Septo-optic dysplasia (SOD), (de Morsier syndrome) is a rare congenital disorder in which there are abnormalities in the development of midline brain structures, the optic nerve(s), and anterior pituitary gland. Serious manifestations and complications arise with each of these features. Patient presentation varies from one child to another.
SOD is a congenital disorder and may display numerous abnormalities. The disease can be easy to miss . At least 2 of the following must be present to diagnose SOD: Abnormalities of the midline brain, hypoplasia of the optic nerve, and abnormalities of the pituitary gland. A third of patients will exhibit all 3 features . Typical newborn features are hypoglycemia, jaundice, microphallus (testes may be undescended), nystagmus, and possible cleft palate. They may be suscepetible to infections as well.
Midline brain abnormalities
Brain anatomy morphogenesis includes absent septum pellucidum and/or corpus callosum in approximately 50% of patients. Some will have cerebellar involvement. Developmental and motor disabilities and delays are common especially in the context of coordination. There may be an association with autism. Seizures in children with or without developmental delay  and sleep abnormalities are other manifestations .
An abnormal vision exam may be the first sign to raise suspicion. Further evaluation and search for accurate diagnosis is prudent. Nystagmus, strabismus, and astigmatism are common. Of those with visual impairment, 80% are classified as legally impaired . Findings on optic exam include hypoplastic disc with a double ring sign, which is characteristic. Another abnormality is a small and/or pale optic disc.
The clinical features vary from one individual to another. Some patients show a deficiency of one hormone and other may have panhypopituitarism. Most children with SOD will exhibit pituitary dysfunction and the subsequent insufficiency of hormones. Pituitary deficiency results in hormone shortages that may lead to neonatal hypoglycemia and hypernatremia. Other lacking pituitary hormones is also seen. Lack of GH causes short stature but patients exhibit normal weight.
Adrenal crisis results in neonatal fatalities. This is attributed to ACTH deficiency. Precocious puberty can occur secondary to hormonal dysfunction and imbalance . One observation is abnormal development of male genitalia. Furthermore, posterior pituitary hormones may also be deficient despite the varying embryological origins of the anterior and posterior glands. Diabetes insipidus may occur. Patients also struggle to maintain thermoregulation.
Earlier diagnosis is pertinent for long term outcomes with regards to hormonal deficiencies, intellectual and motor development, visual impairment, etc.
A complete and thorough history, family history and exam should be performed. Infants with findings suspicious for this disorder should warrant a full workup including:
MRI of brain is crucial for the confirmation of diagnosis . This assesses the size of the anterior pituitary, location of posterior pituitary, presence of infundibulum and presence of septum pellucidum. Also evaluation of corpus callosum and optic nerves is done. Other brain abnormalities may include cerebellar hypoplasia. The findings are abnormalities of corpus callosum, absent septum pellucidum, abnormal hypothalamic pituitary axis, and hypoplasia of the optic nerve(s) and chiasm. These findings are variable from one patient to another.
Pituitary functions tests
All affected patients should be referred to opthalmology as part diagnosis process. Of note, SOD may be diagnosed on prenatal ultrasound.
The team should consist of endocrinologists, ophthalmologists, and neurologists, and other professionals for child and family support services. Neurodevelopmental experts can help the child progress and experience a better quality of life. In cases where SOD is diagnosed during prenatal ultrasonography, patients can opt for genetic counseling and seek social support services to prepare for medical management of the neonate.
The earlier the diagnosis and treatment, the better the outcome and reduction in morbidity. In fact, early identification improves survival .
Research investigations have discovered that some familial cases of SOD are likely secondary to genetic mutations. The implicated genes are HESX1, SOX2, SOX3 and OTX2 . These are transcription factors that play key roles in early forebrain development. Most cases, however, are idiopathic and sporadic . The disorder does not typically recur in future offspring.
A few factors have been linked to SOD. For example, it is more common in younger maternal ages. Also, environmental factors may contribute. Further research is needed to elucidate the complex multifactorial component of SOD.
SOD is rare and is found in 1 per 100,000 population . It occurs in 1 in 10,000 live births. There is no gender preference. An investigation in England linked cases to pregnancies in younger mothers, and backgrounds of low income and unemployment . The former is corroborated by another study as well . While these studies suggest that maternal age is a factor, this is not well established .
SOD can manifest in multiple abnormalities mainly involving early brain development, which takes place at gestational age of 4 to 6 weeks. This period represents the formation of the anterior neural plate. Mutations in genes have been identified in SOD including HESX1, SOX2, SOX3 and OTX2.
