A rare form of spina bifida cystica (saccular, open neural tube defect (NTD)) characterized by a non-neurulated spinal cord (neural placode) on the surface of the cystic extension of dysplastic meninges (non-epidermised posterior meningocele). The spinal cord extends through a spina bifida (posterior vertebral defect) with typically everted or parallel laminae. Nerve roots are connected to the borders of the neural placode and are visible inside the sac. Myelomeningocele is characteristically associated with a Chiari II malformation. It can be either isolated or associated with split cord malformation.