In-Utero Spina Bifida Surgery Restores Brain Structure

A new study suggests that prenatal surgical restoration of myelomeningocele (MMC) hindbrain herniation triggers restoration of normal brain anatomy.

Researchers at the Mayo Clinic (Rochester, MN, USA) reported the outcomes of three consecutive patients with prenatally diagnosed MMC confirmed upon referral between 20 and 21 weeks' gestation via fetal ultrasound and magnetic resonance imaging (MRI). Fetal intervention was offered between 19 and 27 weeks of gestation, with MRI scans performed six weeks after surgery, while the babies were in the womb. The main outcome was prenatal improvement of hindbrain herniation, and obstetrical and perinatal outcomes were also assessed.

The babies were delivered at 37 weeks via cesarean section, with no complications. The results revealed that brain structure had been restored in each baby before birth. None of the babies needed a shunt to drain fluid from the brain after birth, and each baby was discharged from the hospital within three days. Subsequent postnatal follow-ups were unremarkable at both 11 months (baby 1) and three months of age (baby 2), with only mild ventriculomegaly. Antenatal and postnatal follow-up of baby three at one month of age was also unremarkable. The study was published in the April 2020 issue of Mayo Clinical Proceeding.

"Our hypothesis is if we closed the spinal defect in utero, we could prevent inflammation and trauma to the nerves, and most importantly stop the leakage of brain fluid through the base of the skull,” said lead author Rodrigo Ruano, MD, PhD, chair of the Division of Maternal and Fetal Medicine. “We discovered the main benefit of this procedure is not only to close the spine, but the most important thing is to improve the brain structure and the brain anatomy. We can regenerate the brain structure so that it comes back to better development.”

Spina bifida is a birth defect that occurs due to failure of the spinal column to form completely around the spinal cord, leaving part of it exposed. The most severe form is MME, when the spinal cord and the meninges (the tissue that covers the spinal cord) protrude through the spinal column. If the protrusion is large enough, it can block the flow of the cerebrospinal fluid (CSF). If severe enough, it can draw the lowest part of the brain into the opening at the base of the skull, a condition called hindbrain herniation.

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