Houri K. Vorperian, PhD – Slide of the Week

Houri Vorperian Slide of the Week

Title: Cervical vertebral body growth and emergence of sexual dimorphism: a developmental study using computed tomography

Legend: The sex-specific developmental changes in size and shape of the cervical vertebral bodies were examined by placing 23 landmarks at the margins of the vertebral body of each cervical vertebrae in the midsagittal plane of CT scans. The CT studies, ages birth to 20 years, were subdivided into 5-year age cohorts I to IV. Findings are displayed as sex-specific mean vertebral wireframes of the four age cohorts superimposed for each vertebral body for females (left panel/red) and males (right panel/blue). The center panel is a schematic of the male–female difference in the amount and direction of growth occurring at each landmark from age cohort I to cohort IV. Findings reveal developmental sex differences in size and shape for all cervical vertebrae, particularly after age 10 years.  Such difference should be recognized and accounted for in clinical practice.

Citation: Miller, Courtney A., Hwang, Seong Jae, Cotter, Meghan M., & Vorperian, Houri K. (2019). Cervical vertebral body growth and emergence of sexual dimorphism: a developmental study using computed tomography. Journal of anatomy. 234 (6): pp. 764-777.

Abstract: The size and shape of human cervical vertebral bodies serve as a reference for measurement or treatment planning in multiple disciplines. It is therefore necessary to understand thoroughly the developmental changes in the cervical vertebrae in relation to the changing biomechanical demands on the neck during the first two decades of life. To delineate sex-specific changes in human cervical vertebral bodies, 23 landmarks were placed in the midsagittal plane to define the boundaries of C2 to C7 in 123 (73 M; 50 F) computed tomography scans from individuals, ages 6 months to 19 years. Size was calculated as the geometric area, from which sex-specific growth trend, rate, and type for each vertebral body were determined, as well as length measures of local deformation-based morphometry vectors from the centroid to each landmark. Additionally, for each of the four pubertal-staged age cohorts, sex-specific vertebral body wireframes were superimposed using generalized Procrustes analysis to determine sex-specific changes in form (size and shape) and shape alone. Our findings reveal that C2 was unique in achieving more of its adult size by 5 years, particularly in females. In contrast, C3– C7 had a second period of accelerated growth during puberty. The vertebrae of males and females were significantly different in size, particularly after puberty, when males had larger cervical vertebral bodies. Male growth outpaced female growth around age 10 years and persisted until around age 19–20 years, whereas females completed growth earlier, around age 17–18 years. The greatest shape differences between males and females occurred during puberty. Both sexes had similar growth in the superoinferior height, but males also displayed more growth in anteroposterior depth. Such prominent sex differences in size, shape, and form are likely the result of differences in growth rate and growth duration. Female vertebrae are thus not simply smaller versions of the male vertebrae. Additional research is needed to further quantify growth and help improve age and sex-specific guidance in clinical practice.

About the Lab: The Vocal Tract Development Laboratory (VTLab) uses a combination of imaging, acoustics, and vocal tract modeling to understand the lifespan changes of the vocal tract anatomy in typically and atypically developing individuals, and to examine the relation of anatomic changes to speech acoustics.

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