Analysis of pneumatization and neurovascular structures of the sphenoid sinus using cone-beam tomography (CBT)

Computed tomography based evaluation of the association between sphenoid sinus pneumatization patterns and variations of adjacent bony structures in relation to age and gender

Many studies revealed that the sphenoid sinus pneumatization (SSP) affects the protrusion/dehiscence of adjacent structures including optic canal (OC), foramen rotundum (FR), vidian canal (VC), and carotid canal (CC). Knowledge of this relationship bears vital importance to identify the safest surgical route during transsphenoidal procedures. Therefore, we aimed to determine the individualized prevalence of the protrusion/dehiscence of adjacent structures based on sagittal and coronal SSP (SSSP and CSSP) patterns. Computed tomography images of 300 patients were analysed to identify the SSSP and CSSP types, and the protrusion/dehiscence of adjacent structures was determined. The relationship between the variables was examined using statistical analysis in terms of age, gender, and laterality. The most prevalent SSSP type was postsellar (62.7%), followed by sellar (30%), presellar (6.6%), and conchal (0.7%). In 71.3% of patients, five types of CSSP were observed, with 23.6% and 21.7% exhibiting Type IV and V, respectively. Our results indicated that postsellar type, Type IV and V CSSP associated with the highest likelihood of protrusion/dehiscence of OC, FR, VC, and CC. Furthermore, no significant correlation was observed between these qualitative variables and gender, with the exception of the VC dehiscence, the protrusion of OC and CC. No notable differences were identified with respect to laterality. Also, the probability of having postsellar type, Type IV and V CSSP, as well as the protrusion of OC, VC, and CC, decreased with increasing age. Further detailed analysis of this association is required to predict the size of the surgical window and to prevent neurovascular injury.

Determination of safety margin of nasal septum osteotomy for sphenoid sinus in cleft lip and palate patients

BACKGROUND

Nasal septum osteotomy is used for separating the nasal septum and maxilla during a Le Fort I osteotomy. If this osteotomy is applied too high or is tilted into the nasal cavity, the sphenoid sinus and various adjacent vital structures may be damaged, and serious bleeding, neurological complications, blindness or even death may occur. The aim of this study is to determine the safety margin of the nasal septum osteotomy for sphenoid sinus during the Le Fort I surgery in cleft lip and palate (CLP) patients.

METHODS

Twenty cleft lip and palate (the CLP group) and 20 healthy individuals (the control group) were included in this study. Three values (two lines and an angle) were measured by cone beam computed tomography (CBCT). The first line is the line passing through the junction of the spina nasalis anterior point and the lower point of the perpendicular lamina of the palatine bone. The undersired line is the line passing through the junction of the spina nasalis anterior point and the lower anterior border of the base of the sphenoid sinus. The osteotomy angle is the angle between these two lines.

RESULTS

In the control group; a surgical line of 44.11-61.14 mm (mean 51.91 ± 4.32), an undesired line of 52.48-69.58 mm (mean 59.14 ± 5.08) and an angle of 18.22-27.270 (mean 22.66 ± 2.55) were found, while in the CLP group, a surgical line of 34.53-51.16 mm (mean 43.38 ± 4.79), an undesired line of 46.86-61.35 mm (mean 55.02 ± 3.24) and an angle of 17.60-28.810 (mean 22.60 ± 2.81) were found.

CONCLUSIONS

Although the angle to the sphenoid sinus was not significantly affected by CLP, careful planning and consideration of these anatomical differences are crucial to prevent complications and ensure the safety of Le Fort I surgery in CLP patients. Further research with larger sample sizes and subgroup analysis of unilateral and bilateral CLP cases is needed to improve our understanding of these anatomical variations and improve surgical approaches to individuals with CLP undergoing orthognathic procedures.

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.

Type IV optic nerve and Onodi cell: is there a risk of injury during sphenoid sinus surgery?

Objective

This study aims to determine the prevalence and types of Onodi cells through computed tomography and investigate the relationship between Onodi cell and the surrounding structures, paying particular attention to the risky proximity to the optic nerve canal.

Methods

In this study, 430 computed tomography scans of paranasal sinuses were analysed to establish the prevalence and different types of Onodi cells. Furthermore, the relationship between Onodi cell and different patterns of sphenoid sinus pneumatisation and surrounding structures were investigated. Special attention was paid to the relationship between Onodi cell and the optic nerve canal, particularly in cases when the optic nerve canal was bulging by more than 50% into the Onodi cell (Type IV).

Results

The Onodi cell was detected in 21.6% of cases, with the most common being Type I (48.5% right, 54.3% left). Type IV bulging of the optic nerve canal into the Onodi cell was observed in 47.1% of cases on the right side, 41.2% on the left side and bilateral in 11.7% of cases.

Conclusions

In our series, we observed a high prevalence of Type IV optic nerve bulging into the Onodi cell. For this reason, we suggest that clinicians should always try to identify it in a pre-operative setting with computed tomography to avoid catastrophic consequences during endoscopic sinus surgery approaching the sphenoid area.

Is there a relationship between sphenoid sinus pneumatization and carotid canal-intersinus septa connection?

OBJECTIVES

We investigated the relationship between sphenoid sinus (SS) pneumatization types, carotid canal types and carotid canal-intersinus septa connection.

METHODS

The paranasal sinus computed tomography (PNSCT) images of 274 patients (141 males and 133 females) were evaluated retrospectively. SS pneumatization, SS intersinus septation, SS intersinus septa deviation, carotid canal classification, carotid canal dehiscence, carotid canal-intersinus septa connection and presence of Onodi cells were evaluated.

RESULTS

In presellar and sellar SS, type 1 carotid canal was detected. However, type 3 carotid canal was detected more in postsellar SS. On the left side, in 26.4% of the postsellar SS, carotid canal dehiscence was detected. On the right side, carotid canal-intersinus septa connection was detected in 55.8% of the postsellar SS and 35.1% of the sellar SS. On the left side, it was detected 58.3% of the postsellar SS and 30.9% of the sellar SS. In postsellar type SS pneumatized cases, right caroid canal-intersinus septa connection increased by 5.4 fold and left carotid canal-intersinus septa connection increased by 7.3 fold compared to presellar type SS pneumatization. In 2≥ intersinus septa group, left carotid canal-intersinus septa connection increased 5.0 fold compared to 'no septa' group.

CONCLUSION

In this study, we evaluated SS pneumatization types and their relation with carotid canal types and carotid canal-intersinus septa connections. Type 3 carotid canal (protrudation to SS wall) was detected more in postsellar SS. In these cases, surgeons should be very careful during surgery to avoid damage to the internal carotid artery (ICA).

