.
When Wendy drove Lacy back to Johns Hopkins, Vining was thrilled
with her general progress. Developmentally, she said, Lacy was fulfilling
expectations, and even the recurrence of the seizures wasn’t unduly
alarming. “They are very mild,” she said. There were no signs of them on
the EEG and they lasted, in total, less than a minute per day. Vining
speculated that Lacy might have outgrown the dosage of one of her antiseizure medications, and she increased it. After a few weeks, however,
there was no improvement; the seizures were lasting longer, and had
begun to show up on the EEG. Vining switched Lacy to a different anticonvulsant, Trileptal. Another possible cause of the problem was the tiny
nub of occipital lobe that Jallo had left in Lacy’s brain during the
operation. I asked Vining whether Lacy would ever need a “redo” to
remove that final piece of the right hemisphere. She explained that only
time would tell. Vining was hopeful that the new drug would solve the
problem. If it didn’t, she said, they would have to think seriously about
going in again. ♦
http://www.chasa.org/hemispherectomy.htm
hemispherectomy
WHAT IS IT?
A hemispherectomy is the surgical removal of one half of the brain.
WHY IS IT DONE?
A hemispherectomy is performed in children who have severe and
intractable seizure disorders. Many of these children do not
respond to seizure medications and/or the Ketogenic Diet. They
often have severe damage to only one side of the brain (although
not always), and may already have paralysis on one side of the
body (hemiparesis). Hemispherectomy is typically performed on
children with Rasmussen's syndrome and on children who were
born with or who have had strokes in early childhood who have
seizures that are difficult to control and, on other children who
experience the early onset of uncontrollable seizures that are
limited to
one side of the brain. However, hemispherectomy is not
necessarily appropriate for everyone with intractable seizure
disorders.
24
WHERE IS IT DONE?
Hemispherectomy should only be done in hospital's that
have top-notch Pediatric Regional Epilepsy Programs by
neurosurgeons who have extensive experience in pediatric
epilepsy surgery.
PREPARING FOR THE SURGERY
A great deal of preparation goes into determining who is a
candidate for a hemispherectomy. Many patients will
be asked to participate in a neuropsychological exam performed
by a neuropsychologist. The exam will gather information about
the patients current cognitive abilities compared to typically
developing peers.
Patients will be required to undergo long term monitoring of their
seizures in order to determine exactly which part of the brain the
seizures are coming from. This is done in a hospital setting where
the patient is monitored for a period of time (usually one week or
more) hooked up to an EEG and video taped at the same time.
This is often referred to Phase 1. If enough information on the
origin of the seizures is located during Phase 1 and the
neurologists are confident they have found where they are coming
from, a decision may be made as to whether the patient is a
candidate for surgery. If, however, they are not confident they have
gathered enough information but feel the patient is still a candidate
for surgery, the patient would be asked to proceed with Phase 2 of
the long
term monitoring.
During Phase 2, the patient undergoes the surgical placement of
EEG leads directly on the surface of the brain. The placement of
the leads takes several hours. The patient then returns to the long
term monitoring unit until enough seizure activity is captured on the
EEG and video tape. Other tests that may take place during Phase
2 include SPECT and PET scans. Once enough data is collected
the patient returns to the operating room to have the leads
removed and the actual surgery takes place. This may be in the
form of a partial or full hemispherectomy. This procedure often
takes five to twelve hours or in some cases even longer. If a partial
hemispherectomy is performed and there is a concern that any
remaining seizures may travel to the opposite
side of the brain, a Corpus Callosum Sectioning may be done to
prevent the spread of seizures from one side of the brain to the
25
other.
RECOVERY
Children are amazingly resilient. Many children who undergo this
type of brain surgery are able to leave the hospital in a week or so.
Some stay longer due to infection or other complications.
REHABILITATION Each child who undergoes a hemispherectomy
requires some amount of rehabilitation. When the left side of the
brain is removed, the right side of the body is affected. When the
right side of the brain is
removed, the left side of the body is affected. Typically, this comes
in the form of paralysis of the arm and often weakness in the leg.
