Are coding systems of frontal sinuses anatomically reliable? A study of correlation among morphological and metrical features.

Frontal sinuses are of special interest for personal identification thanks to their high variability. A common procedure for comparing ante-mortem and post-mortem material is based on coding systems classifying frontal sinuses according to their morphological and metrical characteristics. However, the calculation of possible combinations is performed on the hypothesis that all the classified features are independent one from each other. This study aims at analysing the correlation among morphological and metrical characteristics of frontal sinuses. Two hundred CT scans of patients equally divided between males and females were segmented through the ITK-SNAP software. Number of accessory septations, scalloping and supra-orbital cells, side asymmetry and superiority, breadth, height, length and volume were extracted from the frontal sinuses of each subject. A possible relationship among morphological and metrical features was analysed through Pearson's correlation test, Mann-Whitney test or chi-square test according to the type of compared data (p < 0.05). In general, a positive correlation was found for all comparisons among metrical measurements (breadth, height, depth and volume) and number of septations, scalloping and supra-orbital cells (p < 0.05), but not between the number of scalloping and supra-orbital cells. In addition, side of asymmetry was positively related with side of superiority of the upper profile of frontal sinuses (p < 0.05). This study proved that morphological and metrical characteristics of frontal sinuses are strictly related one with each other: therefore, the coding systems based on these features should be applied with caution for personal identification, as the number of possible combinations is lower than reported by literature.

Current view on the structure and function of the frontal sinus: literature review.

OBJECTIVE: Introduction: Chronic inflammatory diseases of the mucous membranes of the nose, paranasal sinuses, and pharynx are the most common pathology of the upper airways. Pathological processes develop more often in the maxillary and ethmoidal sinuses than in the frontal ones; however, the clinical course of frontitis is more severe. Fundamental understanding of the specific structure of frontal sinuses is crucial in the awareness of the precursors of the onset and development of its pathology, the choice of methods of diagnostics and treatment. The aim: The paper was aimed at the analysis of the publications on current data related to the structure and functions of the human frontal sinus and its structural components. Materials and methods: The bibliosemantic method has been used during the study. Findings of the current research works on the study of the human frontal sinus have been analyzed. RESULTS: Review: The resulting analysis shows that despite the significant amount of research works devoted to the study of the structure and functions of the frontal sinus, the morphofunctional features of its mucosa and the state of local immune protection remained unknown for a long time. CONCLUSION: Conclusions: The resulting literature review showed that the study of the morphofunctional properties of the frontal sinus is relevant to date that is reflected in the number of research works, elucidating its topographoanatomical, histological, physiological and immunohistochemical features.

The biomechanical significance of the frontal sinus in Kabwe 1 (Homo heidelbergensis).

Paranasal sinuses are highly variable among living and fossil hominins and their function(s) are poorly understood. It has been argued they serve no particular function and are biological 'spandrels' arising as a structural consequence of changes in associated bones and/or soft tissue structures. In contrast, others have suggested that sinuses have one or more functions, in olfaction, respiration, thermoregulation, nitric oxide production, voice resonance, reduction of skull weight, and craniofacial biomechanics. Here we assess the extent to which the very large frontal sinus of Kabwe 1 impacts on the mechanical performance of the craniofacial skeleton during biting. It may be that the browridge is large and the sinus has large trabecular struts traversing it to compensate for the effect of a large sinus on the ability of the face to resist forces arising from biting. Alternatively, the large sinus may have no impact and be sited where strains that arise from biting would be very low. If the former is true, then infilling of the sinus would be expected to increase the ability of the skeleton to resist biting loads, while removing the struts might have the opposite effect. To these ends, finite element models with hollowed and infilled variants of the original sinus were created and loaded to simulate different bites. The deformations arising due to loading were then compared among different models and bites by contrasting the strain vectors arising during identical biting tasks. It was found that the frontal bone experiences very low strains and that infilling or hollowing of the sinus has little effect on strains over the cranial surface, with small effects over the frontal bone. The material used to infill the sinus experienced very low strains. This is consistent with the idea that frontal sinus morphogenesis is influenced by the strain field experienced by this region such that it comes to lie entirely within a region of the cranium that would otherwise experience low strains. This has implications for understanding why sinuses vary among hominin fossils.

Classification of suprabullar pneumatization according to the skull base attachment of the second lamella.

