NICHD Study Update: Does Prenatal Surgery of Myelomeningocele Improve Motor Development Beyond 2 Years Follow-Up?

BACKGROUND AND PURPOSE: 

• The initial report of the NICHD prenatal myelomeningocele study demonstrated improvement in the following   
  • Decreased hindbrain herniation and consequent need for shunting and improved distal neurologic function 
• Long-term outcomes have confirmed shunting benefit but data on neurologic and motor function outcomes were lacking  
• Farmer et al. (Am J Obstet Gynecol., 2018) report the 30-month outcomes for the entire cohort of patients randomized to either prenatal or postnatal repair of myelomeningocele 

METHODS: 

• Follow-up analyses of NICHD sponsored Management of Myelomeningocele Study 
• Women had been randomly assigned to undergo 
  • Standard postnatal repair 
  • Prenatal repair at <26 weeks gestation 
• Primary outcome of the study was a composite of mental development and motor function outcome at 30 days  
• Secondary outcomes 
  • Independent ambulation and the Bayley Sales of Infant Development (2nd edition) 
• Effects and Subgroups
  • Fetal leg movements 
  • Ventricle size 
  • Presence of hindbrain herniation 
  • Gender  
  • Location of the myelomeningocele lesion 
• Within the prenatal surgery group only, these and other baseline parameters were evaluated as predictors of 30-month motor and cognitive outcomes 
• Researchers also assessed if the presence or absence of a shunt at 1 year was associated with 30-month motor outcomes 

RESULTS: 

• Data from 183 subjects were analyzed  
• Prenatal repair improved the primary outcome  
  • Composite score of mental development and motor function was 199.4 ± 80.5 vs 166.7 ± 76.7 (P=.004) 
• Prenatal surgery resulted in improvements in the secondary outcomes of 
  • Independent ambulation (44.8% vs 23.9%, P=.004) 
  • Self-care score (20.8 vs 19.0, P=.006) 
  • Mean Bayley Scales of Infant Development, psychomotor development index (17.3% vs 15.1%, P=.03) 
• Prenatal surgery did not affect cognitive development at 30 months 
• Boys demonstrated slightly better improvement in functional level and psychomotor development index 
• Independent ambulation was associated with 
  • Patients receiving prenatal surgery 
  • The presence of in utero ankle, knee, and hip movement 
  • Absence of a sac over the lesion and a myelomeningocele lesion ≤L3  
• Postnatal motor function showed no correlation with either prenatal ventricular size or postnatal shunt placement 

CONCLUSION: 

• The full cohort data of 30-month cognitive development and motor function supported previous findings 
• Prenatal surgery of myelomeningocele improved motor function, mental development, independent ambulation, self care score 
• Indicators of independent ambulation were identified including presence of in utero joint movement and absence of sac over the lesion and a lesion ≤L3.  
• Future research should focus on longer-term follow up to school age  
• This study did not use fetoscopic methods, which also awaits further research  
  • Primary benefit of fetoscopy would be to avoid requirement for cesarean section
• The ACOG / SMFM Committee Opinion states

Open maternal–fetal surgery for myelomeningocele repair has been demonstrated to improve a number of important pediatric outcomes at the expense of procedure-associated maternal and fetal risks.

Women with pregnancies complicated by fetal myelomeningocele who meet established criteria for in utero repair should be counseled in nondirective fashion regarding all management options, including the possibility of open maternal–fetal surgery.

Interested candidates for fetal myelomeningocele repair should be referred for further assessment and consultation to a fetal therapy center that offers this intervention and possesses the expertise, multi-disciplinary team, services, and facilities to provide detailed information regarding maternal–fetal surgery and the intensive care required for patients who choose to undergo open maternal–fetal surgery.  

Learn More – Primary Sources: 

The Management of Myelomeningocele Study: full cohort 30-month pediatric outcomes.

ACOG SMFM Committee Opinion 720: Maternal–Fetal Surgery for Myelomeningocele