macrocephaly

Definition

Macrocephaly is a condition in which the head is larger than normal.

Description

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 hydrocephalus 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 family trait. Mental deficiency, seizures, and movement disorders are common in macrocephalic children.

Demographics

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 (CSF) 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 gigantism, achondroplasia (dwarfism or small stature), osteogenesis imperfecta, neurofibromatosis, 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 Chiari malformation, abnormal cysts within the brain, and infections such as meningitis.

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, mental retardation, rapid head growth, and slowed growth of the rest of the body.

Diagnosis

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 computed tomography scan (CAT scan), x ray, and magnetic resonance imaging (MRI), to determine the cause of the macrocephaly and the appropriate treatment.

Treatment

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.

Prognosis

For children with benign familial macrocephaly, the prognosis is excellent. These children usually do not have any complications and have normal intelligence. 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.

Prevention

Macrocephaly is often present at birth or is a result of conditions that are present at birth. As of 2004 there was no known prevention.

Parental Concerns

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.

Resources

Books

Key, Doneen. Do You Want to Take Her Home?: Trials andTribulations of Living Life as a Handicapped Person Due to Multiple Birth Defects. Lancaster, CA: Empire Publishing, 2001.

Moore, Keith L., et al. Before We Are Born: Essentials ofEmbryology and Birth Defects. Kent, UK: Elsevier—Health Sciences Division, 2002.

Organizations

Abiding Hearts. PO Box 5245 Bozeman, MT 59717. Web site: www.abidinghearts.com.

American Association on Mental Retardation 1719 Kalorama Road, NW Washington, DC 20009–2683. Web site: www.aamr.org.

March of Dimes Birth Defects Foundation. 1275 Mamaroneck Avenue, White Plains, NY 10605. Web site: www.modimes.org.

"National and Regional Learning and Developmental Disabilities Organizations." Greater Boston Physicians for Social Responsibility. Available online at (accessed October 19, 2004).

Web Sites

"Birth Defects." National Center on Birth Defects andDevelopmental Disabilities. Available online at www.cdc.gov/nebddd/bd/ (accessed October 19, 2004).

[Article by: Deborah L. Nurmi, MS]

Having an abnormally large head.

Macrocephaly
Classification and external resources
An MRI of a patient with benign familial macrocephaly (male with head circumference > 60cm)
ICD-10	Q75.3
ICD-9	756.0
OMIM	248000
DiseasesDB	22519
MedlinePlus	003305

Macrocephaly (from the ancient Greek μακρό- macro- long- + -κέφαλος -kephalos -head), occurs when the head is abnormally large; this includes the scalp, the cranial bone, and the contents of the cranium.

Contents 1 Causes 2 Diagnosis 3 See also 4 References

Causes

Macrocephaly may be due to megalencephaly (enlarged brain), hydrocephalus (water on the brain), cranial hyperostosis (bone overgrowth), and other conditions. It is called "syndromic" when it is associated with any other noteworthy condition, and "non-syndromic" otherwise. It can be caused by genetic conditions or by environmental events.^[1]

Many genetic conditions are associated with macrocephaly, including familial macrocephaly, autism, PTEN mutations such as Cowden disease, neurofibromatosis type 1, and tuberous sclerosis; overgrowth syndromes such as Sotos syndrome (cerebral gigantism), Weaver syndrome, Simpson-Golabi-Behmel syndrome (Bulldog syndrome), and macrocephaly capillary malformation (M-CMTC) syndrome; neuro-cardio-facial-cutaneous syndromes such as Noonan syndrome, Costello syndrome, and cardiofaciocutaneous syndrome; Fragile X syndrome; leukodystrophies (brain white matter degeneration) such as Alexander disease, Canavan disease, and megalencephalic leukoencephalopathy with subcortical cysts; and glutaric aciduria type 1 and D-2-hydroxyglutaric aciduria.^[1]

Environmental events associated with macrocephaly include infection, neonatal intraventricular hemorrhage (bleeding within the infant brain), subdural effusion (collection of pus beneath the outer lining of the brain), and arachnoid cysts (cysts on the brain surface).^[1]

Diagnosis

Macrocephaly is customarily diagnosed if head circumference is greater than 2 standard deviations (SD) above the mean. Relative macrocephaly occurs if the measure is less than 2 SD above the mean but is disproportionately above that when ethnicity and stature are considered. In research, cranial height or brain imaging are also used to determine intracranial volume more accurately.^[1]

See also

• Microcephaly

References

1. ^ ^{a b c d} Williams CA, Dagli A, Battaglia A (2008). "Genetic disorders associated with macrocephaly". Am J Med Genet A 146A (16): 2023–37. doi:10.1002/ajmg.a.32434. PMID 18629877. 

v • d • e Congenital malformations and deformations of musculoskeletal system / musculoskeletal abnormality (Q65-Q76, 754-756.3) Limb/ dysmelia Upper clavicle/shoulder: Cleidocranial dysostosis · Sprengel's deformity · Wallis Zieff Goldblatt syndrome hand deformity: Madelung's deformity · Clinodactyly Lower hip: Dislocation of hip/Hip dysplasia · Upington disease · Coxa valga · Coxa vara knee: Genu valgum · Genu varum foot deformity: Club foot · Flat feet · Pes cavus · Rocker bottom foot Either/both dactyly/digit: Polydactyly/Syndactyly (Webbed toes) · Arachnodactyly · Cenani Lenz syndactylism · Ectrodactyly · Brachydactyly reduction deficits/limb: Acheiropodia · ectromelia (Phocomelia, Amelia, Hemimelia) multiple joints: Arthrogryposis · Larsen syndrome · Rapadilino syndrome Craniofacial Craniosynostosis: Scaphocephaly · Oxycephaly · Trigonocephaly Craniofacial dysostosis: Crouzon syndrome · Hypertelorism · Hallermann-Streiff syndrome · Treacher Collins syndrome other: Macrocephaly · Platybasia · Craniodiaphyseal dysplasia · Dolichocephaly · Greig cephalopolysyndactyly syndrome · Plagiocephaly · Saddle nose Other axial spine: spinal curvature (Scoliosis) · Klippel-Feil syndrome · Spondylolisthesis · Spina bifida occulta ribs: Cervical rib · Bifid rib sternum: Pectus excavatum · Pectus carinatum joint navs: anat, non-congenital arthropathies/deformities/dorsopathies/soft tissue arthropathy/congenital, eponymous signs, proc

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