The skull base attachment of the second lamella and suprabullar pneumatization are likely to be consistent landmarks if they are systematically classified. This study aimed to classify the pneumatization pattern according to the second lamella skull base attachment. A total of 202 computed tomography sides of 101 patients who underwent endoscopic sinus surgery were studied. Suprabullar pneumatization was defined as air cells present above the ethmoid bulla between the second and third lamellae. Its pattern was classified according to the air cell number and location as in the frontal cell classification. Type 0 suprabullar pneumatization was defined as no air cells between the ethmoid bulla and skull base; type 1, as a single suprabullar cell; and type 2, as multiple suprabullar cells above the ethmoid bulla. In type 3 pneumatization, the second lamella extended into the frontal sinus forming a frontal bullar cell. Type 2 was the most prevalent (40.1 %), followed by types 1, 3, and 0 (24.3, 23.3, and 12.4 %, respectively). The distance between the second lamella and anterior ethmoid artery was 8.93, 8.30, 8.50, and 11.25 mm in types 0, 1, 2, and 3 pneumatization, respectively. No patients had intraoperative injuries in the anterior ethmoid artery or lateral lamella. The second lamella skull base attachment and suprabullar pneumatization pattern could be systematically classified and be a consistent landmark to identify the frontal sinus opening.

Role of the Frontal Sinus in Mediating Ocular Vestibular-Evoked Myogenic Potentials by Bone Vibration Stimuli Applied to the Forehead.

This study investigated ocular vestibular-evoked myogenic potential (oVEMP) tests via Fpz and Fz taps to assess the role of the frontal sinus in mediating oVEMP elicitation. Forty healthy subjects and 80 patients with Ménière disease (MD) underwent a series of oVEMP tests via a minishaker tapping at the Fpz and Fz sites in a randomized order. Response rates of oVEMP test via various tapping sites were compared. Dimensions of the frontal sinus were measured via CT scan. A significantly negative correlation between the age and height of the frontal sinus was noted, and the cutoff age for discriminating present and absent Fpz oVEMPs in MD patients was 52 years. Additionally, oVEMPs by Fpz tapping were more efficiently presented in males than females, likely because of the greater resonance by the larger height of the frontal sinus in males (3.88 ± 0.68 cm) than females (3.42 ± 0.67 cm). In conclusion, the height of the frontal sinus plays a role in mediating the elicitation of oVEMPs. The oVEMPs could be easily elicited by the first-order bone vibration (Fpz/Fz tapping) coupled with the second-order resonance effect (with a high extent of the frontal sinus). Thus, initial tapping at the Fpz site is suggested. If it fails, try the Fz site for screening the oVEMPs.

Spontaneous ventilation of the frontal sinus after fractures involving the frontal recess.

PURPOSE: Frontal sinus fractures (FSF) have potentially catastrophic consequences due to frontal recess (FR) obstruction and proximity to the brain and orbit. Lack of follow-up and ability to predict which type of fractures predispose to complications has biased surgeons toward definitive interventions such as sinus obliteration and cranialization. These procedures carry inherent risk and may be unnecessary in a subset of patients. This study seeks to better characterize spontaneous ventilation in subjects with FSFs, including those involving the FR. MATERIALS AND METHODS: Review of a prospectively maintained trauma database between 2009 and 2013 at a level 1 trauma center. Patients with frontal sinus fractures with follow-up imaging (>6 weeks) available were included. The medical records and imaging were reviewed for evidence of spontaneous ventilation of the frontal sinus. RESULTS: Nineteen patients sustained frontal sinus fractures in the study period with mean imaging interval of 67.4 weeks (range, 6-188.4 weeks). Injury mechanisms included fall (32%), assault (31%), motor vehicle accident (17%), pedestrian-versus-automobile (12%), and gunshot wound (8%). 8/19 patients (42%) sustained FSFs involving the FR and 7/8 (87.5%) spontaneously ventilated by time of interval imaging. The one patient with persistent radiographic sinus opacification was associated with a naso orbital ethmoid and medial orbital blowout fracture. 6/19 patients (32%) sustained FSF sparing the FR, and all spontaneously ventilated by the time of interval imaging. 5/19 patients (26%) underwent surgical intervention. CONCLUSIONS: An expectant, sinus-preserving approach to acute FSFs involving the FR is safe and effective. Etiology of re-ventilation failure may be due to tissue obstruction, rather than the frontal recess fracture itself.

Finite element analysis of ramming in Ovis canadensis.

