Goh and other members of the medical team said the surgery took so long because they had to deal with hundreds of interwoven blood vessels in the girls' brains. Before the surgery, doctors rehearsed the procedure in virtual reality using a three-dimensional imaging system developed in Singapore. The system, called VizDExter, was first used in 1998 by doctors at John Hopkins University in Baltimore, Maryland, said Dr. Luis Serra, a Singapore-based researcher who helped develop the technology. Serra told The Associated Press on Tuesday that the Singapore doctors used the 3-D images to consult with a Johns Hopkins' Siamese twins expert, Dr. Benjamin Carson, before separating Ganga and Jamuna. Siamese twins joined at the head are very rare, occurring once in 2 million live births, according to Goh.
Successful separations are even more uncommon.
A similar operation was successfully performed in South Africa in 1997. Ganga and Jamuna, the twins in the Singapore surgery, are the only children of a poor couple from the remote Nepalese mountain village of Khalanga, where Maoist guerrillas are active. Doctors say the girls have distinct personalities. Ganga, who has a cleft palate, is feistier and always hungry, while Jamuna is more shy. The girls' mother, Sandhya, is a kindergarten teacher and their father, Bushan, helps his father in a small business.