Tips and Tricks to Safely Perform an Endoscopic Endonasal Trans-Sphenoidal Pituitary Surgery: A Surgeon's Checklist

The authors aimed to develop an extensive preoperative checklist of CT scan findings during endoscopic access to the ventral skull base and implement it in clinical practice. A comprehensive literature review was conducted to identify the radiological landmarks crucial to endoscopic skull base surgery. Four electronic databases were searched: PubMed, MEDLINE, EMBASE, and Google Scholar using search terms/keywords such as "radiological landmarks," "endoscopic skull base surgery," "CT scan," "pituitary surgery," "anatomical variations," "internal carotid," "optic nerve," "sphenoid sinus," "pneumatization," "dehiscence," and "protrusion". Inclusion criteria were limited to original articles and systematic reviews published in English, between the years 2000 and 2021, which pertained to the radiological landmarks to be identified during endoscopic skull base surgery. Full-text articles were retrieved and collated into a narrative review focused on a 12-item checklist the authors agreed upon. The mnemonic "O ROAD TO SELLA" was used to represent the checklist and include the following landmarks: Sphenoid Ostium, Sphenoid Rostrum, Onodi cells, Anatomic variations of the sphenoid sinus, Distance between the carotids, Tumor characteristics, Optic nerve dehiscence/protrusion, Septation/insertion of the sphenoid sinus, Entrance to the sellar floor, Lateral recess of the sphenoid sinus, cLinoid process pneumatization, and internal carotid Artery dehiscence/protrusion. The checklist is designed to be used by attending physicians, fellows, and residents and the authors intend to implement it into electronic medical records at the institution's medical center to monitor the outcomes of EEPS after implementation.

Sphenoid Sinus Pneumatization Types and Correlation with Adjacent Neurovascular Structures Using Cone-Beam Computed Tomography

Aims: This study aimed to assess the sphenoid sinus pneumatization types and their correlation with adjacent neurovascular structures using cone-beam computed tomography (CBCT). Materials and methods: This cross-sectional study was conducted on 97 CBCT scans of patients over 18 years of age that were retrieved from the archives of the Oral & Maxillofacial Radiology Department of School of Dentistry. Type of sphenoid sinus pneumatization based on its relationship with sella turcica (conchal, presellar, sellar, and postsellar), the correlation of internal carotid artery (ICA) and optic nerve (ON) with the sinus cavity in the axial and coronal planes (smooth or prolonged type), and presence of Onodi cells and their correlation with the sphenoid sinus (lateral, superior, and superolateral) were all evaluated on CBCT sections. Data were analyzed by the Chi-square and Fisher's exact tests (alpha = 0.05). Results: Postsellar type was the most common sphenoid sinus pneumatization type (82.5%). The Smooth type was the most common form of correlation of ON and ICA with the sphenoid sinus. Onodi cells were noted in 28.9% of the cases; among which, the lateral type had the highest prevalence. Conclusion: Considering the high prevalence of sphenoid sinus pneumatization, Onodi cells, and ON and ICA protrusion in our study population, CBCT should be requested prior to trans-sphenoidal surgical procedures to prevent perioperative and postoperative complications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-03796-0.

Positioning Transclival Tumor-Treating Fields for the Treatment of Diffuse Intrinsic Pontine Gliomas

Diffuse intrinsic pontine glioma (DIPG) carries an extremely poor prognosis, with 2-year survival rates of <10% despite the maximal radiation therapy. DIPG cells have previously been shown to be sensitive to low-intensity electric fields in vitro. Accordingly, we sought to determine if the endoscopic endonasal (EE) implantation of an electrode array in the clivus would be feasible for the application of tumor-treating fields (TTF) in DIPG. Anatomic constraints are the main limitation in pediatric EE approaches. In our Boston Children’s Hospital’s DIPG cohort, we measured the average intercarotid distance (1.68 ± 0.36 cm), clival width (1.62 ± 0.19 cm), and clival length from the base of the sella (1.43 ± 0.69 cm). Using a linear regression model, we found that only clival length and sphenoid pneumatization were significantly associated with age (R2 = 0.568, p = 0.005 *; R2 = 0.605, p = 0.0002 *). Critically, neither of these parameters represent limitations to the implantation of a device within the dimensions of those currently available. Our findings confirm that the anatomy present within this age group is amenable to the placement of a 2 × 1 cm electrode array in 94% of patients examined. Our work serves to demonstrate the feasibility of implantable transclival devices for the provision of TTFs as a novel adjunctive therapy for DIPG.

A comparative study of paranasal sinus and nasal cavity anatomic variations between the Polish and Turkish Cypriot Population with CBCT

Background

Genetic and environmental factors especially climatic conditions are thought to influence the shape and size of the paranasal sinuses and anatomic variations may create both a diagnostic and therapeutic challenge. However, no study has been published about the climatic adaptation of the paranasal sinus region in different populations. This study aimed to compare the prevalence of anatomical variants in the paranasal sinus and nasal cavity using Cone-Beam Computed Tomography (CBCT) between Polish and Turkish Cypriot populations.

Methods

The material consisted of volumes acquired utilizing Galileos (Sirona, Germany) as well as Newtom 3G (QR Verona, Newtom, Italy) CBCT units. There were examined 356 Polish and 359 Turkish Cypriot patients in whom paranasal sinuses were included in the field of view. Paranasal sinus anatomic variations were assessed in both populations.

Results

In the Polish population, the most common anatomic variation was septum deviation followed by the Agger nasi cell and concha bullosa with a prevalence of 87.7%, 83.2%, and 54.8% respectively. For the Turkish Cypriot population, the most common anatomic variation was Agger nasi cell followed by concha bullosa and supraorbital ethmoid cells with a prevalence of 81.6%, 68%, and 57.8% respectively. Many anatomic variations were found to show substantial differences among both populations. Incidence rates of hyperpneumatization of the frontal sinus, septum pneumatization, supraorbital ethmoid cells, concha bullosa, uncinate bulla, and internal carotid artery protrusion into the sphenoid sinus were significantly higher in the Turkish Cypriot group, while the incidence of Haller cell, frontal sinus hypoplasia, maxillary sinus hypoplasia, ethmomaxillary sinus, sphenomaxillary plate, and septum deviation were significantly higher in Polish population.

Conclusion

According to the Köppen-Geiger world climatic map, the climate is warmer and drier in Turkish Cypriote populations than in the Polish population. These climatic differences influence the paranasal sinus variations between the Turkish Cypriot and Polish populations that must be taken into account by rhinologic surgeons especially when performing frontal and sphenoid sinus surgery.

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.

