From the Guidelines
The most likely cause of a 9-month-old child with head circumference (COH) at the 3rd centile who was born prematurely at 35 weeks is a combination of prematurity and potential growth failure, as growth failure in infancy or toddlerhood has been associated with worse neurodevelopmental outcomes in individuals with congenital heart disease 1.
Key Considerations
- Premature birth interrupts the normal brain growth that occurs rapidly in the third trimester, which can impact head circumference and overall development.
- Growth failure, as indicated by a head circumference at the 3rd centile, suggests that the child may not be receiving adequate nutrition or may have underlying health issues that need to be addressed.
- The association between poor growth in utero, as measured by weight and head circumference at birth, and worse neurodevelopmental outcomes highlights the importance of monitoring growth and development closely in premature infants 1.
Recommended Approach
- Comprehensive evaluation by a pediatric neurologist and developmental specialist to assess the child's growth, development, and potential underlying health issues.
- Detailed growth measurements, including weight, length, and head circumference plotted on appropriate preterm-corrected growth charts, to monitor growth trajectory.
- Developmental screening and possibly neuroimaging, such as MRI, to evaluate brain structure and identify any potential abnormalities.
- Nutritional optimization, with high-calorie formula or breast milk supplementation if growth remains suboptimal, to support healthy growth and development.
- Regular follow-up every 2-3 months to monitor growth trajectory and developmental milestones, with aggressive early intervention services, including physical, occupational, and speech therapy, as needed to improve long-term outcomes.
Importance of Early Intervention
- The first three years of life represent a critical period for brain development, and early intervention can significantly improve long-term outcomes despite initial growth concerns.
- Premature infants, especially those with congenital heart disease, are at increased risk for developmental delay and require heightened developmental screening and evaluation 1.
From the Research
Possible Causes of Microcephaly
- Microcephaly is defined as a head circumference more than two standard deviations below the mean for gender and age 2
- True microcephaly (head circumference ≤-3SD) results from an imbalance between progenitor cell production and cell death that lead to a reduced number of neuronal and glial cells within the brain, resulting in reduced brain growth 3
- Genetic causes, such as mutations in the polynucleotide kinase 3'-phosphatase (PNKP) gene, can lead to microcephaly, epilepsy, and developmental delay (MCSZ) 4
- Autosomal recessive primary microcephaly (MCPH) is a neurodevelopmental disorder that is characterised by microcephaly present at birth and non-progressive mental retardation, and is associated with mutations in genes such as Microcephalin, WDR62, and CDK5RAP2 5
Factors Contributing to Microcephaly
- Centrosomal abnormalities, which control the mitotic spindle, are associated with most genetic causes of primary developmental microcephaly 6
- Mutations in DNA repair pathway genes can lead to microcephaly, with double-stranded DNA breaks appearing to be a prominent type of damage that needs to be repaired during brain development 6
- Premature birth, such as at 35 weeks, may also be a contributing factor to microcephaly, although the exact relationship between prematurity and microcephaly is not fully understood 2, 3
Diagnostic Approaches
- MRI is the first step in the etiologic research of microcephaly 2
- Genetic testing, such as whole-exome sequencing and molecular genetic testing, can help identify the underlying cause of microcephaly 4, 5
- Prenatal screening, including ultrasound and genetic testing, can detect fetal microcephaly and inform reproductive decisions 4