A study of family head shape: environment alters cranial shape.

A change in the type of cranial deformities (plagiocephaly) presenting to certain clinics has occurred. The purpose of this study was to compare infant head shapes against head shapes of their biologic parents to explore the roles of heredity and environment on cranial shape. Standardized family photographs and anthropometric measurements demonstrated that 30% of the infants had cranial widths 2 standard deviations above norm, while 4.6% had widths exceeding 3 standard deviations. Despite a mean age of only 8 months, 11.6% had widths that were already greater than that of 1 parent. These results demonstrate that plagiocephaly has taken on a new configuration, presenting not only with asymmetry, but also with excessive cranial width.

Comparison of plaster casting with three-dimensional cranial imaging.

OBJECTIVE: The development of a new cranial imaging system to capture a three-dimensional (3D) model of an infant's head has been previously reported. The accuracy of this new system has been independently established. However, before replacing the traditional plaster casting technique, the two methods require a comparison to ensure that the models they produce are equivalent. METHODS: Ten sequential infants were digitized by the 3D imaging system and the plaster casting technique following previously reported protocols. The cast models were also digitized so they could be compared with the digitized images. The two models (3dImage and Cast) were then imported into dimensional analysis software and aligned and registered with well-established registration algorithms. Difference maps that identified the variation between the two surfaces were generated for each pair, and descriptive statistics of these differences were recorded. RESULTS: The mean difference between the cast and the digitized models was 0.052 mm (standard deviation = 0.988), with a root mean square (RMS) difference of 1.028 mm. Two-dimensional slices obtained from the registered 3D surfaces demonstrated excellent agreement between the cranial contours. CONCLUSIONS: In this investigation, the 3D models created by the new imaging system were found to be within 1.0 mm RMS of the models created by the plaster casting technique. Two-dimensional cranial contours demonstrated excellent agreement between the two methods. The results of this investigation confirmed that the new cranial imaging system and the traditional plaster casting technique yield equivalent models.

Multiple-birth infants at higher risk for development of deformational plagiocephaly: II. is one twin at greater risk?

OBJECTIVE: In part 1 of this investigation, we demonstrated that children of multiple birth pregnancies are at higher risk for development of deformational plagiocephaly. In the current investigation, we explore whether certain prenatal and postnatal risk factors predispose one twin over the other by examining the occurrence and severity of plagiocephaly in both discordant (only 1 affected) and concordant (both affected) twin pairs. METHODS: Throughout 1999, we obtained detailed medical histories on 140 sets of twins who had presented for treatment at 1 of 9 treatment centers across the United States. The study cohort consisted of 46 concordant and 94 discordant twin pairs (a total of 280 study participants). Information about prenatal and postnatal history of each infant was obtained through detailed review of the children's medical records as well as analysis of a patient database maintained on all infants who receive treatment. Follow-up interviews were performed to verify the information recorded and to obtain additional information about the child who had not received treatment (if appropriate) or use of reproductive assistance (fertility drugs, intracytoplasmic sperm injection, etc) that had not been previously recorded. Statistical analyses were performed to assess the effects of prenatal and postnatal risk factors (in utero position, in utero orientation, birth weight, neck involvement, sleeping position) with respect to which infant was affected in the discordant twin pairs and to which infant was more severely affected in the concordant twin pairs. RESULTS: Statistical analyses of both discordant and concordant twin pairs demonstrated that the lower in utero infant was significantly more likely to be affected (chi(2) = 17.391). In addition, the more severely affected infant was significantly more likely to have some form of neck involvement (torticollis, neck tightness; chi(2) = 46.380), as well as have been carried in a vertex position (chi(2) = 7.408). Conversely, neither sleeping position nor gender was found to be associated with development of plagiocephaly. CONCLUSIONS: The results of this investigation strongly support an in utero cause of plagiocephaly and demonstrate that intrauterine positioning may play a prominent role in determining both the occurrence and severity of deformational plagiocephaly in twins. These findings confirm that the lower in utero infant is at increased risk for the development of plagiocephaly, likely resulting from the more restrictive intrauterine environment encountered during the later part of the pregnancy.

Development of a new three-dimensional cranial imaging system.

The development of a new three-dimensional (3D) imaging system designed to obtain a digital image of an infant's cranium is described. This system is intended to replace the manual plaster-casting technique currently used during the process of fabricating cranial remodeling bands. The system uses 18 triangulated digital cameras and the projection of random infrared patterns to capture a 360 degrees image of an infant's cranium instantaneously, including the face and top of the head. Accuracy was calculated by comparing models digitized with this system with the same models digitized with high-precision inspection equipment. Safety was documented under guidelines established by the American Council of Governmental Industrial Hygienists. Images were acquired in 0.008 seconds and processed for viewing in software within 2.5 minutes. Accuracy was calculated to be +/-0.236 mm. Hazard analysis confirmed the system to be safe for direct continuous exposure. The data acquired may be viewed as a point cloud, wire frame, or surface on which a digital photograph (ie, texture) is automatically overlaid. Physical models are created by exporting the digital data to a multiaxis milling machine or stereolithography machine. Quantitative data (linear and surface measurements, curvature, and volumes) can be obtained directly from the digital data. The cranial imaging system is a safe and accurate method of obtaining digital 3D images of an infant's cranium. Along with the obvious clinical and manufacturing benefits, it also has significant potential as a research tool for documenting the natural history and evaluating the treatment of plagiocephaly.