Resuming the obsolete term “small head”: when microcephaly occurs without cognitive impairment

Microcephaly is defined as a head circumference measurement of 2 or 3 standard deviations below the mean for age and sex. However, distinguishing the value of −2 or −3 standard deviations as a cutoff is relevant in the clinical practice, since the limit of −3 standard deviations is more frequently associated with cognitive impairment. The use of ultrasound scans in pregnancy has allowed the identification of subjects with a measurement of the head circumference at the limit of the cutoff for gestational age, but who do not subsequently show cognitive delay. The same is true for newborns with a −2 to −3 standard deviations cutoff, and without anomalous clinical signs, for which a cognitive delay is not easily diagnosed. In this case, to define an infant as being affected by microcephaly (with a prognosis usually recognized as harmful) may be unnecessarily distressful for parents or caregivers. In the cases mentioned, resuming the word “small head” instead of microcephaly to define such subjects could be more appropriate and more appreciated.