Fetal myelomeningocele surgery: Only treating the tip of the iceberg

Implication of chromosomal microarray analysis prior to in-utero repair of fetal open neural tube defect

OBJECTIVE

In-utero repair of open neural tube defects (ONTD) is an accepted treatment option with demonstrated superior outcome for eligible patients. While current guidelines recommend genetic testing by chromosomal microarray analysis (CMA) when a major congenital anomaly is detected prenatally, the requirement for an in-utero repair, based on the Management of Myelomeningocele Study (MOMS) criteria, is a normal karyotype. In this study, we aimed to evaluate if CMA should be recommended as a prerequisite for in-utero ONTD repair.

METHODS

This was a retrospective cohort study of pregnancies complicated by ONTD that underwent laparotomy-assisted fetoscopic repair or open-hysterotomy fetal surgery at a single tertiary center between September 2011 and July 2021. All patients met the MOMS eligibility criteria and had a normal karyotype. In a subset of the pregnancies (n = 77), CMA testing was also conducted. We reviewed the CMA results and divided the cohort into two groups according to whether clinically reportable copy-number variants (CNV) were detected (reportable-CNV group) or not (normal-CMA group). Surgical characteristics, complications, and maternal and early neonatal outcomes were compared between the two groups. The primary outcomes were fetal or neonatal death, hydrocephalus, motor function at 12 months of age and walking status at 30 months of age. Standard parametric and non-parametric statistical tests were employed as appropriate.

RESULTS

During the study period, 146 fetuses with ONTD were eligible for and underwent in-utero repair. CMA results were available for 77 (52.7%) patients. Of those, 65 (84%) had a normal CMA and 12 (16%) had a reportable CNV, two of which were classified as pathogenic. The first case with a pathogenic CNV was diagnosed with a 749-kb central 22q11.21 deletion spanning low-copy-repeat regions B-D of chromosome 22; the second case was diagnosed with a 1.3-Mb interstitial deletion at 1q21.1q21.2. Maternal demographics, clinical characteristics, operative data and postoperative complications were similar between those with normal CMA results and those with reportable CNVs. There were no significant differences in gestational age at delivery or any obstetric and early neonatal outcome between the study groups. Motor function at birth and at 12 months of age, and walking status at 30 months of age, were similar between the two groups.

CONCLUSIONS

Standard diagnostic testing with CMA should be offered when an ONTD is detected prenatally, as this approach has implications for counseling regarding prognosis and recurrence risk. Our results indicate that the presence of a clinically reportable CNV should not a priori affect eligibility for in-utero repair, as overall pregnancy outcome is similar in these cases to that of cases with normal CMA. Nevertheless, significant CMA results will require a case-by-case multidisciplinary discussion to evaluate eligibility. To generalize the conclusion of this single-center series, a larger, multicenter long-term study should be considered. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Resuscitation decisions in fetal myelomeningocele repair should center on parents' values: a counter analysis

In our response to, "Parental request for non-resuscitation in fetal myelomeningocele repair: an analysis of the novel ethical tensions in fetal intervention" by Wolfe and co-authors, we argue that parental authority should guide resuscitation decision-making for a fetus at risk for preterm delivery as a complication of fetal myelomeningocele (fMMC) repair. Due to the elevated morbidity and mortality risks of combined myelomeningocele, extreme prematurity, and fetal hypoxia, parents' values regarding the acceptability of possible outcomes should be elicited and their preferences honored. Ethical decision-making in these situations must also consider the broader context of the fetal-maternal dyad. Innovations in fetoscopic approaches to fMMC repair may pose additional complexity to these resuscitation decisions.

Controversies in Fetal Surgery: Prenatal Repair of Myelomeningocele in the Modern Era

Fetal surgery is a constantly evolving field that showed noticeable progress with the treatment of myelomeningocele (MMC) using prenatal repair. Despite this success, there are ongoing questions regarding the optimal approach for fetal myelomeningocele repair, as well as which patients are eligible. Expansion of the inclusion and exclusion criteria is an important ongoing area of study for myelomeningocele including the recent Management of Myelomeningocele Plus trial. The significant personal and financial burden required of families seeking treatment has likely limited its accessibility to the general population.

Historical Clinical Outcomes of Children with Myelomeningocele Meeting the Criteria for Fetal Surgery: A Retrospective Cohort Survey of Brazilian Patients

OBJECTIVE

 To analyze the historical clinical outcomes of children with myelomeningocele (MMC) meeting the criteria for fetal surgery, but who underwent postnatal primary repair.

METHODS

 Data from children undergoing postnatal MMC repair between January 1995 and January 2015 were collected from the Neurosurgery Outpatient Clinic's medical records. Children were included if they had ≥ 1 year of postoperative follow-up and met the criteria for fetal surgery. The children's data were then stratified according to whether they received a shunt or not. The primary outcome was mortality, and secondary outcomes were educational delays, hospitalization, recurrent urinary tract infections (UTIs), and renal failure.

