Surgery's success depends largely on conjoined twins' anatomy

<br>LOS ANGELES (AP) _ The surgery to separate Guatemalan twin girls this week was an apparent success in part because the two did not share a brain, which one doctor called ``a great blessing.''

Friday, August 9th 2002, 12:00 am

By: News On 6

LOS ANGELES (AP) _ The surgery to separate Guatemalan twin girls this week was an apparent success in part because the two did not share a brain, which one doctor called ``a great blessing.''

Maria Teresa and Maria de Jesus Quiej Alvarez were connected at the head by bone, skin and blood vessels, but did not share brain tissue, as some conjoined twins do. That increased their odds of surviving without neurological damage.

In such rare surgeries, that is a key factor and is the reason another pair awaiting surgery may not fare as well.

Egyptian brothers Ahmed and Mohammed Ibrahim are awaiting the surgery at North Texas Hospital for Children in Dallas. Computerized tomography, or CT, scans indicate the boys' brains are not completely separated.

``They will have some deficit, depending on what is shared,'' said pediatric neurosurgeon Dr. Marion L. Walker, a veteran of three similar surgeries who was consulted by his peers at UCLA Medical Center where the Guatemalan girls are hospitalized.

Of all cases of conjoined twins _ there are about 40 born in the United States each year _ those attached at the skull are the rarest. And the surgery to separate them is the riskiest.

Since the cranial operation was first successfully performed in 1952, at least 34 pairs of twins joined at the head have undergone surgery to be separated. About half the twins did not survive, according to a review of medical literature and news reports.

``It is by far the most difficult of all the operations to separate conjoined twins and is probably the most hazardous of all pediatric neurological procedures,'' said Dr. Jeffrey Wisoff of the New York University Medical Center.

Complicating the surgery is the degree to which twins often share brain tissue. During surgery, one of the twins must lose the shared portion, although it can be lost to both depending on what damage it sustains.

Doctors, and conjoined twins who consider the surgery later in life, are aware of the risks.

Twenty-seven-year-old twins from Iran, Laleh and Ladan Bijani, are seeking international help to surgically separate their joined heads. The risks are greater because the sisters have fully grown skulls and brains. They also share an artery that supplies blood to their brains.

Physicians said separation surgery could be fatal for one or both.

Asked if one of them was ready to die for the other, Laleh told The Associated Press earlier this year: ``We have waited for 27 years because we didn't want to choose such a difficult option.''

In the case of the 1-year-old Guatemalan girls, brain tissue was not shared but they did have a web of blood vessels in common. Dividing and rerouting the vessels proved the riskiest part of the 22-hour surgery at the University of California, Los Angeles Medical Center.

The delicate work put both twins at risk of stroke had blood backed up during surgery, said UCLA neurosurgeon Dr. John Frazee.

``The most important veins were those at the back of the head. If we didn't divide those vessels properly, we could have permanently and severely damaged tissue responsible for vision, motion and the potential for language,'' Frazee said.

Exhaustive preparations contributed to the surgery's success, doctors said. They mapped the girls' heads in three dimensions and constructed models that allowed them to chart their every incision, as well as contingency plans.

``It turns out all our calculations worked,'' Dr. Henry Kawamoto Jr., a plastic and reconstructive surgeon, said in an interview following the surgery. ``We didn't have to go to Plan B. It went beautifully.''