The Frontal Sinus and Frontal Recess: Anatomical, Radiological and Surgical Concepts

Clinical anatomy of the paranasal sinuses and its terminology

Since its inception, the International Anatomical Terminology has been an indispensable and widely embraced resource for authors, anatomists, researchers, and medical professionals, ensuring standardized anatomical terminology across various disciplines. Nonetheless, it is widely acknowledged that periodic updates and enhancements are necessary to incorporate the latest scientific knowledge and advancements in imaging techniques. The current version of Terminologia Anatomica includes a section dedicated to the paranasal sinuses, encompassing ethmoidal cells and three sinuses: frontal, sphenoidal, and maxillary. However, the anatomical lexicon pertaining to the paranasal sinuses is more extensive. In clinical practice, multiple terms related to clinically significant structures are commonly employed. This article focuses on the clinical terminology associated with the paranasal sinuses, proposing significant extensions to the existing Terminologia Anatomica. These extensions aim to enrich the anatomical nomenclature and facilitate a harmonious convergence between the language of clinicians and the anatomical lexicon. Further endeavors should bridge the gap in anatomical nomenclature and improve communication between anatomists, researchers, and clinicians, thereby enhancing diagnostic accuracy and improving interdisciplinary research collaboration.

30° anteriorly tilted CT for visualizing the drainage pathway of the frontal sinus

KEY POINTS

The optimal tilt for anteriorly tilted coronal CT was examined. A 30° anteriorly tilted coronal CT best visualized the frontal sinus drainage pathway.

A Cadaveric Feasibility Study of the Biportal Endoscopic Transfrontal Sinus Approach: A Minimally Invasive Approach to the Anterior Cranial Fossa

BACKGROUND AND OBJECTIVES

The trans-sinus transglabellar and bifrontal approaches offer direct access to the anterior cranial fossa. However, these approaches present potential drawbacks. We propose the biportal endoscopic transfrontal sinus (BETS) approach, adapting endoscopic endonasal approach (EEA) techniques for minimally invasive access to the anterior fossa, reducing tissue manipulation, venous sacrifice, and brain retraction.

METHODS

Six formalin specimens were used. BETS approach involves 2 incisions over the medial aspect of both eyebrows from the supraorbital notch to the medial end of the eyebrow. A unilateral pedicled pericranial flap is harvested. A craniotomy through the anterior table of the frontal sinus (FS) and a separate craniotomy through the posterior table are performed. Two variants of the approach (preservative vs cranialization) are described for opening and reconstruction of the FS based on the desired pathology to access. Bone flap replacement can be performed with titanium plates and filling of the external table defect with bone cement.

RESULTS

Like in EEA, this approach provides access for endoscope and multiple working instruments to be used simultaneously. The approach allows wide access to the anterior cranial fossa, subfrontal, and interhemispheric corridors, all the way up to the suprachiasmatic corridor and through the lamina terminalis to the third ventricle. BETS provides direct access to the anterior fossa, minimizing the level of frontal lobe retraction and providing potentially less tissue disruption and improved cosmesis. Cerebrospinal fluid fistula risk remains one of the major concerns as the narrow corridor limits achieving a watertight closure which can be mitigated with a pedicled flap. Mucocele risk is minimized with full cranialization or reconstruction of the FS.

CONCLUSION

The BETS approach is a minimally invasive approach that translates the concepts of EEA to the FS. It allows excellent access to the anterior cranial fossa structures with minimal frontal lobe retraction.

