Longitudinal evolution of Central Nervous System anomalies in fetuses with open spina bifida fetoscopic repair and correlation with neurological outcome.

BACKGROUND: Open spina bifida (OSB) is associated with Central Nervous System anomalies, as abnormal Corpus callosum (CC) and heterotopias. However, the impact of prenatal surgery over these structures remains unclear.

OBJECTIVES: To describe longitudinal changes of Central Nervous System anomalies before and after prenatal OSB repair, and to evaluate their relationship with postnatal neurological outcomes.

STUDY DESIGN: Retrospective cohort study of fetuses with OSB who underwent Percutaneous fetoscopic repair from January 2009 to August 2020. All women had pre- and postsurgical fetal Magnetic Resonance (MR), with an average of one week prior and four weeks after surgery, respectively. We evaluated defect characteristics in the presurgical MR; fetal head biometry, clivus supra-occiput angle, and the presence of structural CNS anomalies, as abnormalities in CC, heterotopias, ventriculomegaly (VMG), and hindbrain herniation (HBH) in both pre- and postsurgical MR. Neurological assessment was performed using the Pediatric Evaluation of Disability Inventory (PEDI) scale in children with 12-months or older, covering three different sections: self-care, mobility, and social/cognitive function.

RESULTS: Forty-six fetuses were evaluated. Pre-and post-surgery MR were performed at a median GA of 25.3 and 30.6 weeks, with a median interval of 0.8 weeks prior surgery, and 4.0 weeks after surgery. There was a 70% reduction in HBH (100% vs. 32.6%, p<0.001), and a normalization of the clivus supra-occiput angle after surgery (55.3 (48.8,61.0) vs. 79.9 (75.2,85.4), p<0.001). No significant increase in abnormal CC (50.0% vs. 58.7%, p=0.157) or heterotopia (10.8% vs. 13.0%, p=0.706) was observed. Ventricular dilation was higher after surgery (15.6 (12.7,18.1) vs. 18.8 (13.7,22.9) mm, p<0.001), with a higher proportion of severe ventricular dilation after surgery (≥15mm) (52.2% vs. 67.4%, p=0.020). Thirty-four children underwent neurological assessment, with 50% presenting a global optimal PEDI result and 100% presenting a normal social/cognitive function. Children with optimal global PEDI presented a lower rate of presurgical anomalies in CC and severe VMG. When analyzed as independent variables to global PEDI scale, the presence of abnormal CC and severe VMG showed an Odds-Ratio of 27.7 (p=0.025, CI 1.53-500.71) for a suboptimal result.

CONCLUSIONS: Prenatal OSB repair did not change the proportion of abnormal CC nor heterotopias after surgery. The combination of presurgical abnormal CC and severe ventricular dilation (≥ 15 mm) is associated with an increased risk of suboptimal neurodevelopment.