Acute sinusitis

Background

• Acute sinusitis is a clinical diagnosis with classical symptoms lasting 4-12 weeks.
• Recurrent acute sinusitis is 2-4 episodes of acute sinusitis with at least 8 weeks between episodes.
• Chronic sinusitis is the persistance of insidious symptoms beyond 12 weeks, with or without acute exacerbations.

Pathophysiology (see also sinus anatomy)

• Acute sinusitis is thought to be caused by a blockage of the mucus outflow tract of the sinus (most commonly the maxillary sinus is affected due to blockage of the maxillary ostium.  This blockage can occur for a number of reasons:
  • oedema secondary to allergic disease
  • traumatic obstruction
  • nasal polyps
  • inflammation secondary to infection/chemical damage
• This then causes a build up of negative pressure within the sinus, and subsequent infection with bacteria.  Acute sinusitis is often secondary to an URTI, AOM, or other ENT infection.

Other things that possibly contribute to acute sinusitis are:

• impaired ciliary function- the drainage of paranasal sinuses are now thought to involve ciliary action.  Cilia are easily damaged by hypoxia which can, again, be caused by allergic and viral disease etc, when there is a lot of oedema as well as in infectious disease where there are toxins produced.  (There are also rare congenital ciliary disorders e.g. Kartaneger’s syndrome)
• Poor quality sinal mucus- e.g. in cystic fibrosis, where the secretions are thick and do not clear from the sinuses, there is an increased risk of infection

Microbiology

• Given that acute sinusitis is often secondary to other ENT infections, it is unsurprising that the main pathogens causing it are:
  • Streptococcus pneumoniae
  • Haemophilus influenzae
  • Moraxella catarrhalis
  • Streptococcus pyogenes
• It should be noted, however, that Staphylococcus aureus is more commonly seen in sphenoid sinusitis, and Pseudomonas aeroginosa (and other anaerobic organisms e.g. E coli) and proteus) is more common in hospitalised patients with things like nasal tubes.

Signs/Symptoms

• Facial Pain and tenderness
  • The pain may be unilateral or bilateral and is felt over the cheek, although it can radiate to the forehead, teeth.  It is often worse on bending down.
  • NB Supra-orbital pain may indicate an ethmoidal sinusitis and a sphenoid sinusitis may not have any pain (sphenoid sinusitis is very hard to diagnose)
• Redness of the nose, cheeks and sometimes eyelids
• Discharge
  • Usually a watery anterior discharge (not very significant) but a purulent post-nasal drip that leaves a foul taste in the back of the mouth.
• Nasal obstruction
• Loss of sense of smell (hyposmia)
• Fever
• Fatigue
• Previous URTI/AOM etc etc

Sinusitis should be suspected if these symptoms persist for over a week (under a week is more likely an URTI).

Diagnosis

• The diagnosis is clinical.  Remember that air-fluid level on CT does NOT mean sinusitis and is found in many asymptomatic patients and even more patients with an URTI.  Endoscopy will only be useful in confirming the site of discharge.

Management

• Most cases will be self limiting and will only require symptomatic treatment
  • Bed-rest and a short course of decongestant (pseudoephedrine) +/- analgesia
• After prolonged symptoms (>5days) a course of topical steroid (beclamethasone) may be tried.
• If the patient still doesn’t respond, sinus drainage with lavage may be needed.

NOTE that antibiotic treatment is NOT routinely used for sinus infections (penicillin V/Amoxicillin may be tried but regularly are ineffective).  This is mainly because they cannot access the sinuses.  If they were to be considered e.g. after surgery, amoxicillin would be a good choice.

Complications

• Mucoceles (chronic epithelial cysts)- are potentially destructive lesions
• Osteomyelitis (particularly with frontal sinusitis)
• Orbital disease (cellulitis, abscess etc)
• Intracranial (subdural) abscess
• Sepsis