Anatomical variants of surgically important landmarks in the sphenoid sinus: a radiologic study in Southeast Asian patients

Evaluation of the relationship between sphenoid sinus morphology and area and volume by computed tomography

OBJECTIVES

The aim of this study is to investigate the effect of sphenoid sinus pneumatization types, Onodi cell (OC), internal carotid artery (ICA), optic nerve (ON) on sinus volume and area on computed tomography (CT) images.

METHODS

The CT images of 150 patients were evaluated. Sphenoid sinus pneumatization types, OC prevalence, protrusion and dehiscence of ICA and ON, the volume and area were evaluated.

RESULTS

The sinus volume and area were statistically higher in patients with bilateral protrusion of ICA and ON then patients without protrusion of ICA and ON. The mean volume and area of sinus were 9949.4 ± 351.0 mm3 and 4570.9 ± 1604.9 mm2, respectively. The volume and area of sphenoid sinus did not differ significantly between groups with and without OC. The postsellar b type sphenoid sinus had the highest volume, while conchal type has the least volume.

CONCLUSIONS

Bilateral protrusion and dehiscence of ICA and bilateral protrusion of ON caused a significant increase in the sphenoid sinus volume and area. The presence of ICA and ON, the pneumatization of the sinus is an anatomical structure that can affect the sinus volume and area. Before the operation, three-dimensional evaluation should be performed to determine whether these structures are bilateral/unilateral and it should be remembered that the sinus volume and area can change.

Anatomical Variations of the Optic Nerve in the Sphenoid Sinus: Do Ethnic Variations Matter?

There are several variations in the anatomical relations of the optic nerve with the sphenoid sinus. Proper understanding of these variations is clinically important to minimize injuries associated with surgical procedures that involve the sphenoid sinus. CT scans of paranasal sinuses obtained prior to any endoscopic surgery in the sphenoid sinus area is useful for designing operative strategies. Ethnic variations in sinonasal anatomy have been documented. The objective was to study the pattern of relationship between optic nerve and the sphenoid sinus using computerized tomographic imaging in a north Indian population, to compare our findings with previous studies in different ethnic groups and find out if ethnic variations in such a relationship matter. A prospective study was conducted on 300 patients who underwent computed tomography of the paranasal sinuses from Sept 2020 to June 2021. Relationship of optic nerves to the sphenoid sinuses was categorized according to DeLano classification. Pneumatization of the anterior clinoid process and bony dehiscence of optic nerve was also observed. Type 1 position of optic nerve was seen in 69.3%, Type 2 in 20.9%, Type 3 in 3% and Type 4 in 6.8% of sinuses. The pneumatization of anterior clinoid process (ACP) was observed in 10.5% and the bony dehiscence of optic nerve was noted in 6.5% sinuses. Bony dehiscence of optic canal had associated ACP pneumatization in 64.1% sinuses.The variability of the relation of optic nerve to the sphenoid sinus even in the persons of same ethnicity precludes a definite role of ethnicity in these variations. Other factors possibly contributing to such a relationship have been discussed.

Morphometry and Intracranial Relations of the Sphenoid Sinus in Context to Endoscopic Transnasal Transsphenoidal Surgery

Introduction Due to the variable degree of pneumatization, the shape and size of the sphenoid sinus are irregular. An endoscopic intranasal transsphenoidal approach is made in sphenoid sinus pathologies, sphenoid sinusitis, and sellar and parasellar diseases. A diagnostic approach to the sphenoid sinus is also done to get a better MRI scan of the pituitary. The present study aims to describe the variant types of sphenoid sinus, morphometry, anatomy, and relations of sphenoid sinus, which will be helpful to surgeons during an endoscopic approach to the sphenoid sinus. Materials and methods We studied 76 cadaveric sphenoid sinuses that were exposed by taking a sagittal section of 38 formalin-fixed cadaveric heads. After examining the inter-sphenoidal septum, it was removed to observe the inside aspect of the sphenoid sinus. Different dimensions of the sinus were noted down. The bulges inside the sinus due to neurovascular structures in relation to the sinus were observed. Results  The most prominent type found was the sellar in 68.4% of cases preceded by the postsellar in 23.7% of cases. Presellar type of pneumatization was seen only in 7.9% of cases and the conchal type was absent. Intersphenoid septum was seen in 92,1% of cases, out of which 11.4% of septums were deficient on the posterior aspect. An internal carotid artery bulge in the sphenoid sinus was seen in 46% of cases. In 27.6% and 19.7% of sphenoid sinuses, bulging of the optic and vidian nerves, respectively, were seen. Some of these structures were dehiscent in the sphenoid sinus. Conclusions To get more space in the sphenoid sinus, the septa in the sinus are removed by surgeons, which may damage the walls of the sphenoid sinus. Knowledge of the relations of neurovascular structures with the sphenoid sinus will be helpful to surgeons during the transsphenoidal endoscopic approach to avoid any injury to these structures.

