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A 55-year-old woman complains of sinus pressure for the past 2 weeks along with headache, rhinorrhea, postnasal drip, and cough. This all started with a cold 3 weeks ago. She has chronic allergic rhinitis, but now the pressure on the right side of her face has become intense and her right upper molars are painful. The nasal discharge has become discolored and she feels feverish. She is diagnosed clinically with right maxillary sinusitis and is prescribed an antibiotic. Two weeks later when her symptoms have persisted, a CT is ordered and she is found to have air-fluid levels in both maxillary sinuses and loculated fluid on the right side. (Figures 31-1 and 31-2.) The antibiotic is changed to amoxicillin/clavulanate and she is given information about nasal saline irrigation for symptom relief. If the symptoms don't improve the clinician plans to send her to ENT for further evaluation.

Figure 31-1

Bilateral maxillary sinusitis on axial CT. Note that fluid levels are greater on the right. (Courtesy of Chris McMains, MD.)

Figure 31-2

Maxillary sinusitis on coronal CT of same patient. (Courtesy of Chris McMains, MD.)

Rhinosinusitis is symptomatic inflammation of the sinuses, nasal cavity, and their epithelial lining.1 Mucosal edema blocks mucous drainage, creating a culture medium for viruses and bacteria. Rhinosinusitis is classified by duration as acute (<4 weeks), subacute (4 to 12 weeks), or chronic (>12 weeks).

  • Rhinosinusitis is common in the United States, with an estimated prevalence of 14% to 16% of the adult population annually.1,2 The prevalence is increased in women and in individuals living in the southern United States.
  • Only one-third to one-half of primary care patients with symptoms of sinusitis actually have bacterial infection.3
  • Sinusitis is the fifth-leading diagnosis for which antibiotics are prescribed in the United States.1
  • Children average 6 to 8 colds per year. Of those, 0.5% to 8% will develop a sinus infection.4,5
  • This problem is responsible for millions of office visits to primary care physicians each year.1

  • Sinus cavities are lined with mucous-secreting respiratory epithelium. The mucus is transported by ciliary action through the sinus ostia (openings) to the nasal cavity. Under normal conditions, the paranasal sinuses are sterile cavities and there is no mucous retention.
  • Bacterial sinusitis occurs when ostia become obstructed or ciliary action is impaired, causing mucus accumulation and secondary bacterial overgrowth.
  • The causes of sinusitis include:6
    • Infection - most commonly viral (e.g., rhinovirus, parainfluenza, and influenza) followed by bacteria infection (e.g., community-acquired acute cases - about half from S. pneumoniae and Haemophilus influenzae followed by Moraxella catarrhalis). In immunocompromised patients, fulminant fungal sinusitis may occur (e.g., rhinocerebral mucormycosis - Figure 31-3).
    • Noninfectious obstruction—Allergic, polyposis, barotrauma (e.g., deep-sea diving, airplane travel), ...

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