Arnold–Chiari Malformations in Pediatric Patients After Fetal Surgery for Meningomyelocele

(1) <b>Background</b>: Fetal surgery for meningomyelocele (MMC) should reduce the occurrence of Arnold-Chiari malformations, hydrocephalus, the associated need for craniocervical decompression, and the need for cerebrospinal fluid shunt insertion. Fetal surgery should improve ambulatory status. (2) <b>Methods</b>: We used retrospective analysis of the documentation and descriptive statistics to summarize the clinical data and measured MRI parameters. The neurosurgical results are presented as the frequency of findings in percentages and compared with the results of the Management of Myelomeningocele Study (MOMS). (3) <b>Results</b>: A total of eight patients who underwent prenatal correction of MMC between 2016 and 2020 participated. MRI detected Chiari II malformation in all patients during prenatal imaging and in 87.5% of the patients at the age of 12 months. Craniocervical decompression was used in 25% of the patients. Shunt-dependent hydrocephalus occurred in 50% of the cases. In 87.5% of the cases, the functional level exceeded the expected ambulatory status. (4) <b>Conclusions</b>: We present the clinical status of our patients. Analysis of the complete cohort confirmed that prenatal surgery is associated with a reduced occurrence of Chiari malformations and reduced associated occurrence of hydrocephalus. Specific lesion levels are not associated with the need for craniocervical decompression. The results of our study are valuable in prenatal counseling and important for treatment planning.