Association of accessory sphenoidal septum with protrusions of sphenoid sinus

PURPOSE

Accessory sphenoidal septum (ASS) is a septal variation that exists in addition to the primary septum of the sphenoid sinus and can be found in or near anatomically essential structures. This study aimed to investigate the relationships between protrusions of vital structures around the sphenoid sinus and the ASSs.

METHODS

This cross-sectional retrospective study is based on the analysis of CBCT scans of 314 patients in axial, coronal, and sagittal planes with 0.2-0.3 slice thicknesses. Optic nerve (ON), internal carotid artery (ICA), both ON and ICA, maxillary nerve (MN), vidian canal (VN) and ASSs were detected, and the relationship between protrusions of these vital anatomical structures and ASS was evaluated.

RESULTS

Statistically significant relationship was observed between the right Type 1 ON protrusion (p < 0.05) and left Type 1 ON protrusion (p = 0.001); left Type 3 ON protrusion (p < 0.05); right Type 4 ON protrusion (p < 0.05) and ASS. Statistically significant relationship was also observed between the right ICA protrusion and ASS (p < 0.05). The right Type 1 VN protrusion (p = 0.001); left Type 2 VN protrusion (p < 0.001); right and left Type 3 VN protrusions (p < 0.001) were found to be significantly associated with the ASS.

CONCLUSIONS

ASSs have significant associations with some protrusions, and they tend to cause potentially severe complications in endoscopic sinus surgery. This variability requires a comprehensive understanding of regional sphenoid sinus anatomy with detailed three-dimensional tomographic imaging.

Anatomical configurations of the optic canal in the sphenoid sinus in a Hispanic population: computed tomography based study

OBJECTIVE

The prevalence of the optic canal anatomical variants across the sphenoid sinus varies widely among different ethnic groups. This study aimed to analyse the anatomical variants of the optic canal and their relationship to sphenoid sinus pneumatisation in a Hispanic population.

METHOD

A review of 320 sphenoid sinuses by high-resolution computed tomography was performed. DeLano's classification of the optic canal, presence of dehiscence, septa insertion, sphenoid sinus pneumatisation and presence of Onodi cells were established.

RESULTS

Dehiscence of the optic canal was observed in 4.7 per cent (n = 15) of the analysed sinuses. Type 4 and 3 optic canals were significantly more frequent among postsellar sphenoid sinuses than other patterns of sphenoid sinus pneumatisation (p = 0.002 and p = 0.018). A type 4 optic canal has a higher tendency to present inserted septum than other optic canal types (p = 0.014).

CONCLUSION

This study described the optic canal variants in a Hispanic population, which complements existing literature addressing other ethnicities.

Radiological anatomical variations of the lateral nasal wall and anterior skull base amongst different populations: A systematic review and meta-analysis

OBJECTIVES

To determine the anatomical variations of the lateral nasal wall and anterior skull base amongst populations in different geographical regions.

DESIGN

Systematic review and meta-analysis.

METHODS

Using PRISMA guidelines, SCOPUS and PUBMED databases were searched from inception until 1 March 2022. The regions and populations identified were from Europe, Asia, Middle East, Australia-New Zealand-Oceania, South America, North America and Africa. Random-effects model was used to estimate the pooled prevalence with 95% confidence intervals (CIs). Heterogeneity was assessed using the I² statistic and Cochran's Q test.

MAIN OUTCOME MEASURES

Anatomical variations of the lateral nasal wall and anterior skull base confirmed by computed tomography scan.

RESULTS

Fifty-six articles were included with a total of 11 805 persons. The most common anatomical variation of the ostiomeatal complex was pneumatization of the agger nasi (84.1%), olfactory fossa was Keros type 2 (53.8%) and ethmoids was asymmetry of the roof (42.8%). Sphenoethmoidal and suprabullar cells have a higher prevalence in North Americans (53.7%, 95% CI: 46.00-61.33) while asymmetry of ethmoid roof more common in Middle Easterns (85.5%, 95% CI: .00-100). Bent uncinate process has greater prevalence in Asians while supraorbital ethmoid cells and Keros type 3 more common in non-Asians. The overall studies have substantial heterogeneity and publication bias.

