Septo-optic dysplasia
Overview
Septo-optic dysplasia is a rare, heterogeneous condition characterised by a combination of pituitary gland hypoplasia, optic nerve hypoplasia and midline abnormalities of the brain, including absence of the corpus callosum and septum pellucidum.1
Causes
Septo-optic dysplasia is a developmental disorder resulting from a defect of normal embryological development. The cause of septo-optic dysplasia is not known. Rare familial recurrence has been reported, suggesting at least one genetic form (HESX1)[3], but in most cases it is a sporadic birth defect of unknown cause and does not recur again with subsequent pregnancies. Septo-optic dysplasia is linked to young maternal age[4]. Indeed one third of Septo-optic births are the result of teenage pregnancies. These data could support an environmental origin of SOD with possible exposure to risk factors such as maternal smoking, alcohol consumption, and use of addictive drugs during early gestation. However, young maternal age in SOD was not associated with low birth weight or low gestation. This lack of association between young maternal age and an adverse developmental environment, as indicated by birth weight and gestation, suggest that maternal factors such as maternal smoking, alcohol consumption, and use of some addictive drugs during early gestation are not a cause of Septo-optic dysplasia.
Diagnosis
* Brain imaging with MRI is an important investigation and an MRI to measure the size of the optic nerves can confirm the diagnosis.9 MRI will indicate the degree of structural abnormality and this indicates the likely endocrine abnormality. * Tests of pituitary function may show hypopituitarism. * Developmental assessment is likely to show retardation.
Prognosis
Appearance of the septum pellucidum and hypothalamic-pituitary axis on MRI predict the likely spectrum of endocrine disorder and prognosis is also dependent upon the degree of abnormality. Early diagnosis improves outcome.11