microcephaly

Definition

Microcephaly is a neurological disorder where the distance around the largest portion of the head (the circumference) is less than should normally be the case in an infant or a child. The condition can be evident at birth, or can develop within the first few years following birth. The smaller than normal head restricts the normal growth and development of the brain.

Description

The word microcephaly comes from the Greek micros meaning small, and kephale meaning head. The small head circumference that is a hallmark of microcephaly has been defined as that which is either two or three standard deviations (a statistical measure of variability) below the normal average head circumference for the age, gender, and race of the child. Put another way, the head size is markedly smaller than the expected size for about 97–99% of other children.

The condition can be present at birth or may develop during the first few years of life. In the latter situation, the growth of the head fails to keep to a normal pace. This produces a small head, relatively large face (since the face keeps growing at a normal rate), and a forehead that slopes backward. The smallness of the head becomes even more pronounced with age. An older child with microcephaly also has a body that is smaller and lighter than normal. This may be a consequence of the restricted brain development.

Demographics

Microcephaly is a rare neurological condition and occurs worldwide. Little detailed information on the prevalence of the disorder is available. Microcephaly does not appear to be more prevalent among any race or one gender.

Causes and symptoms

Microcephaly may have a genetic basis. If the gene defect(s) are expressed during fetal development, the condition is present at birth. This is the congenital form of the disorder. The microcephaly that develops after birth may still reflect genetically based developmental defects. As well, the delayed microcephaly can be caused if the normal openings in the skull close too soon after birth, preventing normal head growth. This condition is also referred to as craniosynostosis.

Other possible causes of microcephaly include infections during pregnancy (rubella, cytomegalovirus, toxoplasmosis), adverse effects of medication, and the excessive use of alcohol by the mother during pregnancy (fetal alcohol syndrome).

The damage from microcephaly comes because of the cramped interior of the skull. This lack of space exerts pressure on the growing brain. This causes impairment and delayed development of functions such as speech and control of muscles. The impaired muscle control can produce effects ranging from a relatively minor clumsiness in body movement to the more serious and complete loss of control of the arms and legs. A child can also be hyperactive and mentally retarded, although the latter is not always present. As a child grows older, seizures may occur.

It should be noted that at times it is diminished growth of the brain that results in microcephaly. Without proper brain growth, the surrounding skull does not expand and microcephaly results.

Diagnosis

Diagnosis of craniosynostosis and microcephaly is made by a physician, typically during examination after birth. A physician may also be alerted to the presence of microcephaly based on the appearance of the head at birth. Other clues in the few years after birth can be the failure to achieve certain developmental milestones, and the appearance of the distinctive facial appearance.

Treatment team

The medical treatment team can consist of family and more specialized physicians and nurses. Parents and care-givers play an important role in supportive care. As various developmental challenges present themselves, physical therapists and special education providers may become part of the treatment team.

Treatment

In the case of craniosynostosis, surgery can be accomplished to reopen the prematurely closed regions of the skull. This allows the brain to grow normally. There is no such treatment for the congenital form of microcephaly. Treatment then consists of providing for the person's comfort and strategies to compensate for physical and mental delays.

Recovery and rehabilitation

Recovery from craniosynostosis can be complete if surgery is done at an early enough age. For a child with other forms of microcephaly, few treatment options are available. Emphasis, therefore, is placed upon maximizing mobility and mental development, rather than recovery. Speech therapists and audiologists can help with hearing and language development. Physical and occupational therapists provide aid in walking and adaptive equipment such as wheelchairs. Special education teachers coordinate educational goals and strategies based upon the child's abilities.

Clinical trials

Although as of April 2004, there are no ongoing clinical trials underway for the study or treatment of microcephaly, research is being done to explore and understand the mechanisms, particularly genetic, of brain and skull development. By understanding the nature of the developmental malfunctions, it is hoped that corrective or preventative strategies might be developed.

Prognosis

With surgery, the prognosis for children with craniosynostosis can be good. However the outlook for children with other forms of microcephaly is poor, and the likelihood of having normal brain function is likewise poor.

Special concerns

As microcephaly is often associated with chromosomal abnormalities, the specific genetic cause for a person's microcephaly should be determined, if possible. Genetic counseling is available to help parents with information about their child with microcephaly and to plan for future pregnancies.

Resources

BOOKS

Parker, J. N., and P. M. Parker. The Official Parent's Sourcebook on Microcephaly: A Revised and Updated Directory for the Internet Age. San Diego: Icon Health Publications, 2002.

PERIODICALS

Woods, C. G. "Human microcephaly." Current Opinions in Neurobiology (February 2004): 112–117.

OTHER

National Institute of Neurological Disorders and Stroke. NINDS Microcephaly Information Page.http://www.ninds.nih.gov/health_and_medical/disorders/microcephaly.htm (April 9, 2004).

ORGANIZATIONS

National Institute for Neurological Diseases and Stroke (NINDS). 6001 Executive Boulevard, Bethesda, MD 20892. (301) 496-5751 or (800) 352-9424. http://www.ninds.nih.gov.

National Institute for Child Health and Human Development (NICHD). 31 Center Drive, Rm. 2A32 MSC 2425, Bethesda, MD 20892-2425. (301) 496-5133; Fax: (301) 496-7101. http://www.nichd.nih.gov.