CONCLUSION

Certain anatomic variants are more common in a specific population. The 'approach of analysis' plays a role in the prevalence estimates and consensus should be made in future studies regarding the most appropriate 'approach of analysis' either by persons or by sides.

Risky anatomical variations of sphenoid sinus and surrounding structures in endoscopic sinus surgery

Purpose

This study aimed to examine the relationship between the sphenoid sinus (SS) and surrounding vital structures such as the internal carotid artery (ICA) and optic nerve canal (ONC) as well as the types of attachment of the sphenoidal septa onto these structures.

Methods

In total, 230 computed tomography (CT) scans were reviewed to study the type of sphenoid sinus pneumatization (SSP), the protrusion and dehiscence of the ICA and ONC, the relationship between the sphenoidal septa and surrounding vital structures as well as pterygoid recess pneumatization (PRP).

Results

The most common SSP was sellar type (58.7%). The rates of protrusion and dehiscence of the ICA were 26.3 and 0.4%, and for the ONC, they were 13 and 1.5%, respectively. The ICA and ONC were most protruded and dehiscent in more extensive SSP. In 21.6% of patients, the intersphenoidal septa (IS) were attached to the wall of the ICA and in 8.6% they were attached to the wall of the ONC. The attachment of IS to the ICA correlated statistically significantly (p < 0.0001) with protrusion of the ICA. Accessory septa were detected in 30.4% of cases with various sites of attachment.

Conclusion

To reduce the risk of injury and complications during endoscopic sinus surgery (ESS), surgeons should consider using CT to identify possible bulging and dehiscence of the ICA/ONC and their relationship to the extent of SSP and also to establish the presence of deviation of the sphenoid septum, and the presence of accessory septa.

Relationships of sphenoid sinus pneumatization with internal carotid artery characteristics

Objective

We explored the clinical significances of the relationships among sphenoid sinus aeration, intersphenoid sinus septum (ISS), and internal carotid artery (ICA).

Methods

We retrospectively reviewed the preoperative paranasal sinus computed tomography scans and the medical charts of 490 patients who were treated by the endoscopic endonasal transsphenoidal approach. We analyzed sphenoid sinus pneumatization, number of ISS, and positional relationships between the ICA and ISS (including ICA prominence and the thickness of surrounding bone).

Results

ISS were often present in the ICAs of patients with presellar pneumatization (36.2%; p = 0.042). Sphenoid sinus pneumatization status significantly differed according to number of ISS (p < 0.001), ICA prominence (p < 0.001), ISS insertion into the ICA (p = 0.042), and distance from ISS to ICA (p = 0.004). When sphenoid sinus aeration was poor, the ICA was not prominent, and the ISS were attached to or lay close to the paraclival ICA.

Conclusions

Patients with presellar pneumatization exhibited less prominent ICAs, and more ISS attached to or near the paraclival ICA, than did other patients. Therefore, particular caution is required when using the endoscopic endonasal transsphenoidal approach to treat patients with poor sphenoid sinus aeration.

The Evaluation of Variations in Patterns of Sphenoid Sinus Pneumatization Using Computed Tomography in a South Indian Population

Background and objective

Knowledge about sphenoid sinus pneumatization is critical for skull base surgeries and functional endoscopic sinus surgery (FESS) in order to avoid serious complications like postoperative meningitis, sinusitis, cerebrospinal fluid (CSF) rhinorrhea, and intracranial hematoma. In this study, we aimed to assess the proportion of anatomical variants in sphenoid sinus pneumatization and to determine the common sphenoid pneumatization pattern in a South Indian population.

Methods

This retrospective study was conducted over a period of six months from July 2019 to December 2019 among 573 patients who underwent non-contrast CT (NCCT) or contrast-enhanced CT (CECT) of the brain, paranasal sinuses (PNS), orbit, and face.

Results

Most of the patients were in the age group of 20-39 years. The male-to-female ratio was 2.45:1. Among the posterior extensions, the most common variant was type D, followed by type C, type B, and type A. Among the clival extensions, the most common variant was Cliv-A, followed by Cliv-B, Cliv-C, and Cliv-D. The most common lateral wall pneumatization was bilateral lateral wall pneumatization followed by unilateral sinus wall pneumatization. Lat-A was the most common lateral wall pneumatization pattern followed by Lat-D, Lat-B, and Lat-C.