For children who have had strokes prior to the surgery, many
come out as they went in. They may be weaker on their effected
side but with intense PT and OT they can often return to their
baseline. The rehabilitation can take as short as a few weeks or
many months. For those children who did not have any form of
paralysis prior to their surgery, the adjustment to having
a hemiparesis can be more difficult. Many children also require
speech therapy as their language skills can be affected by the
surgery. Children typically continue with therapy even after their
rehab is done. If the occipital lobe is removed during the surgery,
the child will have a visual
field cut.
WHAT TO EXPECT AFTER THE SURGERY For many children a
hemispherectomy can be a life-saving operation that can allow the
child to lead a far more
normal life. Often children are seizure free following the surgery.
However, there are children who continue to have seizures even
after the surgery. Some of these children have damage on both
sides of the brain and the seizure activity continues on the
opposite side of the brain which has not been removed. Or, if a
partial hemispherectomy was preformed, the remaining lobe may
continue to seize. Some children may experience changes in their
behavior (good and bad) since their ability to control their
impulsivity and judgment may be diminished. Many children's
cognitive abilities improve once their brain is no longer seizing and
their meds are removed.
It is important to remember that neurosurgery is inherently risky.
Clearly, the benefits must outweigh the risks. For those children
26
who suffer from intractable seizures, a hemispherectomy can give
them a chance of being seizure free and free of the undesirable
side effects of
anticonvulsants.
FOR MORE INFORMATION
Although there is not a whole lot of information available about
hemispherectomy the following references may be helpful.
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Seizures and Epilepsy in Childhood A Guide for Parents by
John M. Freeman, MD
Seizure Freedom by Leanne Chilton - This book gives you a
good look at living with seizures and undergoing brain
surgery from an adult's point of view.
Life With Half a Brain - An article by Maria L. Chang Science World, November 1998
The Discovery Channel's Discovery Health Program
"Lifeline" often features shows on epilepsy and brain surgery
Many times the best resource for information can be a family,
patient or parent of a child who has undergone a
hemispherectomy. They will have a wealth of information to share
with you about their own experience.
Journal articles
This is the html version of the file http://www.hcrc.ed.ac.uk/cogsci2001/pdf-file
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Page 1
Exploring Neuronal Plasticity: Language Development in Pediatric
Hemispherectomies
Stella de Bode (sdebode@ucla.edu
)
UCLA, Department of Linguistics; 405 Hilgard Ave
27
Los Angeles, CA 90095
Susan Curtiss (scurtiss@ucla.edu
)
UCLA, Department of Linguistics; 405 Hilgard Ave
Los Angeles, CA 90095
Abstract
We investigated the categories of neural plasticity and
the genesis of the neural representation for language in
population of 43 pediatric hemispherectomies. We
have chosen to correlate language outcomes with the
stages of neuronal plasticity rather than age at insult
because of the unavoidable confound between the
latter and etiology (Curtiss and de Bode, submitted).
We argue that by examining the neural substrate for
language
and
language
outcomes
posthemispherectomy, it is possible a) to investigate the
progression
of
neural
representation
from
pluripotential and distributed to localized and
specialized and b) to accurately predict language
outcomes.
Introduction and Rationale
It is still unclear whether neural systems underlying
adult organization for language crucially differ from
their respective counterparts in the young brain.
Though the assumption of complete and rapid
recovery of children after brain lesions has been
abandoned by the majority of researchers, there is no
question that the rate and extent of reorganization in
children differ from adults recovering from similar
insults. The two most obvious hypotheses explaining
this phenomenon make two different sets of
assumptions. First, it is possible that language
representation in a young brain is not identical to its
adult counterpart. Indeed, more diffuse brain
organization of the immature brain is suggested both
28
by recent brain imaging studies and language
acquisition research in clinical and normal
populations ((Dapretto, Woods, & Bookheimer,
2000; Mills, Coffey-Corina, & Neville, 1993;
Papanicolaou, DiScenna, Gillespie, & Aram, 1990).
Under this hypothesis faster recovery rates in
children may be explained by the fact that functional
localization and cortical commitment have not yet
reached their peak, i.e. their adult pattern. An
alternative explanation does not need to assume brain
organization that is different from adults. Empirical
support for this hypothesis is provided by
investigations of childhood acquired aphasia. This
research indicates the presence of adult-like neural
representation for language and similar
consequencies of brain damage in children and adults
(Paquier & Van Dongen, 1998). Thus it is possible
that more efficient reorganization is achieved due to
neural plasticity of a young brain, in other words,
with the help of the same mechanisms that are
already in place guiding and supporting brain
maturation in the first decade of life.