The energy produced during the ramming of bighorn sheep (Ovis canadensis) would be expected to result in undesirable stresses in their frontal skull, which in turn would cause brain injury; yet, this animal seems to suffer no ill effects. In general, horn is made of an α-keratin sheath covering a bone. Despite volumes of data on the ramming behavior of Ovis canadensis, the extent to which structural components of horn and horn-associated structure or tissue absorb the impact energy generated by the ramming event is still unknown. This study investigates the hypothesis that there is a mechanical relationship present among the ramming event, the structural constituents of the horn, and the horn-associated structure. The three-dimensional complex structure of the bighorn sheep horn was successfully constructed and modeled using a computed tomography (CT) scan and finite element (FE) method, respectively. Three different three-dimensional quasi-static models, including a horn model with trabecular bone, a horn model with compact bone that instead of trabecular bone, and a horn model with trabecular bone as well as frontal sinuses, were studied. FE simulations were used to compare distributions of principal stress in the horn and the frontal sinuses and the strain energy under quasi-static loading conditions. It was noticed that strain energy due to elastic deformation of the complex structure of horn modeled with trabecular bone and with trabecular bone and frontal sinus was different. In addition, trabecular bone in the horn distributes the stresses over a larger volume, suggesting a mechanical link between the structural constituents and the ramming event. This phenomenon was elucidated through the principal stress distribution in the structure. This study will help designers in choosing appropriate material combinations for the successful design of protective structures against a similar impact.

Theoretical and experimental investigation of the influence of frontal sinus on the sensitivity of the NIRS signal in the adult head.

The sensitivity of the near-infrared spectroscopy signal to the brain activation depends on the thickness and structure of the superficial tissues. The influence of the frontal sinus, which is void region in the skull, on the sensitivity to the brain activation is investigated by the time-resolved experiments and the theoretical modelling of the light propagation in the head. In the time-resolved experiments, the mean-time of flight for the forehead scarcely depends upon the existence of the frontal sinus when probe spacing was shorter than 30 mm. The partial optical path length in the brain, which indicates the sensitivity of the near-infrared spectroscopy signal to the brain activation, in a simplified head model is predicted by Monte Carlo simulation. The influence of the frontal sinus on the sensitivity of the signal depends on the thickness of the skull and the depth of the frontal sinus.

Three-dimensional reconstruction based on computed tomography images of the frontal sinus drainage pathway.

OBJECTIVE: This study aimed to investigate the utility of three-dimensional reconstructions of paranasal sinus computed tomography data in depicting the anatomy of the frontal sinus drainage pathway. METHODS: Twenty-nine patients underwent imaging of the sinuses for various clinical indications. Variations in frontal sinus recess anatomy were determined from 0.75-mm thick coronal, axial and sagittal computed tomography images. Three-dimensional, reformatted images were generated from manually segmented volumes of interest. Observations were made on the variation and usefulness of these reconstructions. RESULTS: Three-dimensional, reformatted images of segmented volumes aided delineation of the spatial relationships of the frontal sinus, frontal sinus drainage pathway, infundibular and meatal direction of drainage, agger nasi cells, ethmoid bulla cells, supraorbital cells, and suprabullar cells. CONCLUSION: Three-dimensional, reformatted images of frontonasal anatomy enable improved understanding of the frontal sinus drainage pathway anatomy and of the spatial relationships between ethmoid air cells in this region. Such images may provide a useful adjunct to surgical planning and education.

Frontal sinuses and head-butting in goats: a finite element analysis.

Frontal sinuses in goats and other mammals have been hypothesized to function as shock absorbers, protecting the brain from blows during intraspecific combat. Furthermore, sinuses are thought to form through removal of ;structurally unnecessary' bone. These hypotheses were tested using finite element modeling. Three-dimensional models of domesticated goat (Capra hircus) skulls were constructed, with variable frontal bone and frontal sinus morphology, and loaded to simulate various head-butting behaviors. In general, models with sinuses experienced higher strain energy values (a proxy for shock absorption) than did models with unvaulted frontal bones, and the latter often had higher magnitudes than models with solid vaulted frontal bones. Furthermore, vaulted frontal bones did not reduce magnitudes of principal strain on the surface of the endocranial cavity relative to models with unvaulted frontal bones under most loading conditions. Thus, these results were only partially consistent with sinuses, or the bone that walls the sinuses, acting as shock absorbers. It is hypothesized that the keratinous horn sheaths and cranial sutures are probably more important for absorbing blows to the head. Models with sinuses did exhibit a more ;efficient' distribution of stresses, as visualized by histograms in which models with solid frontal bones had numerous unloaded elements. This is consistent with the hypothesis that sinuses result at least in part from the removal of mechanically unnecessary bone.

