- Not a severe malformation
- Often an indicator of other malformations – septo-optic dysplasia, holoprosencephaly, Chiari II malformation, schizencephaly, other migration disorders
- <1% associated with HESX1 gene mutation
- Absence of septum pellucidum
- Box-like configuration of frontal horns
- Small optic nerves and chiasm
- Small anterior pituitary gland
- Ectopic bright spot of posterior pituitary
- Look for associated malformations: callosal agenesis, holoprosencephaly, cobblestone cortical malformations, bilateral polymicrogyria
Sarwar, Mohammad. “The septum pellucidum: normal and abnormal.” American Journal of Neuroradiology 10.5 (1989): 989-1005.
Malinger, G., et al. “Differential diagnosis in fetuses with absent septum pellucidum.” Ultrasound in Obstetrics and Gynecology: The Official Journal of the International Society of Ultrasound in Obstetrics and Gynecology 25.1 (2005): 42-49.