Normal Head Growth and the Prediction of Head Size in Infantile Hydrocephalus

Abstract

A study of maximum head circumference measurements was made on normal full-term and premature babies. The survey was a longitudinal one and all measurements were taken personally. 676 full-term and 225 premature babies were involved and a total of 4,639 measurements was taken from these 901 infants. In the majority of cases head circumference values were obtained at birth and then at weekly and later fortnightly intervals up to 18 and 26 weeks of age from full-term and premature babies respectively. From the material collected in the head circumference survey the following were obtained (1) A graph to show the normal range of head circumference in relation to age in full-term infants from birth to 18 weeks. (2) A head circumference/age chart to show the normal range of head size in premature babies from birth to 26 weeks of age. (3) A chart to show the normal range of head circumference at 1 week of age relative to birth weight. This covered a weight range of 3 to 9 lb. and therefore included premature as well as full-term infants. (4) Control lines. These were described with special emphasis on their significance and their use in association with a ratio chart. The "lines" presented were drawn at weekly intervals from 1 to 16 weeks for both full-term and premature babies. Each control line represents a maximum normal rate of head circumference increase. A method has been described for predicting the head size of any individual at 1 year of age in terms of defined groups. This technique resulted from an empirical modification of the use of control lines and depends on a knowledge of the maximum normal head circumference at birth relative to the birth weight. The predictions are made between birth and 16 weeks of age. The following results emerged from the application of this method to cases in the present series: An accurate forecast of the Group indicating head size was made in 90% of 99 cases. Warning of the impending change of Group was given in just less than half of the Group 2 cases. In three-quarters of the Group 3 patients an accurate prediction of the final head size was made four or more weeks in advance of the change and in the remainder at least one week of warning was given in each case. Three examples, forecast correctly to reach Groups 1, 2 and 3, were given. All three had a very rapidly progressive hydrocephalus, but it was possible during the progressive phase, to distinguish between early, moderately early and late arrest by the technique described in this report.