National Organization for Rare Disorders. 55 Kenosia Avenue, Danbury, CT 06813-1968. (203) 744-0100 or (800) 999-6673; Fax: (203) 798-2291. orphan@rarediseases.org. http://www.rarediseases.org.

March of Dimes Birth Defects Foundation. 1275 Mamaroneck Avenue, White Plains, NY 10605. (914) 428-7100 or (888) 663-4637; Fax: (914) 428-8203. askus@marchofdimes.com. http://www.marchofdimes.com.

Brian Douglas Hoyle, PhD

Small size of the head in relation to the rest of the body.

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Microcephaly
Classification and external resources
Boy with microcephaly surrounded by his classmates
ICD-10	Q02.
ICD-9	742.1
OMIM	251200
MeSH	22629

Microcephaly is a neurodevelopmental disorder in which the circumference of the head is more than two standard deviations smaller than average for the person's age and sex. Microcephaly may be congenital or it may develop in the first few years of life. The disorder may stem from a wide variety of conditions that cause abnormal growth of the brain, or from syndromes associated with chromosomal abnormalities. Two copies of a loss-of-function mutation in one of the microcephalin genes causes primary microcephaly.

In general, life expectancy for individuals with microcephaly is reduced and the prognosis for normal brain function is poor. The prognosis varies depending on the presence of associated abnormalities.

Contents 1 Microcephaly 2 Microcephaly and culture 3 Notable microcephalics 4 References 5 See also 6 External links

Microcephaly

Microcephaly is a type of cephalic disorder. This is a disorder characterized by a small head and may be caused by a disturbance in the rapid growing of nerve cells. Microcephaly may also be associated with maternal problems such as alcoholism (which can result in the fetal alcohol syndrome disability), diabetes, or rubella (German measles). After the dropping of atomic bombs on Hiroshima and Nagasaki, a large percentage of women who had been pregnant at the time gave birth to children with microcephaly.^[1] A genetic factor may play a role in causing some cases of microcephaly. Affected newborns generally have striking neurological defects and seizures. Severely impaired intellectual development is common, but disturbances in motor functions may not appear until later in life.

Infants with microcephaly are born with either a normal or reduced head size. Subsequently the head fails to grow while the face continues to develop at a normal rate, producing a child with a small head and a receding forehead, and a loose, often wrinkled scalp. As the child grows older, the smallness of the skull becomes more obvious, although the entire body also is often underweight and dwarfed. Development of motor functions and speech may be delayed. Hyperactivity and mental retardation are common occurrences, although the degree of each varies. Convulsions may also occur. Motor ability varies, ranging from clumsiness in some to spastic quadriplegia in others.

Generally there is no specific treatment for microcephaly. Treatment is symptomatic and supportive.

Microcephaly and culture

Numerous superstitions revolve around microcephalics in Pakistan, ranging from being condemned as outcasts and institutionally shunned to having divine powers attributed to them.^[2] Local myths concerning their origins involve infertile women who practice religious rituals in order to facilitate childbirth, and local religious clergies take the health of the firstborn as a price, cursing them into being a "chooha", mouse/rat in Hindi & Urdu. That child has to be given back to the shrine where it would be raised, and live, as an acolyte. Should she fail to do so, all future children will be born choohas as well. Other Pakistanis believe that priests, chooha-masters, or perhaps even parents, purposefully deform healthy infants by placing pots or metal clamps on the heads of healthy infants and so retard the growth of the brain.^[3]

Notable microcephalics

• Schlitzie, a circus performer best known for his role in the 1932 film Freaks.
• Beetlejuice, a member of Howard Stern's "Wack Pack".
• Zip the Pinhead (Circus "freak show" performer William Henry Johnson) is commonly associated with microcephaly, although he may not have actually had it.

References

1. ^ Hiroshima Peace Site[1]
2. ^ Miles M, Beer D.,"Pakistan's microcephalic chuas of Shah Daulah: cursed, clamped or cherished".Hist Psychiatry. 1996 Dec;7(28 pt 4):571-89.
3. ^ Leroi, Armand. "What Makes Us Human?" Telegraph, 08 January 2006.

See also

• Hydrocephaly
• Macrocephaly
• Seckel syndrome
• Anencephaly

External links

• NINDS Microcephaly Information Page
• Microcephaly Support Group
• The Rat People of Pakistan
• NINDS Overview
• Schlitzie The Pinhead
• Beetlejuice Official Website

v • d • e Congenital malformations and deformations of nervous system (Q00-Q07, 740-742) Brain Neural tube defect Anencephaly (Acephaly, Acrania, Iniencephaly) · Encephalocele · Arnold-Chiari malformation Other Microcephaly · Congenital hydrocephalus (Dandy-Walker syndrome) other reduction deformities (Holoprosencephaly, Lissencephaly, Pachygyria, Hydranencephaly) Septo-optic dysplasia · Megalencephaly CNS cyst (Porencephaly, Schizencephaly) Polymicrogyria (Bilateral frontoparietal polymicrogyria) Spinal cord Neural tube defect Spina bifida · Rachischisis Other Currarino syndrome · Diastomatomyelia · Syringomyelia central nervous system navs: anat/physio/dev, noncongen/congen/neoplasia, symptoms+signs/eponymous, proc

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