Introduction Spinal dysraphism is a result of early developmental abnormalities of the cord. Myelomeningocele, a form of open spina bifida, can be associated with intracranial abnormalities and hydrocephalus. We present two cases of cystic myelomeningocele with spinal abnormalities disproportionate to their intracranial abnormalities.

Methods Case notes review of 2 infants with antenatally diagnosed myelomeningocele and spinal dysraphism.

Case 1: Antenatal diagnosis of myelomeningocele of foetus at 19 weeks. The cystic myelomeningocele continued to increase in size without significant intracranial changes. There was mild ventriculomegaly with no evidence of Chiari II malformations and these findings remained stable throughout pregnancy and foetal MRI at 30 weeks. The baby needed ventriculo-peritoneal shunt inserted day 2 of life.

Case 2: Antenatal diagnosis of myelomeningocele on ultrasound scans at 14 weeks. This continued to increase in size through her pregnancy without changes in the intracranial structures as confirmed by foetal MRI at 31 weeks. Infant had a ventriculo-peritoneal shunt inserted in week 2.

Discussion These two cases suggest that a growing cystic myelomeningocele without accompanying intracranial changes is suggestive of a process of “compensated hydrocephalus” with the cyst bearing the brunt of the increasing pressures. Also, it raises the need for very early shunting in life for unhindered brain growth. We recommend that such cases be considered for early foetal MRI scans and parents be counselled about the severity of the condition and the need for delivery in a tertiary centre to enable early neurosurgical assessment after birth.