Anteriorly Tilted Coronal CT of Paranasal Sinuses for Endoscopic Sinus Surgery

Conventional coronal CT scans of paranasal sinuses, aligned perpendicularly to the nasal floor, often deviate significantly from the endoscopic view during sinus surgery. This discrepancy complicates the interpretation of anatomical structures. In response, we propose the utilization of anteriorly tilted coronal CT slices to enhance anatomical understanding. These slices align more closely with the endoscopic view, fostering an intuitive grasp of paranasal sinus anatomy. This study aims to quantify the tilt of the endoscope to the nasal floor during endoscopic sinus surgery. To figure out the tilt of the endoscopically true coronal slices, we calculated the tilt of the endoscope to the nasal floor in the operative setting by taking pictures of the operation and measuring the image and sagittal CT. Fourteen patients (25 sides of paranasal sinuses) were analyzed. Endoscope tilts to the nasal floor were measured at different anatomical landmarks: 16.2 ± 9.7 degrees (lower edge of ground lamella), 29.8 ± 7.9 degrees (central ground lamella), 62.3 ± 10.1 degrees (most superior part), and 25.6 ± 7.0 degrees (optic canal). In conclusion, we showed the actual tilt of the endoscope to the nasal floor during endoscopic sinus surgery. A 30-degree anteriorly tilted coronal scan for frontal recess and sphenoid sinus is more intuitive than a traditional coronal scan, which helps surgeons understand the complex sinus anatomy.

Exploring the uncharted: Missing anatomical names in the Terminologia Anatomica

Effective communication and precise navigation within the intricacies of the human body rely on robust anatomical terminology. Since its creation by the Federative Committee on Anatomical Terminology (FCAT), the Terminologia Anatomica (TA 1998) has consistently served as the benchmark in the field. However, the constant advancement of anatomical knowledge requires regular revisions, updates, and enhancements of anatomical nomenclature to accommodate the latest scientific discoveries. The recent adoption of the second edition of Terminologia Anatomica (TA 2019) by the International Federation of Associations of Anatomists (IFAA) has drawn attention to certain notable omissions. Despite over a century of dedicated work establishing standard anatomical terminology, specific widely recognized gross anatomical structures are still absent from the official listing in the Terminologia Anatomica. There is, however, a consensus that the inclusion of names for trivial or variably present structures should be avoided. Accordingly, this article focuses on a thoughtfully selected group of anatomical structures, which are so important that they are routinely discussed during anatomy courses, despite their exclusion from the official lists of anatomical terms. These basic structures hold fundamental importance for both anatomy education and clinical practice. Consequently, their appropriate nomenclature warrants consideration for inclusion in future editions of TA.

Current advancements in therapeutic approaches in orthopedic surgery: a review of recent trends

Recent advancements in orthopedic surgery have greatly improved the management of musculoskeletal disorders and injuries. This review discusses the latest therapeutic approaches that have emerged in orthopedics. We examine the use of regenerative medicine, including stem cell therapy and platelet-rich plasma (PRP) injections, to accelerate healing and promote tissue regeneration. Additionally, we explore the application of robotic-assisted surgery, which provides greater precision and accuracy during surgical procedures. We also delve into the emergence of personalized medicine, which tailors treatments to individual patients based on their unique genetic and environmental factors. Furthermore, we discuss telemedicine and remote patient monitoring as methods for improving patient outcomes and reducing healthcare costs. Finally, we examine the growing interest in using artificial intelligence and machine learning in orthopedics, particularly in diagnosis and treatment planning. Overall, these advancements in therapeutic approaches have significantly improved patient outcomes, reduced recovery times, and enhanced the overall quality of care in orthopedic surgery.

Assessment of Frontal Sinus Volume and Cranial Base Length Based on Different Vertical Skeletal Patterns: A Cone Beam Computed Tomographic Study

