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Classification and Diagnosis

  1. Chronic rhinosinusitis (CRS) is defined as symptomatic inflammation of the paranasal sinuses and nasal cavity for a duration longer than 12 weeks.

    1. To make a diagnosis of CRS, two or more of the following cardinal symptoms must be present for 12 weeks or longer:

      1. Mucopurulent drainage (anterior or posterior)

      2. Nasal obstruction/congestion

      3. Facial pain or pressure

      4. Hyposmia or anosmia

    2. In addition to documentation of two or more of the above symptoms, inflammation of the nasal mucosa must be confirmed by one of the following findings:

      1. Polyps in the nasal cavity or middle meatus, confirmed with endoscopy or anterior rhinoscopy

      2. Purulence or edema in the middle meatus or anterior ethmoid cavity

      3. Radiographic (CT) evidence of mucosal thickening, edema, or other findings consistent with inflammation

  2. CRS can be punctuated by acute exacerbations, sometimes referred to as “acute-on-chronic” rhinosinusitis, in which symptoms worsen secondary to an acute infection or other environmental insult.

  3. Subacute rhinosinusitis historically referred to symptoms lasting between 4 and 12 weeks, although recent guidelines have only made diagnostic and treatment distinctions between acute and CRS.

  4. Recurrent acute sinusitis refers to four or more discrete episodes of sinusitis in one year, with asymptomatic periods between episodes, and is treated differently from CRS.


  1. Overall prevalence (all types) ranges from 4.5% to 12.5% in Western populations.

  2. There are generally three subtypes of CRS recognized:

    1. CRS with nasal polyposis (CRSwNP): 20% to 33%

      1. Excessive TH-2 inflammation, eosinophilic infiltration, histamine, IL-5, IL-13

    2. CRS without nasal polyposis (CRSsNP): 60% to 65%

      1. Neutrophilic infiltration, IL-1, IL-16, tumor necrosis factor α (TNF-α)

      2. Can be due to primary/acquired mucociliary failure, immunodeficiency, or anatomic factors

    3. Allergic fungal rhinosinusitis (AFS): 8% to 12%

  3. In practice, there can be overlap of several of the above inflammatory markers and etiologies in both CRSwNP and CRSsNP.

  4. New research is ongoing to further classify CRS based on microscopic, genomic, and microbiomic categorizations.


  1. There are several factors which are thought to contribute to the development of chronic sinusitis. Many of these can overlap, making a targeted diagnosis and treatment plan difficult to develop.

  2. Multiple episodes of acute rhinosinusitis (ARS) (predominately infectious process) may ultimately lead to the development of chronic sinusitis (predominately inflammatory process).

    1. Whereas ARS is marked by a suppurative, neutrophil-predominate infectious etiology, CRS is characterized by an inflammatory response where eosinophils are the predominant inflammatory cells in both atopic and nonatopic individuals.

  3. Contributing factors to CRS include anatomy, local physiologic factors, and systemic physiologic factors.

  4. Anatomic factors

    1. Blockage of the osteomeatal complex, sphenoethmoidal recess, frontal recess, or other natural drainage pathways by anatomic abnormalities can cause or prolong chronic sinusitis.

      1. Septal deviation, turbinate hypertrophy, middle turbinate concha bullosa, paradoxical turbinates, prominent agger nasi cell, Haller cells, prominent ethmoid bulla, pneumatization and inversion of uncinate process, hypoplastic sinuses, accessory maxillary ostia → recirculation

  5. Local physiologic factors

    1. Mucociliary impairment: Ciliary function plays an important role in the clearance ...

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