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Microcephaly - Causes, Symptoms, Diagnosis, Complications, and Treatment

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Microcephaly - Causes, Symptoms, Diagnosis, Complications, and Treatment

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Microcephaly is a neurological condition in which infants are born with a small head. This article describes its causes and management.

Medically reviewed by

Dr. Patel Bhavesh Ashokkumar

Published At August 2, 2022
Reviewed AtMay 29, 2024

What Is Microcephaly?

During pregnancy, the size of the baby’s head depends on the growth of the brain. When the brain stops growing, it hampers the development of the skull, causing comparatively smaller head size. Microcephaly is a birth defect either seen as an isolated condition or along with other birth defects. The development of the brain during pregnancy is sometimes normal, but due to some trauma or damage, the development process is interrupted. Microcephaly is rare, occurring in two to 12 babies per 10,000 births. The condition is often congenital (by birth), but also there are chances of children developing it at a later age.

What Are the Types of Microcephaly?

  • Primary or Congenital: The baby will be born with a small head.

  • Secondary or Acquired: This type develops as the baby grows.

What Are the Causes of Microcephaly?

The baby’s skull grows with the size of his brain. What causes this condition is still unknown. However, there are some condition that affects the development of the brain, such as;

  • Down Syndrome: A chromosomal condition occurs due to an extra pair of chromosome 21 in the baby’s genes. It is responsible for the baby’s brain and body development, and the condition causes distinct facial features, intellectual disabilities, or physical problems in the child.

  • Prenatal Viral Infections: Viral infections like Zika virus, rubella, toxoplasmosis, or cytomegalovirus can play a major role in this condition.

  • Alcoholism During Pregnancy: When a mother is addicted to substance abuse, there are more chances of a child having birth defects like this.

  • Gestational Diabetes: Owing to hormonal changes during pregnancy, sugar levels rise, which causes pregnancy-related diabetes. However, this can be managed with proper diet, exercise, and medication.

  • Metal Poisoning: There are metals like mercury that cause metal poisoning, in turn causing birth defects in the child.

  • Malnutrition in Mother: Diet plays an important role during pregnancy, not only for children but also for mothers. Balancing the diet of the pregnant mother can manage a plethora of conditions.

  • Genetic Mutation: Genes passed from biological parents play a major role in the embryo’s body formation in the mother’s womb. When there are changes in genes in an embryo, there are higher chances of birth-related defects in children, and one of the defects is microcephaly. Untreated phenylketonuria (PKU) is another inherited genetic mutation that is caused when the body is unable to break down an amino acid called phenylalanine.

  • Brain Problems: Complications during birth, like lack of oxygen to the newborn, can cause injury to the brain, and this can cause many fatal conditions to the child.

What Are the Signs and Symptoms Associated With Microcephaly?

Besides the distinctly identifiable smaller head, there are other symptoms of microcephaly. They are as follows:

  • Problems related to eyesight and hearing.

  • Seizures.

  • Poor appetite.

  • High-pitched cry.

  • Hyperactivity.

  • Developmental delays like delayed speech and walking.

  • Trouble in learning.

  • Abnormal muscle tone.

How to Diagnose Microcephaly?

Suppose a mother is going for regular checkups. In that case, there is a chance that the doctor will detect any birth defect before birth or during a prenatal ultrasound in the late second or third trimester. Besides, the condition is developed after birth. In that case, the pediatrician will detect it during regular checkups while measuring the circumference of the baby’s head or complete physical examination with the prenatal birth history of a child. Likewise, obtaining regular milestones while growing up, such as crawling, walking, or speaking the first word, is another measure for checking for intellectual disabilities. Also, the appearance of a head after birth, high-pitched crying, feeding difficulties, and muscle spasms are external signs that this condition shows. If a baby is showing any of the above symptoms while growing up, healthcare providers may suggest the following tests:

  • Computed tomography scan (CT scan).

  • X-rays.

  • Magnetic resonance imaging scan (MRI scan).

  • Blood testing.

  • Genetic testing.

What Are the Complications of Microcephaly?

Sometimes, there are no other complications in a little one except for the small head, but there are chances of some complications like:

  • Congenital Zika Syndrome: It is caused by the Zika virus. It is a bunch of congenital abnormalities affecting the fetus.

  • Cerebral Palsy: Cerebral Palsy is a birth defect caused by abnormal brain development. It results in a defect in muscle tone, movement, and posture.

