Septo-optic dysplasia
Updates to Article Attributes
Septo-optic dysplasia (SOD), also known as de Morsier syndrome, 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).
Epidemiology
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 syndrome) 8
- 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:
Pathology
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.
CT
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
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
- lobar holoprosencephaly: may not be able to be differentiated 8
-<p><strong>Septo-optic dysplasia (SOD)</strong> is a condition characterised by <a href="/articles/optic-nerve-hypoplasia">optic nerve hypoplasia</a> and <a href="/articles/absence-of-septum-pellucidum">absence of septum pellucidum</a> and, in two-thirds of patients <a href="/articles/hypothalamic-pituitary-dysfunction">hypothalamic-pituitary dysfunction</a>. It is best thought of as being part of the <a href="/articles/holoprosencephaly">holoprosencephaly</a> spectrum (see <a href="/articles/classification-system-for-midline-abnormalities-of-the-brain-and-skull">classification system for midline malformations</a>).</p><h4>Epidemiology</h4><p>Septo-optic dysplasia has an estimated prevalence of ~ 1:50,000. There is no recognised gender predilection.</p><h5>Risk factors</h5><p>A number of risk factors have been identified <sup>8,9</sup>:</p><ul>- +<p><strong>Septo-optic dysplasia (SOD)</strong>, also known as <strong>de Morsier syndrome</strong>, is a condition characterised by <a href="/articles/optic-nerve-hypoplasia">optic nerve hypoplasia</a> and <a href="/articles/absence-of-septum-pellucidum">absence of septum pellucidum</a> and, in two-thirds of patients <a href="/articles/hypothalamic-pituitary-dysfunction">hypothalamic-pituitary dysfunction</a>. It is best thought of as being part of the <a href="/articles/holoprosencephaly">holoprosencephaly</a> spectrum (see <a href="/articles/classification-system-for-midline-abnormalities-of-the-brain-and-skull">classification system for midline malformations</a>).</p><h4>Epidemiology</h4><p>Septo-optic dysplasia has an estimated prevalence of ~ 1:50,000. There is no recognised gender predilection.</p><h5>Risk factors</h5><p>A number of risk factors have been identified <sup>8,9</sup>:</p><ul>
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