Macrocephaly is a condition in which the head is larger than normal.
Also called macrocephalia and megalocephaly, macrocephaly is diagnosed
when the circumference of the head is more than two standard deviations
above average for the child's age, sex, race, and period of
gestation. The fontanelle (soft spot) of the newborn is wide, but facial
features are usually normal. Macrocephaly is distinguished from
in that there is no increase in pressure within the head; however,
hydrocephalus can result in macrocephaly in some children. The disorder
can result from a defect in formation during the embryonic stage, as a
result of certain degenerative diseases, as a part of various genetic
syndromes, or as an inherited
trait. Mental deficiency, seizures, and
are common in macrocephalic children.
Because of the many conditions that cause macrocephaly, a true assessment
of its incidence is difficult. It is a relatively rare condition that does
not appear to affect children of any particular race, gender, or
nationality with more frequency.
Causes and symptoms
Macrocephaly may be caused by many conditions. The most common causes for
an enlarged head are megalencephaly, or an enlarged brain, and
hydrocephalus, or excessive cerebrospinal fluid (
) in the brain.
When macrocephaly is a result of megalencephaly, it is often impossible to
determine the cause. However, megalencephaly is often associated with
metabolic diseases such as Canavan's disease or Alexander's
disease or with syndromes such as
, achondroplasia (
or small stature),
, and some chromosomal anomalies. In each of these disorders, there is an
enlargement of brain tissues.
In hydrocephalus, excess CSF collects in the large sections of the brain
called the ventricles. This may occur for many reasons, including
, abnormal cysts within the brain, and infections such as
In some cases, a child may have benign macrocephaly. In these children,
the only abnormality is an enlarged head. Usually there are other family
members with large heads, and the condition is considered a family trait.
These children do not have an underlying condition and usually do not have
any additional complications.
The major symptom of macrocephaly is an enlarged head circumference. Other
symptoms can include, delay in reaching developmental milestones,
, rapid head growth, and slowed growth of the rest of the body.
Macrocephaly is usually diagnosed by the pediatrician during a physical
examination. In some cases this may be the only diagnosis necessary. Some
children will require additional diagnostic imaging procedures, such as
scan (CAT scan), x ray, and
magnetic resonance imaging
(MRI), to determine the cause of the macrocephaly and the appropriate
There is no specific treatment for macrocephaly. Medical care for children
with macrocephaly focuses on management of specific symptoms such as
developmental delays and mental retardation and treatment of the primary
diagnosis responsible for the macrocephaly.
For children with benign familial macrocephaly, the prognosis is
excellent. These children usually do not have any complications and have
. For other children with macrocephaly, the prognosis is dependent upon
the cause. In children with hydrocephalus, the prognosis can be excellent
depending on what type of hydrocephalus they have. Unfortunately, many
children with macrocephaly experience delayed development, slow growth,
seizure disorders, and limited intelligence. All of these are related to
the underlying condition that caused the macrocephaly.
—A congenital disturbance of growth plate development in long
bones that results in a person having shortened limbs and a normal
—A progressive, degenerative disorder of the central nervous
—A serious genetic disease more common in the Eastern European
Jewish population that causes mental retardation and early death.
Canavan disease is caused by the lack of an enzyme called
Chiari II anomaly
—A structural abnormality of the lower portion of the brain
(cerebellum and brainstem) associated with spina bifida. The lower
structures of the brain are crowded and may be forced into the foramen
magnum, the opening through which the brain and spinal cord are
Computed tomography (CT)
—An imaging technique in which cross-sectional x rays of the body
are compiled to create a three-dimensional image of the body's
internal structures; also called computed axial tomography.
—One of several "soft spots" on the skull where the
developing bones of the skull have yet to fuse.
—Excessive growth, especially in height, resulting from
overproduction of growth hormone during childhood or adolescence by a
pituitary tumor. Untreated, the tumor eventually destroys the pituitary
gland, resulting in death during early adulthood. If the tumor develops
after growth has stopped, the result is acromegaly, not gigantism.
Magnetic resonance imaging (MRI)
—An imaging technique that uses a large circular magnet and radio
waves to generate signals from atoms in the body. These signals are used
to construct detailed images of internal body structures and organs,
including the brain.
—A condition in which the brain is abnormally large.
—An abnormally large head.
—A progressive genetic condition often including multiple
café-au-lait spots, multiple raised nodules on the skin
(neurofibromas), developmental delays, slifhtly larger head size, and
freckles in the armpits, groin, and iris. Also known as von
—An inherited disorder of the connective tissue which involves
multiple symptoms, including weakened bones that break easily.
—A measure of the distribution of scores around the average
(mean). In a normal distribution, two standard deviations above and
below the mean includes about 95% of all samples.
When mental deficiency and the attendant diseases or disorders are severe,
the child may require a life-support system. When the mental deficiency is
less severe, the child may be diagnosed with minimal brain dysfunction or
as neurologically handicapped. Minimal brain dysfunction can include any
or all of the following: memory and language problems, neuromotor
functioning problems, and behavior and social problems. The degree of
dysfunction is a key factor in parents' deciding whether the child
can continue to live at home and what type of schooling is appropriate.
Parents and teachers need to be cognizant of the nature of the
child's dysfunction. What was once seen as laziness and lack of
motivation on the child's part has begun in the early 2000s to be
recognized as a medical condition that can be corrected or modified
through psychotherapy. Sometimes, though, a child may suffer several years
of frustrating failure and abnormal development or behavior before the
problem is recognized and he or she is properly diagnosed.
Do You Want to Take Her Home?: Trials and
Tribulations of Living Life as a Handicapped Person Due to Multiple
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Moore, Keith L., et al.
Before We Are Born: Essentials of
Embryology and Birth Defects.
Kent, UK: Elsevier—Health Sciences Division, 2002.
PO Box 5245 Bozeman, MT 59717. Web site:
American Association on Mental Retardation
1719 Kalorama Road, NW Washington, DC 20009–2683. Web site:
March of Dimes Birth Defects Foundation.
1275 Mamaroneck Avenue, White Plains, NY 10605. Web site:
"National and Regional Learning and Developmental Disabilities
Greater Boston Physicians for Social Responsibility.
Available online at
October 19, 2004).
National Center on Birth Defects and
Available online at http://www.cdc.gov/nebddd/bd/ (accessed
October 19, 2004).