Microcephaly after birth injury

How does this happen?

The skull of a baby is made of separate plates with gaps between them. It expands because the brain pushes it outward as it grows. If the brain does not grow, the skull does not either. ²

That gives clinicians a cheap and useful measurement, and it means the shape of the growth curve carries information.

Microcephaly present at birth means the brain did not grow as expected during pregnancy. Causes include infections during pregnancy, genetic conditions, brain malformations, and exposures.

Acquired microcephaly means the head was a normal size at birth and then fell behind. This is the pattern that follows a brain injury around the time of birth. Brain tissue that is lost after severe hypoxic-ischemic encephalopathy, a large perinatal stroke, meningitis or severe low blood sugar does not grow, so over the following months the head crosses downward through the percentile lines. ²

This is why serial measurements matter so much, and why a single number at one visit tells you comparatively little.

What causes it?

Two different questions get mixed together here. The first is what leads to this injury in the body. The second is whether anyone could have prevented it. They are not the same question, and the answer to the first does not settle the second.

Happens even with perfect care

• Genetic conditions, which are a large group and are frequently the answer when microcephaly is present at birth. ¹
• Infections during pregnancy, including cytomegalovirus, toxoplasmosis, rubella and Zika. ¹
• Brain malformations that formed during pregnancy.
• Severe growth restriction from placental problems.
• Metabolic conditions.
• Perinatal stroke or bleeding that could not have been anticipated. ⁴

Associated with gaps in care

These are situations where published standards say what the care team should watch for and do. A gap here does not prove anyone caused your child's injury. It points to where the medical records will have an answer.

Where microcephaly is acquired after birth, the questions are about whatever caused the brain injury.

• A loss of oxygen during labor that was not recognized or acted on. ⁵
• Cooling not offered or started late in a baby with moderate or severe hypoxic-ischemic encephalopathy. ⁶
• meningitis or sepsis not recognized and treated promptly. ⁷
• Low blood sugar not screened for or not treated in a baby with risk factors. ⁸
• Head circumference not measured or not plotted at well visits, so falling head growth went unnoticed for months. This measurement is part of routine care.
• Maternal infection in pregnancy not identified, where screening applies. ⁷

Whether any of this caused a particular child's injury takes a physician expert reading the whole record.

What are the signs, by age?

Signs change as a child grows. A newborn cannot show you a walking problem. Some children look fine at first and show differences months later.

At birth and the first hours

• A head circumference below the expected range at birth, measured and plotted.
• Sometimes a sloping forehead or a head that looks small in proportion to the face.
• Where the cause is a pregnancy infection, other findings may be present such as a small liver and spleen, a rash, or eye findings.

The first week

• Feeding difficulty.
• Seizures. ⁹
• Abnormal tone.
• In acquired cases, nothing at all yet, because the head is still a normal size.

Around 3 months

• Head circumference crossing downward through the percentile lines. This is the key finding in acquired microcephaly.
• Poor visual attention.
• Increasing or decreasing tone.
• Delay in head control.

Around 6 months

• Delay in rolling. ¹⁰
• Continued fall in head growth.
• Feeding difficulty.

Around 12 months

• Not sitting independently. ¹⁰
• Delay across several areas of development.
• Seizures in some children. ¹¹

Toddler years

• Motor delay or cerebral palsy.
• Speech delay.
• Epilepsy in some children.
• A wide range of outcomes, which is worth stating plainly because families are often given a bleak picture at diagnosis.

School age

• Learning differences ranging from mild to significant.
• Epilepsy in a minority.
• Some children with microcephaly attend mainstream school with support.

How is it diagnosed?

The measurement is done with a tape around the widest part of the head, and it is plotted on a growth chart for age and sex. Preterm babies are plotted using corrected age. ³

Two things determine what happens next.

The shape of the curve. Ask to see the measurements plotted over time. A head tracking steadily along a low line means something different from a head crossing downward through the lines.

When it started. Present at birth points to pregnancy. Falling behind afterward points to an injury or process around or after birth. ²

Workup

• MRI, which shows the structure of the brain, any malformation, and the pattern of any injury. ²
• Genetic testing, including chromosomal microarray and often broader sequencing, which finds a cause in a substantial share of cases where microcephaly was present at birth. ¹
• Infection testing for congenital infections. ¹
• Metabolic testing where indicated.
• Hearing and vision assessment, because both are commonly affected and both are treatable in the sense that support can be provided. ^{12 13}
• EEG where seizures are suspected. ⁹

Ask whether the parents' head sizes were measured. Benign familial microcephaly exists, where a small head runs in a family alongside typical development, and it is a genuine and reassuring finding when it applies.

What is the treatment?

There is no treatment that makes the brain or the head grow. Care is about function and about the associated conditions.

• Early intervention therapy, as early as possible. ^{14 15}
• Seizure treatment where epilepsy is present. ¹¹
• Feeding support, including swallow assessment where feeding is difficult or slow.
• Vision and hearing support. ^{13 16}
• Treating an underlying condition where one is found and treatable.
• Developmental follow-up on a schedule, rather than waiting for problems to appear. ¹⁷

If a genetic cause is found, genetic counseling matters for the family, both for understanding and for any future pregnancy.

What is the long-term outlook?

Head size is a poor predictor on its own, and it is often presented to families as though it were a strong one.

Outcomes range from significant intellectual disability to typical development. What predicts more is the underlying cause, what the MRI shows, and whether epilepsy is present. ^{1 2}

Where microcephaly is part of a genetic syndrome, that syndrome usually determines the picture.

Where it followed a severe brain injury, the injury determines the picture.

Where it is familial and the brain is structurally normal, development is often typical.

Ask your neurologist which of those categories your child is in. It is a more useful question than asking what the number means.

What does daily life look like?

Feeding is often the first practical challenge and it can be slow. A feeding assessment is worth asking for early rather than persevering.

Therapy, developmental follow-up, and often seizure management make up the routine.

The social difficulty families report most is the reaction to the diagnosis word itself. Microcephaly is heavily associated in the public mind with one specific outbreak and with a bleak prognosis. Neither is representative of the range. It is reasonable to describe your child by what they do rather than by the label.

What does care cost over a lifetime?

No agency publishes a lifetime cost estimate for microcephaly, because the range of outcomes is so wide.

Where it accompanies intellectual disability, the CDC estimate for that group was about $1,014,000 per person in 2003 dollars. Where it accompanies cerebral palsy, the estimate was about $921,000 in 2003 dollars. ¹⁸ These are separate population estimates that overlap and cannot be added together for one child.

See the cost of care estimator.

What can you do this week?

1. Ask to see the head circumference measurements plotted over time, not just the latest number.
2. Ask whether the head was small at birth or fell behind afterward.
3. Ask whether both parents' heads have been measured.
4. Ask what genetic testing has been done and what is left.
5. Ask what the MRI showed.
6. Arrange hearing and vision assessments.
7. Refer to early intervention today.

What should you ask each specialist?

Take these with you. Write the answers down in the moment, because you will not remember them later.

For the neurologist or geneticist

• Was the head small at birth, or did head growth slow afterward?
• What did the MRI show?
• What genetic and metabolic testing has been done, and what remains?
• Have our head sizes been measured?
• What are you watching for over the next year?

For the pediatrician

• Can I see the growth chart with all the plotted points?
• Are hearing and vision assessments arranged?
• What is the follow-up schedule?

You can also build a printable list with the question generator.