Septo-optic dysplasia

Septo-optic dysplasia (SOD) is a condition characterised by optic nerve hypoplasia and absence of septum pellucidum and, in two-thirds of patients hypothalamic-pituitary dysfunction. It is best thought of as being part of the holoprosencephaly spectrum (see classification system for midline malformations).


Septo-optic dysplasia has an estimated prevalence of ~ 1:50,000. There is no recognised gender predilection.

Risk factors

A number of risk factors have been identified 8,9:

  • maternal diabetes
  • medications
    • quinidine ingestion
    • antiepileptics
  • drug and alcohol abuse
  • cytomegalovirus infection

Clinical presentation

Clinical presentation of septo-optic dysplasia is varied, and mostly dependent of whether or not it is associated with schizencephaly (~ 50% of cases). This association is used to define two forms of the condition 1,8:

  • not associated with schizencephaly
    • visual apparatus more severely affected
    • hypothalamic-pituitary dysfunction present in 60-80% of patients 6,8
    • may present as hypoglycaemia in the neonatal period 6
    • small pituitary gland with hypoplastic or absent infundibulum and ectopic posterior pituitary seen as focus of T1 high signal intensity in median eminence of hypothalamus
    • olfactory bulbs may be absent (Kallmann syndrome8
  • associated with schizencephaly
    • optic apparatus less severely affected
    • cortical anomalies: polymicrogyria, cortical dysplasia
    • may be etiologically different 8
    • sometimes referred to as septo-optic dysplasia plus 8

In addition, a number of other associations are recognised including:


The abnormality develops during 4th-6th weeks of gestation, during early forebrain development. The aetiology of SOD is unknown, with an underlying genetic defect currently accounting for <1% of cases 9.

Radiographic features

All imaging modalities that can visualise the septum pellucidum (ultrasound, CT and MRI) will detect its absence in septo-optic dysplasia. Some additional modality dependent features may also be visible.


In addition to enlarged lateral ventricles with an absent septum pellucidum, CT may demonstrate small optic apparatus (best seen with volumetric scanning and coronal reformats) and associated small bony optic foramina.


MRI is the modality of choice for assessing septo-optic dysplasia.

  • may show a "point down" appearance of the lateral ventricular frontal horns on coronal images
  • absent septum pellucidum
  • hypoplastic pituitary stalk
  • hypoplastic optic chiasm/optic nerves and globes

Treatment and prognosis

The management of SOD requires a multidisciplinary team to assess and treat for hormonal imbalance, vision loss, autism and obesity 9.

History and etymology

Septo-optic dysplasia was first described by George de Morsier (1894-1982), Swiss neurologist in 1956 6, 7.

Differential diagnosis

Related articles

Malformations of the central nervous system

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