Imaging the sphenoid sinus: pictorial essay

Radiologic evaluation of the Vidian canal in the pediatric population

PURPOSE

This examination aimed to display the size and topographic position of the Vidian canal (VC) in normal children.

METHODS

180 pediatric subjects aged 1-18 years were included this computed tomography examination. The distances of VC to certain landmarks, and VC length were measured. The locations of VC according to the sphenoid sinus, and the medial plate of pterygoid process were classified as three types, separately.

RESULTS

The distances of VC to the vomerine crest, midsagittal plane, round foramen, and the superior wall of sphenoid sinus were measured as 12.68 ± 3.17 mm, 10.76 ± 2.52 mm, 8.62 ± 2.35 mm, and 14.16 ± 5.00 mm, respectively. The length and angle of VC were measured as 12.00 ± 2.52 mm, and 16.60 ± 9.76°, respectively. According to the sphenoid bone, VC location was identified as Type 1 in 113 sides (47.5%), as Type 2 in 70 sides (29.4%), and as Type 3 in 55 sides (23.1%). According to the medial plate of pterygoid process, VC location was identified as Type A in 274 sides (76.1%), as Type B in 55 sides (15.3%), and as Type C in 31 sides (8.6%). VC location types correlated with pediatric ages, but not sex or side.

CONCLUSION

With advancing pediatric age, the protrusion of VC into the sphenoid sinus increases, and VC shifts from medial to lateral side of the medial plate of pterygoid process.

Sphenoid Sinus and Related Neurovascular Structures-Anatomical Relations and Variations on Radiology-A Retrospective Study

The aim of this study was to evaluate sphenoid sinus pneumatisation and its anatomical relation with adjacent neurovascular structures in Indian population. We performed a retrospective cross-sectional study, in which the pattern of sphenoid sinus pneumatization was studied on high-resolution computed tomography scans (n = 400), and association of the optic nerve, vidian canal and foramen rotundum along with related morphometric measurements were studied. Out of 400 CT scans, 60.5% were males. Majority had sellar type of pneumatization (89.5%) and single intersinus septum (68%). The most common configuration of relation of optic nerve canal was DeLano type 2 (34.75%). Vidian canal (VC) and Foramen rotundum (FR) were found dehiscent in 40.5% and 6.38% respectively. Average distance of FR from midline on right and left side was 16.3 ± 2.19 mm and 16.7 ± 2.23 mm respectively. Average distance of VC from midline on right and left side was 12.4 ± 5.84 mm and 12.4 ± 4.18 mm respectively. Average right FR to VC distance was 4.17 ± 2.16 mm and left FR to VC was 4.44 ± 2.20 mm. Anatomical variations of the sphenoid sinus are well known. In the present study, we have tried to highlight the importance of knowledge of various anatomical variations in relations to sphenoid sinus as they are critical in planning of surgery. Pre-operative radiological study and correlation is inevitable to assess type and extent of sinus pneumatisation, bony dehiscence and septal terminations to avoid injury to vital structures.

The anatomical and radiological evaluation of the Vidian canal on cone-beam computed tomography images

INTRODUCTION

The aim of this study is to explore the anatomy of the Vidian nerve to elucidate the appropriate surgical approach based on preoperative cone-beam computed tomography (CBCT) images.

MATERIALS AND METHODS

The Vidian canal and its surrounding structures were morphometrically evaluated retrospectively in CBCT images of 400 cases by the Planmeca Romexis program. The types of the Vidian canal were determined and seven parameters were measured from the images.

RESULTS

Three types of the Vidian canal according to the relationship with the sphenoid bone were found as follows: the Vidian canal totally protruded into the sphenoid sinus (19.75%), partially protruded into sphenoid sinus (44.37%) and embedded inside bony tissue of the body of sphenoid bone (35.87%). The position of the Vidian canal was medial (34.62%), on the same line (55.12%) and lateral (10.25%) to the medial plate of the pterygoid process. The distance between the Vidian canal and the vomerine crest, the mid-sagittal plane, the round foramen, the palatovaginal canal, and the superior wall of the sphenoid sinus, the length of the Vidian canal and the angle between the Vidian canal and the sagittal plane was found to be 16.69 ± 2.14, 13.80 ± 2.00, 8.88 ± 1.60, 5.83 ± 1.37, 23.98 ± 2.68, 13.29 ± 1.71 mm and 25.78° ± 3.68° in males, 14.62 ± 1.66, 11.43 ± 1.28, 8.51 ± 1.63, 5.78 ± 0.57, 22.37 ± 2.07, 12.91 ± 1.26 mm and 23.43° ± 3.07° in females, respectively.

CONCLUSIONS

Our results may assist with proper treatment for surgical procedures around the Vidian canal with a high success rate and minimal complications. Therefore, the results obtained in this study contribute to the literature.

