Infant Head Circumference Changes Might Not Predict Later Problems

By Joan Raymond

NEW YORK (Reuters Health) - Although head circumference is routinely measured in childhood, it has little value as a screening tool for later neurocognitive disorders (NCDs), according to researchers.

Despite microcephaly being associated with NCDs and increasing head size with hydrocephalus, the practical value of routine head circumference measurement is unclear, and may cause undue anxiety for parents as well as unnecessary testing for children, they reported. 

"What surprised me was how variable relative head size seemed to be over time in the same children and how weakly it related to underlying neurocognitive problems," Dr. Charlotte Wright, a pediatrician with the Royal Hospital for Sick Children in Glasgow, Scotland, told Reuters Health by email.

Researchers from the universities of Bristol and Glasgow analyzed the results of head circumference measurements and future neurocognitive issues among 10,851 children, all of whom were participants in the Avon Longitudinal Study of Parents and Children (ALSPAC). The cohort was established to understand how genetic and environmental characteristics may affect the development of parents and children.

As part of ALSPAC, all children received child surveillance examinations by local health services, with head circumference measured routinely by health professionals at two, nine and either 18 or 24 months of age.

At age eight, children completed a short version of the Wechsler Intelligence Scale for Children, with a low IQ defined as total IQ below 70. The researchers also used educational records to identify the number of children recorded as needing extra classroom support at the age of 11.

Health records were then examined to identify all children with a range of neurodevelopmental problems including learning disabilities, speech problems, autism, epilepsy, attention deficit/hyperactivity disorder (ADHD), and behavioral problems.

To analyze the data, all head measurements were converted into z scores and then compared with the World Health Organization growth standard. A summary infancy head z score was calculated for each child by using the average of the internally standard deviation scores at eight weeks and nine months plus the 18- or 24-month value where available.

Head size shift was determined by calculating the change in z score between two and nine months (early) and between nine and 18 or 24 months (late). A sustained shift was then defined as a shift of one or more z in one interval with no net recovery in the next interval.

The researchers found that at each age, 2% to 3% of children had scores that were less than two or more than two standard deviations (SDs) below or above the mean, but for most children this was only found at one age.

More than 15% of children showed centile shifts, but less than one-third of these were sustained at subsequent measurements. Only 0.5% showed a sustained shift beyond the normal range, according to the May 18 online report in Pediatrics.

Children with consistently small heads were up to seven times more likely to have an NCD, but 85% of children with small heads had no NCDs, and 93% of children with NCDs had head SD scores within the normal range, the authors wrote.

The researchers also found that centile shifts within the normal range were very common and were reflective of measurement error.

"This finding makes robust assessment of the head trajectory difficult and may result in many children being investigated unnecessarily," the authors wrote. "Extreme head size is neither specific nor sensitive for detecting NCDs, suggesting that routine measurement of HC is unhelpful."

Based on the data, the authors suggested an HC measurement at two to five days after birth and that HC should not be routinely measured as part of a physical examination, as recommended by the American Academy of Pediatrics and the Healthy Child Program in the United Kingdom, the authors wrote.

"We do think clinical practice should change," said Dr. Wright. "The harder we have looked at head measurement the less justification we have found for it, particularly when done routinely in healthy infants," added Dr. Wright.

Part of the issue, too, is the reliability of measurements. "Our research shows that most apparent abnormalities turned out to be human errors, rather than real differences," she said.

"The paper is interesting but no one would say that head circumference is predictive of ADHD, autism, epilepsy, language disorder, learning disability, or intellectual impairment. Rather, it's to make sure the contents of the skull are growing adequately," Dr. Max Wiznitzer, who was not involved in the study, told Reuters Health in an email.

"Just because most findings are not truly abnormal, it does not mean we shouldn't do the measurements," said Dr. Wiznitzer, a pediatric neurologist with Rainbow Babies & Children's Hospital in Cleveland, Ohio, adding that head circumference measurements "should be taught in a quantifiable and reproducible way and the physician should know how to interpret the results in a cost-effective manner."

The authors reported no funding or disclosures.

SOURCE: http://bit.ly/1Beku8w

Pediatrics 2015.

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