Reconstruction and morphometric analysis of the nasal airway of the dog (Canis familiaris) and implications regarding olfactory airflow.

The canine nasal airway is an impressively complex anatomical structure, having many functional roles. The complicated branching and intricate scrollwork of the nasal conchae provide large surface area for heat, moisture, and odorant transfer. Of the previous anatomical studies of the canine nasal airway, none have included a detailed rendering of the maxilloturbinate and ethmoidal regions of the nose. Here, we present a high-resolution view of the nasal airway of a large dog, using magnetic resonance imaging scans. Representative airway sections are shown, and a three-dimensional surface model of the airway is reconstructed from the image data. The resulting anatomic structure and detailed morphometric data of the airway provide insight into the functional nature of canine olfaction. A complex airway network is revealed, wherein the branched maxilloturbinate and ethmoturbinate scrolls appear structurally distinct. This is quantitatively confirmed by considering the fractal dimension of each airway, which shows that the maxilloturbinate airways are more highly contorted than the ethmoidal airways. Furthermore, surface areas of the maxilloturbinate and ethmoidal airways are shown to be much different, despite having analogous physiological functions. Functionally, the dorsal meatus of the canine nasal airway is shown to be a bypass for odorant-bearing inspired air around the complicated maxilloturbinate during sniffing for olfaction. Finally, nondimensional analysis is used to show that the airflow within both the maxilloturbinate and ethmoturbinate regions must be laminar. This work has direct relevance to biomimetic sniffer design, chemical trace detector development, intranasal drug delivery, and inhalation toxicology.

An integrated approach to frontal sinus surgery.

This article the most useful procedures into into a comprehensive integrated approach to frontal sinus surgery. It begins with the least invasive and progresses to the most invasive procedure in a step-by-step fashion, which can be applied as needed. The selection of procedure is governed the patient's disease anatomy,and the surgeons skill. The least invasive procedure that can be used should be attempted first, and then, if more is needed, other procedures can be added, either at the same sitting or in subsequent revisions.

The effect of the modified endoscopic Lothrop procedure on the mucociliary clearance of the frontal sinus in an animal model.

BACKGROUND: The surgical management of recalcitrant frontal sinus disease has been a dilemma for otolaryngologists for many years. Although the osteoplastic flap with obliteration has been the gold standard of treatment for years, the modified endoscopic Lothrop (MEL) procedure recently has been advocated as an alternative. However, little is known about the effect of this procedure on the mucociliary drainage of the frontal sinuses postoperatively and this animal study addresses this issue. METHODS: Fourteen sheep underwent the MEL procedure. The sheep were randomized regarding the use of postoperative irrigation via minitrephines. Each sheep had a nuclear medicine gamma-scintigraphy frontal sinus clearance study via minitrephines performed on each frontal sinus preoperatively and then 3 months postoperatively. Then, the results of these studies were compared. RESULTS: The scans revealed a trend toward faster clearance times postoperatively. However, this decrease was not statistically significant. Importantly, there was no trend or significant increase in clearance times postoperatively. Also, the use of postoperative irrigation was associated with a nonsignificant trend toward faster clearance times postoperatively. CONCLUSION: The MEL procedure has no adverse effects on the mucociliary clearance of the frontal sinus at 3 months postoperatively. Irrigation of the frontal sinus in the immediate postoperative period showed a trend toward improved postoperative mucociliary function at 3 months.

Clinically relevant frontal sinus anatomy and physiology.

Management of frontal sinus disease has evolved considerably with the advent of endoscopic paranasal sinus instrumentation. With this evolution has come the increased demand for anatomic competence among otolaryngologists. Armed with a better understanding of the complex frontal sinus and anterior ethmoid complex anatomy, the otolaryngologist can target the anatomic abnormalities that predispose an individual to frontal sinus disease and limit the effectiveness of medical and surgical management.

[Animal experiments on the frontal sinus development after craniofacial surgery on the frontal bone in Göttingen miniature pigs]. / Tierexperimentelle Untersuchungen zur Stirnhöhlenentwicklung nach kraniofazialer Austauschplastik des Os frontale beim Göttinger Miniaturschwein.

