< b>Cephalic disorder- A congenital condition that stems from damage to,
or abnormal development of, the budding nervous system. Cephalic is a term that
means 'head' or 'head end of the body.' Congenital means the disorder is present
at, and usually before, birth.
Causation-<-u> Cephalic disorders are not necessarily caused by a single factor,
but may be influenced by hereditary or genetic conditions, or by environmental exposures
during pregnancy such as medication taken by the mother, maternal infection, or
exposure to radiation. Some cephalic disorders occur when the cranial sutures (the
fibrous joints that connect the bones of the skull) join prematurely. Most cephalic
disorders are caused by a disturbance that occurs very early in the development
of the fetal nervous system.
Embryology-<-u> The human nervous system develops from a small, specialized
plate of cells on the surface of the embryo. Early in development, this plate of
cells forms a critically important structure called the neural tube, a narrow sheath
that closes between the third and fourth weeks of pregnancy to form the brain and
spinal cord of the embryo. Four main processes are responsible for the development
of the nervous system- cell proliferation, the process in which nerve cells (neurons)
divide to form new generations of cells; cell migration, the process in which nerve
cells move from their place of origin to the place where they will remain for life;
cell differentiation, the process during which cells acquire individual characteristics;
and cell death, a natural process in which cells die.
Health impact-<-u> Damage to the developing nervous system is a major cause
of chronic, disabling disorders and, sometimes, death in infants, children, and
even adults. The degree to which damage to the developing nervous system harms the
mind and body varies enormously. Many disabilities are mild enough to allow those
afflicted to eventually function independently in society. Others are not. Some
infants, children, and adults die, others remain totally disabled, and an even larger
population is partially disabled, functioning well below normal capacity throughout
life.
The principal types of cephalic disorders<-u>, in alphabetical order, include
the following disorders. To learn more about any one of these cephalic disorders,
click on its name below-
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