Septo-optic dysplasia
Septo-optic dysplasia, known also as de Morsier syndrome, is a rare congenital malformation syndrome that features a combination of the underdevelopment of the optic nerve, pituitary gland dysfunction, and absence of the septum pellucidum.
Two or more of these features need to be present for a clinical diagnosis—only 30% of patients have all three. French-Swiss doctor Georges de Morsier first recognized the relation of a rudimentary or absent septum pellucidum with hypoplasia of the optic nerves and chiasm in 1956.
Signs and symptoms
The symptoms of SOD can be divided into those related to optic nerve underdevelopment, pituitary hormone abnormalities, and mid-line brain abnormalities. Symptoms may vary greatly in their severity.Optic nerve underdevelopment
About one quarter of people with SOD have significant visual impairment in one or both eyes, as a result of optic nerve underdevelopment. Developmental delays are more common in children with bilateral optic nerve hypoplasia than those with unilateral optic nerve hypoplasia. Bilateral optic nerve hypoplasia is also associated with a more severe disease course.There may be nystagmus. In cases of bilateral optic nerve hypoplasia this can usually be detected within the first three months of life. It may be followed by strabismus developing in the first year.
Pituitary hormone abnormalities
Underdevelopment of the pituitary gland in SOD leads to hypopituitarism, most commonly in the form of growth hormone deficiency. In severe cases panhypopituitarism may occur.Mid-line brain abnormalities
In SOD, mid-line brain structures such as the corpus callosum and the septum pellucidum may fail to develop normally, leading to neurological problems such as seizures or developmental delay. Patients with seizures are more likely to show additional neurological abnormalities such as cortical dysplasia, polymicrogyria and schizencephaly. Such abnormalities are always identified when spastic quadriplegia is present.Neurological symptoms are typically considered late onset manifestations of SOD. Common initial presentations include epilepsy, development delays and limb weakness. Intellectual abilities vary widely from normal to severe intellectual disability. Early studies indicated intellectual disability occurs in 71% of cases, cerebral palsy occurs in 57%, and behavioral problems occur in 20%, but further research has indicated that these symptoms may be less common and caused by additional neurological abnormalities.