Forensic Identification from Three-Dimensional Sphenoid Sinus Images Using the Iterative Closest Point Algorithm

Forensic identification of human remains is crucial for legal, humanitarian, and civil reasons. Wide heterogeneity in sphenoid sinus morphology can be used for personal identification. This study aimed to propose a new protocol for personal identification based on three-dimensional (3D) reconstruction of sphenoid sinus CT images using Iterative Closest Point (ICP) algorithm. Seven hundred thirty-two patients which consisted of 348 females and 384 males were retrospectively included. The study sample includes 732 previous images as a source point set and 743 later ones as a scene target set. The sphenoid sinus computed tomography (CT) images were processed on a workstation (Dolphin imaging) to obtain 3D images and stored as a file format of Stereo lithography (.STL). Then, a Python library vtkplotter was used to transform the STL format to PLY format, which was adapted to Point Cloud Library (PCL). The ICP algorithm was used for point clouds matching. The metric Rank-N recognition rate was used for evaluation. The scene target set of 743 individuals was compared with the source point set of 732 individual models and achieved Rank-1 accuracy of 96.24%, Rank-2 accuracy of 99.73%, and Rank-3 accuracy of 100%. Our results indicated that the 3D point cloud registration of sphenoid sinuses was useful for assessing personal identification in forensic contexts.

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.

Sphenoid sinus pneumatization: the good, the bad, and the beautiful

PURPOSE

To study different types of extension of sphenoid sinus pneumatization detected by CT and examine their correlation with other anatomical variants.

METHODS

Sphenoid sinus pneumatization was characterized (780 hemi-sinuses) on CT scans. Its incidence and correlations with related anatomical variants were evaluated. Dimensions of surgical window were measured in the lateral type, where pneumatization extends beyond a line connecting Vidian (pteregoid) canal (VC) and foramen rotundum (FR).

RESULTS

The lateral recess of the sphenoid sinus was pneumatized in 27.3% of patients with a mean width of 7.59 mm. The distance separating the FR and the VC correlated strongly with the depth of the lateral recess. There was significant positive correlation between pneumatization of lateral recess and Vidian nerve prominence to other pneumatization patterns (lesser sphenoid, frontal, and Maxillary sinuses) (p < 0.0001). Lateral recess pneumatization in coronal cuts was also significantly correlated with anterior-posterior sphenoid pneumatization in sagittal cuts (p < 0.0001).

CONCLUSION

Pre-operative assessment of sphenoid sinus pneumatization is essential in the endoscopic approach to skull base structures to facilitate surgical access and avoid injury of the nearby structures. Our study showed significant correlation among anatomical variants and different measurements which allows the surgeon to predict abnormal anatomy with high accuracy.

Anatomic Variation for the Endoscopic Endonasal Transsphenoidal Approach

Knowledge of anatomy and its variations is the key to safe and efficient surgery. The endoscopic endonasal route to the sella has evolved to become the preferred route to access a wide variety of diseases. We describe the skeletal, vascular, and neural anatomic variations that could be encountered from the nasal phase, through the sphenoid phase, to the sellar phase of the operative exposure. A preoperative checklist is also provided.

Anatomical Variants, Pneumatization Classification, and Volumetric Studies of the Sphenoid Sinus With High-Resolution Computed Tomography

OBJECTIVES

Aimed to explore the correlation between the volume of the sphenoid sinuses (SS) and sex, age, pneumatization and its anatomical variant types.

MATERIAL AND METHODS

Retrospectively evaluated high-resolution computed tomography images of 170 individuals; were studied by ITK-SNAP software to measure the volume of SS.

RESULTS

The average volume of SS was a significant difference between the gender, the volume of SS in the elderly group (≥65 years old) showed a downward trend. The volume of the SS in the variants of the anterior clinoid processes, pterygoid processes, greater wings, and clivus were significantly higher than in the nonvariants (P < 0.05). With the expansion of pneumatization, the optic nerve (CNII) type 3-4, the internal carotid artery (ICA) type 2-3 and the septal insertion on the ICA have a larger volume, while the occurrence of septal insertion on only the CNII was not correlated with the volume (P > 0.05).

CONCLUSIONS AND SIGNIFICANCE

The volume of SS is closely related to age, sex, the type of pneumatization and anatomical variation. High-resolution computed tomography can facilitate a precise study of anatomical variations and adjacent structures and help ensure the safety of an operation.

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.

The pneumatization of the sphenoid sinus, its variations and relations with surrounding neurovascular anatomic structures: A computerized tomography study

INTRODUCTION AND OBJECTIVES

The wide range of variability of SS pneumatization and relation with surrounding structures can result in serious complications; seeing that, the assessment of regional anatomy is essential for both surgeons and radiologists. We mainly aim to reveal the possible correlation between the SS pneumatization types and protrusion/dehiscence of the adjacent neurovascular structures in a larger population by using computerized tomography (CT) images.

METHODS

The type of SS pneumatization (I-IV), pneumatization of anterior clinoid process (ACP), greater wing of sphenoid (GWS), and pterygoid process (PP) was evaluated. Protrusion and dehiscence of ICA, ON, MN, and VN was noted.

RESULTS

1003 patients were included into the study. ICA, ON, and MN protrusions were not seen in patients with the type I or II SS on both sides. These protrusions were most frequently seen along with the type IV SS on both sides (p < 0.05). ICA, ON, MN, and VN dehiscence was not found in any patients with the type I SS. The rate of ICA protrusion increased with presence of GWS and PP; ICA dehiscence was found to be positively correlated with ACP, GWS, and PP pneumatization.

CONCLUSIONS

Variations, either amount or the extent, of the pneumatization of the SS are related with the presence of protrusion/dehiscence of ICA, ON, MN and VN. Knowing and reporting these relations can decrease the rate of complications during skull base surgery.

Cone Beam Computed Tomography Analysis of Sphenoid Sinus Pneumatization and Relationship with Neurovascular Structures

Background

The sphenoid sinus is considered as the most variable pneumatized structure of the skull.

Purpose

The aim of the present study was to determine the prevalence of the Onodi cell as well as to evaluate the relationship between the sphenoid sinus type of pneumatization and the presence of surrounding neurovascular protrusion using cone beam computed tomography (CBCT).

Methods

The CBCT images of 500 patients/996 sides [203 males (40.6%) and 297 females (59.4%)] were analyzed in this study. The type of sphenoid sinus pneumatization, prevalence of internal carotid artery (ICA) and optic nerve (ON) protrusion and dehiscence, and also the frequency of Onodi cell were assessed.

Results

The percentages of the conchal, presellar, sellar, postsellar (a), and postsellar (b) types of pneumatization were 1%, 11.5%, 35.5%, 38.9%, and 13.1%, respectively. The more the sphenoid sinuses pneumatized, the greater the frequency of ON and ICA protrusion and dehiscence of their wall to the sinus. The prevalence of Onodi cell was 38.8%. A significant correlation was found between ON dehiscence and the presence of Onodi cells.

