BALTIMORE, MD--A veteran surgeon at Johns Hopkins has achievedwhat is believed to be the first successful separation ofconjoined twins without resulting neurologic deficits in a28-hour operation in South Africa. The infants are breathing ontheir own, drinking and eating solid food, and apparentlysuffering no brain damage.
Benjamin S. Carson Sr., M.D., director of pediatric neurosurgeryat The Johns Hopkins Hospital, led the team that separated11-month-old Zambian boys Luka and Joseph Banda, who were bornas type 2 vertical craniopagus twins--joined at the head butfacing opposite directions. The separation was performed December 31.
Carson has done two previous conjoined twin separationsurgeries, one in South Africa and one at Hopkins. He creditedthe current success to "surgical rehearsals" with acomputerized, three-dimensional virtual "toolbox" that allowedhim to "see" computerized reconstructions of the twins' brainsin spectacular detail. Holding mock instruments, Carson was ableto peel away layers of brain tissue, probing and separatingblood vessels. "One actually gets all the surface topography inmind and practice before you really do the operation," says Carson.
The virtual toolbox, called BrainBench, was developed by CieMed,a joint project between Hopkins and the National University ofSingapore established in 1994. BrainBench combines manytwo-dimensional images of a patient's brain obtained by CT orMRI into a single, three-dimensional virtual brain. The effectis like recombining slices of bread back into the original loaf.
The workbench station has a computer monitor suspended so itprojects brain images down onto the work area. A physician putson special glasses and looks down through a chest-high glassscreen at the image of the patient's brain. The glasses let thesurgeon see the brain in three dimensions and BrainBench'scomputer program lets the operator manipulate the image of the3-D brain image as in a real operation.
When Carson later operated on the Banda twins, he found thattheir skulls were like one long tube, with no separation betweenone brain and the other. Even though the twins' brains touched,they shared no gray matter. They did, however, share intricateblood vessels, which flowed into each child's brain. Surgeonshad to sever each vessel, decide which boy would receive it, andcreate a new connection for blood flow and drainage.
The surgery was performed at South Africa's Ga-Rankuwa Hospital,30 miles north of Pretoria. Neurosurgeon Sam Mokgokong, whoinvited Carson to lead the team, said the children continue toimprove. The boys will wear helmets to protect their heads frominjury and will undergo reconstructive surgery to form a bonycovering that will create their individual skulls.
"We won't know for certain about the presence or absence ofdeficits until the twins are older," says Carson, "but we arethrilled at their progress so far."
This is the third time that Carson, 46, has separated conjoinedtwins. In 1994, he traveled to South Africa at the invitation ofMokgokong to separate the Makwaeba girls at the Pretoriahospital. The 7-month-old twins, who also were joined at thehead, died within hours of the surgery because they weresymbiotic, sharing heart and kidney functions.
Prior to that, in 1987, Carson and a 70-member team successfullyseparated 7-month-old boys from Germany. The Binder twins werejoined at the backs of their heads and shared the sagittalsuperior sinus, the major blood drainage system of the brain. This was the first time that doctors separated conjoined twinsusing circulatory bypass, induced hypothermia and deliberatecardiac arrest to preserve brain function during surgery. Thechildren survived; however, they were left with severe neurological deficits.
Conjoined twins form when a single fertilized egg fails todivide completely to create two distinct entities. Twins joinedat the head occur approximately once in every 2 million live births.
Materials provided by Johns Hopkins Medical Institutions. Note: Content may be edited for style and length.
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