Septo-optic dysplasia
Updates to Article Attributes
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).
Epidemiology
Septo-optic dysplasia has an estimated prevalence of ~ 1:50,000. There is no recognised gender predilection.
A number of risk factors have being identified, including 8:
- maternal diabetes
- drugs
- quinidine ingestion
- antiepileptics
- illicit drugs
- cytomegalovirus infection
Clinical presentation
Clinical presentation of septo-optic dysplasia is varied, and largely 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
-
ectopicsmall pituitary with hypoplastic or absent infundibulum and ectopic posterior pituitarymay be presentseen as focus of T1 high signal intensity in median eminence of hypothalamus - olfactory bulbs may be absent (Kallmann syndrome) 8
- associated
wtihwith schizencephaly- optic apparatus less severely affected
- cortical anomalies: polymicrogyria, cortical dysplaisa
- may be etiologically different 8
- sometimes referred to as septo-optic dysplasia plus 8
In addition, a number of other associations are recognised including:
Radiographic features
All imaging modalities which 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
History and etymology
Septo-optic dysplasia was first described by George de Morsier (1894-1982), Swiss neurologist in 1956 6, 7.
-</ul><h4>Clinical presentation</h4><p>Clinical presentation of septo-optic dysplasia is varied, and largely dependent of whether or not it is associated with <a title="Schizencephaly" href="/articles/schizencephaly">schizencephaly</a> (~ 50% of cases). This association is used to define two forms of the condition <sup>1,8</sup>:</p><ul>- +</ul><h4>Clinical presentation</h4><p>Clinical presentation of septo-optic dysplasia is varied, and largely dependent of whether or not it is associated with <a href="/articles/schizencephaly">schizencephaly</a> (~ 50% of cases). This association is used to define two forms of the condition <sup>1,8</sup>:</p><ul>
-<li>ectopic posterior pituitary may be present</li>- +<li>small pituitary with hypoplastic or absent infundibulum and ectopic posterior pituitary seen as focus of T1 high signal intensity in median eminence of hypothalamus</li>
-<li>associated wtih schizencephaly<ul>- +<li>associated with schizencephaly<ul>
- +<li>cortical anomalies: polymicrogyria, cortical dysplaisa </li>
-<li>sometimes referred to as septo-optic dysplasia plus <sup>8</sup>- +<li>sometimes referred to as <strong>septo-optic dysplasia plus</strong> <sup>8</sup>
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