Computed Tomographic Analysis: The Effects of Frontal Recess Morphology and the Presence of Anatomical Variations on Frontal Sinus Pneumatization

Frontal sinus pneumatisation: an isolated finding or a sign of concomitant anatomical variation?

OBJECTIVE

To determine the association between frontal sinus pneumatisation and concomitant anatomical variations in paranasal sinuses as seen on computed tomography.

METHODS

A total of 403 patients who underwent paranasal sinus computed tomography were allocated to three groups according to the degree of frontal sinus pneumatisation (type 1 - hypoplasia; type 2 - medium size; and type 3 - hyperplasia). In this unique model, the prevalence of ipsilateral variations on paranasal sinuses on each side of the head were analysed separately within each pneumatisation group.

RESULTS

The type 3 frontal sinus pneumatisation group showed a greater association with ipsilateral variations of the sphenoid bone. Variations included pneumatisation of the anterior clinoid process, lateral sphenoid recess, pterygoid process and greater wing, and exposure of Vidian canal. This group also showed significant associations with male gender, and the presence of frontal and Onodi cells.

CONCLUSION

Interpretation of the paranasal sinus variations is imperative for pre-operative evaluation in functional endoscopic sinus surgery, particularly in patients with frontal sinus hyperplasia. Attention to variation on the ipsilateral side is informative.

[Modern aspects of surgical treatment of nasal liquorrhea with localization of defect in frontal sinus]

Defects localized in the frontal sinus are difficult for surgical treatment, since there is a large number of anatomical variations in the structure of the naso-frontal canal and the sinus itself. With the development of endoscopic technology and paying attention to the modern tendency of minimal invasive surgery, new invasive approaches to reach frontal sinus, such as endoscopic approach according to Draf I-III and combined approaches were developed and put into practice.

OBJECTIVE

To summarize and to analyze the results of treatment of nasal liquorrhea with localization of the defect in the frontal sinus using endoscopic endonasal and combined intra-extranasal approaches.

MATERIAL AND METHODS

A retrospective analysis of a series of 43 cases of nasal liquorrhea with a frontal sinus defect being treated at the NMRCN Burdenko during the period from 2001 to 2017. To select access, a classification of frontal sinus defects according to their localization was developed. The analysis of demographic and clinical data of patients, as well as intraoperative and postoperative data analysis were done.

RESULTS

In the series of 43 patients, endoscopic endonasal approach was performed in 28 (65%) cases. Combined approach was performed at 15 (35%) patients. The success rate of plastic surgery with endoscopic endonasal approach was 86% (24 of 28), with combined approach - 93% (14 of 15).

CONCLUSION

Endoscopic endonasal and combined approaches are the methods of choice for plastic surgery of defects of the skull base in the frontal sinus as they are effective and safe. The choice of approach depends on anatomical features of the frontal sinus and on the localization of defect.

The Relationships Between Craniofacial Structure and Frontal Sinus Morphology: Evaluation With Conventional Anthropometry and CT-Based Volumetry

The purpose of this study was to investigate the effects of craniofacial structure and nasal septal deviation on frontal sinus morphology 3-dimensionally. This study of anatomy, anthropology, morphology, and radiology included 74 dry skulls as study sample. The craniofacial measurements were made through conventional anthropometric methods by the use of calipers. The nasal septal deviation measurements were done by computerized software on photographs taken from frontal view. Frontal sinus volumes were estimated by the computerized tomography-based volumetry. The relationships between craniofacial structure, nasal septal deviation, and frontal sinus morphology were tested by linear regression and correlation analysis. The analysis of numerical variables and categorical variables within different groups was done by Mann-Whitney U/Kruskal-Wallis, and χ² tests, respectively. There appeared a positive relationship between the dimensions of the frontal sinuses and the maximal cranial length and the nasal height especially on the left side (P < .05). However, after multivariate linear regression model for both factors was created, solely the nasal height kept being a positive factor for frontal sinus size as an independent variable. No statistical relevance was detected between the presence of metopic suture and frontal sinus morphology. Septal deviation itself affected frontal sinus morphometry, but the morphometry did not differ between the deviation side and the opposite side. In conclusion, the cranial structure does not affect the frontal sinus morphology but nasal structure affects. The true influences, among measured craniofacial elements, in relationship with the pneumatization of frontal sinus are appeared to be the nasal structure related.

Incidence of anatomical variations according to the International Frontal Sinus Anatomy Classification (IFAC) and their coincidence with radiological sings of opacification

BACKGROUND

The endonasal access to the frontal recess and sinus may be complicated by a variety of anatomical variations. Previous classifications of these variants were characterized by proper names or position information without anatomical reference. The IFAC is intended to simplify the classification of anatomical variations of the frontoethmoidal complex. The aim of this study was to analyse a representative number of sinus CT scans to assess the incidence of anatomical variations according to the IFAC and to compare the results with previous classifications. In addition, the coincidence of complex anatomical variations and radiological sings of opacification was investigated.

METHODOLOGY/PRINCIPAL

Two hundred and forty-nine sinus CT scans were analysed in multiplanar reconstructions. Exclusion criteria were previous operations on the paranasal sinuses, malignant diseases, and an insufficient image quality. All anatomical variants were analysed according to the IFAC criteria. In addition, the coincidence of radiological sings of opacification and the presence of anatomical variations of the frontal recess and sinus were investigated.

RESULTS

The analysis revealed Agger nasi cells in 95% of the CT scans. Supra agger cells (SACs) were detected in 49% and Supra agger frontal cells (SAFCs) in 25% of the data sets. Suprabulla cells (SBCs) were detected in 89% and Supra bulla frontal cells (SBFCs) in 27% of the scans. Supraorbital ethmoid cells (SECs) were detectable in 9% and interfrontal septal cells in 28% of the scans. Despite a partially strong narrowing of the frontal recess, no increased occurrence of radiological sings of opacification could be detected (p > 0.05).

CONCLUSIONS

Anatomical variations in the frontoethmoidal area are very common. According to the IFAC criteria, in 43% of the patients, cells could be detected with pneumatization to or into the frontal sinus. The IFAC is structured more clearly compared to previous classifications due to the anatomical aspect. It represents the most consistent classification regarding surgical planning. Further studies will demonstrate the scientific and clinical value of this classification.