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Microcephaly

Microcephalies

Microcephaly is a type of neurodevelopmental disorder of children characterized by smaller head size as compared to other children of the same age and gender. In many cases, it occurs due to abnormal development of brain during fetal growth.


Presentation

A smaller than normal head size is the classical symptom of microcephaly. Many children often have a normal head size at birth; but eventually as the child grows, the size of the head appears to become proportionately smaller compared to the rest of the body.

Some percentages of affected children also are dwarf and underweight. In addition, development of other motor functions is delayed and neurological defects are evident. Seizures and convulsions are a common accompaniment of microcephlay. Some children with microcephaly may develop clumsiness while some other may develop spastic qualdriplegia. Affected children develop a large head with a preceding forehead and a wrinkled scalp [6].

Progressive Mental Retardation
Failure to Thrive
  • Failure to thrive and mild facial dysmorphic features were also present. To our knowledge, this complex malformation (neurocutaneous) phenotype has not been previously reported.[ncbi.nlm.nih.gov]
  • ‘However, three or more minor malformations, especially if associated with short stature or failure to thrive, microcephaly or developmental delay, should engender further investigation.’[en.oxforddictionaries.com]
  • Then, they reversed course, saying that the severity of her microcephaly was stronger than they had initially imagined, and she was showing a failure to thrive. They told Gwen she should get ready to say goodbye to her precious girl.[redbookmag.com]
  • Symptoms of the disorder may include unusual facial appearance, difficulty swallowing, failure to thrive, and severe psychomotor retardation. Anomalies of the hands, fingers, or toes, muscle spasms, and seizures may also occur.[web.archive.org]
Absent Nails
  • We report on an adult male with normal intelligence who exhibited an unusual combination of microcephaly, dysostoses of limbs, vertebrae, patellae, and pubic bone, camptodactyly of all fingers, and syndactyly of toes, absent nails on thumbs and some fingers[ncbi.nlm.nih.gov]
Abnormal Eye Movement
  • We report a ten-month old boy with Canavan disease who presented with global developmental delay, seizures, abnormal eye movements and microcephaly.[ncbi.nlm.nih.gov]
Skeletal Dysplasia
  • MMS is an autosomal recessive condition described thus far in only a single First Nations population and causes intrauterine growth restriction, severe microcephaly, craniofacial anomalies, skeletal dysplasia, and neonatal lethality.[ncbi.nlm.nih.gov]
Quadriplegia
  • Patient 2 is currently four years old with severe neurodevelopmental delay, quadriplegia and cortical blindness. Whole exome sequencing (WES) revealed a novel homozygous mutation in ASNS (NM_001178076.1) in each patient (c.970C T:p.[ncbi.nlm.nih.gov]
  • Motor ability varies, ranging from clumsiness in some to spastic quadriplegia in others.[zikavirusnet.com]
  • Motor ability varies, ranging from clumsiness in some to spastic quadriplegia in others. Microcephaly is a type of cephalic disorder.[en.wikipedia.org]
  • 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.[web.archive.org]

Workup

At birth, if microcephaly is suspected, then a thorough checkup should be carried out. In addition, the head circumference should be measured and compared with standardized growth charts. In many cases, the head circumference of the parents can also be measured to determine whether the condition is a common occurrence in the family. Parents should be asked about the developmental milestones of the child to further understand the condition.

If there are signs of developmental delay, certain tests along with Computerized Tomography (CT) scan and Magnetic Resonance Imaging (MRI) of the head will be required to determine the underlying disease conditions [7].

In many cases, it is possible to detect microcephaly by prenatal ultrasound examination carried out during the third trimester. However, the condition can be difficult to diagnose in the early stages of fetal development [8].

Treponema Pallidum
  • Tests for dengue virus, chikungunya virus, Toxoplasma gondii, rubella virus, cytomegalovirus, herpes simplex virus, HIV, Treponema pallidum, and parvovirus B19 were all negative.[ncbi.nlm.nih.gov]

Treatment

  • So far there is no treatment regime to enlarge the child’s head. If craniosynostosis is the underlying cause of microcephaly, then surgery can be done to correct the fusion and provide space for development of child’s brain. However, in other conditions, only supportive therapy is indicated to manage the symptoms and improve the child's quality of life.
  • Medications are given in cases when the child is hyperactive or is experiencing seizures and convulsions. In addition, various types of therapies such as speech, occupational and physical are also employed in the early developmental years.
  • If microcephaly is diagnosed at birth, then frequent examinations are required in order to monitor the brain development of the child. The child’s family is also given education about the disease which is helpful in improving the child's quality of life.

