Sella turcica bridging and ossified carotico-clinoid ligament: Correlation with sex and age

The Coexistence of Carotico-Clinoid Foramen and Interclinoidal Osseous Bridge: An Anatomo-Radiological Study With Surgical Implications

BACKGROUND AND OBJECTIVES

The coexistence of complete carotico-clinoid bridge (CCB), an ossification between the anterior (ACP) and the middle clinoid (MCP), and an interclinoidal osseous bridge (ICB), between the ACP and the posterior clinoid (PCP), represents an uncommonly reported anatomic variant. If not adequately recognized, osseous bridges may complicate open or endoscopic surgery, along with the pneumatization of the ACP, especially when performing anterior or middle clinoidectomies.

METHODS

According to Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews guidelines, a systematic scoping review was conducted up to June 5, 2023. PubMed, Scopus, Web of Science databases, and additional citations were searched. Two hundred high-resolution noncontrast computed tomography (CT) scans (400 sides) and 41 dry skulls (82 sides) were analyzed to identify the different morphology of sellar bridges, focusing on the coexistence of complete CCF and ICB. Two embalmed latex-injected heads with coexisting CCF and ICB were dissected step-by-step to show the anatomic relationship with the surrounding structures from an endoscopic and microscopic perspective.

RESULTS

A total of 19 articles were included. The review identified a complete CCF and ICB rate ranging from 4.92% to 6.3%. The analysis of 200 CT scans revealed a rate of coexistence in 4% of the cases, all encountered in White women. Two different types of interclinoid bridges were identified based on the degree of bone mineralization. Both endoscopic and macroscopic step-by-step dissections highlighted variability in morphology and consistency of the sellar bridges and the close relationship with the cavernous sinus neurovascular structures.

CONCLUSION

The coexistence of CCF and ICB is an anatomic variation found in 4% of cases. Preoperative knowledge of the degree of mineralization and its relationship with surrounding structures is essential to performing safe surgery and minimizing cranial nerve and vascular injuries. Preoperative high-resolution CT scans can adequately identify these anatomic variations.

A morphological study on the sphenoid bone ligaments' ossification pattern

PURPOSE

The sphenoid bone (SB) extracranial ligaments (ECRLs) are the pterygoalar and pterygospinous ligaments (PTAL and PTSL) that are located at the SB lateral pterygoid plate, and inferior to the foramen ovale (FO). Their ossification may affect the mandibular nerve's distribution. The intracranial ligaments' (ICRLs) ossification (the caroticoclinoid ligament-CCLL, the anterior and posterior interclinoid ligaments-AICLL and PICLL) may impede the approaches to the sella. This study highlights the incidence of the ossified ECRLs and ICRLs location, their type (partial, or complete), considering laterality, gender, age, and ligaments' simultaneous presence.

METHODS

The sample consisted of 156 Greek adult dried skulls of both genders and variable age.

RESULTS

Ossified ligaments were identified in 57.05%, predominantly extracranially (42.31%, P = 0.003). ECRLs were predominantly identified unilaterally (30.13%, P < 0.001). The majority of the ossified ICRLs were predominantly identified in male skulls (31.1%, P = 0.048) and the majority of the ECRLs (52.8%, P = 0.028) were predominantly identified at the age of 60 years and above. The PTAL was the most ossified (32.69%), followed by the CCLL (24.36%), the PTSL (16.03%), the PICLL (6.41%), and the AICLL (4.49%).

CONCLUSIONS

Detailed knowledge of the SB morphology and ligaments' ossification extent is essential to improve the technique of the FO percutaneous approach, and sellar approaches, to minimize complications.

The "candy wrapper" of the pituitary gland: a road map to the parasellar ligaments and the medial wall of the cavernous sinus

PURPOSE

The anatomy of the medial wall of the cavernous sinus (MWCS) and parasellar ligaments (PLs) has acquired increasing importance in endoscopic endonasal (EE) surgery of the cavernous sinus (CS), including resection of the MWCS in functioning pituitary adenomas (FPAs). Although anatomical studies have been published, it represents a debated topic due to their complex morphology. The aim is to offer a description of the PLs that originate from the MWCS and reach the lateral wall of the cavernous sinus (LWCS), proposing the "candy wrapper" model. The relationships between the neurovascular structures and histomorphological aspects were investigated.

METHODS

Forty-two CSs from twenty-one human heads were studied. Eleven specimens were used for EE dissection; five underwent a microscopic dissection. Five specimens were used for histomorphological analysis.