  • Dwarfism: It is a genetic mutation that affects the growth of the bones in the body. This disorder creates shortness of height. Moreover, people with this syndrome are often seen with hunched back and bowed legs.

  • Face Deformities: Due to an abnormally small head, facial features are also affected.

  • Seizures: Due to an abnormally small head, there is a chance of brain developmental defects—the deformity related to the brain results in uncontrolled electrical disturbances. The severity of this condition can also cause loss of consciousness in children.

  • Other Problems: Problems with vision, hearing, speech, and walking.

What Is the Treatment for Microcephaly?

Although there is no known cure for the condition, the symptoms or complications can be managed according to severity. Babies with mild microcephaly might not require any treatment. Still, a severe condition associated with the brain does require treatment measures, such as speech therapy, occupational therapy, physical therapy, or drug therapy. Pregnant women should be educated about the importance of diet during and after pregnancy. Additionally, mothers addicted to drugs, smoking, or alcohol should go for rehabilitation therapy before conceiving or at least give their detailed history to the doctor.

What Are the Risk Factors of Microcephaly?

Some common risk factors are

  • Alcohol usage disorder.

  • Substance use disorder.

  • Mercury and lead poisoning.

  • Malnutrition.

  • Gestational diabetes.

  • Infection.

Can Microcephaly Be Prevented?

The risk of the baby being affected by this condition can be lowered by following certain things during pregnancy, such as

  • Intake of a well-balanced diet.

  • Treatment of underlying health issues.

  • Avoiding toxic chemicals.

  • Regular checkups.


Microcephaly is a birth defect caused by many syndromes. The defect results in an underdeveloped skull and brain. Although there are no known treatments available to cure the condition, the symptoms or complications associated with it can be managed. Parents and doctors must give extra attention to the patient's care.

Frequently Asked Questions


What Causes Microcephaly?

There are various potential causes for microcephaly, but the most common are:
- Infections - Toxoplasmosis, rubella, herpes, syphilis, HIV, Campylobacter pylori, cytomegalovirus, and Zika.
- Mother's exposure to toxic chemicals - Alcohol, smoking, arsenic, mercury, and radiation.
- Genetic abnormalities.
- Injuries to the developing brain
- Severe malnutrition.


How Long Do Babies Survive With Microcephaly?

Microcephaly babies' life expectancy depends on many factors, including the condition's severity. Babies with mild microcephaly can live a regular life and meet the same milestones as a child without the disorder. But in severe cases, this condition can be life-threatening.


Can Microcephalic Children Live a Normal Life?

Many babies born with mild microcephaly often have no symptoms and meet milestones like sitting, speaking, and walking as a child without the disorder.


Will Children With Microcephaly Survive?

Yes, children with microcephaly can survive and even live normal lives; however, the mortality rate for infants with microcephaly was 5.8 percent. In addition, babies with mild microcephaly often do not experience health issues other than small head sizes.


Can a Child Grow With Microcephaly?

Microcephaly is a lifelong condition. Children with mild disorders may not experience any other problems, and their heads will grow as they develop but remain smaller than normal.


When Is Microcephaly Ruled Out in Babies?

Microcephaly in babies is diagnosed as early as around 28 weeks or during the third trimester of pregnancy with the help of fetal ultrasound. The healthcare provider will measure the head circumference of the babies soon after birth and confirm the diagnosis.


Which Head Size Is Considered Microcephaly?

When the head circumference measurement is smaller than a certain value for newborns of the same age and sex, it is considered microcephaly. Apparently, newborns with a head circumference of less than 32 cm are considered microcephalus.


Is Microcephaly an Inherited Condition?

Microcephaly occurs when there is a problem during brain development. It is an autosomal recessive gene disorder, and genetics can also play a role in developing microcephaly.


Can Microcephaly Cause Death?

The severe form of microcephaly is a life-threatening condition. The mortality rate for infants with microcephaly was 5.8 percent. However, some infants with moderate to severe conditions survive but may face severe health issues.


Can Microcephaly Be Diagnosed Wrongly?

In most of the visits, the healthcare professional will regularly have a baby check and track their growth. Microcephaly may be misdiagnosed if there is any inaccuracy in the prenatal ultrasound. Even a small fetus with no microcephaly may be misdiagnosed before birth.


What Changes Happen to the Brain Due to Microcephaly?

Microcephaly can affect the brain's development by causing the brain to be much smaller than normal for a child's age. It can also cause developmental problems and learning difficulties due to the brain's size.
Dr. Patel Bhavesh Ashokkumar
Dr. Patel Bhavesh Ashokkumar



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