Sinusitis

Sinusitis is an inflammation of the paranasal sinuses, which may or may not be as a result of infection, from bacterial, fungal, viral, allergic or autoimmune issues. Newer classifications of sinusitis refer to it as rhinosinusitis, taking into account the thought that inflammation of the sinuses cannot occur without some inflammation of the nose as well (rhinitis).

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There are several paired paranasal sinuses, including the frontal, ethmoid, maxillary and sphenoid sinuses. The ethmoid sinuses can also be further broken down into anterior and posterior, the division of which is defined as the basal lamella of the middle turbinate. In addition to the acuity of disease, discussed below, sinusitis can be classified by the sinus cavity which it affects:

There are several paired paranasal sinuses, including the frontal, ethmoid, maxillary and sphenoid sinuses. The ethmoid sinuses can also be further broken down into anterior and posterior, the division of which is defined as the basal lamella of the middle turbinate. In addition to the acuity of disease, discussed below, sinusitis can be classified by the sinus cavity which it affects:

• Maxillary sinusitis - can cause pain or pressure in the maxillary (cheek) area (e.g., toothache, headache)
• Frontal sinusitis - can cause pain or pressure in the frontal sinus cavity (located behind/above eyes), headache
• Ethmoid sinusitis - can cause pain or pressure pain between/behind eyes, headache
• Sphenoid sinusitis - can cause pain or pressure behind the eyes, but often refers to the vertex of the head

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. All forms of sinusitis may either result in, or be a part of, a generalized inflammation of the airway so other airway symptoms such as cough may be associated with it.

By duration

Sinusitis can be acute (going on less than four weeks), subacute (4-12 weeks) or chronic (going on for 12 weeks or more).

All three types of sinusitis have similar symptoms, and are thus often difficult to distinguish.
Acute sinusitis

Acute sinusitis is usually precipitated by an earlier upper respiratory tract infection, generally of viral origin. Virally damaged surface tissues are then colonized by bacteria, most commonly Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis and Staphylococcus aureus. Other bacterial pathogens include other streptococci species, anaerobic bacteria and, less commonly, gram negative bacteria. Another possible cause of sinusitis can be dental problems that affect the maxillary sinus. Acute episodes of sinusitis can also result from fungal invasion. These infections are most often seen in patients with diabetes or other immune deficiencies (such as AIDS or transplant patients on anti-rejection medications) and can be life threatening. In type I diabetes, ketoacidosis causes sinusitis by Mucormycosis.

Chronic sinusitis

Chronic sinusitis is a complicated spectrum of diseases that share chronic inflammation of the sinuses in common. The causes are multifactorial and may include allergy, environmental factors such as dust or pollution, bacterial infection, or fungus (either allergic, infective, or reactive). Non allergic factors such as Vasomotor rhinitis can also cause chronic sinus problems.

Symptoms include: Nasal congestion; facial pain; headache; fever; general malaise; thick green or yellow discharge; feeling of facial 'fullness' worsening on bending over; aching teeth.

Very rarely, chronic sinusitis can lead to Anosmia, the inability to smell or detect odors. In a small number of cases, chronic maxillary sinusitis can also be brought on by the spreading of bacteria from a dental infection.

Attempts have been made to provide a more consistent nomenclature for subtypes of chronic sinusitis. A task force for the American Academy of Otolaryngology - Head and Neck Surgery / Foundation along with the Sinus and Allergy Health Partnership broke Chronic Sinusitis into two main divisions, Chronic Sinusitis without polyps and Chronic Sinusitis with polyps (also often referred to as Chronic Hyperplastic Sinusitis). Recent studies which have sought to further determine and characterize a common pathologic progression of disease have resulted in an expansion of proposed subtypes. Many patients have demonstrated the presence of eosinophils in the mucous lining of the nose and paranasal sinuses. As such the name Eosinophilic Mucin RhinoSinusitis (EMRS) has come into being. Cases of EMRS may be related to an allergic response, but allergy is often not documentable, resulting in further subcategorization of allergic and non-allergic EMRS.

Role of biofilms

Biofilms are complex aggregates of extracellular matrix and inter-dependant microorganisms from multiple species, many of which may be difficult or impossible to isolate using standard clinical laboratory techniques. Bacteria found in biofilms may show increased antibiotic resistance when compared to free-living bacteria of the same species. It has been hypothesized that biofilm-type infections may account for many cases of antibiotic-refractory chronic sinusitis. A recent study found that biofilms were present on the mucosa of 3/4 of patients undergoing surgery for chronic sinusitis