RESULTS

Two groups of PLs with a fan-shaped appearance were encountered. The anterior group included the periosteal ligament (55% sides) and the carotico-clinoid complex (100% sides), formed by the anterior horizontal and the carotico-clinoid ligaments. The posterior group was formed by the posterior horizontal (78% sides), and the inferior hypophyseal ligament (34% sides). The periosteal ligament originated inferiorly from the MWCS, reaching the periosteal dura. The anterior horizontal ligament was divided in a superior and inferior branch. The superior one continued as the carotid-oculomotor membrane, and the inferior branch reached the CN VI. The carotico-clinoid ligament between the middle and anterior clinoid was ossified in 3 sides. The posterior horizontal ligament was related to the posterior genu and ended at the LWCS. The inferior hypophyseal ligament followed the homonym artery. The ligaments related to the ICA form part of the adventitia.

CONCLUSION

The "candy wrapper" model adds further details to the previous descriptions of the PLs. Understanding this complex anatomy is essential for safe CS surgery, including MWCS resection for FPAs.

Morphology of the Sella Turcica: A Meta-Analysis Based on the Results of 18,364 Patients

BACKGROUND

This meta-analysis aimed to present data on the sella turcica (ST) morphology and variations. Furthermore, a detailed morphometric analysis of the ST was conducted.

METHODS

Major online databases such as PubMed, Scopus, Embase, Web of Science, and the Cochrane Library were searched through. The overall search process was conducted in three stages.

RESULTS

This meta-analysis was based on the results of 18,364 patients and demonstrates the most up-to-date and relevant data regarding the morphology of the ST in the available literature. Four classification methods of the ST shape can be distinguished, in which the most commonly occurring variants are the normal ST (55.56%), the U-shaped ST (73.58%), the circular type of ST (42.29%), and non-bridging ST (55.64%). The overall midpoint height of the ST was 6.59 mm (SE = 0.13). The overall length of the ST was 9.06 mm (SE = 0.15). The overall volume of the ST was 845.80 mm3 (SE = 288.92). Four main classification methods of ST morphology can be distinguished in the available literature. Various morphometric characteristics of the ST may be applied in clinical practice to evaluate its shape, dimensions, and normal or pathological variants.

Osseous Bridges of the Sphenoid Bone: Frequency, Bilateral and Sex Distribution

Sellar (caroticoclinoid and interclinoid), pterygospinous and pterygoalar bridges are osseous bars of the sphenoid bone, which enclose additional foramina in the skull base and could cause entrapment of nerves, occlusion of vessels and obstruction of surgical corridors. This study aimed to investigate the frequency of sphenoid bone bridges in Bulgarians and to assess the bilateral and sex differences in their distribution. This study was performed on head CT scans of 315 Bulgarians, 148 males and 167 females. The sellar bridges were the most common type of sphenoid bridging; particularly the caroticoclinoid bridge. The pterygospinous bridge was a relatively common finding and the pterygoalar bridge was the most infrequent type of bridging. The total frequency of sellar bridges did not differ significantly between both sides and sexes. The pterygospinous bridge did not indicate significant bilateral differences but showed considerable sex differences concerning the left-side occurrence, which was significantly higher in the male series. There were no considerable bilateral and sex differences in the distribution of the pterygoalar bridging. There were no significant correlations between the different types of sphenoid bone bridges, but each type of bridging showed significant positive correlations between the right and left side co-occurrence in males and females.

Sella Turcica Bridging and its Association with Dental Anomalies

Aim:

This study aimed to study the overall incidence of DA and its association with Sella Turcica bridging (STB).

Background:

Dental anomalies (DA) are associated with morphological changes in the Sella Turcica (ST).

Materials and Methods:

We retrieved the pretreatment patient records from March 2018 - March 2020 from the archives of the Orthodontics Department (n=806). We excluded the records with missing radiographs, concomitant cleft lip/ palate, history of surgical repair of cleft lip/ palate or any other craniofacial anomaly, history of trauma, and prior orthodontic treatment. A total of 676 patient records were included for initial screening, out of which 103 patients had DA (study group). A similar number of records (n=103) without any DA were randomly selected to constitute a control group. Determination of the extent of STB was done by calibrated and trained examiner. Age and sex were also recorded.

Results:

The incidence of DA was 15.24%. The most common anomalies recorded were impacted canines (6.8%) and hyperdontia (3.7%), followed by agenesis (2.1%) and others. Type III bridging in patients with DA was 22.3%, while being 9.7% in the control group. Type II bridging was observed in 36.8% of patients with DA as compared to 29.1% in the control group. The presence of partial and complete STB in patients with dental anomalies was significantly higher than in the control group (P=0.006). The study group showed significant association with STB (OR: 2.33; P=0.003; 95%CI: 1.33-4.11) after adjusting for sex.

Conclusion:

The results of our study revealed a significant association between STB and DA.

