Frontal Outflow Research Articles

Frontal Sinus Posterior Table Fractures in a Goat

Problem The goal of this study was to investigate how patency of the nasofrontal outflow tract would affect the healing of the frontal sinus in the setting of displaced, posterior table fractures in the adult goat (Capra Hircus). Methods Prospective animal study. Posterior table fractures were created in twenty adult goats (Capra Hircus). The nasofrontal outflow tract was obstructed in 10 goats and left patent in 10. Gross, radiologic, and histological evaluation was carried out at six months post operatively. Results All posterior table fractures healed without gross or radiological evidence of mucosal ingrowth. Obstruction of the nasofrontal outflow tract resulted in an increased rate of mucocele formation. Histological analysis did not reveal significant mucosal ingrowth in either group. Conclusion An occluded nasal frontal outflow tract leads to an increase rate in mucocele formation at 6 months. There is no gross or radiographic evidence that mucosal ingrowth into the posterior table occurs at 6 months. These findings would suggest that not all significantly displaced posterior table fractures need to be surgically addressed if the nasofrontal outflow tract is patent. Significance Posterior frontal sinus table fracture treatment is based on poorly controlled animal studies from 30 years ago and small case series reports. Our aim in this study was to determine changes in the frontal sinus at 6 months after a displaced, comminuted frontal sinus fracture was created. We hope to provide evidence demonstrating that not all posterior table fractures need to be treated, especially if the nasofrontal outflow tract is intact.

Long-Term Results after Endoscopic Sinus Surgery Involving Frontal Recess Dissection

To assess long-term follow-up on a cohort of patients who underwent endoscopic frontal sinus surgery with identification and preservation of the natural frontal outflow tract. Retrospective chart review, telephone interview, and endoscopic evaluation on a previously studied cohort of patients at a university affiliated medical center. Two hundred patients who underwent endoscopic frontal sinus surgery were previously studied and reported after short-term (mean = 12.2 mo) follow-up. One hundred fifty-two (76%) patients were available for long-term (mean 72.3 mo) follow-up and assessment of subjective symptoms. Fifty-seven of 152 (37.5%) patients also had nasal endoscopy for evaluation of objective findings. The percentage of patients responding to telephone interview reporting overall improvement after surgery was 92.4%. Endoscopic assessment revealed patency of the frontal sinus in 67.6% of the patients after initial surgery. Thirteen additional patients had patent sinuses after revision procedures, bringing overall patency rate to 71.1%. We found statistically significant correlation of asthma and smoking and poor subjective and objective outcome. Long-term assessment of subjective and objective findings in our previously reported cohort of patients who underwent frontal sinus surgery indicates that the frontal sinus, similar to any other sinus, can be successfully treated surgically by preserving the natural frontal sinus outflow tract.

Estimation of the contribution of intercontinental transport during the PEACE campaign by using a global model

A quasi–real–time calculation system for the global distribution of ozone (O3) and its precursors, including CO, NOx, and nonmethane hydrocarbons (NMHCs), has been newly developed by using a 3–D chemical–transport model. The model is driven by meteorological data from the National Centers for Environmental Prediction (NCEP), and produces daily 7–day forecast of the distribution of chemical species. The model was used in daily flight planning for the Pacific Exploration of Asian Continental Emission (PEACE)–A and –B aircraft measurement campaigns in January and April–May 2002, respectively. Model–calculated meteorological fields show good agreement with aircraft observations. The model also reproduced events such as polluted air masses in the lower troposphere (LT) corresponding to post–frontal outflow, a high–concentration CO plume in the upper troposphere (UT) in late spring, and the observed plume that was transported by deep convection over central China. The amount of CO transported into the free troposphere (FT) by deep convection was estimated to be about 6 Tg CO over China in May 2002. Meridional and seasonal variations in the long–range transport (LRT) of CO tracers, Asian CO tracers, and CO tracers produced from the oxidation of CH4 and NMHCs were all evaluated using tagged CO tracers. LRT CO comprised about 36% of the total CO budget in December–February 2001/2002, and about 20% in March–May 2002 in the free troposphere over Japan. In late spring, the concentration of Asian CO over southern Japan decreased compared to that in winter because the wind direction shifted from northwesterly to easterly or southerly.

Outcomes of Frontal Mucocele Marsupialization: Endonasal and External Approaches

Frontal sinus mucoceles are known to undergo repeated recurrences, and the management of this disease constitutes a challenge regarding the ideal treatment. The aim of this study was to evaluate the postoperative results of the endoscopic ventilation approach in the treatment of frontal mucoceles. We retrospectively reviewed the charts of 24 subjects with mucocele who underwent endoscopic marsupialization. The preoperative characteristics of the frontal sinus on computed tomography scans were compared with the postoperative results. Postoperative endoscopic examination revealed in 15 nasal sides wide patency of the frontal outflow tract. The ostium was patent but had become slightly narrowed in nine nasal sides. Restenosis of the ostium was found in six cases. A membranous type of obstruction in the region of the frontal outflow tract was related to a better outcome.

Clouds and trace gas distributions during TRACE‐P

This paper addresses the question: To what extent do trace gas distributions correspond to cloudiness? Observations taken during NASA's TRACE‐P experiment indicate that there can be statistically significant differences in trace gas concentrations between clear‐sky and cloudy areas. During the TRACE‐P mission, frontal outflow of Asian emissions from the Pacific Rim to the western, North Pacific was sampled by NASA's DC‐8 and P‐3B aircraft. On several occasions, enhanced CO mixing ratios were observed in and around frontal clouds. A more detailed analysis of trace gas distributions revealed CO enhancements of 30% in the lower free troposphere (1–5 km) for cloudy regions as compared to clear areas. These enhancements exist within clouds as well as above and below clouds. In the upper free troposphere (5–11 km), overall enhancement in CO of 15% was observed although enhancements are mainly restricted to observations within clouds. These in‐cloud observations were enhanced by factors of 1.5 to 2 over clear air data. Similar enhancements were seen for many other anthropogenic tracers. By contrast, distributions for O3 revealed no clear differences between cloudy and clear regions suggesting that other influences (e.g., stratosphere‐troposphere exchange) might complicate any correspondence with local cloudiness. Expected cloud influences on oxidation chemistry were evident in enhanced OH concentrations above clouds and depressed OH below clouds. These findings are particularly relevant to current and future satellite investigations of the troposphere. Understanding the potential biases created by the inability to probe cloudy regions will improve the interpretation of regional and globally averaged satellite observations.

Frontal sinus stents.

The formation of scar tissue, synechiae, or osteogenesis in the narrow frontal outflow tract after instrumentation of the frontal sinus has led to attempts to enlarge the frontal duct or stenting. Prospective pilot study. Sixty-four Freeman frontal sinus stents were used to maintain patency in 46 patients. Stents were inserted using an endoscopic technique in 26 sinuses containing polyps, 20 with pansinusitis, and 18 cavities with stenosis of the frontal duct. External incisions with frontal sinusotomy were required to remove the stenosis and insert the stent in nine sinuses. Polypoid degeneration, granulation, purulent drainage, and lateralization of the middle turbinate were encountered infrequently. Frontal obliteration was subsequently required in six sinuses. The Freeman frontal sinus stent prevented blockage of the outflow tract in patients who had removal of disease in the sinus or duct or treatment of frontal stenosis.

Endoscopic Management of Frontal Sinus Disease

Educational objectives: To understand the different anatomic variations of the frontal outflow tract and to know the indications for and the surgical technique of endoscopic frontal sinusotomy.