Denominator of Cranial Vault Asymmetry Index: Choosing Between Longer and Shorter Diagonal Lengths

Since it was proposed in this journal in 2001, the cranial vault asymmetry index (CVAI) has been an important parameter for assessing cranial shape. However, different publications currently use different variables in the denominator of the CVAI formula. We thus investigated the use of long and short diagonal lengths as variables in the denominator of the CVAI formula. We searched the databases of PubMed, Google Scholar, and Scopus for articles published between 2016 and 2022 that cited the original work article of CVAI. Articles were included if they were written in English and if the denominator of the CVAI formula was specified. For multiple articles by the same author, only the most recent article was included. In total, 30 articles were included; 10 articles used the longer diagonal length as the denominator and 20 articles used the shorter diagonal length. No uniform trend was observed by a country or journal of publication. Application of the CVAI formula using different denominators yielded interchangeable results, and the resulting values had only negligible differences clinically. However, it would be necessary to create a standard formula for using the CVAI as a parameter for reporting cranial shape assessments consistently.