The presence of eosinophils in the mucous lining of the nose and paranasal sinuses has been demonstrated for many people, and this has been termed eosinophilic mucin rhinosinusitis (EMRS). Cases of EMRS may be related to an allergic response, but allergy is not often documented, resulting in further subcategorization into allergic and nonallergic EMRS.A more recent, and still debated, development in chronic sinusitis is the role that fungi play in this disease. Whether fungi are a definite factor in the development of chronic sinusitis remains unclear, and if they are, what is the difference between those who develop the disease and those who remain free of symptoms. Trials of antifungal treatments have had mixed results.Recent theories of sinusitis indicate that it often occurs as part of a spectrum of diseases that affect the respiratory tract (i.e., the "one airway" theory) and is often linked to asthma.Both smoking and secondhand smoke are associated with chronic rhinosinusitis.Other diseases such as cystic fibrosis and granulomatosis with polyangiitis can also cause chronic sinusitis. Pathophysiology
Biofilm bacterial infections may account for many cases of antibiotic-refractory chronic sinusitis. Biofilms are complex aggregates of extracellular matrix and interdependent microorganisms from multiple species, many of which may be difficult or impossible to isolate using standard clinical laboratory techniques. Bacteria found in biofilms have their antibiotic resistance increased up to 1000 times when compared to free-living bacteria of the same species. A recent study found that biofilms were present on the mucosa of 75% of people undergoing surgery for chronic sinusitis.
The FDA recommends against the use of fluoroquinolones when other options are available due to higher risks of serious side effects.A short-course (3–7 days) of antibiotics seems to be just as effective as the typical longer-course (10–14 days) of antibiotics for those with clinically diagnosed acute bacterial sinusitis without any other severe disease or complicating factors. The IDSA guideline suggest five to seven days of antibiotics is long enough to treat a bacterial infection without encouraging resistance. The guidelines still recommend children receive antibiotic treatment for ten days to two weeks. Corticosteroids
For unconfirmed acute sinusitis, nasal sprays using corticosteroids have not been found to be better than a placebo either alone or in combination with antibiotics. For cases confirmed by radiology or nasal endoscopy, treatment with intranasal corticosteroids alone or in combination with antibiotics is supported. The benefit, however, is small.For confirmed chronic rhinosinusitis, there is limited evidence that intranasal steroids improve symptoms and insufficient evidence that one type of steroid is more effective.There is only limited evidence to support short treatment with corticosteroids by mouth for chronic rhinosinusitis with nasal polyps. There is limited evidence to support corticosteroids by mouth in combination with antibiotics for acute sinusitis; it has only short-term effect improving the symptoms. Surgery
For sinusitis of dental origin, treatment focuses on removing the infection and preventing reinfection, by removal of the microorganisms, their byproducts, and pulpal debris from the infected root canal.