Learn About Microcephaly

What is the definition of Microcephaly?

Microcephaly is a condition in which a person's head size is much smaller than that of others of the same age and sex. Head size is measured as the distance around the top of the head. A smaller than normal size is determined using standardized charts.

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What are the causes of Microcephaly?

Microcephaly most often occurs because the brain does not grow at a normal rate. The growth of the skull is determined by brain growth. Brain growth takes place while a baby is in the womb and during infancy.

Conditions that affect brain growth can cause smaller than normal head size. These include infections, genetic disorders, and severe malnutrition.

Genetic conditions that cause microcephaly include:

  • Cornelia de Lange syndrome
  • Cri du chat syndrome
  • Down syndrome
  • Rubinstein-Taybi syndrome
  • Seckel syndrome
  • Smith-Lemli-Opitz syndrome
  • Trisomy 18
  • Trisomy 21

Other problems that may lead to microcephaly include:

  • Uncontrolled phenylketonuria (PKU) in the mother
  • Methylmercury poisoning
  • Congenital rubella
  • Congenital toxoplasmosis
  • Congenital cytomegalovirus (CMV)
  • Use of certain drugs during pregnancy, especially alcohol and phenytoin

Becoming infected with the Zika virus while pregnant can also cause microcephaly. The Zika virus has been found in Africa, the South Pacific, tropical regions of Asia, and in Brazil and other parts of South America, along with Mexico, Central America, and the Caribbean.

When should I contact a medical professional for Microcephaly?

Most often, microcephaly is diagnosed at birth or during routine well-baby exams. Talk to your health care provider if you think your infant's head size is too small or not growing normally.

Contact your provider if you or your partner has been to an area where Zika is present and you are pregnant or thinking about becoming pregnant.

What should I expect during a doctor appointment?

Most of the time, microcephaly is discovered during a routine exam. Head measurements are part of all well-baby exams for the first 18 months. Tests take only a few seconds while the measuring tape is placed around the infant's head.

The provider will keep a record over time to determine:

  • What is the head circumference?
  • Is the head growing at a slower rate than the body?
  • What other symptoms are there?

It may also be helpful to keep your own records of your baby's growth. Talk to your provider if you notice that the baby's head growth seems to be slowing down.

If your provider diagnoses your child with microcephaly, you should note it in your child's personal medical records.

Skull of a newborn
Ultrasound, normal fetus - ventricles of brain
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What are the latest Microcephaly Clinical Trials?
A Phase 1/2 Open-label Intrathecal Administration of MELPIDA to Determine Its Safety and Efficacy for Patients With Spastic Paraplegia Type 50 (SPG50) Caused by Mutation in the AP4M1 Gene.

Summary: MELPIDA is proposed for the treatment of subjects with SPG50 and targets neuronal cells to deliver a fully functional human AP4M1 cDNA copy via intrathecal injection to counter the associated neuronal loss. Outcomes will evaluate the safety and tolerability of a single dose of MELPIDA, which will be measured by the treatment-associated adverse events (AEs) and serious adverse events (SAEs). Second...

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Primordial Registry at Nemours/Alfred I. duPont Hospital for Children

Summary: The goal of this registry is to collect information on individuals with Microcephalic Osteodysplastic Primordial Dwarfism Type II (also called MOPDII) and other forms of microcephalic primordial dwarfism. The study team hopes to learn more about these conditions and improve the care of people with it by establishing this registry.

What are the Latest Advances for Microcephaly?
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Scientometric Analysis of Public Health Emergencies: 1994-2020.
Who are the sources who wrote this article ?

Published Date: December 10, 2021
Published By: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

What are the references for this article ?

Antoniou E, Orovou E, Sarella A, et al. Zika virus and the risk of developing microcephaly in infants: a systematic review. Int J Environ Res Public Health. 2020;17(11):3806. PMID: 32471131 pubmed.ncbi.nlm.nih.gov/32471131/.

Centers for Disease Control and Prevention website. Zika virus. www.cdc.gov/zika/index.html. Updated September 20, 2021. Accessed January 19, 2022.

Kinsman SL, Johnston MV. Congenital anomalies of the central nervous system. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 609.

Mizaa GM, Dobyns WB. Disorders of brain size. In: Swaiman KF, Ashwal S, Ferriero DM, et al, eds. Swaiman's Pediatric Neurology: Principles and Practice. 6th ed. Philadelphia, PA: Elsevier; 2017:chap 28.