Conclusion

The present study demonstrated a significant relationship between the sinus type and frequency of neurovascular protrusions. Therefore, the sphenoid sinus extent of pneumatization might be useful in predicting the risk of iatrogenic damage to the surrounding structures.

Anatomical and Volumetric Analysis of the Sphenoid Sinus by Semiautomatic Segmentation of Cone Beam Computed Tomography

This investigation was performed to analyze and evaluate anatomical and volumetric data of the sphenoid sinus by semiautomatic segmentation of cone beam computed tomography (CBCT) datasets.This analysis was carried out on cone beam computed tomography images of 100 patients. By using the discretionary software "ITK-Snap", the volumetric investigation of 197 sphenoid sinuses was conducted. The statistical analyses were carried out by using the paired and independent Student t-test. In addition, the Pearsons chi-square test was performed. P values P < 0.05 were considered significant.The volumetric mean was 4.438 ± 2.434 cm for the right and 4.809 ± 3.000 for the left side. Results did not indicate statistically significant differences according to the side, irrespective of gender (P > 0.05). The further investigation of differences between male and female patients did assess significant results (P < 0.05), males (10.477 ± 3.851 cm) present a larger total sinus volume than females (8.219 ± 3.574 cm). In accordance to patients' age (median 54 years), smaller volumes were related to younger patients and larger volumes to older ones. But, no statistically significant results in accordance to age could be detected (χ = 1.258; P > 0.05).Endoscopic sinus surgery of the vulnerable and intricate anatomy of the sphenoid sinus requires an explicit knowledge and orientation about the anatomical variations such as septums and volumetric capacity. Concerning this matter, semiautomatic segmentation of CBCT images can aid the surgeon in preoperative planning. Our investigation shows that a small sinus volume, that is, affecting female patients and a complex sinus anatomy by the occurrence of a septum, especially located close to neurovascular structures could essentially aggravate endoscopic sphenoid sinus surgery. In this regard, volumetric analysis of the sphenoid sinus by CBCT images can provide presurgical information and facilitates an individualized treatment.

A new classification proposal for sphenoid sinus pneumatization: a retrospective radio-anatomic study

OBJECTIVES

The sphenoid sinus variations are very diverse and the frequency of these sinus variations is high. During operations involving the sphenoid sinus, such as pituitary surgeries, the surgeon should have detailed information about these variations. The aim of this study is to reclassify the sphenoid sinus pneumatizations in detail and to evaluate the incidence of pneumatization types in a Turkish population according to this classification.

METHODS

New classification proposal was made. In accordance with the proposed new classification, sphenoid sinus pneumatizations were evaluated on CBCT images.

RESULTS

When the posteroanterior pneumatization of 128 patients was evaluated; 2.3% conchal, 3.9% presellar, 35.9% sellar, and 57.8% postsellar pneumatization was detected. Of these cases, 28.9% had anterior pneumatization on the right and 23.4% on the left. When lateral direction pneumatizations were evaluated, lateral body type was found to be the most common on both right (44.1%) and left (42.5%) sides.

CONCLUSION

In this study, sphenoid sinus pneumatizations were evaluated three-dimensionally with the help of CBCT, and a new classification suggestion was made to eliminate the classification confusion we encountered in our previous studies. Pneumatizations and variations can affect the field of operation and even change planning. It should be taken into account that the paranasal sinuses may have variations due to their surgical importance and their close association with many vital structures.

Preoperative Computed Tomography Imaging of the Sphenoid Sinus: Striving Towards Safe Transsphenoidal Surgery

Introduction  Preoperative high-resolution computed tomography (HRCT) is essential in patients undergoing transsphenoidal surgery to identify potential high-risk anatomic variations. There is no consensus in the literature, as to which grading system to use to describe these variants, leading to inconsistent terminology between studies. In addition, substantial variability exists in the reported incidence of anatomic variants. In this study, we performed an institutional imaging analysis and literature review with the objective of consolidating and clearly defining these sphenoid sinus anatomical variations. In addition, we highlighted their surgical implications and propose a checklist for a systematic assessment of the sphenoid sinus on preoperative CT. Methods  Review of the literature and retrospective analysis assessing several imaging parameters in 81 patients who underwent preoperative HRCT imaging for endoscopic transsphenoidal tumor resection from January 2008 through July 2015 at Rush University Medical Center. Results  The most common sphenoid pneumatization patterns were sellar (45%) and postsellar (49%) types. Anterior clinoid process (ACP) pneumatization was seen in 17% of patients with high concordance of ipsilateral optic nerve (ON) protrusion. ON protrusion and dehiscence was present in 17 and 6% of patients, respectively. Internal carotid artery (ICA) protrusion and dehiscence was present in 30 and 5% of patients, respectively. Dehiscence rates from local bone invasion overlying the ICA and ON occurred in 17 and 4% of cases, respectively. Conclusions  Our study highlights and reviews the key variants that have potential to impact surgical complications and outcomes in a heterogeneous patient population. The proposed preoperative CT checklist for patients, undergoing transsphenoidal surgery, consistently identifies these higher risk anatomical variants.

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.

Automatic forensic identification using 3D sphenoid sinus segmentation and deep characterization

Recent clinical research studies in forensic identification have highlighted the interest in sphenoid sinus anatomical characterization. Their pneumatization, well known as extremely variable in degrees and directions, could contribute to the radiologic identification, especially if dental records, fingerPrints, or DNA samples are not available. In this paper, we present a new approach for automatic person identification based on sphenoid sinus features extracted from computed tomography (CT) images of the skull. First, we present a new approach for fully automatic 3D reconstruction of the sphenoid hemisinuses which combines the fuzzy c-means method and mathematical morphology operations to detect and segment the object of interest. Second, deep shape features are extracted from both hemisinuses using a dilated residual version of a stacked convolutional auto-encoder. The obtained binary segmentation masks are thus hierarchically mapped into a compact and low-dimensional space preserving their semantic similarity. We finally employ the ℓ₂ distance to recognize the sphenoid sinus and therefore identify the person. This novel sphenoid sinus recognition method obtained 100% of identification accuracy when applied on a dataset composed of 85 CT scans stemming from 72 individuals. Automatic Forensic Identification using 3D Sphenoid Sinus Segmentation and Deep Characterization from Dilated Residual Auto-Encoders.

Anatomic Sphenoid Cell Variants: Introduction of the Retrosphenoid Cell and Relevance in the Presentation and Management of Sinus Disease

Background

Despite the well-appreciated variability in sphenoid sinus anatomy, there are no documented cases of retrosphenoid cells in the literature to date.

