Q: What was the longest operation ever?

A: Actually, the longest surgery on record occurred in 2001 and lasted more than four straight days—103 hours to be exact. A team of 20 doctors at Singapore General Hospital worked in shifts to separate Ganga and Jamuna Shrestha, 11-month-old twins conjoined at the head. Not only did the girls share a cranial cavity, their brains were partially fused. Typically such separation procedures might take 30 hours—still an eternity in surgical terms—but once underway, doctors discovered that the girls' brains were even more tightly enmeshed than expected.

"When we were planning the surgery, we did not expect it to last so long," says Dr. Keith Goh, who led the operation. "During the course of the surgery, we found that the two brains were so closely adherent to each other that we had to individually coagulate, separate, and divide the blood vessels that were going between the two brains and all the brain tissue that was adherent." He's talking about hundreds of tiny blood vessels, each of which had to be traced and identified as belonging to one or the other of the girls. Moreover, the girls' brains were not merely connected, they were wrapped around each other like a helix, adding to the complexity. And in the end, each twin's skull needed to be refashioned, using a blend of bone material and Gore-Tex fibers.

The surgery was facilitated by computer-imaging technology that allowed surgeons to create 3D scans of the sisters' brains and to rehearse in advance. As a side note, neurosurgeon and sometime presidential aspirant Ben Carson, a pioneer in the field, served as an advisor to the team.

Most important, perhaps, the operation was a success: Though Ganga contracted meningitis seven years afterward and passed away, Jamuna is now 15, alert and well, and can talk, sing, and attend school.

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