Septo-optic dysplasia

Definition

Septo-optic dysplasia (SOD) is a rare, congenital disorder. Findings include optic nerve hypoplasia with a thin or absent septum pellucidum and/or corpus callosum and pituitary dysfunction. Optic nerve hypoplasia is mandatory for the diagnosis of SOD.

Description

SOD also known as DeMorsier's syndrome is a combination of optic nerve underdevelopment (hypoplasia) with abnormalities of a part of the brain called the septum pellucidum and/or corpus callosum. Endocrine disorders such as dwarfism, decreased thyroid gland function (hypothyroidism), dehydration, delayed or precocious puberty and reduced blood sugar may occur from dysfunction of the pituitary gland of the brain. SOD has also been associated with congenital architectural brain anomalies.

Causes and symptoms

The cause of SOD is thought to be related to intrauterine viral infections or diabetes during pregnancy. Antiseizure medications, alcohol and illicit drugs have also been linked to SOD. In addition vascular abnormalities and uncommonly genetics are thought to play a role.

Patients afflicted with SOD can present at any age depending on the severity of the symptoms. Signs and symptoms such as failure to thrive, prolonged jaundice, body temperature dysregulation, decreased blood sugar, small genitalia or muscular flaccidity can herald the diagnosis of SOD in newborns.

Older children may complain of visual difficulties and be found to have strabismus (crossed eyes), nystagmus (involuntary, jerky eye movements) or inability to fixate on an object. In addition pupillary and color vision abnormalities may be noted. The optic nerves will appear small and grey or pale in color and can be surrounded by a yellowed halo signifying hypoplasia or atrophy.

A large percentage of SOD patients will have endocrine disorders. By far growth hormone deficiencies are the most common in patients with optic nerve hypoplasia. Growth hormone deficiency can lead to reduced blood sugar, while abnormal levels of reproductive hormones can result unusual pubertal development. Reduced levels of thyroid-stimulating hormone will cause suboptimal thyroid gland functioning (hypothyroidism). Other endocrine problems include increased urination, dehydration and death.

In some instances patients will have behavioral and cognitive problems resulting from brain maldevelopment or endocrinologic disorders.

Diagnosis

Suspicion for the diagnosis of SOD is based on clinical findings described above. In addition magnetic resonance imaging (MRI) of the brain focusing on the visual pathways, hypothalamus-pituitary region and other mid-line structures and septum pellucidum is invaluable for solidifying the diagnosis.

Treatment team

Pediatricians, endocrinologists, optometrists, ophthalmologists, neuro-ophthalmologists and neurologists can all contribute to patient care.

Treatment

SOD is treated symptomatically. Hormone deficiencies are managed with hormone replacement therapy while the best possible visual acuity is achieved with corrective spectacle lenses.

Recovery and rehabilitation

Patients with extremely poor vision may benefit from a low vision specialist. He or she may be able to prescribe a visual apparatus to maximally improve visual function.

Special concerns

Patients with severe visual depression may have difficulty obtaining a driver's license or gainful employment.

Resources

BOOKS

Liu, Grant T., Nicholas J. Volpe, and Steven L. Galetta. Neuro-Ophthalmology Diagnosis and Management, 1st ed. Philadelphia, PA: W. B. Saunders Company, 2001.

PERIODICALS

Campbell, Carrie. "Septo-optic dysplasia: a literature review." Optometry 72, no. 7 (July 2003): 417-426.

ORGANIZATIONS

National Organization for Rare Disorders. PO Box 1968, Danbury, CT 06813-1968. 202-744-1000 or 800-999-NORD; Fax: 203-798-2291. orphan@rarediseases.org. http://www.rarediseases.org.

National Eye Institute. National Institute of Health, Bldg. 31, Rm. 6A32, Bethesda, MD 20892-2510. 301-496-5248. 2020@b31.nei.nih.gov. http://www.nei.nih.gov.