Introduction Evaluating craniofacial growth is an essential component of orthodontic treatment, and it is assessed by examining the cranial base. The anterior cranial base is regarded as a stable structure, and the frontal sinus is also recognised as a contributing component in the formation of the cranial base. The frontal sinus, a cavity present in the frontal bone, displays variation in both size and shape and has an impact on the overall structure of the skull and face. This study aims to evaluate the impact of vertical skeletal pattern and gender on the volume of the frontal sinus. Materials and methodology In this study, 90 cone beam computed tomography (CBCT) scans from the record's section were included, comprising 46 males (55.44%) and 44 females (48.88%) aged 20 to 35 undergoing orthodontic treatment. The assessment involved evaluating vertical skeletal patterns using a lateral cephalogram derived from the CBCT scans, and volumetric analysis of the frontal sinus was conducted using Dolphin Imaging software (version 11.9; Dolphin Imaging and Management Solutions, Chatsworth, California). Statistical analysis was performed on the collected data using SPSS software, version 20.0 (IBM Corp., Armonk, NY). Pearson correlation, a one-way ANOVA test to determine any statistically significant differences between the means of both frontal sinus volume and cranial base length groups individually and an independent t-test to compare the sample means between the frontal sinus volume and cranial base length groups were performed. Results: A non-significant association was observed between frontal sinus volume and cranial base length in skeletal open bite (p = 0.73) and skeletal deep bite (p = 0.12) between males and females, which implies there is no substantial association between frontal sinus volume (p = 0.08) and cranial base length (p = 0.41) in the different vertical skeletal patterns.  Conclusion: Frontal sinus volume was similar in subjects with a skeletal open bite and a deep bite. Males and females did not show a difference in frontal sinus volume. Hence, it was concluded that frontal sinus volume and anterior cranial base cannot be used as parameters to predict vertical malocclusions.

Osteomyelitis of Frontal Sinus: A Rare Sequelae of Acute Bacterial Sinusitis Associated With Anatomical Variations in the Frontal Sinus Drainage Pathway

Frontal osteomyelitis is characterized by localized osteal inflammation of the frontal bone. This is a rare complication of acute frontal sinusitis. The present case is being reported to highlight the likely role of anatomical variations in frontal sinus drainage pathways in the causation of this complication apart from other known predisposing factors like young age and immunocompromised state. The patient initially presented with seizures, fever, and headache and was diagnosed with viral encephalitis. However, the symptoms gradually progressed to cause right eye swelling and an increase in the severity of headache without any nasal complaints. Diagnostic nasal endoscopy revealed mucopurulent secretions in both nasal cavities. Computed tomography and magnetic resonance imaging diagnosed the anatomical variations, the extent of sinus involvement, and frontal osteomyelitis. Antimicrobial therapy for an extended duration of four weeks, along with functional endoscopic sinus surgery resulted in excellent outcomes.

Influence of Orthodontic Treatment on Changes in the Maxillary Sinus Dimensions

Objective This study aimed to investigate the correlation of craniofacial morphology with maxillary sinus morphology and to evaluate whether orthodontic treatment facilitates maxillary sinus enlargement in adults. Materials and methods A total of 45 adult women underwent cephalography and computed tomography before and after orthodontic treatment. All participants were classified into three groups: skeletal class I, II, and III. The average dimensions and volume of the maxillary sinus were calculated in each subgroup. Furthermore, multiple regression analysis was used to analyze the correlations of maxillary sinus dimensions with 20 cephalometric variables. Results Before treatment, the maxillary sinus width, height, depth, and volume were 32.2 ± 3.9 mm, 39.5 ± 3.8 mm, 38.6 ± 1.8 mm, and 36,179.3 ± 5,454.0 mm3 in skeletal class I, 33.9 ± 6.2 mm, 37.3 ± 3.5 mm, 38.6 ± 2.4 mm, and 34,729.8 ± 6,686.6 mm3 in skeletal class II, and 32.0 ± 4.3 mm, 41.8 ± 5.0 mm, 38.0 ± 2.8 mm, and 35,592.3 ± 10,334.3 mm3 in skeletal class III, respectively. Despite no significant differences in maxillary sinus width, depth, or volume, the height was significantly lower in the skeletal class II than in the other two. Regardless of the skeletal pattern, maxillary sinus height and volume increased considerably after treatment. Moreover, the maxillary sinus width was substantially involved in pretreatment U1 to SN and overbite and posttreatment U1 to NA and overjet. Conclusion Except for the height, the maxillary sinus dimensions were almost similar, irrespective of the skeletal classification. The posttreatment sinus height and volume were significantly greater than the pretreatment values, although the sinus width and length showed no significant changes during orthodontic treatment. This implies that orthodontic treatment may facilitate the enlargement of the maxillary sinus even after physical growth.