RESULTS

 Over the 20-year period, 231 children with MMC were followed up. Based on clinical data recorded at the time of birth, 165 (71.4%) qualify of fetal surgery. Of the 165 patients, 136 (82.4%) underwent shunt placement. The mortality rate was 5.1% in the group with shunt and 0% in the group without, relative risk (RR) 3.28 (95% confidence interval, 95% CI, 0.19-55.9). The statistically significant RRs for adverse outcomes in the shunted group were 1.86 (95% CI, 1.01-3.44) for UTI, 30 (95% CI, 1.01-537) for renal failure, and 1.77 (95% CI, 1.09-2.87) for hospitalizations.

CONCLUSION

 Children with MMC qualifying for fetal surgery who underwent shunt placement were more likely to have recurrent UTIs, develop renal failure, and be hospitalized. Since approximately half of the shunt procedures could be avoided by fetal surgery, there is a clinical benefit and a possible financial benefit to the implementation of this technology in our setting.

Fetal myelomeningocele repair: a narrative review of the history, current controversies and future directions

Fetal surgery is a relatively new field of medicine. The purpose of this narrative review is to present the history of how fetal surgery became the standard of care for myelomeningocele (MMC), the current controversies of this treatment, and active areas of research that may change how MMC is treated. Fetal surgery for MMC emerged out of the University of California, San Francisco in the 1980s in the laboratory of Dr. Michael Harrison. Initial research focused on testing the hypothesis that the in utero repair of MMC could improve outcomes in the ovine model. Evidence from this model suggested that in utero repair decreases the secondary damage to the exposed neural tissue and improves post-natal neurologic outcomes, opening the door for human intervention. This was followed by the Management of Myelomeningocele Study (MOMS), which was a multicenter randomized controlled trial comparing the prenatal versus postnatal MMC repair. The MOMS trial was stopped early due to the improved outcomes of the prenatal repair, establishing the open fetal MMC repair as the standard of care. Since the MOMS trial, two primary areas of controversy have arisen: the operative approach and criteria for the repair. The three operative approaches include open, endoscopic and a hybrid approach combining open and endoscopic. Several of the inclusion and exclusion criteria from the MOMS trial have been challenged, to include body mass index, gestational diabetes, other fetal abnormalities, maternal infections and Rh alloimmunization. New areas of research have also emerged, exploring cell based therapies to improve fetal outcomes, alternatives to fetal surgery and alternatives to primary skin closure of the fetus.

Fetal spina bifida: What we tell the parents

Worldwide, about 150 000 infants are born with spina bifida yearly, making this condition one of the most common fetal central nervous system anomalies compatible with life. Over the last decade, major changes have been introduced in the prenatal diagnosis and management of spina bifida. In this review, we provide a brief summary of the current management of fetal spina bifida and present essential information that should be provided to expecting parents when their fetus has been diagnosed with spina bifida. This information is focused around common parental questions, as encountered in our typical clinical practice, to facilitate knowledge translation.

Fetal surgical intervention for myelomeningocele: lessons learned, outcomes, and future implications

Fetal myelomeningocele (fMMC) closure (spina bifida aperta) has become a care option for patients that meet inclusion criteria, but it is clear that fetal intervention, while improving outcomes, is not a cure. This review will: (1) focus on the rationale for fMMC surgery based on preclinical studies and observations that laid the foundation for human pilot studies and a randomized controlled trial; (2) summarize important clinical outcomes; (3) discuss the feasibility, efficacy, and safety of recent developments in fetal surgical techniques and approaches; and (4) highlight future research directions. Given the increased risk of maternal and fetal morbidity associated with prenatal intervention, accompanied by the increasing number of centres performing interventions worldwide, teams involved in the care of these patients need to proceed with caution to maintain technical expertise, competency, and patient safety. Ongoing assessment of durability of the benefits of fMMC surgery, as well as additional refinement of patient selection criteria and counselling, is needed to further improve outcomes and reduce the risks to the mother and fetus. WHAT THIS PAPER ADDS: High-quality prospective studies are needed to broaden the indication for fetal surgery in the general myelomeningocele population. Innovative minimally invasive approaches have had promising results, yet lack comprehensive and robust experimental or clinical evaluation. Important information to help families make informed decisions regarding fetal surgery for myelomeningocele is provided.

An Overview of Contemporary Outcomes in Fetal Cardiac Intervention: A Case for High-Volume Superspecialization?

Fetal cardiac interventions (FCI) offer the opportunity to rescue a fetus at risk of intrauterine death, or more ambitiously to alter disease progression. Most of these fetuses require multiple additional postnatal procedures, and it is difficult to disentangle the effect of the fetal procedure from that of the postnatal management sequence. The true clinical impact of FCI may only be discernible in large-volume institutions that can commit to a standardized postnatal approach and have sufficient case volume to overcome their FCI learning curve.