Incidence of anomalous canals in the base of the skull: a retrospective radio-anatomical study using cone-beam computed tomography

Correlation Analysis on Anatomical Variants of Accessory Foramina in the Sphenoid Bone for Oncological Surgery

The sphenoid bone presents several anatomical variations, including accessory foramina, such as the foramen meningo-orbitale, the foramen of Vesalius, the canaliculus innominatus and the palatovaginal canal, which may be involved in tumor invasion or surgery of surrounding structures. Therefore, clinicians and surgeons have to consider these variants when planning surgical interventions of the cranial base. The prevalence of each variant is reported in the published literature, but very little information is available on the possible correlation among different variants. Here, 300 CT scans of patients (equally divided among males and females) were retrospectively assessed to investigate the presence of the foramen meningo-orbitale, the foramen of Vesalius, the canaliculus innominatus and the palatovaginal canal. Possible differences in the prevalence of each accessory foramen according to sex were assessed, as well as possible correlations among different variants through the Chi-square test (p < 0.01). Overall, the prevalence of the foramen meningo-orbitale, the foramen of Vesalius, the canaliculus innominatus and the palatovaginal canal was 30.7%, 67.7%, 14.0% and 35.3%, respectively, without any difference according to sex (p > 0.01). A significant positive correlation was found between the foramen of Vesalius and canaliculus innominatus, both in males and in females (p < 0.01). In detail, subjects with canaliculus innominatus in 85.7-100.0% of cases also showed the foramen of Vesalius, independently from sex and side. The present study provided novel data about the prevalence of four accessory foramina of the sphenoid bone in an Italian population, and a correlation between the foramen of Vesalius and the canaliculus innominatus was found for the first time. As these accessory foramina host neurovascular structures, the results of this study are thus useful for appropriate planning surgical procedures that are tailored to the anatomical configuration of the patient and for improving techniques to avoid accidental injuries in cranial base surgery. Knowledge of the topography, frequencies and the presence/absence of these additional foramina are pivotal for a successful procedure. Clinicians and surgeons may benefit from these novel data for appropriate recognition of the variants, decision-making, pre-operative and treatment planning, improvement of the procedures, screening of patients and prevention of misdiagnosis.

Comprehensive microsurgical anatomy of the middle cranial fossa: Part I-Osseous and meningeal anatomy

The middle cranial fossa is one of the most complex regions in neurosurgery and otolaryngology-in fact, the practice of skull base surgery originated from the need to treat pathologies in this region. Additionally, great neurosurgeons of our present and past are remembered for their unique methods of treating diseases in the middle fossa. The following article reviews the surgical anatomy of the middle fossa. The review is divided into the anatomy of the bones, dura, vasculature, and nerves-in two parts. Emphasis is paid to their neurosurgical significance and applications in skull base surgery. Part I focuses on the bony and dural anatomy.

Investigation of the prevalence and main features of skull-base anomalies and characteristics of the sphenoid sinus using cone-beam computed tomography

Objectives

This study aimed to define the prevalence and characteristics of skull base anomalies and the features of sphenoid sinus pneumatization (SSP).

Materials and Methods

Five hundred cone-beam computed tomography scans were evaluated retrospectively for the presence of fossa navicularis magna (FNM), canalis basilaris medianus (CBM), sphenoid emissary foramen (SEF), and/or Onodi cells (OC). Patterns of the SSP and sphenoid sinus mucosa dimensions (SSMD) were also recorded.

Results

The prevalence of FNM, CBM, SEF, and OC was 26.0%, 22.4%, 47.4%, and 18.4%, respectively. Two hundred sixty-two (52.4%) sellar-type SSP were defined, followed by post-sellar 191 (38.2%), pre-sellar 31 (6.2%), and conchal 16 (3.2%) types. The frequency of SSMD less than 1 mm, 1-3 mm, and greater than 3 mm was 40.6%, 38.4%, and 21.0%, respectively. An SEF was detected more frequently in females, while SSMD greater than 3 mm was more frequent in males. An FNM was more prevalent in the 18-29 and 30-39 age groups and SEF was significantly less frequent in patients over 60 years of age compared to other age groups. A sinus mucosa larger than 3 mm was more common in the younger than 18 year group. The frequency of post-sellar-type pneumatization was lower in patients younger than 18 years.

Conclusion

Skull-base anomalies are common and may be detected incidentally during imaging procedures. The sphenoid sinus, its variations, and pneumatization patterns should also be taken into consideration in imaging procedures performed for various purposes.

ANATOMICAL VARIATIONS OF THE PARIETAL FORAMEN AND ITS RELATIONS TO THE CALVARIAL LANDMARKS: A CROSS-SECTIONAL CADAVERIC STUDY

OBJECTIVE

The aim: Estimate the prevalence of the parietal foramen in the adult human skulls of Ukrainian origin, and study its morphology and relationships to main anatomical landmarks of the skull.

