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.
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.
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.
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.
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.
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.
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.
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.
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
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.