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For the first time, doctors have successfully performed fetal brain surgery to treat a rare blood vessel abnormality that can be fatal to newborns.
Experts said the accomplishment, for a condition known as a vein of Galen malformation (VOGM), is "exciting." But they also cautioned that this is one case, and more research is needed to know whether the prenatal brain procedure is a good strategy.
VOGM is rare, occurring in an estimated 1 in 60,000 births, and is often detected during routine ultrasounds late in pregnancy.
The condition arises when misshapen arteries in the brain make a wrong connection: Instead of sending blood to smaller capillaries that feed the brain and slow down the flow of blood, the arteries connect directly to a large vein that drains blood from the brain back to the heart.
That results in a surge of blood into the vein, which can put enormous stress on a newborn's heart and lungs. (Before birth, conditions in the womb keep that from happening.)
In the most serious cases, newborns can develop heart failure within a couple days of birth, or suffer other dangerous complications such as brain swelling and high blood pressure in the lung arteries.
"About 50% to 60% of newborns will get into trouble right after birth," said Dr. Darren Orbach, co-director of the Cerebrovascular Surgery and Interventions Center at Boston Children's Hospital.
At that point, the standard treatment is a procedure called an embolization: A neurosurgeon inserts a thin, flexible tube called a catheter into an artery in the baby's groin, then threads it up into the brain. From there, special materials -- a "glue" or soft coils -- are injected to close off the artery-to-vein connections and slow down the rush of blood.
But even with treatment, about 40% of those newborns die, Orbach said. Many others are left with serious impairments from their brain injury.
That's an improvement, he noted, from years ago, when severe cases of VOGM were nearly always fatal.
But he and his colleagues at Boston Children's and Brigham and Women's Hospital wanted to see if they could do better -- by intervening with an embolization before birth, to prevent severe complications.
First, Orbach said, they had to find a reliable way to predict, during pregnancy, which newborns would likely go downhill fast. In prior research, they found that the width of a particular fetal brain structure -- viewable on MRI of the pregnant mom -- was such a predictor. Above a certain threshold, it was a near certainty that newborns would rapidly suffer severe problems.
Then they developed the plan for translating standard embolization into a prenatal procedure -- "borrowing" needle-based tactics, Orbach said, from their colleagues who perform fetal heart surgeries.
That involves passing a needle through the uterine wall and, to treat VOGM, through a soft spot in the back of the fetal skull. A "micro-catheter" is advanced through the needle, guided by ultrasound imaging, to perform the embolization.
Reporting in the journal Stroke, the researchers describe their first successful procedure -- on a fetus that was 34 weeks and 2 days old, and had a 99% chance of severe problems after birth.
The procedure itself went off smoothly: Through imaging, the doctors saw an immediate reduction in excess blood flow out of the brain, and a drop-off in the heart's workload. The procedure did cause a premature rupture of membranes, so the baby was delivered two days later, by labor induction.
The newborn suffered no heart problems, and at the age of 6 weeks, is now doing well, Orbach said: She is eating normally, gaining weight, needs no medications and shows no signs of brain injury.
A pediatric cardiologist who was not involved in the case called the results exciting and promising.
As far as heart issues, it's likely the baby is out of the woods, said Dr. Gary Satou, of UCLA Mattel Children's Hospital in Los Angeles.
The longer-term questions, he said, are related to the brain -- including whether the baby will reach developmental milestones in the normal time frame.
The case is only the first in a larger clinical trial that the Boston team is conducting, with oversight from the U.S. Food and Drug Administration (FDA).
"You need data on a larger number of cases before you can draw conclusions," Satou said.
Dr. Colin Derdeyn performs embolizations on newborns with VOGM at University of Iowa Health Care in Iowa City.
He called the fetal procedure "pioneering," and said the outcomes in this first case are encouraging. But he also cautioned on the unknowns.
"Safety issues may crop up in future procedures, and this approach through the veins may not be consistently successful in preventing heart failure," Derdeyn said in an American Heart Association statement.
Orbach said the trial is designed to enroll 20 patients. Safety questions include whether the fetal procedure can trigger brain bleeding or a stroke. It's also unknown, Orbach said, whether some babies will need a repeat embolization after birth.
A broader question down the road is: Can this general tactic be used to treat any other conditions found prenatally?
"We haven't accessed the fetal brain this way before," Orbach said. If it can be done safely, he noted, that would open up questions about delivering medications, or even gene therapies, to the fetal brain.
"But that's looking far into the future," Orbach said.
SOURCES: Darren Orbach, MD, PhD, co-director, Cerebrovascular Surgery and Interventions Center, Boston Children's Hospital, associate professor, radiology, Harvard Medical School, Boston; Gary Satou, MD, director, pediatric echocardiography, and co-director, UCLA Fetal Cardiology Program, UCLA Mattel Children's Hospital, UCLA Medical Center, Los Angeles, and past chairman, congenital cardiac defects committee, American Heart Association, Dallas; American Heart Association, news release, May 2, 2023; Stroke, May 4, 2023, online
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