The two accounts need not be mutually exclusive.
It is possible that what seems like wider functional
distribution is, in fact, the reflection of both
exuberant neuronal connectivity and increased
neuronal excitation characteristic of an immature
brain. This suggestion is supported by the findings of
some recent brain imaging studies. Dapretto et al.
(2000) demonstrated that both phonological and
semantic conditions activated similar though not
completely identical areas in adults and children.
Furthermore, cortical areas activated only by specific
linguistic tasks in adults showed reliable activation
during all tasks in children. The authors interpret
these findings in terms of increased functional
specialization with development and redundancy in
the neural system subserving language early in
development. Taking these conclusions one step
further, we suggest that the dichotomy of
‘pluropotential and distributed’versus ‘specialized
and localized’exists only on the functional level.
On the neurobiological level, language representation
29
in children is similar to adults, but this similarity is
masked by diffuse connectivity and exuberant
synaptic proliferation that characterize the young
brain.
For the purpose of this paper we assume that an
innate endowment and cortical representation for
language are present from birth. We also assume that
quantitative differences of an immature cortex lead to
some qualitative differences (such as pluripotential
Page 2
cortex and distributed functional organization in
infants) but represent a developmental continuum
within the framework of similar language
representation in children and adults. What do we
attribute to the processes underlying quantitative
differences between the young and mature brains?
Similar to animal research, morphometric and brain
imaging studies (EEG, glucode metabolism, blood
flow volumes, etc.) in humans imply the presence of
the period of massive overproduction of synapses,
dendritic arbors and exuberant connectivity. This
period, known as the Critical Maturation Period,
leads to the next stage of development - the process
of elimination when neuronal/synaptic numbers,
density, connectivity are adjusted to their respective
adult values. Though there is no complete data
regarding the exact timetables of these events for the
entire brain, it is known, for example, that these
overproduction/adjustment processes in the frontal
lobes continue into adolescence (Huttenlocher, 1993).
The outline of our hypothesis is shown in Table. 1:
Table 1. Rationale for our hypothesis
Young brain
Adult brain
Similar language representation
Neurobiological level
Morphological/Quantitative changes underlying brain maturation
(synaptogenesis, dendrtic proliferation, neuronal volume adjustment)
Functional level
Pluripotential & Specialized &
distributed localized
Methods
30
Subjects consisted of 43 patients who underwent
hemispherectomy for intractable seizures at the
UCLA Medical Center. Etiology was catalogued
according to the following breakdown:
developmental pathology - 28 subjects
(hemimegalencephaly - HM, cortical
dysplasia/multilobar involvement - ML, and prenatal
infarct); acquired pathology - 15 subjects
(Rasmussen’s encephalitis - RE and postnatal
infarct). Postoperative spoken language outcome
was rated based on spontaneous speech samples from
0 = no language to 6 = fluent mature grammar.
Language scores were defined on the basis of stages
in normal language development. The complete
information regarding the breakdown of our
population is shown in Table 3.
Discussion
Based on the animal studies we suggest that the
Critical Maturation Period in humans is limited by
the following thresholds: the lower threshold that is
characterized by the completion of
neuro/morthogenesis and establishment of experience
independent connectivity; and the upper threshold of
the completion of the period of neuronal/synaptic
adjustment. Next, following Greenough et al. (1999)
we assume that the following components underlie
functional and neurological maturation of language:
(1) developmental processes that are insensitive to
experience, i.e. the genetic envelope of
predetermined plasticity; (2) an experience-expectant
period of neuronal plasticity also known as the
Critical Maturation Period; and (3) an experiencedependent period of neuronal plasticity which
underlies the ability to encode new experiences
throughout the lifespan (Table 2). We thus
hypothesized that superimposing effects of specific
etiologies on these developmental stages would allow
for more accurate prediction of language outcomes
following hemispherectomy, since in our model
functional reorganization reflects underlying
neurobiological reorganization.
Our results confirmed our hypothesis in that
postoperative language outcomes correlated with
31
etiology. This would be expected since as shown in
Table 2 different etiologies result in different
potential for recovery (due to timing and extent).
