Reference Values for Cranial Morphology Based on Three-dimensional Scan Analysis in 1-month-old Healthy Infants in Japan

Abstract

Currently, molded helmet therapy is used to treat infants with deformational plagiocephaly. However, the indices of normal cranial shape remain unclear, and thus, the prevalence of deformational plagiocephaly is unknown, particularly in Japan. We investigated the reference values for cranial morphological characteristics in 1-month-old Japanese infants using a three-dimensional scanner, to determine the prevalence of deformational plagiocephaly. One hundred fifty-three healthy infants who visited three hospitals (from April 2020 to March 2021) were enrolled. Cranial shape was measured using a three-dimensional scanner and was analyzed using image analysis software. Outcome measures were cranial volume, length, width, length-width ratio, circumference, asymmetry, and vault asymmetry index; cephalic index; and anterior, posterior, and overall symmetry ratios. The cranial vault asymmetry index >3.5% or ≥10% were diagnosed as deformational or severe deformational plagiocephaly, respectively. The mean age at measurement was 35.7 days. The mean cranial volume was 559 mL; cranial length, 129 mm; cranial width, 110 mm; length-width ratio, 118%; cephalic index, 85.2%; cranial circumference, 377 mm, cranial asymmetry, 6.4 mm; cranial vault asymmetry index, 5.0%; and anterior, posterior, and overall asymmetry ratios, 93.1%, 91.3%, and 96.4%, respectively. The prevalence of deformational and severe deformational plagiocephaly was 64.7% and 6.6%, respectively. Sex-based differences were observed for cranial volume and width. The results obtained in this study can be considered standard values that can facilitate the differentiation of abnormal infant cranial morphological characteristics for Japanese medical practitioners.

Three-Dimensional versus Two-Dimensional Evaluations of Cranial Asymmetry in Deformational Plagiocephaly Using a Three-Dimensional Scanner

“…As shown in our measurement precision analyses, the 3D scanner used in our current study was useful for considering human errors between measurers in 2D evaluations [ 7 , 8 ]. Normal reference values of the measurement variables obtained by the 3D scanner in 1-month-old healthy Japanese male or female infants were shown in our recently published report [ 26 ].…”

Evaluating Cranial Growth in Japanese Infants Using a Three-dimensional Scanner: Relationship between Growth-related Parameters and Deformational Plagiocephaly

“… 14 , 19 ) According to these criteria, most infants in Japanese studies, including this present study, were considered hyperbrachycephalic. 11 , 17 , 20 ) Koizumi et al suggested the following standards for classifying CI in Japanese infants: mesocephaly, 79.2%-93.8%; brachycephaly, 93.9%-101.1%; and hyperbrachycephaly, 101.2% or more. 20 ) Based on these standards for Japanese infants, the infants in this study met the standards for mesocephaly.…”

“…In our previous report, we found that the incidence of DP is high among Japanese infants, with approximately 5% of healthy infants requiring helmet therapy. 10 , 11 ) Concerns that the number of infants requiring cranial correction will increase in the future and that the limited availability of 3D scanners will delay accurate diagnosis have already been raised. Early registration of handheld 3D scanners as medical devices is therefore desirable.…”

“…The principles of 3D scanners have been explained in detail in our previous report. 11 ) The infants' heads were protected using an elastic wig cap to prevent hair tangling. The 3D data were reconstructed by combining the overlapping regions of each successively scanned frame and converting them into standard triangulated language files as the standard format for 3D images.…”

“…Fig. 1 shows the method used to determine the parameters based on a previous report, 11 ) with some changes in the materials. The plane connecting the sellion (SE; the lowest point of the nasal root) and the points of the left and right tragions (TR; the upper edge of the tragus) were used as the reference plane (level 0).…”