Does Frontal Recess Cell Variation Associate with the Development of Frontal Sinusitis? A Narrative Review

Chronic rhinosinusitis (CRS) can have a significant impact on quality of life. With persistent symptoms and the failure of initial medical treatments, surgical management is indicated. Despite the excellent results of endoscopic sinus surgery for persistent CRS, it is quite a challenging procedure for frontal sinusitis given the complex anatomy and location of the frontal sinus. Frontal recess cells significantly contribute to the complexity of the frontal sinus, and numerous studies have sought to establish their association with sinusitis. This review offers a comprehensive understanding of frontal recess cells, their different classifications, their prevalence among different populations, and their relationship to sinusitis. After an extensive review of the current literature, the International Frontal Sinus Anatomy Classification (IFAC) is the most recent classification method and a preferred practical preoperative assessment tool. Although the agger nasi cell is the most prevalent cell among all reported populations, ethnic variations are still influencing the other cells' distribution. Studies are inconsistent in reporting a relationship between frontal recess cells and sinusitis, and that is mainly because of the differences in the classification methods used. More research using a standardized classification method is needed to understand the association between frontal recess cells and sinusitis.

Change of frontal sinus in age of according to the international frontal sinus anatomy classification

BACKGROUND

The radiological and surgical anatomy of the frontal sinus should be well-known in all age groups to successfully manage frontal sinus diseases and reduce the risk of complications in sinus surgery.

PURPOSE

To define frontal sinus and frontal cells according to the International Frontal Sinus Anatomy Classification (IFAC) criteria in pediatrics and adults.

MATERIAL AND METHODS

A total of 320 frontal recess regions of 160 individuals (80 pediatric, 80 adults) who underwent a computed tomography (CT) scan of the paranasal sinus (PNS) were included in the study. Agger nasi cells, supra agger cells, supra agger frontal cells, suprabullar cells, suprabullar frontal cells, supraorbital ethmoid cells, and frontal septal cells were evaluated in the CT analysis.

RESULTS

The incidence rates of the investigated cells were determined to be 93.1%, 41.9%, 60.0%, 76.3%, 58.5%, 18.8%, and 0% in the pediatric group, respectively, and 86.3%, 35.0%, 44.4%, 54.4%, 46.9%, 19.4%, and 3.4% in the adult group, respectively. Considering the unilateral and bilateral incidence of the cells, agger nasi cells were highly observed bilaterally in both the pediatric group (89.87%) and the adult group (86.48%).

CONCLUSION

Our study results show that IFAC can be used as a guide to increase the chance of surgical treatment in the pediatric and adult groups and that the prevalence of frontal cells can be determined radiologically and contributes to the generation of estimations of the prevalence of frontal cells.

Computed tomography analysis of the anterior ethmoid genu of the frontal recess in non-diseased sinuses

OBJECTIVE

Knowledge of anatomical variations of the frontal recess and frontal sinus and recognition of endoscopic landmarks are vital for safe and effective endoscopic sinus surgery. This study revisited an anatomical landmark in the frontal recess that could serve as a guide to the frontal sinus.

METHOD

Prevalence of the anterior ethmoid genu, its morphology and its relationship with the frontal sinus drainage pathway was assessed. Computed tomography scans with multiplanar reconstruction were used to study non-diseased sinonasal complexes.

RESULTS

The anterior ethmoidal genu was present in all 102 anatomical sides studied, independent of age, gender and race. Its position was within the frontal sinus drainage pathway, and the drainage pathway was medial to it in 98 of 102 cases. The anterior ethmoidal genu sometimes extended laterally and formed a recess bounded by the lamina papyracea laterally, by the uncinate process anteriorly and by the bulla ethmoidalis posteriorly. Distance of the anterior ethmoidal genu to frontal ostia can be determined by the height of the posterior wall of the agger nasi cell rather than its volume or other dimensions.

CONCLUSION

This study confirmed that the anterior ethmoidal genu is a constant anatomical structure positioned within frontal sinus drainage pathway. The description of anterior ethmoidal genu found in this study explained the anatomical connection between the agger nasi cell, uncinate process and bulla ethmoidalis and its structural organisation.

