Unilateral optic nerve hypoplasia with asymmetric septum: A case report of unilateral septo-optic dysplasia

Septo-optic dysplasia is an uncommon diagnosis comprised in part of a unique composition of congenitalmalformations of the central nervous system. It is defined by three principle findings: optic nerve hypoplasia, absence of the septum pellucidum, and clinical pituitary dysfunction. The syndrome may be associated with various cerebral defects including ectopic posterior pituitary, dysgenesis of the corpus callosum, and malformations of cortical development such as schizencephaly. Septo-optic dysplasia has been compared to holoprosencephaly due to the presence of anterior midline defects and is thought to be a less severe form of lobar holoprosencephaly. Certain neuroradiological featuresmay predict clinical outcomes: patientswithmalformations of cortical development or ectopic posterior pituitary are at higher risk for neurodevelopmental or endocrine dysfunction, respectively. Here we report a case of unilateral optic nerve hypoplasia with asymmetric appearance of the septum pellucidum thought to be due to ipsilateral absence of the septal leaflet in an otherwise healthy infant with exotropia. This is the first case of suspected unilateral septo-optic dysplasia described in the literature.