Growth pattern in the Apert syndrome.

Abstract

In this paper, we demonstrate that a discernible and unique growth pattern characterizes the Apert syndrome. The keys to understanding Apert newborn measurement values are brain size and cranial configuration. Both true megalencephaly and coronal synostosis are present at birth. Thus, the head is unusually heavy and the cranium is disproportionately high. Mean newborn length and weight are above the normal 50th centile. Of our newborn patients, 16% exceeded 4,000 g in weight. Preterm infants were appropriate or slightly large for gestational age. A biphasic linear growth pattern was found. In childhood, deceleration of linear growth occurs so that most values fall between the 5th and 50th centiles. From adolescence to adulthood, deceleration becomes more pronounced. This 2-step linear growth deceleration results in large measure from rhizomelic shortness of the lower limbs. Puberty takes place within the normal time frame. Although a disproportionate amount of the megalencephaly accounts for the dramatic increase in head height, the widely patent midline calvarial defect, allowing the brain to expand anteriorly into the metopic area, and some increase in the head breadth permit the mean head circumference at birth to normalize slightly above the 50th centile. During the growth period, the head circumference was studied in surgically unoperated Apert patients from the 1960s and earlier. The natural history of the growing cranium consists of gradual deceleration in head circumference from slightly above the 50th centile at birth to within or at -2 SD later on.