The Radiological Evaluation of the Mastoid Process and Its Implications for Surgical Approaches

Abstract

Background and objective In various surgical procedures, in approaching the posterior fossa and the posterolateral cranial base, surface markings are used to locate the groove for transverse and sigmoid sinuses, and their junction. Determining these surface landmarks, especially the mastoid bone and its surrounding anatomical formations, is extremely valuable. The purpose of this study was to examine the anatomical features and the relationship between the mastoid process and surrounding structures on cone-beam CT (CBCT) images. Methods Before starting this retrospective study, approval was obtained from the Ethics Committee of Gaziantep University (approval date: 04/12/2019; number: 470). Individuals who consulted the Department of Oral and Maxillofacial Radiology of Gaziantep University's Faculty of Dentistry between 2015-2018 for any reason and whose CBCT images were taken were included in this study. Frankfort horizontal plane was used for the standardization of the images. Measurements were made on three different sections: coronal, transverse, and sagittal. Results The cohort consisted of 149 females and 98 males; the mean age of the participants was 45.72 ± 17.12 years. It was determined that homogeneity was achieved in terms of data distribution between genders according to age (p=0.777). Additionally, it was determined that there was a statistically significant difference between the genders in all parameters except anterior inclination angle (AIA), and higher values were found in males. Conclusion We believe that the results obtained from this study may contribute toward decreasing the complication rate and increasing success in surgical procedures, especially with respect to approaching the posterior fossa and the posterolateral cranial base.

Keywords: cone-beam computed tomography (cbct); craniofacial morphometry; mastoid process; posterior fossa; skull base.

Figure 1. Parameters measured in coronal sections

a: mastoid height; b: distance between mastoid notch and external acoustic meatus; c: bimastoid width 1

Figure 2. Parameters measured in transverse sections

a: oblique sagittal distance; b: oblique coronal distance; c: longest oblique sagittal distance; d: longest oblique coronal distance; e: bimastoid width 2

Figure 3. Parameters measured in sagittal sections

a: anterior inclination angle; b: distance between porion and mastoid notch; c: mastoid length (blue line: porion-mastoid notch, red line: mastoid length); d: porion-mastoidale