Complications hit twins' surgery
(CNN) -- The operation to separate two conjoined Iranian sisters will take longer than expected with surgeons battling against unstable blood pressure levels as they slowly split apart the twins' fused brain.
The complicated and delicate process of paring apart the brains of 29-year-old Laden and Laleh Bijani -- who are joined at the head -- began late Monday, said Dr. Prem Kumar Nair, a spokesman for Raffles Hospital in Singapore where the operation is taking place.
Separating them is one of the most challenging parts of the surgery, dubbed "Operation Hope."
"As we have found with the skull bones, the two brains have been found to be very adherent to each other," Nair said.
"Although the brains are distinctly separate, because they have been fused for the last 29 years, they are very adherent to each other. Dissection to separate them is thus taking a long time," he told a press conference.
Earlier, surgeons completed the process of rerouting a large vein that serves both their brains, a critical stage in the long, difficult procedure that began on Sunday and is expected to last days.
An international team of neurosurgeons, dozens of doctors, plus support staff created a bypass for Ladan, using a vein grafted from her leg.
This caused another complication, Nair said, as blood circulation between the twins became unstable.
But fluctuations in pressure were still within "acceptable levels," Nair said.
More hurdles ahead
Opening the skulls and forming the bypass formed the first major stage of the operation.
The next stage involved severing blood vessels and veins around the brains.
Then, neurosurgeons began the slow process of carefully cutting through the sisters' brain tissue.
In a statement, the hospital said dissection to separate the brains "is taking a long time because neurosurgeons have to carefully cut through the tissues millimeter by millimeter."
The bypass was considered one of the most risky aspects of the surgery which could prove fatal to one or both of the twins. The sisters, both law graduates, said they were willing to accept the risks and face those dangers to lead separate lives.
But Nair warned of further hurdles ahead.
"That was one tough part of the surgery, the other tough part is the actual separation of the brain. At the end of the day we are trying to achieve separation," he said.
The operation is a landmark procedure. Although Singapore doctors performed a similar operation in 2001 on infant Nepalese girls, surgery on adult twins is unprecedented.
The operation is more difficult in adults than in children, who have more recuperative powers.
Twins joined at the head are the rarest of conjoined twins, occurring one in every 2 million births. Twins joined elsewhere occur once in every 100,000 births.
The Bijanis' operation is considered elective because the women likely would live a normal life span without it.
However, testing has shown the sisters have high intracranial pressure, which, if untreated, could cause frequent debilitating migraines and impaired vision as well as deteriorating brain function, the hospital said.
The sisters have made an impression on Singapore's public, in part because of their cheerful demeanor before the operation. Cards, flowers, and offers of support have been sent to the hospital from around the world.
The hospital is paying for pre-operative fees and the medical costs involved in operation. The operating surgeons are waving their professional fees. The government of Iran said Monday it will pay $300,000 for post-operative care.
-- CNN Medical Correspondent Dr. Sanjay Gupta and Journalist Michael Dwyer contributed to this report.