The anatomic analysis of the vidian canal and the surrounding structures concerning vidian neurectomy using computed tomography scans

INTRODUCTION

The type of endoscopic approach chosen for vidian neurectomy can be specified by evaluating the vidian canal and the surrounding sphenoid sinus structures.

OBJECTIVE

The variations and morphometry of the vidian canal were investigated, focusing on the functional correlations between them which are crucial anatomical landmarks for preoperative planning.

METHODS

This study was performed using paranasal multidetector computed tomography images that were obtained with a section thickening of 0.625mm of 250 adults.

RESULTS

The distributions of 500 vidian canal variants were categorized as follows; Type 1, within the sphenoid corpus (55.6%); Type 2, partially protruding into the sphenoid sinus (34.8%); Type 3, within the sphenoid sinus (9.6%). The pneumatization of the pterygoid process is mostly seen in vidian canal Type 2 (72.4%) and Type 3 (95.8%) (p<0.001). The mean distances from the vidian canal to the foramen rotundum and the palatovaginal canal were greater in the vidian canal Type 2 and 3 with the pterygoid process pneumatization (p<0.001). The prevalence of the intrasphenoid septum between the vidian canal and the vomerine crest and lateral attachment which ending on carotid prominence were much higher in vidian canal Type 3 than other types (p<0.001). The mean angle between the posterior end of the middle turbinate and the lateral margin of the anterior opening of the vidian canal was measured as 33.05±7.71°.

CONCLUSIONS

Preoperative radiologic analysis of the vidian canal and the surrounding structures will allow surgeons to choose an appropriate endoscopic approach to ensure predictable postoperative outcomes.

The sphenoid sinus, foramen rotundum and vidian canal: a radiological study of anatomical relationships

Introduction

The sphenoid sinus is an important structure in ventral skull base surgeries that is surrounded by several vital anatomical structures including the internal carotid arteries, optic nerve and cranial nerves inside the cavernous sinus. In addition, the foramen rotundum is a small canal deeply situated in the base of the skull, which represents the way for exit of the maxillary nerve. Understanding of the sphenoid bone anatomical relationships is central to the expanded endonasal approaches to the skull base.

Objective

To record and analyze the measurement indexes of the sphenoid sinus and foramen rotundum in the coronal plane of normal computer tomography scans.

Methods

Patients underwent paranasal sinuses computer tomography scan from June 2014 to November 2015 were retrospectively entered this cross-sectional study. We obtained several morphometric measurements from both the right and left sides using computer software. We also classified foramen rotundum and vidian canal types and determined position of the foramen rotundum regarding to base of lateral pterygoid plate.

Results

One-hundred patients with the mean age of 38.56 ± 18.51 years entered this study. Mean bilateral FR distances were 38.48 ± 3.87 mm. Average right and left FRs distances to midline were 19.00 ± 2.07 and 19.34 ± 2.17 mm, respectively (p = 0.03). Twenty-eight cases (28%) had type I vidian canal, 48% and 24% had type II and III vidian canals, respectively. Four patients (4%) had type I rotundum foramen, 28% and 44% had type IIa and IIb, respectively and 24% had type III rotundum foramen. The position of foramen rotundums regarding to the base of lateral pterygoid plate was online in 50% of cases, medially placed in 47% and laterally placed in 3% of cases.

Conclusion

The results of this study can be used to provide a better anatomical understanding of the area, which is necessary for endoscopic skull base surgeons.