Surgical anatomy of the frontal recess--is there a benefit in multiplanar CT-reconstruction?

Anatomical variations in the sinus region are not necessarily pathological, but they may complicate the anatomy of the lateral nasal wall and contribute to the occurrence or persistence of chronic inflammatory diseases. In this study the interpretations of initial coronal CT scans were significantly altered following multiplanar CT-reconstruction. Assuming that a multiplanar analysis includes coronal views, we may conclude that imaging in three planes yields more information and provides a substantial benefit in the planning and performance of a surgical procedure on the paranasal sinuses.

[Evaluation of the frontal recess cells with image-guided system].

Objective:To investigate the value of image-guided system in identifying the frontal recess cells.Method:We collected 30 cases that underwent image-guided frontal sinus surgery from November 2014 to December 2015. These frontal recess cells were devided into 2 groups based upon their locations in the frontal sinus ostium. Group A consists of the agger nasi cells, type Ⅰfrontal cells, type Ⅱ frontal cells and suprabullar cells; group B consist of type Ⅲ frontal cells, type Ⅳ frontal cells, frontal bullar cells, interfrontal sinus septal cells and supraorbital ethmoid cells. Visual analogue scale (VAS) was used to evaluate the degree of demand of image guide system on the location of frontal recess cells, and then analyzed the value of image guided system on the frontal recess cells.Result:In all 30 patients the imageguided frontal sinus surgery was successfully completed.The demand degree of image-guided system on frontal recess cells by VAS was slight for the agger nasi cells, type Ⅰfrontal cells, type Ⅱ frontal cells and suprabullar cells; the demand degree was general for the frontal bullar cells and interfrontal sinus septal cells; the demand degree was obvious for type Ⅲ frontal cells, type Ⅳ frontal cells and supraorbital ethmoid cells. Frontal recess cells of group B were more depended on image guided system than those of group A, and the difference was signicant(P <0.01).Conclusion:Imageguided system is valuable in distinguishing for type Ⅲ frontal cells,type Ⅳ frontal cells supraorbital ethmoid cells and interfrontal sinus septal cells.Furthermore,it is significantly helpful for accurate removal of these frontal recess cells in endoscopic frontal sinus surgery.

Multiplanar computed tomographic analysis of frontal recess cells: effect on frontal isthmus size and frontal sinusitis.

BACKGROUND: Frontal recess anatomy can be very complex, with accessory cells such as frontal, agger nasi, and intersinus septal cells encroaching on the frontal recess and possibly contributing to obstruction of the frontal sinus. In this study, we determined the prevalence of these cells and their relationship to frontal sinusitis in patients who have (revision group) and have not (primary group) had previous sinus surgery. DESIGN: Multiplanar computed tomographic images were reconstructed on a computer workstation to determine the presence of frontal, agger nasi, and intersinus septal cells and frontal sinusitis. We also measured the diameter and area of the frontal isthmus for each sinonasal cavity. We were able to retrieve 106 of 117 images from a surgical database encompassing the previous 2 years. SETTING: Tertiary care academic practice of the senior author. RESULTS: Frontal cells were found in 25.5% of frontal recesses, including 29.6% of sides in the primary group and 21.9% of sides in the revision group. We identified 33.0% of patients as having unilateral or bilateral frontal cells. Type I cells were the most common cell (18.4% of primary sinuses). The presence of frontal sinusitis and the diameter and area of the frontal isthmus were not significantly different for those patients with compared with patients without frontal cells. Intact agger nasi cells were identified in 86.7% of primary sinuses and 53.5% of revision sinuses. There was no increased incidence of frontal sinusitis in patients with persistent agger nasi cells in the revision group. CONCLUSIONS: When we evaluated multiplanar reconstructions, we identified frontal cells in 33.0% of patients overall, which was more common than previously reported. The findings of agger nasi cells indicated that these cells were likely addressed in less than half of previous sinus procedures. However, frontal cells and retained agger nasi cells were not associated with a higher incidence of frontal sinusitis, and there was no association between the size of the frontal isthmus and the presence of frontal sinusitis. Although anatomic variations in the frontal recess are likely to play a role in frontal sinusitis, mucosal inflammatory processes are likely to be a much more important etiologic factor.

