MOMS Trial (Management of Myelomeningocele Study): In-utero Spina Bifida Repair

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By Mary J. Dufton

Dr. James Drake provided an  overview of an exciting  breakthrough of the past year, the Management of Mylomenginocele (MOMS) trial, which was published in the New England Journal of Medicine in March 2011.   The MOMS trial compared two approaches to the treatment of babies with spina bifida mylomenginocele: surgery on the baby in the womb at the gestational age of approximately 24 weeks with a second cesarian section at term ( or as close as possible to it); and the usual standard surgery for myelomeningocele after the baby is born.

The study compared several important outcomes.  The first outcome was whether or not the mother and baby survived and whether or not the baby needed a shunt.   The secondary  outcomes examined the baby’s spinal cord level functioning compared to the anatomical bony level on the lower spine, their level of functioning developmentally and whether or not they were ambulatory. 

Magnetic Resonance Imaging (MRI) has been a very useful tool in the trial because it provided important detail in examining the status of the foetus and the pregnancy.  The degree of Chairi malformation, the size of the ventricles, the organ structures and the myelomeningocele can all be seen on the MRI.

The trial, which began in 2001, was very carefully conducted.  It was meant to happen over two years, but it took ten because it was not easy to recruit patients.  The mothers had to go to one of the three trial centres and stay there if they received the in-utero repair.  

While 1,037 families were screened, only 187 were entered into the trial. Having a body mass index was over a certain level excluded 230 patients.  Some decided not t to proceed once they were told about the risks.  And there may have also been some more abnormalities or conditions that weren’t recognized before the MRI.

The patient groups were very well balanced.  The infants receiving the in-utero repair had slightly higher lesions, which were expected to have a slightly worse outcome.  Because the in utero surgery infants were born prematurely, their birth weights were lower.   They also had a higher incidence of respiratory distress, which is common in premature babies; however that didn’t seem to have any dramatic adverse effects.  Of the infants operated on before birth, there were two deaths but they were unrelated to this treatment.

There were significant differences in the shunt rate of the infants treated before birth compared to those carried to term.   The shunt rate was 40 per cent in the patients that were treated with in-utero surgery and 82 per cent in patients who were carried to term. Imaging  performed on the infants predicted whether or not they needed a shunt.   A committee determined that 96 per cent of the patients carried to term should have had a shunt whereas 64 per cent of the in-utero group should have a shunt. 

The Chiari malformation in the patients receiving the in-utero surgery was reduced and there was also improved mobility in the lower extremities.  At thirty months, 42 per cent of the in-utero group were walking versus 20 per cent in the group that were carried to term.

Although the results are promising, it is important to be cautious.  There are still some significant risks for the infant and the mother, and the use of less invasive approaches should be investigated.

What's next?  A meeting will be held to discuss the issues further and particularly, treatment options for patients across Canada and within North America.  Patients can be referred to the United States where there are the three centres that participated in the trial.  There is definitely a need for probably one  Canadian centre to offer this treatment.

Experts are needed in both foetal surgery and in the management of high-risk pregnancies.  The paediatric neurosurgery part is less important, because it's a fairly standard operation.  The issues of obstetrics and anaesthetics seem to be much more important.  And it is critical to reduce the complications for the mother.

A National Institute of Health meeting was held in October to discuss the issue, within the United States, about where the surgery should be done, by whom and the physicians who will be responsible for the patients.  In his concluding remarks Dr Drake said, “I think we all believe that there is good application for improved technology to make this operation better and less risk to the mother.”