(Reuters Health) - Twin baby girls joined at the head who were separated on June 6, 2017, are continuing their recovery, with one showing some developmental delays compared with her sister, according to an update of the case that also provides details of the techniques used in the surgery.
The surgical team at Children's Hospital of Philadelphia used a 3D printer and special rings to gradually separate the girls' brains before undertaking the 11-hour operation that gave Erin and Abby Delaney lives of their own at the age of 10 months.
At age 21 months, Erin could sit independently, verbally identify both parents, manipulate objects and had normal strength and muscle tone. "She was expected to continue to have a slightly delayed but otherwise normal developmental course," the Philadelphia team reports in the New England Journal of Medicine.
Abby experienced more complications after the surgery and "was expected to have more neurocognitive difficulties than her sister, but she continued to have developmental gains," they write. She doesn't seem to be as ambidextrous as most children that age, she was beginning to sit independently and she verbally identified one parent.
Formal cognitive testing has not been done, lead author and neurosurgeon Dr. Gregory Heuer told Reuters Health in a telephone interview, but "early on what we worry more about is motor delays. So far they've exceeded the expectations. They're having this continual increase in their development. In fact, the one twin who was a little behind her sister is making more rapid gains, which is a good sign for us."
Abby's case was more complicated, in part because the girls shared a large vein that sends blood from the brain back to heart. But in her case, some of the deeper veins that help in that purpose had remodeled themselves to compensate.
Both girls have been with their parents in Mooresville, N.C., since just before Thanksgiving 2017. They continue to be followed by nutritionists, developmental pediatricians and other specialists.
A hospital spokeswoman was unable to produce an estimate of how much it cost to separate the girls.
Having twins joined at the head occurs in 1 out of every 1.7 million births. Having the connection extend into the brain tissue is rarer still. The surgery was done before the girls' first birthday because the infant brain tends to be more adaptable and better able to regenerate.
Before the separation operation, surgeons cut the fused part of the skull that joined the babies. They also created ring-like devices that fit on their heads and gradually pushed the girls apart at a rate of 2 millimeters per day for several months starting when the girls were 3 months old. This technique also helped reorient the girls, born with their heads connected at an angle, to straighten them out and make the surgery easier.
Plastic models fashioned by 3-D printing techniques helped Heuer and his team plan their surgery, particularly the fact that the twins shared that key blood vessel and a small portion of the brain's frontal lobe.
Heuer said that in retrospect, there are a few things he might have done differently, such as pushing the twins' heads apart more slowly.
"The problem is, every twin is connected in a different way, so some of the lessons we learned here will be applicable and some won't," he said.
In two or three years, the girls will need more surgery to cover the openings in their skulls that remain after the separation surgery.
But even at this point, said Dr. Heuer, "their lives have changed and we're proud of that, in that before they could never give each other a hug or hold each other. I'd like to think this surgery has had a big impact on their life, in a good way."
SOURCE: https://bit.ly/2MqGb2D The New England Journal of Medicine, online January 23, 2019.