Objective

This study defines and determines the prevalence of retrosphenoid cells as identified on computed tomography (CT) imaging and intraoperative endoscopy and reviews the prevalence of other related anatomical variants of the sphenoid sinus.

Methods

Retrospective study of 300 random noncontrast sinus CT scans of patients with chronic rhinosinusitis presenting to a tertiary rhinology center. All identifiable anatomic variations and any presence of retrosphenoid cells and their pneumatization patterns were recorded. The prevalence of various anatomic variations of the sphenoid sinus was also calculated.

Results

A total of 300 sinus CT scans were included in the study. Protrusion of both the internal carotid artery (42.6%) and optic nerve (19.7%) into the sinus was more prevalent than the dehiscence of either one. A retrosphenoid cell was identified in 2% of CT scans. Other anatomic variants were less prevalent.

Conclusion

Meticulous review of preoperative imaging is key in identifying rare and complex sphenoid cell variations in planning surgical approaches and potential treatment strategies for the unusually pneumatized sphenoid air cells. Various manifestations of sinus disease can be localized to this area, and suspicion of a retrosphenoid cell should be raised in patients presenting with recalcitrant headache.

Effect of Sphenoid Sinus Pneumatization on the Surgical Windows for Extended Endoscopic Endonasal Transsphenoidal Surgery

BACKGROUND

Little is known on the impact of the pattern and extent of pneumatization of the sphenoid sinus (SS) on the dimensions of the surgical windows used in extended endoscopic endonasal transsphenoidal approaches. We therefore investigated whether the distances between the 2 optic canals and between the paired paraclival carotid arteries are influenced by the pattern and extent of pneumatization of the SS.

METHODS

One hundred high-resolution computed tomography scans from 47 adult female and 53 adult male patients were analyzed. The pattern of SS pneumatization was classified into conchal, presellar, and sellar types. Sellar-type sinuses were then classified according to a newer detailed classification system. Maximal anteroposterior (AP), transverse (TR), and craniocaudal diameters of the SS, interoptic distance at the limbus sphenoidale (IODL) and at the entrance of the optic canal (IODE) and the intercarotid distance between the paraclival carotids (ICD) were measured. A 2-tailed Mann-Whitney U test and Pearson correlation coefficient (R) were used for statistical analysis. A P value <0.05 was considered statistically significant.

RESULTS

Positive correlation was found between IODL and both AP and TR diameters of the SS; between IODE and both AP and TR diameters of the SS; and between ICD and all diameters of the SS. The highest correlation for each of the IODL, IODE, and ICD was noted with the TR diameter of the SS.

CONCLUSIONS

During the development of the SS, pneumatization progress likely exerts quantitative and direction-specific forces, which gradually increase the interoptic and intercarotid distances.

Three-dimensional analysis of sphenoid sinus uniqueness for assessing personal identification: a novel method based on 3D-3D superimposition

Sphenoid sinuses are considered the most variable structures of human body: therefore, they may be used for personal identification, through the application of 3D segmentation procedures. This study aims at proposing a new protocol for personal identification based on 3D-3D superimposition of sphenoid sinuses segmented from head CT scans. Adult subjects (equally divided among males and females) who underwent two head CT scans were extracted from a hospital database. Sphenoid sinuses were segmented through ITK-SNAP software and the corresponding 3D models were automatically superimposed to obtain 40 matches (when they belonged to the same person) and 260 mismatches (when they were extracted from different individuals). The RMS (root mean square) point-to-point distance was then calculated for all the superimpositions: differences according to sex and group (matches and mismatches) were assessed through the Mann-Whitney test (p < 0.05). On average, the RMS value was almost ten times smaller in matches (0.22 ± 0.11 mm) than in mismatches (2.16 ± 0.57 mm) with a statistically significant difference according to group (p < 0.05), but not to sex (p > 0.05). The study proposed a new method for assessing personal identification from segmented 3D models of sphenoid sinuses, useful in the forensic contexts where other methods might not be implementable or successful.

Classification and volumetric study of the sphenoid sinus on MDCT images

PURPOSE

We aimed to determine the position and size of the sphenoid sinus (SS) in our study and compare the results of the measurements relative to age, gender, and the presence of pituitary adenoma using multidetector computerized tomography (MDCT).

METHODS

We retrospectively evaluated the paranasal sinus computerized tomography (CT) images of 200 individuals (age range of all the individuals 4-84 years; 101 females, 99 males; age range of individuals with pituitary adenoma 15-63 years; 15 females, 9 males) with 24 pituitary adenomas. The shape of SS were identified and classified, volume were measured by MDCT also for individuals with pituitary adenoma.

RESULTS

It was determined that the volume averages were significantly affected by the type of SS. Among all the individuals studied, the sellar type of SS was most frequently observed (41.5%), followed by the postsellar type (38.5%), and the least observed was the presellar type (9%). The volume of the SS is bigger in males than females although the volume is not affected by the presence of pituitary adenomas. The development of the SS continues until the age of nine.

CONCLUSION

The morphology and morphometry of the SS show individual differences. These anatomic variations are important for decision making and application for surgical interventions (especially transsphenoidal surgery).

Surgery for Pediatric Pituitary Adenomas

Pituitary adenomas are a rare but important central nervous system tumor in children. Because of differences in growth and development, the manifestations of pituitary adenomas in children may differ from those seen in adults. Unlike adult patients, the pediatric population more often presents with clinically secretory adenomas. Although medical management is first-line treatment of prolactinomas, transsphenoidal surgery is appropriate for most children with Cushing disease and gigantism. Although some pediatric patients present surgical challenges because of small anatomic dimensions or an incompletely developed sphenoid sinus, transsphenoidal surgery can be safely and effectively undertaken in most children, with low complication rates.

Evaluation of volume of the sphenoid sinus according to sex, facial type, skeletal class, and presence of a septum: a cone-beam computed tomographic study

We have used cone-beam computed tomographic (CT) images to retrospectivelyevaluate the influence of sex, skeletal class, facial type, and the presence of septa on the volume of the sphenoid sinus in 172 images from 85 men (mean (SD) age 28 (2) years) and 87 women (mean (SD) age 30 (1) years). Skeletal class and facial type were calculated for each patient from multiplanar reconstructions using NemoCeph® software. Volumetric analysis of the sphenoid sinus was made with the help of the ITK-SNAP® 3.4.0 segmentation software, while the presence or absence of septa in the sphenoid sinus was evaluated with the Carestream 3D Imaging® software 3.4.3. We analysed the results using two-way ANOVA, Student's independent sample t test, and Fisher's exact test, as appropriate, and probabilities of <0.05 were accepted as significant. Sex (p=0.0946), facial type (p=0.790), and skeletal class (p=0.120) had no significant influence on the volume of the sphenoid sinus, and nor did the volumes of the right and left sphenoid sinuses (p=0.0923), or the presence of a septum within the sinus (p=0.330) in its volume.

