Spontaneous closure of myelomeningocele.

Fetal repair of myelomeningocele has been increasingly offered to mothers of children with myelomeningocele after the seminal Management of Myelomeningocele (MOMs) trial, which demonstrated decreased reliance on ventriculoperitoneal shunt following fetal closure. We present the case of a fetus diagnosed with a lumbar myelomeningocele in utero whose mother refused in utero closure and who was subsequently born with a skin-covered defect. A fetal MRI was obtained on a mother with a male fetus diagnosed with open neural tube defect at 20 weeks of gestation. The child demonstrated spinal dysraphism extending from L2 to L5 and associated Chiari II malformation with lateral and third ventriculomegaly. Based on our institutional criteria and the criteria of the MOMs trial, the parents were offered fetal repair of the myelomeningocele; however, they declined because of concerns about risks to the mother. At birth, the patient was found to have a skin-covered meningocele. He underwent elective repair of his occult meningocele and detethering of his spinal cord. Intraoperative findings demonstrated spinal nerve roots attached to the arachnoid within the defect, and a closed, tubularized neural placode. This represents a unique case in which a fetus with a clinical picture consistent with open spinal defect was found to have a lesion more consistent with meningocele on postnatal operative interrogation. Knowledge that this can occur should be taken into consideration when discussing fetal closure, although the frequency of this occurrence is not known. Additionally, identification of this case sheds light on the mechanism by which occult myelomeningoceles form.