Orthodontic Treatment Does Not Affect Frontal Sinus Development in Female Adults: A Clinical Study

Frontal sinus growth is gradual and lasts until post-puberty. However, the influence of biomechanical stimuli, such as orthodontic treatment, on frontal sinus development after the growth period has ended remains unclear. This study was designed to elucidate the impact of orthodontic treatment on the frontal sinus morphology of adult females. Sixty women were included and divided into three groups, based on the Frankfort mandibular plane angle. All participants underwent computed tomography and lateral cephalometry before and after treatment. Although two participants exhibited frontal sinus agenesis, most exhibited a bilaterally symmetric frontal sinus without fusion. The frontal sinus width and height were almost similar, irrespective of the vertical skeletal pattern, where the frontal sinus depth was significantly larger in the average mandibular plane angle group than in the low- and high-angle groups. Furthermore, the sinus volume in the low-angle group was likely smaller than that in the average and high-angle groups. On comparing pre-treatment and post-treatment measurements, minimal or no changes to the frontal sinus dimension were detected after treatment. In conclusion, orthodontic treatment did not affect frontal sinus development after the end of growth.

[History of frontal sinus surgery and current view of the problem. Part 2]

Surgical treatment of inflammatory diseases of the frontal sinus is one of the biggest challenges of modern otorhinolaryngology. Close proximity of the frontal sinus and frontal sinus drainage pathways to the skull base, the orbit and the anterior ethmoid artery, great limitations with its visualization and instrumentation, and high risk of the frontal recess scarring cause difficulties in either endoscopic or external approaches to the frontal sinus. At the same time endoscopic approach to the frontal sinus is considered as preferred method of frontal sinusitis surgical treatment by majority of peers nowadays. The introduction of extended approaches to the frontal sinus pathology treatment with frontal sinus floor and interfrontal sinus septum drill-out as well as superior septectomy with common drainage pathway formation gave an opportunity to greatly decrease a rate of indications for external frontal sinus procedures. In this paper historical backgrounds of endonasal approaches to frontal sinuses are presented, current controversies in proper selection of extent and methods of the frontal sinus surgery are analyzed and endoscopic as well as external approaches to frontal sinuses are summarized.

[History of frontal sinus surgery and current view of the problem. Part 1]

Surgical treatment of inflammatory diseases of the frontal sinus is one of the biggest challenges of modern otorhinolaryngology. Close proximity of the frontal sinus and frontal sinus drainage pathways to the skull base, the orbit and the anterior ethmoid artery, great limitations with its visualization and instrumentation, and high risk of the frontal recess scarring cause difficulties in either endoscopic or external approaches to the frontal sinus. At the same time endoscopic approach to the frontal sinus is considered as preferred method of frontal sinusitis surgical treatment by majority of peers nowadays. The introduction of extended approaches to the frontal sinus pathology treatment with frontal sinus floor and interfrontal sinus septum drill-out as well as superior septectomy with common drainage pathway formation gave an opportunity to greatly decrease a rate of indications for external frontal sinus procedures. In this paper historical backgrounds of endonasal approaches to frontal sinuses are presented, current controversies in proper selection of extent and methods of the frontal sinus surgery are analyzed and endoscopic as well as external approaches to frontal sinuses are summarized.

Three-Dimensional Volumetric Analysis of Frontal Ethmoidal Cells and Evaluation of Influential Factors: A Helical Computed Tomography Study

In the present study, we aimed to assess frontal ethmoidal cells by using segmentation 3D software to establish a possible correlation between volume variation and both gender and age, as well as a relationship with Keros classification. Helical computed tomography images were obtained from 71 patients for analysis, in which the agger nasi cell, supra agger cell, supra agger frontal cell, supra bulla frontal cell, supraorbital ethmoidal cell, supra bulla cell, and frontal septal cell were identified and segmented to obtain their volume. Significant differences in volume were found for age and gender regarding agger nasi cells (p-value = 0.017), supra agger cells (p-value < 0.001), and frontal septal cells (p-value = 0.049). In the frontal septal cells, an increase of one year in age reduced the volume by 0.309, on average. According to Keros classification, the mean volumes were 10.07 and 25.64, respectively, for types II and III, both being greater than that of type I. Extracting volumetric data by using segmentation software in agger nasi cells, supra agger cells, and frontal septal cells may be useful for obtaining additional information related to age, in addition to possibly contributing to elucidating the anatomical variations in the region and an identification forensic tool.

