Classification

Rhinosinusitis is generally classified according to the duration into: (1,2)

• acute rhinosinusitis (ARS) - if duration of symptoms is less than 12 weeks
• chronic rhinosinusitis (CRS) - if lasting more than 12 weeks (with or without acute exacerbations)

Acute rhinosinusitis can be further divided into

• acute viral rhinosinusitis (common cold) - duration of symptoms of less than 10 days
• acute post-viral rhinosinusitis - defined by an increase in symptoms after 5 days or persistent symptoms after 10 days with less than 12 weeks duration.
• acute bacterial rhinosinusitis—defined by the presence of at least three symptoms or signs of
  • discoloured discharge (with unilateral predominance) and purulent secretions
  • severe local pain (with unilateral predominance)
  • fever (>38°C)
  • elevated erythrocyte sedimentation rate or C reactive protein
  • ‘double sickening’ (i.e. a deterioration after an initial milder phase of illness)
• in recurrent acute sinusitis
  • there are four or more episodes of acute bacterial rhinosinusitis per year without signs or symptoms of sinusitis between episodes
  • each episode should meet the diagnostic criteria for acute bacterial sinusitis

Reference:

1. Rosenfeld RM, Piccirillo JF, Chandrasekhar SS, et al. Clinical practice guideline (update): adult sinusitis. Otolaryngol Head Neck Surg. 2015 Apr;152(2 Suppl):S1-39.
2. Peters AT, Spector S, Hsu J, et al. Diagnosis and management of rhinosinusitis: a practice parameter update. Ann Allergy Asthma Immunol. 2014 Oct;113(4):347-85.