A New Normal: A Pilot Examination of the Modern Cephalic Index

Introduction: The cephalic index (CI) is the width-to-length ratio of the head. Brachycephalic head shapes are wider than the norm and have a higher CI. In 1994, the American Academy of Pediatrics recommended babies sleep on their backs to combat rates of sudden infant death syndrome, which correlated to a sudden increase in the incidence of brachycephaly in the American population. The commonly accepted “normal” CI comes from a table that was published in the 1970s and should be updated for the modern population. The purpose of this study is to examine the modern average CI, compare measurements from today’s population to the highly referenced 1970s table, and examine what genealogical factors may impact a person’s CI measurement. Methods: Fifty-nine subjects were measured for cephalic width and length. CI was calculated for all subjects, and statistical analysis was performed. Results: There was a clinically significant increase in CI in every age group since the 1970s. The only statistically significant differences were between ethnicity and ethnicity-sex subgroups (not between age or sex groups). Conclusions: The CI has changed in recent years, and based on these pilot data, the modern CI may be impacted more by ethnicity than age and sex. Clinical Relevance: The typical CI in the modern generation is higher from the previously used 1970s standard tables. Updated measurements would aid clinicians when determining the need for cranial remolding orthoses and provide insight into the outcomes of treatment for deformational head shapes (whether via orthoses or other methods).