Mapping the frontal sinus ostia using virtual endoscopy.

OBJECTIVES/HYPOTHESIS: To determine the relative location of the frontal sinus opening to other frontal cells using virtual endoscopy; and to assess whether the relative location of the frontal sinus ostium can be predicted. STUDY DESIGN: Retrospective analysis of high-resolution computed tomography scans from 50 adult patients without frontal sinus disease or previous sinus surgery. METHODS: Using virtual endoscopy software, 100 frontal recesses were mapped for the presence and relative position of the frontal sinus ostium to the following cells: agger nasi (ANC); frontal bullar; frontal types 1, 2, and 3; supraorbital ethmoid; suprabullar; and intersinus septal cells. RESULTS: ANC and frontal type 3 cells were present in 92% and 45% of frontal recesses, respectively. All other cell types had a prevalence of ≤ 25%. Fifty percent of recesses had two rows of ostia anterior to posterior (AP), and the frontal opening was anterior in 52%. When there were three rows of cells AP (39%), the frontal opening was in the center in 64% of cases. Thirty-five percent of recesses had two rows of ostia medial to lateral (ML), and the frontal opening was medial 80% of the time. When there were three rows of openings ML (45%), the frontal opening was in the center 56% of the time. CONCLUSIONS: The frontal sinus recess is variable and complex. Virtual endoscopy can be used to analyze the frontal recess and assist in presurgical planning. Although there is variability in the ostial configuration present in the frontal recess, the probable position of the frontal sinus ostium can be predicted.

The frontal intersinus septal air cell: a new hypothesis of its origin.

BACKGROUND AND PURPOSE: Air cells are often seen within the frontal intersinus septum. These cells have traditionally been thought to arise from displaced ethmoid cells from the frontal recess. This study explores the possibility that such cells may actually be diverticula from the frontal sinuses themselves and not of a direct ethmoid origin. MATERIALS AND METHODS: A prospective study of 200 consecutive CT scans in the coronal and axial planes was performed on patients without a history of recent trauma. The images were interpreted independently by a radiologist and an otolaryngologist. The CT studies were evaluated for the presence of a central intersinus septal air cell. If such a cell was identified, it was further classified as either being completely isolated from both frontal sinuses by a bony rim or as a communicating diverticulum from one of the frontal sinuses. If a central cell was present, it was also assessed for how much of the height of the intersinus septum it involved (lower one-half or full height). RESULTS: There was a complete concordance of the results between the 2 observers. An intersinus septal air cell was seen in 61 (30.5%) of the 200 cases, and 85.3% of these cells were clearly seen to communicate anteromedially with either one of the frontal sinuses or both frontal sinuses (3 cases). In 9 (4.5%) of the 200 cases, the central cell had no demonstrable connection to either frontal sinus. Of the 61 cases with a central cell, 55 (90.16%) of the cells occupied the full height of the septum, and 6 (9.84%) only involved the lower half of the septum. CONCLUSION: Contrary to the present convention that frontal intersinus septal cells originate as displaced ethmoid cells from the frontal recess, we found that most such cells are actually diverticula from the frontal sinuses themselves.

Quantitative histologic features of the normal frontal sinus.

The entire mucosa from 30 normal frontal sinuses was removed, stained by the whole mount method, and the density of goblet cells and mucous glands was determined. There was an average of 6,300 goblet cells per square millimeter without statistically significant differences between the various walls. The glands were small and seromucous. In 87% of the sinuses, the gland density was less than 0.2 glands per square millimeter, and the total gland count did not exceed 40. This represents a totally negligible mucus production, which must be derived predominantly from the goblet cells. The density proved significantly higher in the inferior parts of the sinuses. The findings are discussed in relation to other areas of the respiratory tract.

Multiplanar reconstructed computed tomography images improves depiction and understanding of the anatomy of the frontal sinus and recess.

