Septo-optic dysplasia plus syndrome

The patient is a 5-year-old male with a history of medicated panhypopituitarism and psychomotor development delay. Ophthalmologic examination revealed an absence of light perception and a pale optic disc on the left side.

Brain MRI revealed a hypoplastic left optic nerve and optic chiasm, with complete absence of the septum pellucidum (Figure 1). A small sella turcica and pituitary gland were noted, consistent with pituitary hypoplasia (Figure 3). The left olfactory bulb was also smaller, compatible with hypoplastic left olfactory bulb (Figure 2).

Additionally, the patient presented with bilateral perisylvian polymicrogyria, with insular and frontoparietal involvement, more extensive on the right side (Figures 4a and 4b).

There was caudal descent of the cerebellar tonsils through the foramen magnum (Figure 5), with a downward shift of 12 mm on the right and 16 mm on the left, accompanied by slight moulding of the bulbomedullary junction, which findings are consistent with a Chiari type 1 malformation.

Overall, these findings are compatible with septo-optic dysplasia plus syndrome.

We report a clinical case of a patient with the complete triad of septo-optic dysplasia (SOD) as seen on MRI, which includes optic nerve and optic chiasm hypoplasia, absence of the septum pellucidum, and pituitary hypoplasia. Concomitant cortical malformation (polymicrogyria) made the diagnosis of SOD plus syndrome. Additionally, a hypoplastic left olfactory bulb and a Chiari type 1 malformation were also identified.

SOD, previously termed de Morsier syndrome, is a rare congenital disorder, equally prevalent in both genders. It develops during the 4^th to 6^th weeks of gestation, a critical period for the morphogenesis of the anterior neuronal plate. Most cases are sporadic [1].

SOD is characterised by optic nerve hypoplasia, which may be either unilateral or bilateral, pituitary hypofunction, and midline brain abnormalities, such as agenesis of the septum pellucidum and/or corpus callosum. The diagnosis of SOD requires the presence of two or more of these features. When associated with cortical malformations, such as schizencephaly or polymicrogyria, the condition is referred to as SOD plus syndrome [2-4].

Clinical presentation is highly varied and includes development delay, visual impairment, seizures, and signs and symptoms of pituitary dysfunction. SOD should be suspected when a newborn presents with hypoglycemia, jaundice, microphallus and nystagmus. This condition may present later in childhood [1,3].

MRI is the preferred imaging modality to make the diagnosis of SOD and SOD plus syndrome, since it enables adequate evaluation of the brain, orbits, and sellar region. MR with 3D acquisitions and MPRs is recommended. Coronal images show absent or hypoplastic septum pellucidum, with flat-roofed ventricles and inferiorly pointed frontal horns. Look for corpus callosum anomalies. Small optic nerves are better evaluated on coronal T2WI. Anterior pituitary hypoplasia, ectopic posterior pituitary and a thin or absent infundibulum are some of the pituitary malformations that may be present. Always look for anomalies of cortical development. Ventral midline fusions are not present in this condition [4].

Imaging is essential for making the precise diagnosis of SOD and SOD plus syndrome and treatment planning. Early diagnosis allows timely management of visual, neurological and hormonal disturbances and, therefore, better prognosis [1].

All patient data have been completely anonymised throughout the entire manuscript and related files.