Conclusion

Our study intends to classify the sphenoid sinus pneumatization pattern and identify the most common variant among them, thereby guiding the skull base and FESS surgeons in choosing the correct mode of the operative procedure and also anticipating and avoiding complications of surgery.

Assessment of variations in sphenoid sinus pneumatization in Indian population: A multidetector computed tomography study

Background and Purpose:

The purpose of our study was to assess the prevalence of variations in the extent of sphenoid pneumatization in the Indian population and compare with existing literature.

Materials and Methods:

This retrospective study included 500 patients who underwent CT of the paranasal sinuses. The multiplanar reformations of paranasal sinus were assessed for the type of pneumatization of the sphenoid sinus and type of clival, lateral recess, lesser wing, and anterior recess extensions.

Results:

The conchal, presellar, incomplete sellar, and complete sellar types comprised 0%, 1.2%, 22.2%, and 76.6% of patients. The extensions of pneumatization subtypes in the study population were clival in 76.6% subjects; lateral recess, lesser wing, and anterior recess in 59.7%, 20.4%, and 20.4% of sinuses, respectively. The pure forms were seen in 25.4% and combined forms in 61% of sinuses. The presellar type (1.2%) was less common and sellar type (98.8%) being common in our population compared to the Caucasian and East Asian population. The sphenoid sinuses were extensively pneumatized in our population compared to the Chinese and Caucasian population, the prevalence being 76.6%, 68%, and 44.5% for clival; 59.7%, 46%, and 28.3% for lateral recess; 20.4%, 32%, and 12% for lesser wing extension, respectively. The pure forms were relatively less common and combined forms being more common compared to the Chinese and Caucasian population in our study.

Conclusion:

The extent of pneumatization of the sphenoid sinus has clinical and surgical implications in sellar and central skull base lesions, and variability in different populations confirms that ethnicity influences the differences in prevalence.

A systematic review of the surgical anatomy of the orbital apex

PURPOSE

The orbital apex is the narrowest part of the orbit, housing the link between the intracranial cavity and orbit. Knowledge of orbital apex anatomy is crucial to selecting a surgical approach and reducing the risk of complications. Our purpose is to summarize current knowledge on surgical anatomy and attempt to reach a consensus on definition of the orbital apex.

METHODS

The online databases of Embase, the Cochrane library, Web of Science and PubMed (MEDLINE) were queried in a comprehensive bibliographic search on the (surgical) anatomy of the orbital apex and consisted of a combination of two subjects, using indexed terms and free text: "Orbital Apex" and "Orbital Anatomy."

RESULTS

A total of 114 relevant papers were included in this review. Numerous anatomical variations are described in the literature. Variations of the optic canal include duplication (0.64%) and keyhole anomaly (2.65%). Variations in pneumatization of the anterior clinoid process were unilateral in almost 10%, bilateral in 9%, and normal in 72%. A rare variant of the superior orbital fissure (SOF) is Warwick's foramen, which appears as if the lowest portion of the SOF was separated from the main fissure by a transverse bony bridge.

CONCLUSION

The definition of the orbital apex varies in the literature, and further research would most likely identify additional variations. A universal definition reporting these variations and pathology and imaging findings is essential for determining the optimal surgical approach to the orbital apex.

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.

The impact of sphenoid sinus pneumatization type on the protrusion and dehiscence of the adjacent neurovascular structures: A prospective MDCT imaging study

RATIONALE AND OBJECTIVES

Sphenoid sinus (SS) pneumatization is greatly variable. Precise determination of the pattern of SS pneumatization and its relationship to the vital neurovascular structures will provide a more comprehensive understanding of the regional SS anatomy to avoid the risk of potentially serious neural and vascular injury. We aimed to study the relationships among SS pneumatization type, extent of pneumatization, and protrusion/dehiscence of adjacent neurovascular structures using the multi-detector computed tomography.

MATERIALS AND METHODS

One hundred seventy healthy patients were prospectively examined by multi-detector computed tomography of the head. The type of pneumatization of the SS was determined. The protrusion/dehiscence of the internal carotid artery, optic nerve, vidian nerve, and maxillary nerve into the SS cavity was evaluated. The relationships between the SS pneumatization type and the extent of protrusion/dehiscence of the examined variables were statistically analyzed.

RESULTS

We had 70 patients with no protrusion/dehiscence, 37 patients with unilateral protrusion/dehiscence, and 63 patients with bilateral protrusion/dehiscence. The presellar type was dominant (61.4%) in the group with no protrusion/dehiscence, the sellar type was dominant (56.8%) in the group with unilateral protrusion/dehiscence, and the postsellar type was dominant (55.6%) in the group with bilateral protrusion/dehiscence. The protrusion rates of the internal carotid artery, optic nerve, vidian nerve, and maxillary nerve in the postsellar type were 50.6%, 52.3%, 56.9%, and 54.1%, respectively (p< 0.001).

