What is Septo-Optic Dysplasia?
Septo-optic dysplasia (SOD) is characterized by the abnormal development of parts of the brain and nervous system. It is a congenital condition, meaning that it occurs during fetal development and is present at birth.
Features of Septo-Optic Dysplasia
Three main physical features define SOD:
- Underdevelopment (hypoplasia) of the optic nerves that transmit visual information from the eyes to the brain.
- Abnormal development of the septum pellucidum, a thin membrane in the center of the brain. The septum pellucidum may be underdeveloped or entirely absent. Another structure in the middle of the brain, the corpus callosum, may also be affected.
- Underdevelopment of the pituitary gland, a gland at the base of the brain that controls growth, reproduction, and other functions.
Only about a third of children born with SOD exhibit all three of these core features. In most cases, only two of the features are present. As a result of the variability, the symptoms of SOD vary widely from case to case. As a result, some scientists believe that SOD should be considered a spectrum of related disorders rather than a single disorder.
Symptoms of Septo-Optic Dysplasia
Not all people with SOD will experience all of the potential symptoms of the disorder. Signs and symptoms of SOD may include:
- Blindness (in one or both eyes)
- Involuntary eye movements
- Abnormal alignment of the eyes
- Weak muscle tone
- Growth hormone deficiency that causes short stature
- Lethargy or sleepiness
- Weight gain
- Abnormal genital development
- Early or delayed puberty
- Difficulty with automatic body functions such as temperature regulation, thirst, and hunger
- Low blood sugar
- Sleep disruptions
- Developmental delays
- Intellectual disabilities
What Causes Septo-Optic Dysplasia?
In most cases, the cause of SOD is unknown. Abnormal changes (mutations) in a small number of genes have been noted in some cases, but no mutations are present in most cases. Therefore, scientists believe that the disorder is probably the result of an interaction between environmental factors and genetic predispositions.
Possible environmental factors that may increase the risk of SOD development include:
- Viral infections
- Disruption of blood flow to the fetus during crucial stages of development during pregnancy
- Exposure of the fetus to certain medications or drugs
Is Septo-Optic Dysplasia Hereditary?
Most children born with SOD do not have a family history of the disease, and parents who have one child with SOD do not seem to be more likely to have another child with the disorder. This suggests that SOD is typically not inherited by a child from their parents.
However, a small number of cases have occurred in multiple members of the same family. In most cases, the mutations associated with SOD appear to be inherited in an autosomal recessive pattern. This means that a child must inherit two copies of the mutated gene, one from each parent, to develop the disorder. If both parents carry one of the disorder-causing mutations, they have a 25 percent chance of having a child affected by the disorder with each pregnancy. In 50 percent of their pregnancies, the child will carry the mutation but not develop the condition. In 25 percent of pregnancies, their child will not carry the mutation and will not pass the disorder-causing mutation to their children.
SOD seems to have been inherited in an autosomal dominant pattern in a small number of inherited cases. In these cases, the disorder develops if the child inherits even one copy of the mutated gene.
How Is Septo-Optic Dysplasia Detected?
The structural malformations of SOD are present at birth, but it may be months or years before the symptoms are noticed. Early treatment of hormone deficiencies typically improves outcomes, so early diagnosis is vital. Early signs of the disorder may include:
- Vision impairment
- Involuntary eye movements
- Slow growth
- Developmental delays
- Low blood sugar in early childhood
- Excessive thirst
How Is Septo-Optic Dysplasia Diagnosed?
A doctor may suspect SOD if a child presents symptoms consistent with the disorder, and other potential causes of the symptoms can be ruled out. The diagnostic process may include:
- Assessment of the child’s medical history
- Physical and neurological exams
- Assessment of the child’s growth patterns and hormone function
- Blood tests to measure hormone and blood sugar levels
- Imaging exams to look for abnormal development of the optic nerves, septum pellucidum, and pituitary gland
PLEASE CONSULT A PHYSICIAN FOR MORE INFORMATION.
How Is Septo-Optic Dysplasia Treated?
No treatment will reverse the physical malformations of SOD or the symptoms they cause. Treatments and therapies focus on lessening the impact of symptoms and improving the child’s quality of life. Treatment approaches may include:
- Hormone replacement therapy
- Vision therapies
- Physical therapy
- Occupational therapy
How Does Septo-Optic Dysplasia Progress?
SOD is not a progressive disease. The disorder’s underlying structural malformations do not worsen over time. However, some symptoms, such as hormonal deficiencies, may cause ongoing problems and require life-long monitoring and treatment. Possible long-term impacts of SOD may include:
- Sexual development problems
- Intellectual impairment or learning disabilities
How Is Septo-Optic Dysplasia Prevented?
The cause of SOD is unknown in most cases, making it difficult to identify ways to prevent it. In the absence of a definite known cause, avoidance of risk factors is the best way to reduce the risk of the disorder. Potential risk factors for SOD include:
- Viral infections during pregnancy
- Smoking or alcohol use during pregnancy
- Drug use during pregnancy
- Pregnancy at a young age
- Exposure to some medications (including some anticonvulsants and quinine)
Septo-Optic Dysplasia Caregiver Tips
- Learn as much as you can about SOD and optic nerve hypoplasia. These disorders are rare and highly variable, so your child’s experience is going to be unlike that of any other child with SOD. The more you know about the condition, the better able you’ll be to help your child deal with the impacts of SOD.