Co-existence of the Onodi cell with the variation of perisphenoidal structures

The presence of the Onodi cell (OC) may be accompanied by morphological variations of the neighboring anatomic structures. Such variations carry significant surgical implications and challenges. Pneumatization of the sphenoid sinus induces anterior clinoid pneumatization (ACP), affects the type of the Vidian nerve (VN) canal or alters the courses of the internal carotid artery (ICA), and the optic nerves (ONs) are strongly depending on it. Onodi cell pneumatization may reach and surround the optic nerve in various extension. Our aim in the study was to investigate the effect of Onodi cell's potential co-existence on these structures. This study was planned as a retrospective and cross-sectional study. This study performed in a tertiary referral center. Coronal computerized tomography images of 999 patients were examined. Using an 64 slices tomography machine, images taken at 3-mm sections were reconstructed using a bone algorithm and evaluated. OCs were present at 212 of the total 320 sides in 160 patients. Type-2 was found to be the most prevalent type of VN canal configuration (Type-2: VN canal partially protrudes into the sphenoid sinus or into the floor of the sphenoid) among all patients (66.5 %) and among those with OCs (71.2 %). The presence or absence of the OC did not cause a statistically significant alteration of the intrasphenoidal course of the VN. The presence of OCs was found to be significant (p < 0.01) in accompanying pneumatization of the anterior clinoid process (34.4 %, 73/212), protrusion (80.1 %, 170/212) and dehiscence (36.3 %, 77/212) of the optic nerve, and protrusion (59 %, 125/212) and dehiscence (20.8 %, 44/212) of the ICA. In 108/320 sides where OCs were absent, no significant correlations existed. This study shows that in the co-existence of an OC, ACP, protrusion and dehiscence of the optic nerve and ICA are encountered at significantly higher rates, while the course of the VN is not necessarily altered.

Sensitivity and specificity of computed tomography and magnetic resonance imaging in the diagnosis of isolated sphenoid sinus diseases

OBJECTIVES/HYPOTHESIS

The sphenoid sinus is uncommonly affected by inflammatory or neoplastic lesions. Initial onset of isolated sphenoid sinus diseases (ISSD) is generally asymptomatic. The objectives of this study were to estimate the sensitivity and specificity of computed tomography (CT) and magnetic resonance imaging (MRI) in diagnosing ISSD and establish guidelines to declare hidden ISSD through correlation of radiological diagnosis to final pathological diagnosis.

STUDY DESIGN

A prospective cohort study.

METHODS

There were 66 patients with isolated sphenoid sinus lesions presenting to Ain-Shams University Hospitals, Cairo, Egypt. Provisional diagnosis of ISSD was done by CT and MRI, followed by histopathologic and immunohistochemical staining, and if needed microbiological examination of resected specimens to establish the final diagnosis.

RESULTS

Patients were classified into four groups according to the type of lesion: inflammatory, neoplastic, bony dysplastic disorders, and sphenoid sinus roof defect-related lesions. Radiological imaging provided the greatest diagnostic information and guided management. The sensitivity of CT and MRI in diagnosing inflammatory lesions was 95% versus 61%, whereas those of the neoplastic group were 72% and 100%, respectively. In the osseous group the sensitivity was 100% for both CT and MRI, whereas in sphenoid sinus roof defect the sensitivity was 50% and 100% for CT and MRI, respectively.

CONCLUSIONS

Because of CT's superiority in defining the bony margins and MRI's superior soft tissue resolution, CT and MRI should be used in a complementary manner in the evaluation of isolated sphenoid sinus disease in addition to mapping the lesion better and identifying intracranial and intraorbital extension. The use of one modality only should be restricted to straightforward lesions.

The neglected anatomical and clinical aspects of pterygoid canal: CT scan study

PURPOSE

To present the variable positions of pterygoid canal (PC) relative to sphenoid sinus floor and cavity, which may be helpful for understanding pathologic and surgical conditions related to sphenoid sinus region.

MATERIALS AND METHODS

Coronal sinonasal CT images of 300 adult patients, in the Department of Radiology at Al-Jala Traumatology Hospital, Benghazi, Libya, were investigated for the positional variation and dehiscence of PC. Of the patients, there was equal gender distribution, ages ranged between 16 and 82 years (mean age 34.6 years). The position of PC was categorized as below the sinus floor, within the floor, and within the sinus cavity (protrusion).

RESULTS

Canals located under the floor were identified in 38.3% (230/600), within-the-floor canals were encountered in 39.6% (238/600); and canals protruding into the sinus cavity (i.e., within sinus cavity) were observed in 22% (132/600). Dehiscence of the bony wall of PC was recognized in 26% (157/600). Coexistence of PR and protruding PC was found in 16.5% (99/600), 7.3% (44/600) on the right side and 9.2% (55) on the left side. Statistically, there was significant association between PR and PC protrusion (p = 0.000).

CONCLUSION

The anatomical and positional variations of PC are highly encountered. Surgeons addressing vidian neurectomy must be familiar with the positional variations of PC in the preoperative CT images for easier and safer nerve identification and transection.

CT evaluation of the vidian canal localization

The primary purpose of our work is to show that the vidian canal can be determined on CT imaging. The secondary goal is to establish the position and configuration of the vidian canal visualization. The CT imaging of vidian canals of 150 patients were examined in axial and coronal sections in 3 mm thickness made at 3 mm intervals. The varying course of the canal inside the bone, bone structure and diameter of the canal were investigated. In all cases, the canal was seen, and in 4 of the cases (1.3%) the canal was separated into two parts by a septum on its initial portion. In 36% of the cases it was embedded in the sphenoid corpus, partially protruded in 54% of the cases, and was connected to the bone with a stalk inside the sinus in 10% of the cases. The bony structure of the canal showed continuation in 68%, with 32% showing dehisans. The incidence of dehisans was 77% in the stalked cases and 45% in the protruded cases. It was determined that it is possible to evaluate the position and configuration of the vidian canal with CT imaging. This may be useful for diagnosing vidian nerve pathology and performing surgical intervention such as vidian neuroectomy and sinus surgery.