Adam J. Cohen, MD

A congenital hypoplasia of the optic nerve resulting from the defective development of the retinal ganglia cells and their axons.

Septo-optic dysplasia
Classification and external resources
ICD-10	Q04.4
ICD-9	742.2
OMIM	182230
DiseasesDB	32732
MeSH	[1]

Septo-optic dysplasia (SOD), also known as de Morsier syndrome^[1][2] is a congenital malformation syndrome made manifest by hypoplasia (underdevelopment) of the optic nerve and absence of the septum pellucidum (a midline part of the brain).

Although not included in the name, hypopituitarism is sometimes included in the definition.^[3]

Neuroradiologically, intracranial malformations associated with septo-optic dysplasia include agenesis of the septum pellucidum, schizencephaly, and lobar holoprosencephaly.

Contents 1 Presentation 1.1 Optic nerve 1.2 Pituitary 1.3 Septum pellucidum 1.4 Variability 2 Causes 3 References

Presentation

This section does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (July 2009)

Optic nerve

The optic nerve hypoplasia is generally manifested by nystagmus (involuntary eye movements, often side-to-side) and a smaller-than-usual optic disk. The degree of visual impairment is variable, and ranges from normal vision to complete blindness. When nystagmus develops, it typically appears by 1–8 months of age, and usually indicates that there will be a significant degree of visual impairment, but the severity is difficult to predict in infancy. Although there are many measures to compensate for visual impairment, no treatment is available to induce normal optic nerve function.

Pituitary

The degree of pituitary deficiency is also variable, and ranges from normal function, to deficiency of a single hormone, to deficiency of both anterior and posterior hormones. It is often unclear if the hypopituitarism is due to a primary pituitary dysfunction or is secondary to a hypothalmic dysfunction. Hypopituitarism in this syndrome is most often manifested by growth hormone deficiency. If severe, it can lead to diagnosis in the first days of life by causing hypoglycemia, jaundice, and micropenis (if a boy). The cause of the jaundice is unknown, and an unusual aspect of it (compared to most neonatal jaundice) is that it can be largely a conjugated (direct) hyperbilirubinemia suggestive of obstructive liver disease. It typically resolves over several weeks once hormone replacement is begun. All of the pituitary hormones can be replaced, and this is the treatment for deficiencies. Septo-optic dysplasia is one of the most common forms of congenital growth hormone deficiency.

Septum pellucidum

The brain effects are also variable and range from normal intelligence to severe mental retardation. Seizures sometimes occur. Prediction of intellectual outcome in infancy is difficult. Various types of early intervention or equivalent programs can help a child reach full developmental potential, but if brain impairment is significant, it cannot be made normal by any treatment.

Variability

Septo-optic dysplasia is a highly variable disorder. It is rare for siblings to present with identical features of the Septo-optic dysplasia spectrum. Many patients present with additional developmental defects outside the Septo-optic dysplasia triad. In particular digital defects are common.

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)^[4], 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^[5]. 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.

References

1. ^ synd/2548 at Who Named It?
2. ^ G. de Morsier. Études sur les dysraphies, crânioencéphaliques. III. Agénésie du septum palludicum avec malformation du tractus optique. La dysplasie septo-optique. Schweizer Archiv für Neurologie und Psychiatrie, Zurich, 1956, 77: 267-292.
3. ^ septo-optic dysplasia at Dorland's Medical Dictionary
4. ^ Dattani MT, Martinez-Barbera JP, Thomas PQ, et al. (1998). "Mutations in the homeobox gene HESX1/Hesx1 associated with septo-optic dysplasia in human and mouse". Nat. Genet. 19 (2): 125–33. doi:10.1038/477. PMID 9620767. 
5. ^ McNay DE, Turton JP, Kelberman D, et al. (2006). "HESX1 mutations are an uncommon cause of septo-optic dysplasia and hypopituitarism". J Clin Endocrinol Metab. 92 (2): 691–7. doi:10.1210/jc.2006-1609. PMID 17148560. 

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