CONCLUSION

The prevalence of protrusion/dehiscence of the neurovascular structures is significantly related to the type of SS and increases as the degree of SS pneumatization increases.

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.

Assessment of sphenoid sinus types in patients with cleft lip and palate on cone-beam CT

PURPOSE

The aim of this study is to examine the sphenoid sinus morphology and variations in patients with cleft lip and palate (CLP) on cone-beam computed tomography (CBCT) images, and to compare them with healthy controls.

METHODS

CBCT images of 54 patients (28 males and 26 females,) with CLP and 54 age- and gender-matched healthy individuals (28 males and 26 females) were retrospectively evaluated. Sphenoid sinus main types (conchal, presellar, sellar, postsellar), sellar subtypes, clival and lateral extensions, and sinus septation were analyzed in CLP and control groups. The data were statistically analyzed using Chi-square test to compare the groups.

RESULTS

A statistically significant difference was found between CLP and control groups for sphenoid sinus main types (p < 0.05). Presellar type was more commonly observed in CLP group (18.5%), while the postsellar (31.5%) and clival (17.7%) types were more frequent in control group. There was a significant difference between the groups among different sellar sinus subtypes (p < 0.05). A significant difference was detected between the groups for clival extensions of sphenoid sinus (p < 0.05), but no difference was found for the lateral extensions (p > 0.05). No significant difference was determined between groups for sphenoid sinus septation (p > 0.05).

CONCLUSION

Significant differences were found between the CLP and control groups in terms of sphenoid sinus main types, sellar subtypes and the clival extensions. Knowledge of sphenoid sinus pneumatization in patients with CLP is important for preventing complications during transsphenoidal surgery.

Anatomical Variations of the Nose and Paranasal Sinuses: A Computed Tomographic Study

To evaluate the anatomical variations in computed tomographic (CT) images of paranasal sinuses and to investigate association between them.

DESIGN

Retrospective study.

SETTING

Tertiary care center in the southern part of India.

SUBJECTS

Radiological images of paranasal sinuses belonging to chronic rhinosinusitis patients managed between June 2016 and November 2018.

METHODS

The studied characteristics in the CT images included the deviated nasal septum (DNS), concha bullosa (CB), Haller cell (HC), Onodi cell (OC), pneumatization of anterior clinoid process (ACP), pterygoid base (PB), superior turbinate, inferior turbinate, crista galli (CG), and nasal septum. The height of the lateral lamella of the cribriform plate, the sphenoid pneumatization pattern, and the optic nerve relationship with sphenoid sinus were studied separately. The associations between these factors, and with maxillary sinus opacifications were also investigated. A total of 151 adult patients' CT images were analyzed. The most common manifestations noted were DNS, CB and pneumatized PB, seen in 83.4%, 49% and 47% of the patients respectively. The rates of HC, OC, pneumatized septum, pneumatized CG, and pneumatized ACP were 39%, 23%, 27%, 43% and 27% in that order. Rates of most of these variations were within the range reported in the literature. Chi square test revealed that the OC was independently associated with pneumatized CG and pneumatized septum. The maxillary sinus opacification was related to DNS and CB, but not with protrusion of tooth root into the sinus. Most of the anatomical variations were comparable with the reports across the globe, however, the associations between these variations weren't common in our cohort.

Morphometric Analysis of Sphenoid Sinus in Patients With Nasal Septum Deviation

This retrospective study aimed to assess the association of the volume and types of the sphenoid sinus with deviated nasal septum by analyzing multislice computed tomography images. A total of 93 patients with a deviated nasal septum and 70 healthy controls were included in the study. Patients with sinonasal morbidities other than deviation were excluded. Three-dimensionally reconstructed computed tomography images of the study participants were acquired. A total of 326 sphenoid sinus volumes from the patient and control groups were obtained and compared between the groups. Sphenoid sinus volumes and the angle of the deviation were measured for standardization and assessment of the severity. Deviated nasal septum was found on the right in 49.5% (n = 46) and on the left in 50.5% (n = 47) of the study participants. Deviation angles were in the range from 7.2° to 22.4° and the mean value was 13.2° ± 5.0°. The measured volumes were in the range from 1.8 cm to 9.6 cm with a mean of 4.8 ± 1.5 cm. In the control group, the median values for the sphenoid sinus volumes were 4.40 cm (0.80-8.90 cm) on the right and 4.20 cm (0.90-8.70 cm) on the left. In the study group, sphenoid sinus volumes were found to be statistically significantly different between those on the ipsilateral and contralateral side of the septal deviation. Sphenoid sinus volumes were significantly smaller on the same side with septal deviation compared with those on the contralateral side. There was no statistical relationship between the presence of septal deviation, age and gender, and the type of sphenoid sinus.

