Neurosurgeons separating 29-year-old Iranian sisters joined at the head cut through brain tissue millimeter by millimeter today after rerouting a shared vein and stitching in a new one.
The team of doctors also contended with unstable pressure levels inside the twins' fused skulls as they began uncoupling their brains. The risky, marathon procedure _ which could kill both women _ began about 10 p.m. EDT Saturday and could take four days.
The brains of Ladan and Laleh Bijani are separate but stuck together, a Raffles Hospital spokesman said.
"They have to be teased apart very slowly," Dr. Prem Kumar said. "Cut. Teased apart. Cut. Teased apart. In the process, you encounter a lot of blood vessels and other tissues. That's taking a long time."
"Parts of the blood vessel and the brain can be ripped apart if you're not careful," Kumar said, adding surgeons were working "millimeter by millimeter."
Dr. Marc Mayberg, chairman of neurosurgery at the Cleveland Clinic in Ohio, said surgeons could cut viable tissue if the twins' brains are fused together.
"But presumably, in the area where the two brains are touching, there isn't much function emanating from there at the moment, so theoretically one would think you could go through tissue like that," Mayberg said.
The operation was complicated further when the team discovered that the pressure in the twins' brains and circulatory system was fluctuating. Kumar said the fluctuations were within "tolerable levels," but he was not prepared to explain what would happen if that changed.
Mayberg said the pressure fluctuations could be fatal. "If the pressure is due to the fact that there is insufficient drainage from this vein, in either cranium, that could be a life-threatening condition," he said.
On Monday, five neurosurgeons completed one of the most dangerous steps in the surgery by rerouting the shared vein and successfully attaching a vein graft from Ladan Bijani's thigh. The shared vein, thick as a finger, drained blood from the twins' brains to their hearts.
Although a large part of the twins' fused skull was severed in two, the blood vessels will not be disconnected _ and the new vein will not be put to work in Ladan Bijani's head _ until after the brains are separated, Kumar said. Their bodies are otherwise distinct.
The operation could kill one or both of the sisters, but after a lifetime of compromising on everything from when to wake up to what career to pursue, the sisters said they would rather face those dangers than continue living joined. "If God wants us to live the rest of our lives as two separate, independent individuals, we will," Ladan Bijani said.
An international team of 28 doctors and about 100 medical assistants were enlisted for the surgery. The Iranian government said Monday it would pay the nearly $300,000 cost of the operation and care for the twins.
This is the first time surgeons have tried to separate adult craniopagus twins _ siblings born joined at the head. The surgery has been performed successfully since 1952 on infants, whose brains can more easily recover.
Because the operation is a medical first, surgeons have encountered unexpected obstacles not seen in infants. It took longer to cut through portions of their skulls because their older bones were denser than previously believed, Kumar said.
As the procedure dragged on, surgeons tried to get adequate rest, slipping out of the operating room for breaks when their expertise was not needed, Kumar said.
Conjoined twins surgery
Doctors in Singapore are performing a pioneering operation to separate two adult Iranian twin sisters joined at the head.
LATEST SUCCESSFUL SURGERIES ON HEAD-JOINED TWINS:
1987 German boys
1997 Zambian girls
2000 Australian girls
2001 Nepalese girls
2002 Guatemalan girls
FACTS ABOUT CONJOINED ( SIAMESE) TWINS:
Name - From twins Chang/ Eng Bunker, born 1811 in Siam (Thailand)
Statistics - One in every 100,000 births is a conjoined twin
Origin - Single fertilized egg separates only partially, develops in conjoined fetus (always identical twins of same sex, mostly female)
Survival rate: 5% - 25%
Connected: 23% at lower torso
4% at upper torso (head)
73% at mid torso
Source: Raffles Hospital, Conjoined Twins Information, Reuters, CNN, BBC, KRT Photo Service Graphic: Jutta Scheibe, Morten Lyhne