Developmental plasticity, i.e. reinnervation and
neuronal sparing, seem to be more efficient in
etiologies with later onset. In addition, when
pathology disrupts genetically determined processes
(as in hemimegalencephaly and cortical dysplasia)
functional development seems to be particularly
compromised. Thus the best language scores were
found in Rasmussen’s encephalitis and the poorest in
hemimegalencephaly. Moreover, etiology
Page 3
(developmental or acquired) consistently emerged as
a significant variable distinguishing linguistic
outcomes in all statistical analyses. In all cases it was
possible to predict postsurgery language outcomes by
considering the effect of specific etiologies within the
framework of the categories of neural plasticity. It
should be noted that we have deliberately chosen to
relate functional outcomes and the broad
categories/stages of neuronal plasticity instead of
providing direct correlations with age at insult. It is
our belief that in such correlations the confound
between etiology and age at insult is unavoidable
(Curtiss, de Bode and Mathern, submitted).
The rate and quality of neuronal reorganization
reflected in language outcome also confirmed the left
hemisphere’s predisposition to support language,
since children with an isolated right hemisphere had
significantly more problems acquiring/restoring their
language. Importantly, however, though age at
surgery for two of our RE children was as old as 12,
neither of them has remained mute after left
hemispherectomy, suggesting that language
specialization had not yet reached its peak, and
reorganization was still possible. Our preliminary
research also indicates that even in the most severely
compromised cases, language development follows
the normal course of language acquisition albeit on a
prolonged scale. These findings lead us to suggest
that innate language universals are resilient to brain
32
damage, although language representation in the
brain does not seems to be anatomically-bound to the
left hemisphere only.
Table 2. The impact of specific etiologies on the categories of neural
plasticity
Stages/Etiology
Genetic Envelope (innate
constraints specifying
cortex differentiation
including ensembles that
would support languagerelated properties)
Experience-Expectant
Period (=Critical
Maturation Period, inputdependent period of
maximum plasticity)
Experience-Dependent
Period (plasticity
underlying the ability to
incorporate new
experiences throughout the
lifespan)
Normals
normal
birth – 12 years, reduced
vulnerability to injury
normal, life-long
Hemimegalencephaly
affected
increased vulnerability
Cortical Dysplasia
affected-to-normal
variable
Infarct prenatal
affected-to-normal
variable
Infarct postnatal
normal
reduced vulnerability to
injury similar to normals
Rasmussen’s Encephalitis
normal
33
reduced vulnerability to
injury similar to normals
Limited in most cases,
thus lowered FSIQ
Acknowledgements
We are grateful to all the children and their parents
who have graciously agreed to participate in this
study.
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in Atypical Populations (pp. 67-117). New Jersey:
Lawrence Erlbaum.
Outcomes Of Hemispherectomies
http://www.cerebromente.org.br/noticias/hemisferct.htm
Hemispherectomy is a radical operation that involves removing
literally half the brain. It's used in extreme cases, for children who
suffer uncontrollable brain seizures that don't respond to normal
treatments.
Over the past 30 years, 58 such operations were performed on
children at Johns Hopkins. At a recent reunion of patients and
families, they traded stories with doctors and each other about what
their lives are like.
Hopkins neurology professor Eileen Vining, M.D., says it's clear that
removing half of their brains gave them the best chance for a normal
life.
"It leaves them permanently hemiplegic (paralyzed on all or part of
one side of their body)," says Dr. Vining. "The children look as
though they've had a stroke. But all of them can walk, most of them
run, some of them even run races. The little girls do ballet. They're
able to function well from a language point of view even when we
remove the left hemisphere."
Dr. Vining says the operation presents a remarkable mystery: even
with that much brain tissue removed, things like language, memories,
and emotions - our very personalities - seem to remain intact.
The Johns Hopkins University.
Brain picture
http://library.thinkquest.org/C005704/media/brain_hem.gif
http://www.web-us.com/brain/LRBrain.html - VISIT THIS WEBSITE
FOR LEFT – RIGHT DOMINANCE ETC AND QUIZ!!
35
 The hemispherectomy’s resurgence in popularity and development over
the last eight years is largely due to the work of specialist paediatric
neurosurgeons at Johns Hopkins Institute in Baltimore, particularly the
work of John Freeman, a pediatric neurologist who has been at Johns
Hopkins nearly his entire career.
http://www.focusstones.com/images/fs_illust_brain.jpg