According to the literature, the development of the frontal sinus is a result of the active immigration of cells from the ethmoidal complex into the os frontale. This migration theory is in contrast to the results in patients with Apert's syndrome. When front-orbital advancement at the age of a few months is performed in these patients--at a time when the frontal suture is not yet closed--a sinus developed despite the distance between nasal root and os frontale, being up to 2 cm. In order to investigate the development of the frontal sinus, an animal study in 12 juvenile Goettingen minipigs (age 5-6 weeks) with histologically pronen un-developed frontal sinus was performed. To exclude the emigration of ethmoidal complex cells into the frontale bone an orthotopical transposition of the frontale bone into the os occipitale was performed. Histologically the development of a frontal sinus in the frontal bone was excluded before transplantation. The macro- and microscopic comparison with a control group revealed that in the orthotopical transplants in the os occipitale an epithelium-lined sinus developed beginning from the 35th week. Based on our histomorphological results, a development scheme for the genesis of the sinus frontalis and a model is drawn.

Frontal sinus outflow anatomy.

Most of the studies of frontal sinus anatomy were completed 50 to 70 years ago. The information they provide is not necessarily relevant or helpful to the modern rhinologic surgeon who approaches the frontal sinus transnasally and endoscopically. We performed anatomical dissections of the outflow tract of 82 frontal sinuses in 41 cadaver heads to illustrate the various drainage patterns from the frontal sinus to the nose and to correlate these drainage sites with the distance and angle from the pyriform aperture. We found that the frontal sinus drained anterior to the uncinate process in 24 specimens (29.3%) with an average distance of 3.65 cm from the pyriform aperture and 58 degrees from the nasal floor. The frontal sinus drained posterior to the uncinate process in 56 specimens (68.3%) with an average distance of 4.10 cm and 65 degrees from the nasal floor. In this latter group, most of the sinuses (51 specimens) drained into the ethmoid infundibulum. Two of the specimens had a hypoplastic frontal sinus with no outflow tract at all. These findings are different from those described in the early 20th century.

Diagnostic techniques in chronic sinusitis: endoscopy, sinusomanometry.

The first endoscope was conceived as early as 1806. Since then successive technical advances led endoscopy of the nose and paranasal sinuses to a routine procedure. From the rediscovery of the rigid telescopes by Hopkins in the fifties, progress has stemmed essentially from the quality of the more powerful cold lights and the improvement in the light output of the fiber optics. Exam procedures of the nose and sinuses are conducted under general as well as local anesthesia, and are commonly combined with concomitant diagnostic procedures: measure of the mucociliary clearance with indicators, biopsies, smear sampling for bacterial and fungal examinations, and sinusomanometry which can help to estimate the patency of the maxillary ostium and of the nasofrontal duct. Sinus endoscopy has been widely used to correlate efficiency of other diagnostic techniques such as plain X-rays, CT scanners, A and B mode ultrasonography. A similar work should be done for MRI. Endoscopic exploration is the key to the management of chronic pathology as it brings precise information on the quality of the naso-sinus mucosa, the presence of secretions and, combined with sinusomanometry, the functional state of the ostia or ducts.

Methods for measurement/evaluation of the maxillary and frontal sinus ostial function.

Several test methods for evaluation of the maxillary and frontal sinus ostial function have been described. The test methods can be divided up as follows. Invasive methods: Measurements during spontaneous breathing and measurements during artificial pressure application. Non-invasive methods: Methods with pure stable xenon and xenon133. The most physiological invasive method is measurement during spontaneous nasal breathing and simultaneous recording of the pressure difference over the ostium and air flow through the ostium. Hereby, the ostial resistance can be calculated and the equivalent ostial diameter be estimated. Ostial equivalent diameters up to 2.5 mm can be calculated. By measurement of the pressure difference between the sinus and nose during application of a constant air flow of 1 liter per minute into the sinus, the pressure increase corresponds to the equivalent ostial diameter. Ostial equivalent diameters up to 4.7 mm can be estimated. Non-invasive methods with stable xenon and xenon133 permit an overall evaluation of the ventilation of the paranasal sinuses. However, these methods will only give indirect information about the ostial condition. The non-invasive methods have to be compared with the invasive methods in order to find out if the wash out curves correspond to the equivalent ostial diameter.