Clinical presentation of hydrocephalus following prenatal and postnatal myelomeningocele repair: a Hydrocephalus Clinical Research Network study

Introduction: Differences in timing and presentation of hydrocephalus following prenatal and postnatal myelomeningocele (MMC) repair are not well-characterized. This study aimed to determine how age, head size, and ventricular size differ at hydrocephalus presentation in patients treated with prenatal and postnatal MMC repair.

Methods: The Hydrocephalus Clinical Research Network Core Data Project was queried to identify MMC patients who received prenatal or postnatal surgery requiring permanent CSF diversion by either shunting or an endoscopic third ventriculostomy (ETV), with or without choroid plexus cauterization (CPC), from April 2008-December 2023. The primary variable of interest was age at primary CSF diversion procedure. Secondary variables of interest included absolute head circumference (HC), HC percentile, and fronto-occipital horn ratio (FOHR).

Results: 1044 patients from 14 centers were included; 125 (12%) underwent prenatal MMC repair and 919 (88%) underwent postnatal MMC closure. Median age at primary CSF diversion procedure was 4.1 months in the prenatal repair cohort versus 0.6 months in the postnatal closure cohort (p < 0.001). Absolute HC (45.0 cm versus 38.0 cm, p< 0.001), HC percentile (100.0 versus 97.0, p< 0.001), and FOHR (0.60 versus 0.56, p< 0.001) were greater in the prenatal versus postnatal repair cohort. Linear mixed models adjusting for treatment site revealed that MMC patients treated prenatally underwent CSF diversion 3.75 months (95% CI 1.17-6.33; p< 0.001) later and had greater HC percentiles (+13.01%; 95% CI 7.80-18.22; p< 0.001) but similar FOHRs (-0.77; 95% CI –4.67-3.14; p=0.700) to those treated postnatally.

Conclusion : Patients developing hydrocephalus following prenatal MMC repair undergo CSF diversion later and have larger heads than those developing hydrocephalus following postnatal MMC closure; however, FOHRs are similar between groups. The disparity between HC and FOHRs may suggest increased brain parenchymal and/or extra-axial volume in children receiving prenatal MMC repair, although further study is required. These results have implications on follow-up timing for MMC patients.