Microcephaly

Microcephaly is a neurological condition in which improper brain development results in an individual having an abnormally small head. The condition may be evident at birth, or it may develop within the first few years of a child’s life. It is typically the consequence of slower-than-normal brain growth in the womb or soon after birth, which in turn may be caused by various environmental or genetic factors. Microcephaly has no known treatment, and children diagnosed typically have developmental issues. However, early supportive managements, such as speech and occupational therapies, are still able to boost these children’s quality of life and development.

The foremost sign of microcephaly is a significantly smaller head size or circumference around the top of the child’s head. The circumference dimensions are compared to standardized growth charts to identify the child’s ranking, in terms of percentiles, with respect to others of the same sex and age. Children with smaller head sizes are categorized in the lower percentiles. Those diagnosed with microcephaly have circumferences well below the average and may have measurements even lower than the first percentile. More severe cases of microcephaly may also present with backward-sloping foreheads. Early detection is aided by regular wellness checkups, especially for very young children. Parents of newborn children are encouraged to monitor their children’s physical appearance and growth and report any apparent irregularities to their pediatrician.

Background

Microcephaly is the consequence of irregular brain development, starting either in the womb or during infancy. It is often caused by a chromosomal abnormality or other genetic condition that may also result in other, concurrent conditions, such as Down syndrome. Microcephaly may also be a result of craniosynostosis, the untimely coalescing of joints between the bone plates that form a skull, thus preventing the full development of an infant’s brain. Infants with no additional brain flaws may undergo surgery to separate the fused bone plates, which provides additional space for brain growth. Cerebral hypoxia—limited oxygen supply to the fetal brain—may cause microcephaly, given that pregnancy and birthing impediments reduce the oxygen supplied to the fetal brain.

Infections (toxoplasmosis, cytomegalovirus, German measles, chickenpox), alcohol consumption, severe malnutrition, and drug use during pregnancy can also greatly jeopardize fetal brain development. Mothers diagnosed with phenylketonuria (PKU) can give birth to children whose systems are unable to properly degrade the amino acid phenylalanine, thus resulting in microcephaly starting in the womb. Many children diagnosed with microcephaly show normal intelligence and development, though complications such as lack of coordination and balance, dwarfism (shorter physiques), facial deformities, hyperactiveness, seizures, and delays in speech, movement, and intellectual development may still appear, depending on the severity of the condition.

For more complicated cases of microcephaly, pediatricians can refer patients to pediatric neurologists. Parents and guardians who notice smaller head sizes or delays in development should first measure head circumferences of members of the child’s immediate family, including parents and any siblings, to serve as a comparison. It can be helpful to visit a pediatrician accompanied by a family member or friend, to serve as support or witness in remembering any information the pediatrician may provide. Likewise, prepared questions can aid the doctor in identifying the proper and most relevant treatments. Parents should ask doctors about the child’s likely condition, any additional tests required, available treatments, recommended pamphlets or informational websites, and their chances of conceiving more children with microcephaly. The pediatrician will have to perform a physical examination and create a comprehensive medical report for the child, including the prenatal, birth, and family history. Both the child’s and the child’s parents’ head circumferences should be measured to identify any potential family history of having smaller-sized heads. For children showing developmental delays, pediatricians may require a head computed tomography (CT) scan or magnetic resonance imaging (MRI) in addition to blood tests to discover the source of the delay.

Overview

Microcephaly is a rare condition; in the United States, the CDC has reported that as of 2017, state tracking systems estimate between two and twelve new cases for every ten thousand live births. Early detection of the condition can minimize the severity of complications with correct and constant therapeutic treatment. There is currently minimal to no treatment available to reverse microcephaly or its associated complications, apart from surgery to relieve the premature bone development caused by craniosynostosis. Instead, microcephaly treatment concentrates on management of the condition through speech, physical, and occupational therapies. Pediatricians may still prescribe medication to alleviate specific complications caused by microcephaly, such as seizures and hyperactivity.

Microcephaly is more likely to emerge in families with certain genetic conditions, such as Cornelia de Lange syndrome, Down syndrome (trisomy 21), cri du chat syndrome, Rubinstein-Taybi syndrome, Seckel syndrome, Smith-Lemli-Opitz syndrome, and Edwards syndrome (trisomy 18). Cornelia de Lange syndrome delays growth within the womb and after birth and often leads to intellectual difficulties, arm and hand malformations, and characteristic facial features. Persons with Down syndrome have weaker cognitive and muscle functions and distinct facial features and show considerable intellectual disability. Edwards syndrome slows womb growth, causes organ defects and irregular head shapes, and attenuates newborn survival within the first month of life. Newborns with cri du chat syndrome have a recognizable, high-pitched cry (comparable to a cat’s cry, hence the name) and are born with weaker muscles, mental disabilities, distinct features (wide-set eyes, small jaw, low-set ears), and a low birth weight. Microcephaly can also develop if mothers are exposed to viruses or contaminants during pregnancy, such as the Zika virus, methylmercury poisoning, rubella, toxoplasmosis, cytomegalovirus, or uncontrolled PKU. Once an outbreak of the Zika virus was confirmed in Brazil in 2015 and the first cases began being reported in US territories in 2016, the Centers for Disease Control and Prevention (CDC) launched studies to determine whether there was a link between women contracting the virus during pregnancy and giving birth to a baby with microcephaly (the instinces of microcephaly had greatly increased in Brazil during the outbreak of the virus). After much research, the CDC concluded that there was a causal connection between the virus and microcephaly as well as other birth defects, and the organization advised that pregnant women avoid traveling to areas where Zika was known to be spreading.

Parents with a history of genetic conditions are more likely to have children with microcephaly and may wish to seek genetic counseling prior to having a child. Correct prenatal care and avoidance of alcohol and drugs during pregnancy can help reduce the chances of microcephaly. During prenatal checkups, doctors can advise mothers on proper prenatal care and diagnose any maternal conditions, such as uncontrolled PKU. Upon diagnosis, parents should gather a group of trusted professionals to aid in the child’s educational and treatment-related transition. Experts can guide families toward local resources and state and federal programs that support children with disabilities. It may also be helpful to seek out other families or support groups for people in similar situations.

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