Sinusitis

Inflammation of the paranasal sinus mucosa, most commonly occurring as a complication of viral upper respiratory tract infection, classified by duration into acute (resolving within four weeks), subacute (four to twelve weeks) and chronic (persisting beyond twelve weeks), with the acute form overwhelmingly viral in origin and bacterial superinfection representing a distinct minority requiring specific identification before antibiotic treatment is warranted.

Pathophysiology

Viral upper respiratory tract infection causes mucosal oedema and impaired mucociliary clearance within the sinus ostia, predisposing to secondary bacterial infection in a minority of cases when normal sinus drainage and ventilation are sufficiently compromised. Chronic sinusitis reflects a more complex, multifactorial inflammatory process, often associated with nasal polyposis, allergic disease or anatomical factors, and is managed as a distinct condition from acute bacterial sinusitis.

Facial pain or pressure, typically localised over the affected sinus (maxillary, frontal, ethmoid or sphenoid), together with nasal congestion and purulent nasal discharge, characterises the typical presentation of acute sinusitis.

Reduced sense of smell, headache, and worsening of facial pain on bending forward or with changes in position, commonly accompany the core symptoms.

Features suggesting bacterial rather than purely viral acute sinusitis include symptoms persisting beyond ten days without improvement, severe symptoms with high fever and facial pain lasting at least three to four consecutive days at the outset of illness, or worsening of symptoms after initial improvement (a biphasic pattern), any of which support a diagnosis of acute bacterial rhinosinusitis rather than the far commoner uncomplicated viral process.

Red flag features requiring urgent assessment include periorbital swelling or erythema, visual disturbance, severe headache with neurological signs, or altered consciousness, any of which raise concern for orbital or intracranial complications of sinusitis, which although uncommon can be serious and rapidly progressive.

Diagnosis is clinical for the great majority of presentations, based on the characteristic symptom pattern and duration, without the need for imaging or microbiological testing in uncomplicated acute disease.

Nasal endoscopy, where available, allows direct visualisation of purulent discharge and mucosal changes, supporting the diagnosis particularly in atypical or persistent presentations.

Computed tomography of the sinuses is reserved for chronic sinusitis being considered for surgical intervention, suspected complications (orbital or intracranial extension), or where the diagnosis remains uncertain after appropriate clinical assessment, rather than used routinely for acute uncomplicated disease.

Allergy testing and assessment for nasal polyposis are relevant components of the assessment for chronic sinusitis, given the frequent association with underlying allergic or inflammatory nasal disease in this population.

Symptomatic treatment, including analgesia, saline nasal irrigation and intranasal corticosteroids (which have evidence for symptomatic benefit even in the absence of confirmed bacterial infection), forms first line management for the great majority of acute sinusitis presentations, reflecting the predominantly viral aetiology.

Antibiotics are reserved for acute sinusitis meeting the specific criteria for likely bacterial infection, with amoxicillin or amoxicillin with clavulanic acid as typical first line choices where treatment is indicated, and a watchful waiting approach with delayed or no antibiotic prescription is appropriate for the majority of presentations not meeting these criteria, given the substantial rate of spontaneous resolution.

Decongestants may provide short term symptomatic relief but should be limited to a few days of use given the risk of rebound congestion with prolonged use.

Chronic sinusitis is managed with prolonged courses of intranasal corticosteroids and saline irrigation as first line therapy, with assessment and treatment of any underlying allergic disease, and referral to otolaryngology for consideration of endoscopic sinus surgery in patients with persistent symptoms despite optimised medical treatment or with significant nasal polyposis.

Suspected orbital or intracranial complications require urgent same day assessment, imaging and, where confirmed, urgent multidisciplinary management involving otolaryngology and, according to the specific complication, ophthalmology or neurosurgery, given the potential for rapid and serious deterioration.