Relationship between sphenoid sinus volume and protrusion of internal carotid artery and optic nerve: a 3D segmentation study on maxillofacial CT-scans

PURPOSE

Anatomy of sphenoid sinuses has acquired a growing importance with the diffusion of transsphenoidal surgical procedures. A common risk in these practices is the damage of internal carotid artery (ICA) and optic nerve (ON), which may protrude into the sphenoid air cavities. This study aims at analysing the relationships between sphenoid sinuses volume and protrusion of ICA and ON.

METHODS

260 head CT-scans were retrospectively analysed (equally divided among males and females, age range 20-92 years). Volume was segmented through ITK-SNAP software. In addition, the subjects were classified into four groups: no protrusion of any structure (group 1), protrusion of ICA (group 2), protrusion of ON (group 3), protrusion of both ICA and ON (group 4). Possible statistically significant differences in prevalence of the four groups according to gender were assessed through Chi-squared test (p < 0.05). Differences in volume between the four groups were assessed through one-way ANOVA test (p < 0.05), separately for males and females.

RESULTS

Group 1 was the most frequent (40.0%), followed by group 4 (27.7%) and group 2 (18.5%), without any difference according to gender. For what concerns volume, cases of ICA and concomitant ICA + ON protrusion had significantly larger sinuses, whereas isolated ON protrusion did not modify sinus volume.

CONCLUSIONS

Results show that protrusion of ICA is positively related with the volume of sphenoid sinuses, whereas the same relation was not verified for ON: surgeons should accurately consider possible ON protrusion in each case, as it may occur independently from sphenoid sinuses volume.

Post-mortem X-ray computed tomography (PMCT) identification using ante-mortem CT-scan of the sphenoid sinus

PURPOSE

To evaluate forensic identification of individuals through visual comparison of sphenoid sinus anatomical configuration using ante- and post-mortem CT-scans.

METHOD AND MATERIALS

Ante- and post-mortem head CT-scan of 33 individuals were retrospectively collected. Ten head CT-scans were randomly selected from various neurological contexts and added to the ante-mortem group. Ten other head CT-scans were randomly selected from our post-mortem PACS and added to the post-mortem group. These CT-scans were assigned into 2 groups for analysis: an ante-mortem group (33 + 10) and a post-mortem group (33 + 10). For ethics and to avoid identification bias, CT-scans were anonymized - not showing any head structure but only sphenoid sinuses. An anatomical based classification system using the sphenoid sinuses anatomical variations was created according to anatomical and surgical literature. This classification was used by readers to identify in two different steps a maximum of matched and then unmatched scans.

RESULTS

The first reader had a sensitivity of 100% [CI: 89.4%-100%] and a specificity of 100% [CI: 99.8%-100%]. Sensitivity and specificity were respectively 93.9% [CI: 79.8%-99.3%] and 99.9% [CI: 99.6%-100%] for the second reader. Positive and negative predictive values were respectively 100% [CI: 89.4%-100%] and 100% [CI: 99.8%-100%] for the first reader. Positive and negative values were respectively 96.9% [CI: 83.8%-99.9%] and 99.9% [CI: 99.7%-100%] for the second reader. Inter-reader variability was estimated by Cohen's kappa and an excellent agreement was found.

CONCLUSION

We reported an excellent validity and reliability of subjective visual comparison of ante- and post-mortem CT-data using an anatomical based classification of the sphenoid sinus.

Pneumatization of the sphenoid sinus, dorsum sellae and posterior clinoid processes in computed tomography

Purpose

Assessment of sphenoid sinus (SS), posterior clinoid process (PCP), and dorsum sellae (DS) pneumatisation is significant when planning surgical approaches both to intra- and extrasellar pathologies. The authors analysed pneumatisation of the SS, with particular attention paid to pneumatisation of the PCP and DS.

Material and methods

The study was based on 100 computed tomography angiography examinations. SS, PCP, and DS pneumatisation grades were assessed using the classification system proposed by Hardy. The analyses were conducted in sagittal planes: midline plane (MP), sagittal posterior clinoid plane right (SPCP-R), and sagittal posterior clinoid plane left (SPCP-L). The occurrence of the highest pneumatisation grade (IVB according to Hardy), which encompasses DS and PCP, prompted the authors to conduct a further analysis in the coronal plane. In this way, seven DS and PCP pneumatisation symmetry types were identified.

Results

In the MP and SPCP-R, the most frequent pneumatisation grade was grade III (41% and 38%, respectively). In the SPCP-L, grade IVA prevailed (41%). Grade IVB was found in 12% of the SPCP-R images, 10% of the SPCP-L images, and in 12% of the MP images. Consistent pneumatisation grades in all analysed planes were found for 64% of cases. This was usually grade III noted in 28% of cases.

Conclusions

SS pneumatisation is characterised by considerable individual variability. There are a number of SS pneumatisation classification systems, but the system proposed by Hardy is the most useful for assessment of DS and PCP pneumatisation. Grade III of SS pneumatisation is the most common. Pneumatisation encompassing DS and PCP was found in 10-12% of cases.

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.

Transoral robotic surgery for sellar tumors: first clinical study

OBJECTIVE

The aim of this study was to confirm the feasibility of an innovative transoral robotic surgery (TORS), using the da Vinci Surgical System, for patients with sellar tumors. This technique was designed to offer a new minimally invasive approach, without soft-palate splitting, that avoids the rhinological side effects of classic endonasal approaches.

METHODS

The authors performed a prospective study of TORS in patients with symptomatic sellar tumors. Specific anatomical features were required for inclusion in the study and were determined on the basis of preoperative open-mouth CT scans of the brain. The main outcome measure was sellar accessibility using the robot. Resection quality, mean operative time, postoperative changes in patients' vision, side effects, and complications were additionally reported.

RESULTS

Between February and May 2016, 4 patients (all female, mean age 49.5 years) underwent TORS for resection of sellar tumors as participants in this study. All patients presented with symptomatic visual deficits confirmed as bitemporal hemianopsia. All tumors had a suprasellar portion and a cystic part. In all 4 cases, the operation was performed via TORS, without the need for a second surgery. Sella turcica accessibility was satisfactory in all cases. In 3 cases, tumor resection was complete. The mean operative time was 2 hours 43 minutes. Three patients had a significant visual improvement at Day 1. No rhinological side effects or complications in patients occurred. No pathological examination was performed regarding the fluid component of the tumors. There was 1 postoperative delayed CSF leak and 1 case of transient diabetes insipidus. Side effects specific to TORS included minor sore throat, transient hypernasal speech, and 1 case of delayed otitis media. The mean length of hospital stay and mean follow up were 8.25 days and 82 days, respectively.