The homeobox gene HESX1, serves as a repressor of transcription. It is significant in pituitary development. Murine studies have enabled the isolation of 5 homozygous and 8 heterozygous mutations. The homozygous mutations are associated with autosomal recessive inheritance while the latter are correlated to autosomal dominance inheritance  . The homozygous mutations exhibit complete penetrance unlike the heterozygous, which is partially penetrant and therefore milder  .
The SOX2 mutation results in severe bilateral optic defects such as microphthalmia and anophthalmia. This mutation is also associated with abnormalities of the corpus callosum and under development of the anterior pituitary . The SOX 2 mutation further reflects short stature, esophageal atresia, hearing loss, developmental delays, and male genital defects .
Complications with pituitary insufficiency
The anterior pituitary synthesizes numerous hormones: GH, adrenocorticotropic hormone (ACTH), follicle stimulating hormone (FSH), luteinizing hormone (LH), thyroid stimulating hormone (TSH), and prolactin. One or more may be affected. The pathophysiological effects of pituitary hormone deficiency can result in life threatening complications and death.
Growth hormone deficiency is frequently found in SOD patients. If GH and cortisol are deficient, a potentially life threatening complication is hypoglycemia. Low cortisol can be fatal due to adrenal crisis. While most cases result in late puberty, precocious puberty may occur due to low FSH and LH. Also hypogonadism is found in males. Insufficient thyroid hormone affects metabolism and many other physiological processes as well. Diabetes insipidus may be observed even though antidiuretic hormone (ADH) is secreted by the posterior pituitary.
There are no preventative measures since SOD is either genetically inherited or sporadic. Long term outcomes of children affected with SOD could be improved the earlier the condition is discovered and the sooner intervention is implemented.
Septo-optic dysplasia (SOD) is a rare congenital disorder that requires 2 of 3 features to be present to confirm diagnosis . These are brain midline abnormality, optic nerve hypoplasia, and pituitary gland abnormality. While genetic mutations have been discovered, most cases are idiopathic and sporadic and likely the disease is multifactorial.
It is important to recognize and diagnose the condition early so that intervention can reduce mortality. The deficiency of pituitary hormones can be detrimental. Main complications include hypoglycemia and hypernatremia. Low growth hormone (GH) and low cortisol level are associated with the former. Newborn fatality can occur with low cortisol levels and the subsequent adrenal crisis. Visual symptoms are common and include nystagmus and astigmatism. Impairment is often severe. An optic exam is indicated in all patients. Since key brain structures may be affected, there are significant developmental and motor delays. Seizure may also be present.
A diagnosis is confirmed with MRI, which would depict abnormal or absent midline structures such as corpus callosum, septum pellucidum, pituitary gland, and hypolasia of one or both optic nerves and chiasm. Laboratory studies testing for hormone levels are also crucial.
Treatment consists of a multidisciplinary approach comprised of specialists in neurology, endocrine, and ophthalmology. These experts in addition to neurodevelopmental professionals work as a cohesive team to provide the best management for the patient.
Septo-optic dysplasia is the condition in which babies and children are diagnosed with abnormal development of the middle structures of the brain, the optic (eye) nerve, and the pituitary gland. The parts of the brain that are affected play a role in many functions and activities such as development of intelligence and motor skills. The optic nerve allows us to see and have eye coordination. The pituitary gland releases very important hormones such as growth hormone, thyroid, and sex hormones. In fact, this gland is involved in producing cortisol, the stress hormone that plays a role in may functions especially during emergencies.
This disorder is seen in boys and girls. While there is a genetic mutation responsible, it is not usually inherited. It is not likely to recur in other children in the family. It may be more common in younger mothers but this is not clear.
Some of the signs and symptoms in the newborn are low blood sugars, high sodium, jaundice (yellow skin), small penis in boys, and maybe cleft palate. Not all babies and children will the same signs and symptoms. As soon as you or your child's doctor notices developmental delay, visual problems or other signs, an MRI in addition with blood tests are done on the child. The MRI will show the abnormalities normally associated with septo-optic dysplasia. The lab tests will determine if there are low levels of the main hormones discussed above. Any abnormal lab may lead to further tests.
Treatment includes replacing deficient hormones. Also it is important to establish care at a tertiary center with a team of doctors and specialists managing the child. The sooner the treatments begin, the better for the child. Neurodevelopmental experts will help the child progress and get the most from school and social activities.