A single “normal” head circumference, that is one which lies within two standard deviations above and below the mean for age and sex, may prove misleading, since it gives no clue as to rate of head growth. Serial head circumference measurements should, therefore, be a routine part of the physical examination of infants and children. When such measurements are plotted on the composite graphs, abnormal growth patterns are readily discernible. Rapid upward deviation may signify correctable conditions, such as hydrocephalus, subdural hematomas or effusions. Marked slowing or arrest of head growth offers a poor prognosis for mental development. But even a single measurement outside the range of normal should lead to further evaluation of the child. Birth to 36 months: Boys Head circumference-for-age and Weight-for-length percentiles
In children, deviations from the normal range of head circumference (HC) have traditionally been related with cerebrospinal fluid dynamics abnormalities. In adults, this neglected parameter is helpful in the diagnosis and understanding of the pathophysiology of some CSF abnormalities. It has been demonstrated that HC is related to height. Because humans have increased in stature dramatically during the last 50 years, pediatric charts for head growth physiology and normal HC values in adults should be reevaluated.
HC obtained in Spanish adult people are greater than those reported in the classical Nellhaus graphs in both men and women aged 18. These findings should be considered in the management of hydrocephalus in adults today 1).
Shunt-treated children have smaller head circumferences at 2 and 3 years of age than healthy children. Low weight, short height, etiology of intraventricular hemorrhage, and frequent shunt valve revisions are predictors for decreased head circumference. Prospective, randomized studies comparing skull growth using fixed and adjustable pressure-regulated shunt valves and flow-regulated valves are needed 2).