PATIENTS AND METHODS

Materials and methods: A cross-sectional observational study of PF was conducted with 42 random cadaveric adult human skull roofs (calvaria) collected from the laboratory and museum of Human Anatomy Department, Kharkiv National Medical University, Ukraine. The patency and the length of the PF canal were determined, and PF external/internal diameters and the distance to the calvarial landmarks from PF were measured using the caliper. Mean and standard deviation were calculated to compare with the existing data.

RESULTS

Results: In the present study 85.7% (n = 36) of the calvaria had the PF, 54.8% (n = 23) had bilateral location of PF, 30.9% (n = 13) had unilateral presence of PF (right side: 23.8%, n=10 and left side: 7.1%, n=3), and 14.3 % (n = 6) demonstrated bilateral absence of PF.

CONCLUSION

Conclusions: An anatomical variation in parietal foramen is not uncommon, and the differences can be based on multiple factors like geography and race. It is important to have detailed information on anatomical variations in different population groups to facilitate surgical and radiological interventions.

Morphological Measurement and Anatomical Variations of the Clivus Using Computed Tomography

Objectives The aim of this study was to evaluate the clivus morphology, including fossa navicularis magna (FNM), canalis basilaris medianus (CBM), and craniopharyngeal canal (CC), on computed tomography (CT) images.

Design This is a retrospective study.

Setting Faculty of Dentistry, Department of Dentomaxillofacial Radiology.

Participants The CT images of 500 patients (253 males; 247 females) were evaluated.

Main Outcome Measures The prevalence of FNM, CBM, and CPC; the length, width, and depth of FNM; and CBM types were recorded. Also, a morphological analysis of the clivus (length of the clivus, angle between the clivus and the posterior margin of the foramen magnum, angle between the clivus and the dens axis, and anteroposterior diameter of the foramen magnum) was performed.

Results FNM was identified in 5.4%, CBM in 4%, and CC in 0.8% of the study group. Type 5 CBM was not found. Type 6 was the most common CBM type. There was no significant correlation between the age and gender of patients with FNM. There were significant differences between the clivus length, the angle between the clivus and the dens axis, the anteroposterior diameter of the foramen magnum, and gender. Also, there was a significant difference between the angle between the clivus and the foramen magnum and age.

Conclusions The anatomical variations of the clivus are rare and important for the oral and maxillofacial radiologist to make the differential diagnosis. These anatomical variations should not be confused with pathologic formations. The morphological measurements and anatomical variations of the clivus can be evaluated in detail on CT images.

[Applications of cone beam computed tomography of the craneofacial structure in medical specialties. A review]

Cone-beam computed tomography (CBCT) of the craniofacial structure has demonstrated its usefulness in the dental area during the last decades, thus it has become a fundamental tool in the diagnosis, planning, and evaluation of treatment, and although it was not developed for the exclusive use in dentistry, as it is commonly considered, it is used in other areas such as medicine. It is specifically used in the head and neck area where different medical specialties interact, and at the same time these interact with dental specialties, so knowing the advantages of CBCT over different imaging technologies in the medical area is necessary. The purpose of this review was to describe the applications of observation, diagnosis, planning, and evolution of treatments using maxillofacial HSCT in different medical specialties. This work highlights the use of TCHC in different medical applications and highlights where it is most useful compared to other technologies.

Anatomical variations of clivus: a descriptive anatomical study

PURPOSE

The clivus is a part of the sphenoid bone. It may show some anatomical variations such as fossa navicularis magna (FNM), canalis basilaris medianus (CBM) and craniopharyngeal canal (CPC). These variations have been associated with conditions like meningitis and tumors of skull base. Inadequate information about these structures may pose a risk of inaccurate diagnosis resulting in unwarranted interventional procedures. Hence, the knowledge about the prevalence of these variations is important. Thus, the objective of this study was to determine the prevalence of fossa navicularis magna, craniopharyngeal canal and canalis basilaris medianus and its types utilizing cone-beam computed tomography (CBCT) images.

METHODS

Retrospectively, a total of 350 CBCT scans were evaluated for the presence of FNM, CBM, its types and CPC. The analysis was done by two observers independently. Cohen's kappa statistics was used to determine the interobserver agreement.

RESULTS

FNM was noted in 19.4% cases, CBM in 9.7% cases, whereas CPC was not identified in any case. Type 5 was the most common type of CBM. There was no significant difference (p > 0.05) between genders and age groups for the prevalence and a highly significant (p < 0.01) substantial agreement between observers for the prevalence of FNM and highly significant (p < 0.01) moderate agreement for the prevalence of CBM and its types was obtained.

CONCLUSION

FNM, CBM, CPC, albeit rare anatomical variations of clivus, knowledge of these structures is important for radiologists, anatomists and surgeons to avoid misdiagnosis and provide awareness to the individual of a higher possibility of meningitis or tumors of the skull base.