The term sinusitis refers to inflammation of the mucosal lining of the paranasal sinuses. However, as sinusitis is invariably accompanied by inflammation of the adjacent nasal mucosa, a more accurate term is rhinosinusitis.
The European Academy of Allergology and Clinical Immunology defines acute rhinosinusitis as, “Inflammation of the nose and the paranasal sinuses characterised by two or more of the following symptoms: blockage/congestion; discharge (anterior or postnasal drip); facial pain/pressure; reduction or loss of smell, lasting less than 12 weeks.” Additional symptoms—such as toothache, pain on stooping, and fever or malaise—help make the clinical diagnosis (box 3).4
The European Academy also suggests that worsening symptoms after five days or persistent symptoms beyond 10 days (but less than 12 weeks) indicate non-viral rhinosinusitis, whereas viral disease lasts less than 10 days.4
Box 3: Symptoms of rhinosinusitis
- • Nasal obstruction or congestion
- • Hyposmia (reduced sense of smell)
- • Facial pressure, pain, tenderness
- • Rhinorrhoea (anterior or postnasal)
- • Fever or malaise (acute infection)
- • Toothache (upper teeth)
The definition of chronic rhinosinusitis is nasal congestion or blockage lasting more than 12 weeks and accompanied by one of the following three sets of symptoms: facial pain or pressure; discoloured nasal discharge or postnasal drip; or reduction or loss of smell (box 4).
Box 4: Timescale for rhinosinusitis
- • Acute: <4 weeks
- • Subacute: 4-12 weeks
- • Chronic: >12 weeks
- • Acute exacerbation: sudden worsening of chronic sinusitis with return to baseline after treatment
The precipitating factor in acute sinusitis seems to be blockage of the sinus ostium, typically the maxillary sinus ostium situated under the middle turbinate (fig 1). It is this obstruction with mucus retention and subsequent infection that produces the signs and symptoms characteristic of rhinosinusitis. Whereas viral upper respiratory tract infections trigger most cases, the rising prevalence of rhinosinusitis might relate to a similar rise in incidence of allergic rhinitis.5
A small proportion of cases can arise as a result of dental root infection (odontogenic sinusitis). The bacteriology of acute rhinosinusitis differs from that of chronic rhinosinusitis (box 5).
Fig 1 Anatomy of the osteomeatal complex
Box 5: Bacteriology of acute and chronic rhinosinusitis
- Haemophilus influenzae, Streptococcus pneumoniae (rarely: anaerobes, Gram negative bacteria, Staphylococcus aureus, Moraxella catarrhalis, Streptococcus pyogenes)
- Anaerobes, Gram-negative bacteria, S aureus (rarely: fungal)