Assessment of a Patient-Specific, 3-Dimensionally Printed Endoscopic Sinus and Skull Base Surgical Model

Importance

Three-dimensional (3D) printing is an emerging tool in the creation of anatomical models for simulation and preoperative planning. Its use in sinus and skull base surgery has been limited because of difficulty in replicating the details of sinus anatomy.

Objective

To describe the development of 3D-printed sinus and skull base models for use in endoscopic skull base surgery.

Design, Setting, and Participants

In this single-center study performed from April 1, 2017, through June 1, 2017, a total of 7 otolaryngology residents and 2 attending physicians at a tertiary academic center were recruited to evaluate the procedural anatomical accuracy and haptic feedback of the printed model.

Interventions

A 3D model of sinus and skull base anatomy with high-resolution, 3D printed material (VeroWhite) was printed using a 3D printer. Anatomical accuracy was assessed by comparing a computed tomogram of the original patient with that of the 3D model across set anatomical landmarks (eg, depth of cribriform plate). Image-guided navigation was also used to evaluate accuracy of 13 surgical landmarks. Likert scale questionnaires (1 indicating strongly disagree; 2, disagree; 3, neutral; 4, agree; and 5, strongly agree) were administered to 9 study participants who each performed sinus and skull base dissections on the 3D-printed model to evaluate anatomical accuracy and haptic feedback.

Main Outcomes and Measures

Main outcomes of the study include objective anatomical accuracy through imaging and navigation and haptic evaluation by the study participants.

Results

Seven otolaryngology residents (3 postgraduate year [PGY]-5 residents, 2 PGY-4 residents, 1 PGY-3 resident, and 1 PGY-2 resident) and 2 attending physicians evaluated the haptic feedback of the 3D model. Computed tomographic comparison demonstrated a less than 5% difference between patient and 3D model measurements. Image-guided navigation confirmed accuracy of 13 landmarks to within 1 mm. Likert scores were a mean (SD) of 4.00 (0.71) for overall procedural anatomical accuracy and 4.67 (0.5) for haptic feedback.

Conclusions and Relevance

This study shows that high-resolution, 3D-printed sinus and skull base models can be generated with anatomical and haptic accuracy. This technology has the potential to be useful in surgical training and preoperative planning and as a supplemental or alternative simulation or training platform to cadaveric dissection.

Posterior ethmoid cell expansion towards the inferolateral region of the sphenoid sinus: a computed tomography study

OBJECTIVE

The aim of this study was to investigate the anatomical imaging characteristics of posterior ethmoid cells (PEs) expanding towards the inferolateral region of the sphenoid sinus (SS).

METHODS

This study included a total of 278 inpatients (556 sides) whose paranasal sinus computed tomography (CT) scans were reviewed and collected from May 2018 to February 2019. The anatomical imaging characteristics of PEs expanding towards the inferolateral region of the SS were observed.

RESULTS

PEs expanding towards the inferolateral region of the SS formed an inferolateral spheno-ethmoid cell (ISEC). ISECs were observed on three sides (0.54%; 3/556) in three cases (1.08%; 3/278). All of the ISECs were present unilaterally on the right side of the SS. The ISECs originated from the most posterior ethmoid cell; they were first located at the medial aspect of the orbital apex, pneumatized continually backward to the inferomedial wall of the orbital apex, and then extended into the lateral region of the SS. The ISECs further extended laterally, inferiorly and posteriorly beyond the sphenoid body into the greater wing and/or pterygoid process.

CONCLUSION

An ISEC is a rare variation of ethmoid air cells. Preoperative recognition of ISECs is essential to achieve safe and effective endoscopic sinus surgery because of the important anatomical location.

Posterior Maxillary Sinus Wall: A Landmark for Identifying the Sphenoid Sinus Ostium

IMPORTANCE

Safe entry into sphenoid sinus is critical in endoscopic sinus and skull base surgery. A number of surgical landmarks have been used to identify the sphenoid sinus ostium during endoscopic endonasal surgery with variable reliability and intraoperative feasibility.

