Microcephaly (Small Head) and Birth Injuries

Microcephaly is a diagnosis given to infants with a head significantly smaller than what is considered standard. A diagnosis of microcephaly in a baby can be an indication that the baby suffered hypoxic-ischemic encephalopathy (brain damage caused by limited oxygen at or around the time of birth), which can increase the risk of cerebral palsy, developmental delays, and other serious disabilities (1).

Problems with normal head growth may be the first indication that a baby has a neurological problem.  Microcephaly is a neurodevelopmental disorder, meaning it is caused by a problem with the brain/central nervous system.

There are two forms of microcephaly, each based upon the cause of the subsequent condition (4):

• Congenital microcephaly: Congenital microcephaly is a type of microcephaly brought about by genetic abnormalities, it can be passed down genetically or can arise as the result of genetic mutation.
• Acquired microcephaly: Acquired microcephaly occurs when the brain is damaged by an injury like HIE or birth asphyxia. In cases of acquired microcephaly, the head is often a normal size at birth, but as the baby grows, the head and brain begin to appear smaller than is expected. Usually, acquired microcephaly comes as the result of HIE or another traumatic brain injury around the time of birth.

Microcephaly is usually defined as a head circumference of more than 2 standard deviations below the mean for the baby’s age and gender (2). Microcephaly may be present at or near the time of birth, or it may develop in the first few years of life. Children with severe microcephaly often have reduced brain function, and may not live as long as their peers (1).  Due to this, it is crucial for the medical team to prevent or quickly rectify conditions that can cause microcephaly.

While microcephaly is sometimes caused by genetic abnormalities (congenital microcephaly), it is often caused by insults to the brain at or near the time of birth (2). Listed below are some complications that can occur during or near birth that may cause acquired microcephaly if managed poorly:

• Hypoxic-ischemic encephalopathy (HIE)
• Brain bleed (hemorrhage)
• Traumatic brain injury
• Maternal infection
• Ischemic stroke
• Placental insufficiency

A microcephaly diagnosis is made based upon the circumference of the baby’s head in relation to the standard circumference for babies of a similar age and gender. Sometimes microcephaly can be diagnosed during the late second trimester or third trimester via ultrasound, but most often it is diagnosed after the baby is born. After birth, microcephaly is diagnosed by measuring the distance around the newborn’s head and comparing it to a standardized growth chart. In addition, further tests such as MRI scans can be run to help confirm a microcephaly diagnosis (1).

Microcephaly is a lifelong condition and there is currently no cure. Infants with severe microcephaly may experience serious medical complications and may require supportive care for these related needs (2). Severe microcephaly is often associated with the following long-term complications (3):

• Cerebral palsy
• Developmental delays
• Intellectual disabilities
• Seizures
• Hearing and vision loss