Other Cephalic
Disorders
(credit for
this information goes to
Neurology
Channel)
Acephaly
is usually associated with the development of a parasitic "twin"
attached to an otherwise normal fetus, usually at the neck. The
acephalic fetus has no head or heart and cannot survive
independently; blood circulation comes from the heart of the
otherwise normal "twin."
Exencephaly
usually is found in embryos as an early stage of anencephaly. It
is characterized by development of the brain outside the skull.
In most cases, the brain tissue degenerates as pregnancy
progresses. Exencephalic embryos rarely survive to term.
Macrocephaly
is characterized by an abnormally large head circumference. It
may be inherited and may or may not be associated with other
disorders, such as dwarfism, neurofibromatosis, mental
retardation, or tuberous sclerosis. Some cases may be caused by
an enlarged brain or by hydrocephalus.
Micrencephaly
is characterized by an abnormally small brain. It can be caused
by a genetic factor but is more often associated with maternal
alcoholism, diabetes, and exposure to German measles (rubella).
Newborns with Micrencephaly usually have profound neurological
defects, seizures, and greatly impaired intellectual
development. Motor function problems may appear later in life.
Octocephaly
is characterized by agnathia, the total or virtual absence of a
lower jaw, and a poorly functioning airway. This is a fatal
condition that may occur alone or with holoprosencephaly.
Craniostenoses
are an extremely rare group of cephalic disorders, characterized
by skull deformities caused by premature fusion of various
fibrous joints (cranial sutures) connecting the bones of the
head.
Scaphocephaly
is
fusion of the sagittal suture, the joint connecting the two
parietal (top and sides of the head) bones of the skull, causing
a long, narrow head. This is the most common of the
Craniostenoses.
Plagiocephaly
is
unilateral fusion (joining of one side) of the fibrous joint
between the occipital and parietal bones, causing asymmetrical
(one side) flattening of the skull. It is thought to be caused
by a brain malformation, an excessively small or tight
intrauterine environment, or a spasm or tightening of the neck
muscles.
Brachycephaly
is
fusion of the joint between the skull's frontal and parietal
bones, causing foreshortened front-to-back diameter of the
skull.
Trigonocephaly
is
fusion of the metopic suture, part of the frontal joint between
the two halves of the skull's frontal bone, causing a V-shaped
deformity at the front of the skull, a triangular prominence of
the forehead, and closely set eyes.
Oxycephaly
is closure of the
coronal suture and any other suture or fusion of all cranial
sutures. This is the most severe form of Craniostenoses.
