SOD/ONH F.A.Q.'s
Kathy Clark RN CS MSN
Pediatric Nurse Practitioner    

• What is ONH/Optic Nerve Hypoplasia?
  In order for people to "see", the brain must receive the messages sent from the eye. The optic nerves carry this information from the eye to the brain. If this nerve is too small, less information will be sent to the brain, and vision will be impaired. Hypoplasia means "underdeveloped". This may mean that the nerves of both eyes are completely unformed, with complete blindness, or that one optic nerve is smaller than average, with little impact on vision. Most people with ONH also have nystagmus (involuntary movement of the eyes) and strabismus (crossed eye). Many children with ONH have abnormal brain structures, such as absence of the septum pellucidum and corpus callosum. Some children will also have hormone deficiencies.
  
  
• What is SOD /Septo-optic dysplasia?
  Septo refers to the center structure of the brain, the septum pellucidum. This is a membrane that separates the anterior horns of the lateral ventricles of the brain. The pituitary gland and hypothalamus are located in the center of the brain. Optic refers to the optic nerves, which come together in the center of the brain. Dysplasia means "formed incorrectly". SOD is used to describe the condition of optic nerve hypoplasia (ONH) and pituitary or hypothalamic deficiencies. While pituitary deficiencies are rare in children, the combination of ONH and pituitary deficiency is even more rare.
  
  

• What is de Morsier Syndrome?
  This term refers to those children with SOD who are missing all pituitary hormones (panhypopituitarism) and who also have bilateral optic nerve hypoplasia.
  
  
• What are the brain structures that can be affected by ONH/SOD?
  Misplacement (ectopic) or absence of the pituitary gland or the pituitary stalk; absence or decreased size of the corpus callosum; absence or decreased size of the septum pellucidum; arachnoid cyst; hypoplasia of the cerebellum; microcephaly. Only arachnoid cysts may require treatment, such as a shunt.
  
  
• What is the cause of SOD/ONH?
  There is no known cause. The pituitary and optic nerve areas develop at the same time in fetal life, at about six weeks of gestation. Up to one third of babies with SOD are breech babies; this is not the cause of SOD.
  
  
• What is the role of the pituitary gland?
  The pituitary, or master gland, controls the function of many other glands - the thyroid, adrenals, ovaries, testes. It also produces growth hormone and anti-diuretic (water saving) hormone.
  
  
• What is the role of the hypothalamus?
  The hypothalamus has some control over the pituitary gland. There are other areas in the hypothalamus that control hunger, thirst, body temperature, and some facets of behavior.
  
  
• What is the range of problems seen in children with SOD? The pituitary gland may be completely absent, resulting in a life-threatening condition at birth. Some children are not diagnosed until later in childhood. Children may need only one hormone replaced, or all hormones. Puberty could be normal, early, or require hormone replacement. A very small number of children with SOD will require total care during their life, and will not achieve independence. Most children attend regular schools with some support. Vision will range from no impairment to complete blindness.
  
  
• What are the life expectancy and health risks of children with SOD?
  The first year of life is the most difficult for children with SOD. At highest risk are children with panhypopituitarism who cannot control their body temperature and those who have no sense of thirst. Despite these risks, mortality rates are very low. Children with SOD are expected to lead full, active, and healthy lives.
  
  
• What specialists should I see?
  A child with ONH should be seen by an ophthalmologist, who will examine the eyes thoroughly and order MRI imaging of the entire brain. If this shows any structural changes indicating SOD the child should be seen by a pediatric endocrinologist. The pediatric endocrinologist will examine the child and make careful measurements of growth. Blood testing will screen for hormone deficiencies such as thyroid, cortisol, growth hormone, and early or late puberty. A bone age x ray will be done to determine the child's biologic age. Infants should be enrolled in their local Early On intervention program. Children diagnosed later in life should be evaluated for learning needs by a pediatric psychologist. Children with seizures will also see a pediatric neurologist.