OBJECTIVE

To determine if the posterior wall of the maxillary sinus is a reliable landmark to determine the depth of the sphenoid sinus ostium during anterior to posterior dissection.

DESIGN, SETTING, AND PARTICIPANTS

Prospective study of adult patients undergoing endoscopic sinus surgery between August 2016 and September 2017. Measurements were made intraoperatively between the depth of the posterior maxillary sinus wall and sphenoid sinus ostium.

MAIN OUTCOMES AND MEASURES

The primary measurement is the distance between the depth of the posterior maxillary sinus wall and sphenoid sinus ostium. Additional data points included age, gender, surgical indication, and primary versus revision endoscopic sinus surgery.

RESULTS

Forty-five patients (38% male, 62% female) with an average age of 56 were enrolled, resulting in 88 operated sides. The average distance between the depth of the posterior wall of the maxillary sinus and the sphenoid ostium was 1.5 mm ± 1.4 mm. The most common position of the sphenoid sinus ostium was posterior to the level of the posterior maxillary sinus wall (54%), followed by same level (23%) and anterior (23%). There was no significant difference between different disease states (P = .75) and between primary and revision cases (P = .13).

CONCLUSIONS AND RELEVANCE

The posterior wall of the maxillary sinus serves as an adjunctive intraoperative landmark to determine the depth of the sphenoid sinus ostium. While the posterior wall of the maxillary sinus approximates the depth of the sphenoid sinus ostium, the relative position is variable and can be anterior or posterior.

Rhinogenous optic neuritis with full recovery of vision - The role of endoscopic optic nerve decompression and a review of literature

BACKGROUND

Optic neuritis resulting from paranasal sinusitis is an infrequently described but clinically important and treatable entity. The role of optic nerve decompression has been well established in atraumatic optic neuropathies which are compressive in origin. However, its role in optic neuritis and other infective or inflammatory processes is lacking, and the role for early surgical intervention remains controversial.

CASE REPORT

In this case report, we describe a patient who presented with sudden onset of right vision loss secondary to optic neuritis from pansinusitis. He was treated with systemic antibiotics and steroids along with an urgent endoscopic sinus surgery with optic nerve decompression. Full restoration of his vision was recorded within 24 h of surgical decompression.

CONCLUSION

Optic neuritis secondary to paranasal sinusitis is a clinically important entity and timely diagnosis and decompression is key to vision restoration.

Neurovascular Surgical Keys Related to Sphenoid Window: Radiologic Study of Egyptian's Sphenoid

OBJECTIVES

The anatomic variations of the sphenoid sinus and its relation to the surrounding neurovascular structures are a subject of interest. The purpose of this study was to radiologically assess the frequency of protrusion/dehiscence of key neurovascular landmarks surrounding the Egyptians' sphenoid.

METHODS

This is a cross-sectional descriptive study of sinonasal computed tomography of the sphenoid sinus in 500 adult Egyptians, conducted at Mansoura University Hospitals; Egypt, over a period of 1 year. Two archives were used for collecting the data; the hard archive and the electronic archive. Variables of interest included the extent of sphenoid sinus pneumatization; intersphenoid septation pattern; protrusion/dehiscence of the internal carotid artery, optic nerve, maxillary nerve, and vidian nerve; and detection of the Onodi cell.

RESULTS

Population of this study included 265 women and 235 men. Their ages ranged from 18-68 years. The bilateral sellar-type pneumatization was shown as the most common pneumatization type (96.8%). Pneumatizations of the pterygoid process, anterior clinoid process, and greater wing of the sphenoid were identified in 9.3%, 8.9%, and 31.8% consequently. A single intersphenoid septum was detected in 85.2%, whereas multiple intersphenoid septums were noted in 11.6%. Protrusion of the internal carotid artery, optic nerve, vidian nerve, and maxillary nerve was recorded in 8.5%, 9.1%, 6.6%, and 3.4% consequently, while dehiscence was reported in 7.2%, 15%, 11.9%, and 4.2% consequently as well. Onodi cell was recognized in 18%.

CONCLUSIONS

This radiologic study highlights significant variations of surgically important anatomic structures related to the sphenoid sinus in Egyptians.