Morphology of Sella Turcica and Bridging Prevalence Correlated with Sex and Craniofacial Skeletal Pattern in Eastern Asia Population: CBCT Study

Purpose

Sella turcica bridging (STB) refers to a rare anatomical variation formed by the ossification of the ligament between the anterior and posterior clinoid processes. The presence of the STB was significantly correlated with craniofacial skeleton classification and a higher prevalence rate in skeletal Class III. The current study is aimed at investigating the dimensions of sella turcica and the prevalence of STB in different sexes and on the three craniofacial skeletal patterns using cone beam computed tomography (CBCT).

Materials and Methods

A total of 159 adults (66 males and 93 females), including 3 different craniofacial skeletal patterns (skeletal Classes I, II, and III), were included in the study. The sella turcica dimensions and the prevalence of STB were calculated. An independent t-test and generalized linear model were used to compare the differences in the sella turcica dimensions and the skeletal relations. The Spearman rank correlation coefficient was used to analyze the correlations between sella turcica dimensions and skeletal relation.

Results

The sella length (SL) was 11.05 ± 1.80 mm for males and 10.77 ± 1.56 mm for females. The anterior clinoid distance (ACD) which was measured for the anterior width of sella turcica showed 25.83 ± 2.04 mm and 24.04 ± 2.28 mm for males and females, respectively (p < 0.0001). The overall percentage of complete bridging and partial bridging was 6.6% and 56.9%, respectively. Complete bridges were more common in males (males: 9.1%, females: 4.8%), and partial bridges were more frequent in females (males: 49.2%, females: 62.4%). Both sexes differed with respect to sella turcica dimensions. Moreover, males had a significantly larger ACD, posterior clinoid distance (PCD), and diameter of sella turcica (DST), on both sides, relative to females.

Conclusion

The prevalence rate of complete STB in the Taiwanese population was 6.6%. Significant differences between sexes were found in sella turcica dimensions. The prevalence rates of STB as well as the sella turcica dimensions did not significantly differ between different craniofacial skeletal patterns (skeletal Classes I, II, and III).

Segmentation procedures for the assessment of paranasal sinuses volumes

BACKGROUND

The paranasal sinuses are complex anatomical structures, characterised by highly variable shape, morphology and size. With the introduction of multidetector scanners and the development of many post-processing possibilities, computed tomography became the gold standard technique to image the paranasal sinuses. Segmentation allows the extraction of metrical and shape data of these anatomical components that can be applied for diagnostic, education, surgical planning and simulation, and to plan minimally invasive interventions in otorhinolaryngology and neurosurgery.

DISCUSSION

Our aim was to provide a review of the existing literature on segmentation, its types and application, and the data obtained from this procedure. The literature search was conducted on PubMed (including Medline), ScienceDirect and Google Scholar databases, using the keywords as follows: 'paranasal sinuses', 'frontal sinus', 'maxillary sinus', 'sphenoid sinus', 'ethmoid sinus', in all possible combinations with the keywords 'segmentation' and 'volumetric analysis'. Inclusion criteria were: articles written in English, on living human subjects, on the adult population and focused on paranasal sinuses analysis.

CONCLUSION

This article provides an overview of the types and main application of segmentation procedures on paranasal sinuses, and the results provided by the studies on this topic.

Sphenoid sinuses: pneumatisation and anatomical variants-what the radiologist needs to know and report to avoid intraoperative complications

PURPOSE

Sphenoid sinuses are pneumatised structures, placed in the body of the sphenoid bone, with highly variable morphology. The strict relationships with vascular and nervous structures determine the importance of their anatomical variants in otorhinolaryngology and neurosurgery; a precise understanding of the complex anatomy and anatomic variations of these structures is pivotal for radiological diagnosis of paranasal sinuses pathology and for surgical planning, to avoid potential complications. Our aim is to describe the anatomical variants of sphenoid sinuses, and to help general radiologists and specialists in endoscopic surgery in becoming familiar with these sensitive anatomical structures.

METHODS

A literature search of PubMed and Embase (Elsevier) databases was performed using the keywords "sphenoid sinus" and "anatomy, "sphenoid sinus" and "anatomic variants", "sphenoid sinus", and "anatomic variations".

RESULTS

We described the anatomical variants of the sphenoid sinuses anatomy, according to their size, shape, degree of pneumatisation, protrusion of anatomical structures into their lumen, superimposition of ethmoid cells (Onodi cells), and presence of accessory septations CONCLUSION: The information provided by this study may help in the identification and description of the anatomical variations of the sphenoid sinuses and their relationship to neurovascular structures.

