Morphometric Study of the Mastoid Process and its Role in Sex Differentiation: A Nigerian Computed Tomography Study

Abstract

Background: The mastoid process can be utilized in forensic identification due to its resistance to alterations and population variations in its morphology. The study investigated the role of mastoid parameters in the determination of sex in a Nigerian population. Aims and Objectives: The aim of this study was to determine the gender differences in measurements of the mastoid process. Furthermore, the study aimed at assessing the percentage accuracy of using the mastoid variables in sex discrimination. Materials and Methods: This cross-sectional study used computed tomographic images of the brain, stored in the radiology unit of a referral hospital in Delta State, Nigeria. Permission was granted by the hospital’s Ethics Board. The measurements of the mastoid process were taken on images of 310 patients (170 males and 140 females) aged 20–80 years. Data were summarized using means and standard deviations. Gender, side, and age group comparisons were assessed using the independent t-test, paired t-test, and analysis of variance, respectively. The association between variables was probed using Pearson’s correlation test. The discriminant function analysis was used to determine the accuracy of correct sex allocation. The probability value was set at <0.05. Results: All the measurements were larger in males than in females (P < 0.05). All except the conventional height, oblique sagittal diameter, and mediolateral inclination angle showed significant differences between age groups (P < 0.05). The true height and oblique coronal diameter showed a significant positive correlation with age (0 <r< 0.05) (P < 0.05). The lateral intermastoid distance was the best sex-discriminating variable (89.4%). Using all nine variables, the accuracy of sex prediction was 89.7%. Conclusion: The sexually dimorphic mastoid dimensions can collectively be used for sex determination with acceptable accuracies, in cases where only the fragmented parts of the temporal bone are available in Delta State, Nigeria.