A bony defect of the sphenoid air sinus found in male cadaver: a case report

The sphenoid sinus one of the posterior group of sinus, considered one of the most difficult sinuses due to its deep location in the skull. The interest in the understanding of the anatomy of the sphenoid sinus increased markedly during the last decades due to the development of endoscopic transsphenoidal approaches to the intracranial structures. The important anatomical relations of the sphenoid sinus make it one of the difficult and challenging structures for the surgeons. In this case report, we present one of the anatomical variations that was found during cadaveric dissection of the head. In this case we found abnormal bony defect in the lateral wall of the sinus, the defect closed just by the lining mucosa of the sinus and the dura from its intracranial side. A point may be of clinical importance to the related nearby structures.

Volumetric assessment of sphenoid sinuses through segmentation on CT scan

PURPOSE

Computed tomography represents the gold standard for the assessment of morphological characteristics of sphenoid sinuses, whose anatomy has acquired a novel interest because of the recent introduction of transsphenoidal surgery and robot-assisted procedures. One of the most relevant parameters for planning surgical intervention is the volume of sphenoid sinuses, and with time few population studies have been published. However, at present, no data are available concerning the relation between volume and anatomical variants of sphenoid sinuses.

METHODS

We retrospectively evaluated head CT-scans of 100 patients (age range 25-99 years; mean age males 45.0; mean age females 50.5 years) to calculate the volume of sphenoid sinuses through automatic segmentation. Possible statistically significant differences according to sex and variants of pneumatization, and type of sinus were assessed, respectively, through Student's t test and one-way ANOVA test (p < 0.05).

RESULTS

Average volume of sphenoid sinuses in males was 10.005 ± 5.101 cm³, in females 7.920 ± 3.176 cm³. Differences according to sex were statistically significant (p < 0.05). Patients with pneumatization of pterygoid processes, dorsum sellae and anterior clinoid processes had a significantly higher volume than unaffected subjects. Moreover, differences of volume according to the type of sphenoid sinus were statistically significant (p < 0.05).

CONCLUSIONS

Results show that volume of sphenoid sinuses strongly depend upon the type of sinus and possible pneumatization variants. Moreover, the important of ethnic variability is confirmed.

Detailed Anatomical Analysis of the Sphenoid Sinus and Sphenoid Sinus Ostium by Cone-Beam Computed Tomography

The aim of this study is the evaluation of the anatomical structures of sphenoid sinus ostium used as a reference point for transsphenoidal surgery by cone beam computed tomography. The authors' study was performed using the cone-beam computed tomography images of 16 to 82-year old 200 (112 female, 88 male) patients (Newton 5G, Verona, Italy). Septum deviation of sphenoid sinus and the distance between 2 ostia were evaluated by coronal and axial sections, respectively. Pneumatization degree of sphenoid sinus, diameter of sphenoid sinus ostium, and distance lower edge of superior turbinate to sphenoid sinus ostium were measured by using sagittal sections. The sellar type was the most common pneumatization type of sphenoid sinus in authors' study. While the C-type septum deviation was observed as the most common, T-type deviation was the least type. Sphenoid sinus ostium was bilaterally in 71.5% of individuals, and it was not found in 10% of individuals included in the study. A significant decrease was determined in diameter of the left sphenoid sinus ostium with aging. The distances between 2 sphenoid sinus ostia were 7.30 ± 2.77 mm for women and 6.09 ± 2.58 mm for men, respectively. No statistical differences were found in women and men in terms of distances between the lower edge of the right and left superior turbinate and sphenoid sinus ostium on their sides. Consequently, making detailed preoperative radiological evaluation of anatomic variations of sphenoid sinus and sphenoid sinus ostium is important in terms of guiding the surgeon in the process of a successful transsphenoidal surgery.

Anatomical variants of sphenoid sinuses pneumatisation: a CT scan study on a Northern Italian population

Sphenoid bone may be affected by different variants of pneumatisation, which have a relevant importance from a clinical and surgical point of view. The description of such variants in different populations may give useful information. However, few articles describe the variability of sphenoid pneumatised structures and none of them focuses on Northern Italian population. Variants of pneumatisation of sphenoid bone were described in a sample of 300 Northern Italian patients who underwent a CT scan. More than fifty-seven percent of patients showed a form of anatomical variant: the most common form was the pneumatised pterygoid processes (39.6%), followed by dorsum sellae (32.9%) and clinoid processes (20.3%), without statistically significant differences between males and females (p > 0.01). In 26.3% of patients, a combined pneumatisation of these three structures was observed, being the combination pterygoid processes-dorsum sellae the most frequent (11.3%). In 9.3%, all the three sphenoid structures were affected. This article is the first description of the prevalence of different variants of pneumatisation in a Northern Italian population: the occurrence of such forms has to be acknowledged for their possible clinical and surgical consequences.