The Draf III procedure: A review of indications and techniques

The Draf Ⅲ procedure involves the creation of a common frontal sinus cavity. The most common indication for the Draf Ⅲ procedure is chronic rhinosinusitis of the frontal sinuses despite the failure of more conservative interventions such as bilateral Draf Ⅱa procedures. Primary Draf Ⅲ may be indicated in patients with a high risk of failures such as those with severe polyposis and those with a frontal sinus opening less than 4 mm on computed tomography imaging. Other indications for the Draf Ⅲ include access for tumor removal and repair of traumatic fractures of the frontal sinus. The “inside‐out” Draf Ⅲ procedure is the standard approach when the frontal recess anterior–posterior diameter is wide enough for instrument access, usually larger than 4–5 mm. The “outside‐in” Draf Ⅲ procedure can be done when the frontal recess is too narrow to safely accommodate instruments. Regular follow‐up with debridement should be done to prevent neo‐ostium stenosis.

Rare Presentations of Frontal Sinus Fungus Ball: A Systematic Review

Introduction The sinus fungus ball is an agglomeration of debris and hyphae, mainly caused by Aspergillus fumigatus, within the paranasal sinus, commonly affecting a single sinus, and it only rarely affects the frontal sinus.

Objective To identify the state of the art of fungus ball in paranasal sinuses, especially related to the epidemiology of the disease in the frontal sinus. Additionally, this article reports a rare case of fungus ball in the frontal sinus in an adult male, and discusses the variables of this condition related to the patient.

Data Synthesis All of the 8 cases of fungus ball in the frontal sinus reported in this study affected male patients: 40% had unilateral disease, and 60%, bilateral disease, contrary to the incidence data of fungus ball in the other paranasal sinuses, which reports unilateral prevalence. However, in the present study, this index changes, with 50% of unilateral and 50% of bilateral incidence regarding frontal sinus involvement. The average age of the patients was 65.36 years (range: 60-74 years). The etiologic agent was Aspergillus spp., and the endonasal endoscopic therapeutic approach corresponded to 80% of cases, while frontal osteoplasty accounted for 20% of cases, reaffirming the prevalence data from other studies.

Conclusion Despite being a low-incidence entity, frontal sinus fungus ball should be considered in patients with pain in the frontal region refractory to the usual clinical treatments.

Three dimensional computer tomography analysis of frontal recess cells, difficulties in identification cells in patients witch diffuse primary chronic rhinosinusitis. The International Frontal Sinus Anatomy Classification (IFAC)

ABSTRACT BACKGROUND: The International Frontal Sinus Anatomy Classification (IFAC) is a consensus document created to standardize and specify the naming of cells within the region of the frontal recess and frontal sinus. The aim of this study was to analyze the difficulties in identifying cells according to the IFAC in patients with diffuse primary chronic rhinosinusitis. METHODS: Three independent reviewers examined triplanar computed tomography (CT) scans to assess the anatomy of the frontal recess using the IFAC system. CT scans were chosen randomly and divided into 3 groups: CT scans of patients not presenting sinus complaints (control group), CT scans of patients affected by diffuse primary chronic rhinosinusitis non-type 2, and CT scans of patients affected by diffuse primary chronic rhinosinusitis type 2. RESULTS: Identification of all frontal cell types was accurate in patients not presenting sinus complaints (p-value <0,05). Patients scoring 9 or more points in the Lund-Mackay scoring system demonstrated a statistically increase of risk of improper identification of frontal recess cells (p-value <0,0001). CONCLUSIONS: Due to the large number of possible anatomical variants and changes caused by the chronic inflammatory disease, the IFAC nomenclatura is easier to apply to non-type 2 primary diffuse CRS patients with low scores in the L-M scores scale than to primary diffuse type 2 CRS patients with higher M-L scores.