Sinusitis is inflammation of the paranasal sinuses, which may be due to infection, allergy, or autoimmune issues. Most cases are due to a viral infection and resolve over the course of 10 days. It is a common condition; for example, in the United States more than 24 million cases occur annually.
There are several paired paranasal sinuses, including the frontal, ethmoid, maxillary and sphenoid sinuses.
The ethmoid sinuses is further subdivided into anterior and posterior ethmoid sinuses, the division of which is defined as the basal lamella of the middle turbinate.
In addition to the severity of disease, discussed below, sinusitis can be classified by the sinus cavity which it affects:
Maxillary – can cause pain or pressure in the maxillary (cheek) area (e.g., toothache, headache)
Frontal – can cause pain or pressure in the frontal sinus cavity (located above eyes), headache
Ethmoid – can cause pain or pressure pain between/behind the eyes and headaches
Sphenoid – can cause pain or pressure behind the eyes, but often refers to the vertex, or top 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.
Bacterial and viral acute sinusitis are difficult to distinguish. However, if symptoms last less than 10 days, it is generally considered viral sinusitis. When symptoms last more than 10 days, it is considered bacterial sinusitis (usually 30% to 50% are bacterial sinusitis). Hospital acquired acute sinusitis can be confirmed by performing a CT scan of the sinuses.
For sinusitis lasting more than eight weeks, diagnostic criteria are lacking. A CT scan is recommended, but this alone is insufficient to confirm the diagnosis. Nasal endoscopy, a CT scan, and clinical symptoms are all used to make a positive diagnosis. A tissue sample for histology and cultures can also be collected and tested. Allergic fungal sinusitis (AFS) is often seen in people with asthma and nasal polyps. Examining multiple biopsy samples can be helpful to confirm the diagnosis. In rare cases, sinusoscopy may be made.
Nasal endoscopy involves inserting a flexible fiber-optic tube with a light and camera at its tip into the nose to examine the nasal passages and sinuses. This is generally a completely painless (although uncomfortable) procedure which takes between five to ten minutes to complete.