Prognosis

Microcephaly cannot be treated. The treatment regime that is administered is supportive in nature, primarily geared towards improving the quality of life of the affected children. The life expectancy of children with microcephaly is greatly reduced and the chances of having a normal brain function are poor.

Etiology

Abnormal development of the brain during infancy or fetal growth can lead to a head size that is smaller than normal. In many cases, microcephaly occus as a result of genetic factors. Other factors which can also favor abnormal brain development include the following:

Epidemiology

The average prevalence of microcephaly is estimated to be 25%. The condition of microcephaly can also lead to intellect disability; however, in about 15% cases, the child has normal intellectual levels [3]. In a study carried out on children affected by microcephaly, it was found that 10.5% of them had IQ scores below 70; whereas, 28% of them had IQ scores 70 – 80. In the US, about 25,000 infants annually develop microcephaly [4].

Sex distribution
Age distribution

Pathophysiology

The growth of the head depends on the brain development. When the brain cannot grow at a normal rate, microcephaly develops. Various genes and genetic defects have a pivotal role to play in the development of microcephaly. Studies have postulated the fact that mutation occurring in the DNA repair pathway is one of the major causes of poor brain growth. In addition to genetic mutations, centrosomal abnormalities are another factor that favor the development of microcephaly [5].

Prevention

It is not always possible to prevent the development of microcephaly. However, parents with affected children may want to consider genetic counseling for future pregnancies [9].

In addition to this, pregnant mothers can take certain steps to avoid exposing the fetus to alcohol, drugs, toxins and other chemical compounds. Pregnant women are also advised to consume a nutritious diet to avoid malnutrition because severe malnutrition has been identified as a potential risk factor for poor brain development during fetal growth [10].

Summary

Children affected with microcephaly have to face serious developmental problems and deteriorated quality of life. So far, there is no treatment for correcting this condition; however, if supportive therapies are introduced in the early stages; the quality of life of the affected children can be improved. Interplay of various genetic and environmental factors is known to play a role in the causation of microcephaly [1].

Patient Information

Microcephaly is a condition in which the head of a child is smaller than normal for his age. It is frequently accompanied by  underlying disorders of the brain and mental retardation. It usually results from genetic abnormalities. Exposure of the fetus to toxins, alcohol and chemicals during pregnancy also causes poor brain growth and contributes to the development of microcephaly. Symptoms of microcephaly include seizures, convulsions, high pitched crying, mental retardation and developmental delays. The diagnosis of microcephaly is made by measuring the head circumference of the affected child. Thereafter, several tests to determine the growth of the child are done at various stages of growing years. There is no specific treatment for microcephaly. Medications are given for managing the symptoms of seizures, convulsions and hyperactivity. Speech and occupational therapy are also indicated to improve the quality of life.

References

Article

  1. Nard JA.Abnormal head size and shape. In: Common & Chronic Symptoms in Pediatrics, Gartner JC, Zitelli BJ (Eds), Mosby, St. Louis 1997
  2. Gleeson JG, Dobyns WB, Plawner L, Ashwal S. Congenital structural defects. In: Pediatric Neurology Principles and Practice, 4th ed, Swaiman KF, Ashwal S, Ferriero DM (Eds), Mosby Elsevier, Philadelphia 2006. p.399.
  3. Gale CR, O'Callaghan FJ, Bredow M, et al. The influence of head growth in fetal life, infancy, and childhood on intelligence at the ages of 4 and 8 years. Pediatrics 2006; 118:1486.
  4. Sells CJ.Microcephaly in a normal school population. Pediatrics 1977; 59:262.
  5. Mahmood S, Ahmad W, Hassan MJ. Autosomal Recessive Primary Microcephaly (MCPH): clinical manifestations, genetic heterogeneity and mutation continuum. Orphanet J Rare Dis 2011; 6:39.
  6. Klingseisen A, Jackson AP. Mechanisms and pathways of growth failure in primordial dwarfism. Genes Dev 2011; 25:2011.
  7. Sugimoto T, Yasuhara A, Nishida N, et al. MRI of the head in the evaluation of microcephaly. Neuropediatrics 1993; 24:4.
  8. Kurmanavicius J, Wright EM, Royston P, et al. Fetal ultrasound biometry: 1. Head reference values. Br J ObstetGynaecol 1999; 106:126.
  9. Tolmie JL, McNay M, Stephenson JB, et al. Microcephaly: genetic counselling and antenatal diagnosis after the birth of an affected child. Am J Med Genet 1987; 27:583.
  10. Spohr HL, Willms J, Steinhausen HC. Prenatal alcohol exposure and long-term developmental consequences. Lancet 1993; 341:907.

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Last updated: 2019-07-11 22:21