CONCLUSIONS

To our knowledge, this is the first report of the surgical treatment of sellar tumors by means of a minimally invasive TORS. This approach using the da Vinci Surgical System seems feasible and constitutes an innovative neurosurgical technique that may avoid the adverse side effects and technical disadvantages of the classic transsphenoidal route. Moreover, TORS allows an inferosuperior approach to the sella turcica, which is a key point, as the tumor is approached in the direction of its growth.

Assessment of sphenoid sinus related anatomic variations with computed tomography

Introduction

Frequent and broad application of endoscopic sinus surgery (ESS) in parallel with experience makes it imperative to know the anatomy and the existing pathology very well before surgery. This study examines the association between anomalies in the sphenoid sinus area in paranasal sinuses computed tomography (PNS-CT) and pathological findings and determines variations of sphenoid sinus.

Methods

A total of 200 cases (100 women, 100 men) who had PNS-CT in the emergency and radiology polyclinics within the period of one year were included in this study. Bone tissue anomalies and soft tissue pathologies were assessed in the CT.

Results

Pterygoid process was found in 36.75% of our cases, anterior clinoid pneumatization was found in 21.25%; vidian canal in 34.25%, foramen rotundum in 17.5% and ICA in 12.75% had protrusion into the sphenoid sinus; 8.25% were found to have onodi cell, 11.25% were found to have multiple septation, 16.75% were found to have mucosal thickening and 2.5% were found to have retention cyst.

Conclusion

The importance of PNS-CT in terms of determining anatomic variations before ESC and predicting possible complications during surgery has been emphasized once more. In our study, as sphenoid sinus pneumatization increased, the projection of neighbouring vein and nerve structures into the sinus was found to increase as well.

Enhancing Mass Lesion of the Sphenoid: Atypical Presentation of Ongoing Pneumatization

Sinus pneumatization is a complex variable process that begins in early life and continues for many years. We present a case of a 6-year-old boy with progressive headaches and neurologic symptoms suggestive of intracranial pathology. The presence of enhancing tissue within the sphenoid sinus created a diagnostic dilemma which leads to a transsphenoidal biopsy. Knowledge of imaging characteristics associated with incomplete pneumatization can help differentiate it from more ominous skull base pathology and prevent unnecessary testing. We describe four-year imaging follow-up in a patient with incomplete pneumatization of the sphenoid sinus presenting as an enhancing mass lesion with subsequent follow-up imaging demonstrating gradual regression and increased aeration of the sphenoid sinus.

Intrasphenoid septations inserted into the internal carotid arteries: a frequent and risky relationship in transsphenoidal surgeries

Introduction

When an expanded endonasal transsphenoidal surgical approach is performed, intrasphenoid septations must be completely resected. If these structures are close to the internal carotid artery (ICA), then their manipulation might cause vascular injury.

Objective

The objective of this study is to describe the frequency of intrasphenoid septations in the internal carotid artery protuberance (ICAp).

Methods

Computed tomography (CT) scans of 421 patients were analysed. Intrasphenoid septations (classified as intersphenoid or accessory) and their relationship to the ICAp were described. Additionally, a sphenoid sinus classification was performed based on their degree of pneumatisation to determine whether a difference exists in the frequency of intrasphenoid septations inserted into ICAp with regard to sinus type.

Results

The patient mean age was 39 ± 21.4 years. Overall, 219 patients (52%) had septations in the ICAp; 359 patients (85.3%) had intersphenoid septations; of the latter, 135 (37.6%) had septations in the ICAp. This frequency was higher among patients with sphenoid sinus type 4 or 5 (44.7% and 43.5%, respectively). Accessory septations were found in 255 patients (60.6%); 140 of these septations (54.9%) were in the ICAp. Among 351 patients with types 3, 4 or 5 sphenoid sinuses (i.e., only well-pneumatised sphenoid sinuses), 219 (62.4%) had septations in the ICAp. These frequencies are higher than those reported in most previous studies.

Conclusion

The frequency of intrasphenoid septations in the ICAp found is considerable. It is higher among patients with more pneumatised sinuses. This finding justifies an appropriate pre-operative study, and careful attention must be paid during transsphenoidal surgery.

Contribution of the computed tomography of the anatomical aspects of the sphenoid sinuses to forensic identification

INTRODUCTION

Body identification is the cornerstone of forensic investigation. It can be performed using radiographic techniques, if antemortem images are available. This study was designed to assess the value of visual comparison of the computed tomography (CT) anatomical aspects of the sphenoid sinuses, in forensic individual identification, especially if antemortem dental records, fingerprints or DNA samples are not available.

MATERIAL AND METHODS

This retrospective work took place in a French university hospital. The supervisor of this study randomly selected from the picture archiving and communication system (PACS), 58 patients who underwent one (16 patients) or two (42 patients) head CT in various neurological contexts. To avoid bias, those studies were prepared (anonymized, and all the head structures but the sphenoid sinuses were excluded), and used to constitute two working lists of 50 (42+8) CT studies of the sphenoid sinuses. An anatomical classification system of the sphenoid sinuses anatomical variations was created based on the anatomical and surgical literature. In these two working lists, three blinded readers had to identify, using the anatomical system and subjective visual comparison, 42 pairs of matched studies, and 16 unmatched studies. Readers were blinded from the exact numbers of matching studies.

RESULTS

Each reader correctly identified the 42 pairs of CT with a concordance of 100% [97.5% confidence interval: 91-100%], and the 16 unmatched CT with a concordance of 100% [97.5% confidence interval: 79-100%]. Overall accuracy was 100%.

CONCLUSION

Our study shows that establishing the anatomical concordance of the sphenoid sinuses by visual comparison could be used in personal identification. This easy method, based on a frequently and increasingly prescribed exam, still needs to be assessed on a postmortem cohort.

Anterior clinoid process and the surrounding structures

BACKGROUND

The anterior clinoid process (ACP) is located close to the optic nerve, internal carotid artery, ophthalmic artery, and can be easily injured in an ACP-related surgery. An anatomical study clearly defining the ACP is of great importance. In addition, computed tomographic (CT) images may be a new tool for the anatomical analysis of ACP compared with the use of a cadaver and skull study, and more data related to ACP can be measured by CT images.

PURPOSE

We studied the anatomical structure of ACP and the structures surrounding it to provide information to surgeons for ACP-related surgery.

METHODS

Computed tomography angiographic images of 102 individuals were reviewed. The measurement was performed on coronal, sagittal, and axis planes after multiplanar reformation. The length of ACP and the distance between apex of ACP and sagittal midline were measured in the axial plane; the classification of ACP and the occurrence rate of bone bridge were also viewed in axial plane. The thickness of ACP was measured in sagittal plane.