- Get support from others who know what it’s like to live with SOD. The MAGIC Foundation maintains resources, including links to online support groups, for families living with SOD and optic nerve hypoplasia.
Septo-Optic Dysplasia Brain Science
The three core features of SOD are abnormal development of areas in and near the brain. They include:
- The optic nerve. In particular, the optic nerve head (or optic disc), where nerve fibers called ganglion cell axons exit the eye, is usually much smaller than usual. The number of ganglion cell axons in the optic nerve is also smaller than usual, and the nerve itself may be atypically thin.
- The septum pellucidum. This is a thin membrane in the center of the brain between the two cerebral hemispheres. It is connected to the corpus callosum, a layer of nerve fibers that connects the two hemispheres. In SOD, the septum pellucidum is underdeveloped or completely absent, and the corpus callosum may also be affected.
- The pituitary gland. In SOD, the pituitary gland, located at the base of the brain, is typically smaller than normal. Deficiency of growth hormone is the most common result. Deficiencies of thyroid-stimulating hormone, corticotropic hormone, and vasopressin may also occur.
Septo-Optic Dysplasia Research
Title: A More Engaging Visual Field Test to Increase Use and Reliability in Pediatrics
Principal investigator: Ava K. Bittner, OD, PhD
Kids in Distress Clinic of The Eye Care Institute
Fort Lauderdale, FL
Most young children do not think that visual field (VF) testing of peripheral vision is similar to a game; therefore, it is not surprising that they have difficulty maintaining attention during VF testing. Thus, the test reliability suffers. Poor VF reliability has been a longstanding, major issue since it leads to an increased number of tests and/or longer duration of time needed to determine when there are actual vision losses. Providers are less likely to obtain VF tests in children since the results are of doubtful value and challenging to interpret when they are inconsistent. Effectively this means that children with untreated, slowly progressive eye diseases may go undiagnosed and incur greater visual losses. The investigators aim to create a prototype device that the investigators hypothesize will make VF testing more engaging for young children, thus increasing their attention and consistency of their responses to the test stimuli, which should improve VF reliability. The components include a microdisplay video screen (1.5” diameter) as the fixation target (instead of the standard LED light) displaying video clips of popular cartoon characters and audio clips of impersonated cartoon character voices presented by the test operator to provide instructional feedback based on the child’s performance during testing. Improved VF reliability from the investigators’ intervention would translate to improved diagnosis and care for young childrens’ peripheral vision loss through widespread implementation of the investigators’ innovative, affordable, and readily adaptable system at eye care providers’ offices.
Title: Endocrine Dysfunction and Growth Hormone Deficiency in Children With Optic Nerve Hypoplasia
Principal investigator: Mark Borchert, MD
Children’s Hospital Los Angeles
Los Angeles, CA
- The prevalence of endocrinopathies, and growth hormone (GH) deficiency in particular, among young children diagnosed with optic nerve hypoplasia (ONH), is higher than is commonly thought.
- Early treatment of children with ONH and GH-deficiency can prevent adverse outcomes.
Subjects for this study will be recruited from active and newly enrolled subjects in our larger ONH study. The study duration is three years, and we anticipate 38 subjects will enroll. Subjects will be recruited for this study if they present with either growth deceleration or at least one subnormal result for IGF-1 or IGFBP-3.
Baseline information collected includes height, weight, head circumference, examinations by an endocrinologist and ophthalmologist, endocrine laboratory testing, fundus photography, electrophysiology testing, head MRI, and a developmental assessment. A glucagon stimulation test will be performed, and subjects deemed GH-deficient and having delayed growth will be assigned to GH treatment, in line with standard clinical practice. Those with normal development but determined to be GH-deficient by a glucagon stimulation test will be randomized to treatment with GH vs. control (no intervention; observation only).
Subjects assigned or randomized to treatment with GH will be provided with GH for the duration of their participation in the study. Enrolled subjects will return every four months to monitor progress. Subjects will undergo a physical examination at each visit, including height, weight, head circumference, and body fat. In addition, subjects assigned or randomized to growth hormone will have laboratory testing of thyroid, IGF-1, and IGFBP-3 hormones and fasting lipid levels.
Title: Biological Clock Dysfunction in Optic Nerve Hypoplasia
Study director: Casandra Fink
Children’s Hospital Los Angeles
Los Angeles, CA
Optic Nerve Hypoplasia (ONH) is a leading cause of blindness in children. For unclear reasons, the incidence of ONH is increasing, with ONH affecting about 1 in 10,000 live-born infants. In addition to visual deficits, ONH is associated with varying degrees of hypopituitarism, developmental delay, brain malformations, and obesity. Although genetic mutations have been rarely observed to result in ONH, the causes of ONH are largely not known. However, in limited anatomical observations, the suprachiasmatic nuclei (SCN) located in the anterior hypothalamus, which generate circadian rhythms, have been observed to be abnormal in children with ONH. Thus, children with ONH may have biological clock dysfunction.
In collaborative studies with Dr. Mark Borchert of Children’s Hospital Los Angeles (CHLA), we have recently discovered that one-half of children with ONH have grossly abnormal sleep-wake patterns, as assessed by actigraphy. Although not known for children with ONH, abnormal sleep-wake patterns have been observed to be associated with neurocognitive impairment and obesity. We also observe that nocturnal melatonin administration can improve abnormal sleep-wake cycles in these children, raising the possibility of treating abnormal rhythmicity in children with ONH.