Association between sella turcica bridging and altered direction of dental eruption: A case-control study

Background

Calcification between the anterior and posterior clinoid processes, also the so-called sella turcica bridging, has been associated in some studies with skeletal anomalies as well as with dental and eruption disturbances. It was hypothesized that sella turcica bridging was associated with an altered direction of dental eruption. The aim of the study was to assess whether there was a relationship between the degree of calcification and the presence or absence of an alteration in the tooth eruption direction.

Material and Methods

A case-control multicenter study was conducted. The study population consisted of 150 subjects (age 10-50 years), 30 of which presented some type of alteration of the direction canine eruption (impactation or transposition) (cases) and 120 selected at random who did not present altered direction of dental eruption (controls). Cases and controls were matched by age, sex, and approximate date of starting orthodontic treatment. Lateral cephalometric radiographies were obtained and the extent of the sella turcica bridging was measured using a Vernier caliper and scored as no calcification, partially calcified, and completely calcified.

Results

The frequency of a partially or completely calcified sella turcica bridge was significantly higher among cases with altered direction of dental eruption as compared with controls. There was a trend towards a shorter length of sella turcica in subjects with two or more canine eruption alterations. Sella turcica bridging was unrelated to sex, but it was significantly influenced by age.

Conclusions

Sella turcica bridging is frequently detected in subjects with altered direction of dental eruption of canines. Key words:Dental eruption, sella turcica bridging, anterior clinoid process calcification, posterior clinoid process calcification, cephalometric radiographs.

Skull base ligamentous mineralisation: evaluation using computed tomography and a review of the clinical relevance

Objectives

To determine the frequency, morphologic and demographic characteristics, and clinical relevance of the mineralisation of six skull base ligaments (interclinoid, caroticoclinoid, petrosphenoid, posterior petroclinoid, pterygospinous, and pterygoalar).

Methods

This is a retrospective review of 240 CT scans of the paranasal sinuses (ages 6–80 years). A limited systematic review was performed primarily using Embase and Medline databases.

Results

Ligamentous mineralisation was well delineated on CT and occurred at ≥ 1 location in 58.3% of patients. There was a nonsignificant trend towards a greater incidence with advancing age. The interclinoid and posterior petroclinoid ligaments were most commonly mineralised (22.1% and 18.3%, respectively); the petrosphenoid and pterygoalar ligaments were least frequently mineralised (10.8% and 6.3%, respectively). The mean age of patients with posterior petroclinoid mineralisation was significantly greater than those with interclinoid and petrosphenoid mineralisation and was not seen in patients aged 6–20 years. The literature review highlighted the clinically relevant potential for mineralised ligaments to cause barriers to surgical access (e.g. to the foramen ovale), increase the risk of neurovascular injury during surgery at the skull base (e.g. during anterior clinoidectomy), and predispose to neural impingement.

Conclusions

Skull base ligamentous mineralisation is commonly encountered on CT imaging. Given the potentially significant clinical implications, an understanding of the morphological appearances is of importance to those planning interventions at the skull base. To the authors’ knowledge, this study is the first to comprehensively evaluate such a wide range of skull base ligaments using CT. For some ligaments, the incidence on CT has not been previously described.

The carotico-clinoid bar: A systematic review and meta-analysis of its prevalence and potential implications in cerebrovascular and skull base surgery

BACKGROUND

The caroticoclinoid bar (CCB) is implicated in both transcranial and endonasal surgery. Its morphology reflects differences in the microsurgical anatomy of the parasellar area while its manipulation during an anterior or middle clinoidectomy can result in ICA injury. Although safe surgical access to the paraclinoidal region is related to adjustment of surgical technique according to CCB anatomical variants, a review of the literature indicates the lack of a systematic assortment of published data regarding the prevalence of this variable structure. As such the topic needs further investigation.

OBJECTIVE

To systematically review and document the prevalence of the CCB and its anatomic variations.

METHODS

3 Databases were systematically reviewed according to the PRISMA statement through August of 2018 for the identification of relevant studies.

RESULTS

A total of 27 articles (7,521 subjects/specimens, 14,449 sides) were included in this meta-analysis. The overall pooled prevalence of the CCB was 32.6% (95% CI 26.6% - 38.8%) when measured over subjects/specimens and 23.6% (95% CI 19.7% - 27.6%) when measured over sides. Overall prevalence of the CCB reported from imaging studies was 23.1% (95% CI 8.9% - 41.4%) when measured over subjects/specimens and 18.7% (95% CI 12.6% - 25.7%) when measured over sides. Moreover, the CCB was slightly more prevalent (p = 0.050), on the right side.

CONCLUSION

Our results indicate considerable CCB prevalence rates and that imaging studies report lower prevalence rates. Although meticulous preoperative investigation is mandatory, surgeons carrying for patients with parasellar pathologies should always be vigilant about this structure.