Teaching NeuroImage: Prenatal Diagnosis of Limited Dorsal Myeloschisis

The fetus of a 34-year-old primigravida with gestational diabetes but no folate deficiency was found to have a posterior sacral cystic lesion at 21-week ultrasound. Fetal MRI at 22 weeks revealed a 2.3 × 1.1 × 2.2 cm hyperintense cystic lesion, resembling a meningocele without bony or intracranial abnormalities (Figure 1). Postnatally, a midline fluid-filled sacral mass with squamous epithelial covering was seen (Figure 2A).1 Neurologic examination was normal. Postnatal MRI confirmed the diagnosis of limited dorsal myeloschisis (LDM) and also detected Chiari I malformation (Figure 1). LDM should be considered in posterior sacral cystic lesions without bony abnormalities and has a better prognosis than meningoceles.2