Hopkins doctor to join 'Siamese team'

March 18, 1994|By Jonathan Bor | Jonathan Bor,Sun Staff Writer

Dr. Benjamin Carson, a Johns Hopkins neurosurgeon, will travel to South Africa next month to join 24 doctors in the separation of Siamese twin girls who are attached at the backs of their heads.

At a press briefing today, Dr. Carson said the twins, who are 6 months old, appear to have separate brains but share a major blood vessel. Most likely, surgeons will have to split the vessel and reconstruct the halves so that each child has a functioning blood supply.

Never before have surgeons successfully divided conjoined twins who share tissue inside the skull. About 60 separations of this type have been performed, and in all cases the children have either died or suffered significant brain damage.

Dr. Carson said yesterday he hoped this operation would succeed because of advanced technology and the superior know-how that comes with experience.

The children, Mahlatse and Nthabiseng Makwaeba, live in a village about 200 miles north of Pretoria. They are black South Africans, daughters of a housewife and an employee of the agriculture department of Lebowa, a black homeland in the racially-divided nation.

Surgery, which can take between 10 and 24 hours, will take place in a teaching hospital of the Medical University of Southern Africa, a bi-racial institution that has trained most of the country's black doctors.

"The doctors involved have done me a great honor by inviting me because frankly, I think they could do it without me," said Dr. Carson, 42, an African-American who is chief of pediatric neurology at Hopkins.

The operation is similar to one performed at Johns Hopkins Hospital in 1987, in which 70 doctors, nurses and specialists separated twin boys from Germany who were conjoined at the backs of their heads. The brothers, Patrick and Benjamin Binder, returned to Germany and are believed to be mentally retarded and living in institutions.

Dr. Carson said yesterday that he has attempted to contact the family over the years to learn of the boys' conditions, but his letters have gone unanswered.

He blamed their mental impairment primarily on brain infections after surgery.

In the upcoming case, however, doctors hope to avoid infection by transplanting sheets of dura -- the leathery material that forms a protective envelope around the brain -- once their brains are separated.

Dura was not available when the Binders were separated.

A team of heart surgeons probably will stop the girls' hearts and lower their body temperatures -- placing them in a form of suspended animation -- before they divide and reconstruct the blood vessel.

Once the girls are separated, doctors will restore body temperature and blood flow, cover the exposed brain tissue with dura, then close the scalp using flaps of skin from the girls' backs.

At a later date, surgeons will use a titanium mesh to replace the circular piece of skull removed from each girl's head.

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