211. Prenatal Closure of Myelomeningocele Reduces Chiari Associated Brainstem Dysfunction

Authors: Paige Lundy, MD; Paul Grabb, MD; Emmanuel Vlastos, MD (Kansas City, KS)

Introduction:Prenatal closure of myelomeningoceles reduces the anatomic severity of Chiari II malformations versus postnatal closure.  Translating anatomic change into functional outcome, however, has not been shown.  Symptom frequency ascribed to the brainstem has not been through to differ between groups.  Severity of these symptoms between groups however, has not been addressed. 

Methods:We reviewed imaging and records for Chiari malformation anatomic and functional severity, ventricular size, myelomeningocele level, and clinical course of neonates repaired either prenatally (n=13) or postnatally (n=45) over four years.

Results:Twelve neonates (27%) in the postnatal group had significant functional Chiari symptoms within the first month of life, as defined by: neurogenic dysphagia requiring gastrostomy, airway protection, and respiratory insufficiency requiring tracheostomy, vocal cord surgery, or repeated admission with intubation.  Anatomically, two had “mild”, six had “moderate”, and four had “severe” Chiari malformation. No child with significant Chiari symptoms had absence of Chiari malformation on imaging.  Two underwent Chiari decompressions without improvement. None with prenatal closure experienced significant “Chiari symptoms”, or anatomically had moderate or severe Chiari malformations.  Shunts were placed in 64% and 8% of the postnatal and prenatal groups, respectively. Endoscopic techniques were employed in four infants, two in each group.  Ventricular sizes at birth were a median of 16mm and 19mm for prenatally and postnatally closed neonates, respectively.  Median gestational ages were 36.6 and 38 weeks, for prenatal and postnatal closures, respectively.  Median and mean functional myelomeningocele levels were nearly identical for both groups at L4.

Conclusion:Despite historical autopsy findings of disorganized brainstem nuclei in this population and more recent publications that broadly address any apnea ascribed to the Chiari malformation as not influenced by timing of repair, we found prenatal repair is associated with reduction in significant physiology dysfunction traditionally ascribed to the Chiari malformation and brainstem in these neonates.