Fetal surgery for myelomeningocele: After the Management of Myelomeningocele Study (MOMS)

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Abstract

Myelomeningocele (MMC) is the most frequently occurring congenital abnormality of the central nervous system and leads to significant physical disabilities. Historically treatment involved postnatal closure with management of the associated sequelae including ventricular shunting. The mechanism of neurologic damage that begins with abnormal neurulation followed by continued injury over the course of gestation made MMC a plausible candidate for in-utero surgical repair. Animal and early human studies demonstrated the feasibility of fetal closure. The benefit of in-utero closure was debated until the results of the prospective randomized multicenter Management of Myelomeningocele Study (MOMS trial) were published, demonstrating a decreased need for shunting, reversal of hindbrain herniation, and better neurologic function in the prenatal repair group compared to postnatal repair with maternal complications and prematurity as a trade-off. As such, fetal MMC closure has become a standard of care option for prenatally diagnosed spina bifida. This paper reviews the MOMS trial and the journey of fetal MMC closure since that time.

Section snippets

Background and significance of the MOMS trial

Myelomeningocele (MMC), the most frequently occurring congenital abnormality of the central nervous system, occurs due to failure of the neural tube to close in the first four weeks after conception and is characterized by a fluid-filled sac containing an exposed spinal cord and nerves. The consequence of an open neural tube defect is abnormal development of the central nervous system, resulting in hydrocephaly, hindbrain herniation, and neural elements that become damaged from exposure to the

The MOMS trial

The MOMS trial was a prospective, multicenter randomized trial comparing prenatal and postnatal myelomeningocele closure sponsored by the National Institutes of Health [31]. Three fetal surgery centers performed the clinical care (CHOP, Vanderbilt University, and University of California, San Francisco), while George Washington University served as the Data and Study Coordinating Center (DSCC). Patients were initially referred to the DSCC to determine potential candidacy in the MOMS trial.

Post-MOMS trial results at CHOP

Since the MOMS trial concluded, we have performed more than 190 fetal MMC closures at CHOP. Maternal and neonatal outcomes for the first 100 cases have been published with outcomes similar to those of the MOMS trial [35]. These data in comparison with MOMS trial outcomes are presented in Table 1 [31], [35]. The proportion of women referred for fetal MMC repair, deemed appropriate candidates and accepting fetal surgery, was 17.7%. Similarly, of the initial 1087 women who underwent screening for

Technique for open fetal surgery for MMC – modifications and improvements since the MOMS trial

In general, centers performing in-utero MMC repair follow perioperative management and utilize surgical techniques similar to those used in the MOMS trial. Typically anesthesia involves a combination of general and epidural anesthesia. The epidural serves a dual function of postoperative pain management. The laparotomy is performed according to surgeon's preference, either low transverse or vertical with placental position playing a role in preoperative planning. For example, in the case of an

Challenges in the post-MOMS era

Since the publication of the MOMS trial, fetal MMC repair has become a standard of care option for prenatally diagnosed spina bifida [39]. As such, the demand has increased and the number of centers performing the procedure has increased. The ability to perform fetal MMC repair outside the rigors of a trial has been in question, as was raised in the editorial accompanying the MOMS trial [40]. Subsequently a position statement was published to create guidelines for centers beginning to perform

Conclusion

Open fetal surgery for fetal MMC closure has become a standard of care treatment option for pregnancies complicated with spina bifida. This procedure is associated with decreased risk for shunting, reversal of hindbrain herniation and improved neurologic outcomes with an increase in maternal complications and prematurity. Continued research endeavors should include outcomes assessment and innovation to optimize minimally invasive techniques. Optimization of patient selection criteria and

Practice points

  • •

    Open fetal MMC repair is associated with decreased need for shunting, reversal of hindbrain herniation, and improved motor outcomes.

  • •

    Risks associated with open fetal MMC repair include preterm labor, spontaneous rupture of membranes, oligohydramnios, and membrane separation, all of which may lead to preterm delivery.

  • •

    Hysterotomy in open fetal MMC repair is performed in the fundus and is associated with an increased risk of uterine rupture or dehiscence in the index pregnancy and any subsequent

Research directions

  • •

    Continuing development of minimally invasive techniques including tissue engineering approaches.

  • •

    Further evaluation of factors associated with optimum patient selection criteria.

  • •

    Outcomes monitoring across multiple centers.

Conflict of interest statement

None declared.

Funding sources

None.

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