AIMS: The use of multiplanar reconstructed computed tomography (CT) images of frontal recess and sinuses was assessed with regard to depiction and understanding of anatomy and effect on surgical approach. MATERIALS AND METHODS: Three otorhinolaryngologists and one radiologist read CT scans of 43 patients referred for routine paranasal sinus scans. Spiral (helical) CT scans were obtained and coronal and parasagittal reconstructions were imaged. Three hundred forty-two readings were analyzed. The scans were assessed in the coronal plane and then in the parasagittal plane. The images were assessed for (i) Bent and Kuhn classification of frontal ethmoidal sinus air cells, (ii) size of frontal sinus ostium (assessed as unsure, normal, small, or large), (iii) use of parasagittal scans regarding additional understanding of the anatomy with particular reference as to how the agger nasi cell and frontal ethmoidal cells were arranged in a three-dimensional space, and (iv) if the parasagittal scan and subsequent three-dimensional picture created altered the surgical approach. The first two criteria were assessed in the coronal plane and then in the parasagittal plane. RESULTS: There was no statistically significant difference between the Bent and Kuhn classification of frontoethmoidal cells on coronal and reconstructed parasagittal images (t-test; p > 0.05). The parasagittal scans were significantly better than the coronal scans for identifying and assessing the size of the frontal sinus ostium (p < 0.001; chi-square test). Assuming an intraobserver change rate (repeat error) of 10% on CT scan observations, an exact binomial test was performed on S-PLUS, which showed that there was a significant (p < 0.001) proportion of observers who changed their rating after looking at the parasagittal scan. There also was significant improvement in observers' abilities to identify and classify the size of the frontal ostium as reflected by the number of observers who changed from being unsure on the coronal scans to sure on the parasagittal scans. Observers felt that the parasagittal scans improved their three-dimensional understanding of the anatomy of the frontal recess by 58% on a 10-point Lickert scale. In 55% of these observations, the surgical plan was altered by a mean of 70.2% on a 10-point Lickert scale based on additional information obtained by viewing the parasagittal scans. CONCLUSIONS: The three-dimensional understanding of the frontal recess is improved greatly by using both coronal and parasagittal reconstructed images as compared with coronal images alone. This had important implications on the planning of the surgery in the frontal recess.

Formation of chondrous and osseous tissues in micromass cultures of rat frontonasal and mandibular ectomesenchyme.

Rat frontonasal and mandibular mesenchyme was isolated from day-12 1/2 (stage-22) rat embryos and cultured at high density for up to 12 days. The stage chosen was based on the observation that mandibular mesenchyme at this stage became independent of its epithelium with respect to the production of both cartilage and bone. Frontonasal cultures developed aggregates of anastomosing columns of cells within 2 days. These grew as the cells enlarged, laying down an Alcian-blue-positive matrix by day 3 of culture. Significant mineral was detected by von Kossa staining by day 5 at which time the aggregates covered a large portion of the culture, eventually covering the entire micromass by day 10-12. Mandibular cultures developed centrally located nodular aggregates by 3 days of culture. These nodules increased in number, spreading outwards as the cells enlarged, laying down an Alcian-blue-positive matrix by day 4 and mineral by days 6-7. At this time the nodules began to elongate and coalesce, but never covered the entire culture over the 12-day period. Antibody staining revealed that in both cultures the cells were initially positive for type I collagen. Subsequently, the aggregates began expressing type II collagen, followed by type X, which coincided with the onset of mineralization. At this time some cells were negative for these cartilage markers, but positive for osteoblast markers, bone sialoprotein II, osteocalcin and type I collagen. In addition osteonectin and alkaline phosphatase were demonstrable in all of the aggregate cells late in the culture period. This provided clear evidence that chondroblast and osteoblast differentiation was proceeding within these cultures. The culture of rat facial mesenchyme should prove very useful, not only for the analysis of bone and cartilage induction and lineage relationships, but also in furthering our knowledge of craniofacial differentiation, growth and pattern formation by extending our analysis to a mammalian system.