RESULT

In Chinese population, 12.3% of the ACP is gasified, and the pneumatization of ACP has a relationship with the pneumatization of sphenoid sinus. The length and thickness of ACP are similar to that in previous studies in cadaver. The apex of ACP is relatively stationary to the C3 and C4 segments of the internal carotid artery. The occurrence rate of anterior and middle clinoid bone bridge was 7.8%; the occurrence rate of anterior and posterior clinoid bone bridge was 9.3%.

CONCLUSIONS

The anatomical structure of ACP can be studied effectively in CT images. Recognizing the anatomical characteristics of the ACP and optic strut is important in decreasing the incidence of surgical complications of an anterior clinoidectomy and in the proper intraoperative management to prevent these complications.

Safe Corridor to Access Clivus for Endoscopic Trans-Sphenoidal Surgery: A Radiological and Anatomical Study

PURPOSE

Penetration of the clivus is required for surgical access of the brain stem. The endoscopic transclivus approach is a difficult procedure with high risk of injury to important neurovascular structures. We undertook a novel anatomical and radiological investigation to understand the structure of the clivus and neurovascular structures relevant to the extended trans-nasal trans-sphenoid procedure and determine a safe corridor for the penetration of the clivus.

METHOD

We examined the clivus region in the computed tomographic angiography (CTA) images of 220 adults, magnetic resonance (MR) images of 50 adults, and dry skull specimens of 10 adults. Multiplanar reconstruction (MPR) of the CT images was performed, and the anatomical features of the clivus were studied in the coronal, sagittal, and axial planes. The data from the images were used to determine the anatomical parameters of the clivus and neurovascular structures, such as the internal carotid artery and inferior petrosal sinus.

RESULTS

The examination of the CTA and MR images of the enrolled subjects revealed that the thickness of the clivus helped determine the depth of the penetration, while the distance from the sagittal midline to the important neurovascular structures determined the width of the penetration. Further, data from the CTA and MR images were consistent with those retrieved from the examination of the cadaveric specimens.

CONCLUSION

Our findings provided certain pointers that may be useful in guiding the surgery such that inadvertent injury to vital structures is avoided and also provided supportive information for the choice of the appropriate endoscopic equipment.

Transsphenoidal Approach in Endoscopic Endonasal Surgery for Skull Base Lesions: What Radiologists and Surgeons Need to Know

In the last 2 decades, endoscopic endonasal transsphenoidal surgery has become the most popular choice of neurosurgeons and otolaryngologists to treat lesions of the skull base, with minimal invasiveness, lower incidence of complications, and lower morbidity and mortality rates compared with traditional approaches. The transsphenoidal route is the surgical approach of choice for most sellar tumors because of the relationship of the sphenoid bone to the nasal cavity below and the pituitary gland above. More recently, extended approaches have expanded the indications for transsphenoidal surgery by using different corridors leading to specific target areas, from the crista galli to the spinomedullary junction. Computer-assisted surgery is an evolving technology that allows real-time anatomic navigation during endoscopic surgery by linking preoperative triplanar radiologic images and intraoperative endoscopic views, thus helping the surgeon avoid damage to vital structures. Preoperative computed tomography is the preferred modality to show bone landmarks and vascular structures. Radiologists play an important role in surgical planning by reporting extension of sphenoid pneumatization, recesses and septations of the sinus, and other relevant anatomic variants. Radiologists should understand the relationships of the sphenoid bone and skull base structures, anatomic variants, and image-guided neuronavigation techniques to prevent surgical complications and allow effective treatment of skull base lesions with the endoscopic endonasal transsphenoidal approach.

Anatomical features of skull base and oral cavity: a pilot study to determine the accessibility of the sella by transoral robotic-assisted surgery

The role of transoral robotic surgery (TORS) in the skull base emerges and represents the natural progression toward miniinvasive resections in confined spaces. The accessibility of the sella via TORS has been recently described on fresh human cadavers. An anatomic study is mandatory to know if this approach would be feasible in the majority of patients regardless of their oral morphological features. From 30 skull base CT scans from patients who were asked to open their mouth as wide as they can, we measured specific dimensions of the oral cavity and the skull base, such as length of the palate, mouth opening and distance from the sella to the palate. All data were acquired on a sagittal midline plane and on a 25° rotation plane, which simulated the axis of the robotic instruments. Looking at the projection of the dental palatine line on the sella, we studied possible predictive factors of sellar accessibility and tried to bring objective data for surgical feasibility. We also proposed an angle α to study the working angle at the skull base. We observed that the maximal mouth opening was a good predictive factor of sellar accessibility by TORS (p < 0.05). The mouth aperture threshold value for a good sensitivity, over 80 %, was comparable to the mean value of mouth opening in our series, 38.9 and 39.4 mm respectively. Moreover, we showed a statistically significant increase of the working angle α at the skull base comparing the lateral access to the midline one (p < 0.05). This seemed to quantitatively demonstrate that the robotic arms placed at the labial commissure of the mouth can reach the sella. From these anatomical features and previous cadaveric dissections, we assume that TORS may be feasible on a majority of patients to remove pituitary adenomas.

Sphenoid sinus types, dimensions and relationship with surrounding structures

The human sphenoid sinus is an extremely variable cavity and an important landmark in hypophyseal surgery. The aim of this study was to investigate the relationship between the sphenoid sinus type, size, extent of pneumatization and occurrence of protrusions of the adjacent neurovascular structures. A total of 51 randomly selected skulls (≥20 years of age, 33 male; 102 sinuses) were analyzed using cone beam computed tomography to estimate pneumatization extension beyond the body of the sphenoid (planum sphenoidale, pterygoid process, greater wings, clivus, dorsum sellae) and protrusions of the maxillary, mandibular, optic or pterygoid nerve or the internal carotid artery. Difference in pneumatization type between the left and the right-sided sinus was observed in 45% of the skulls. Conchal pneumatization was registered in 2%, presellar in 24%, sellar in 41% and postsellar in 33% of total sinuses. Presellar sinuses frequently pneumatized planum sphenoidale and sporadically other structures, and were characterized by sporadic optic nerve protrusions. Sellar and particularly postsellar sinuses were characterized by simultaneous pneumatization extensions and neurovascular protrusions. In the case of postsellar-type sinuses, the probability of these multiple interactions was not affected by their actual size, while it increased with the increasing sinus dimensions in the case of sellar-type sinuses. A more detailed analysis indicated that increasing sinus height, length or width increased the probability of interactions and pneumatization of particular surrounding structures. Data suggest that the sphenoid sinus pneumatization type and dimensions might be used to estimate the risks of iatrogenic injury during transsphenoidal surgical procedures.