Septo optic dysplasia

Septo optic dysplasia is a syndrome complex also known as DeMorsier syndrome.As the name of the syndrome implies it is composed of two major findings including absence of septum pellucidum and hypoplasia of optic nerves (1).

Hypothalmic pituitary dysfunction is found in two thirds of these patients. Though the clinical presentation is variable,visual dysfunction and growth retardation may also be noted in these patients. Seizures are seen in 50 % of the patients (2).It is hypothesised that a combination of genetic abnormalities and in utero insults are responsible for this syndrome complex. The genetic abnormality is thought to be an abnormal expression of genes in basal prosencephalon (1).

Box like or squared off configuration of frontal horns and low lying fornices suggest absence of septum pellucidum on MRI images (1). Optic nerve hypoplasia can be identified in only 50 % of cases. Fat suppression sequences can be used for better characterisation of optic hypoplasia (2). Ophthalmological examinations are more useful in identification of the hypoplastic nerves.

The imaging appearances which include the association of other anomalies can be grouped in two categories (1). Malformations of cortical development (schizencephaly, gray matter heterotopia) are seen in the first category associated with partial or complete absence of septum. Concurrent schizencephaly is seen in 50% of patients (2). The association of olfactory hypoplasia is also reported in rare cases (3).
The second group has features that overlap with lobar holoprosencephaly with ventriculomegaly and hypoplasia of white matter. The cerebral cortex is normal, though absences of anterior falx cerebri and genu of corpus callosum have been noted.