Sinusitis
Duration-based Classification
Acute rhinosinusitis: <4 weeks
Subacute rhinosinusitis: 4–12 weeks
Chronic rhinosinusitis: >12 weeks (with or without nasal polyps)
Recurrent acute rhinosinusitis: ≥4 episodes per year, each episode lasting <4 weeks, with complete resolution between episodes
Pathophysiology
Typically follows a viral upper respiratory tract infection (URTI).
Inflammation and oedema of the nasal passages cause obstruction of sinus drainage, leading to mucus stasis and potential secondary bacterial infection.
The most commonly affected sinus is the maxillary sinus (due to its drainage pattern).
The ethmoids can also be frequently involved.
Etiology
Viral: Most acute sinusitis (rhinosinusitis) cases are viral (commonly rhinovirus, influenza virus, parainfluenza virus).
Bacterial: Only a minority (<2% of viral URTIs) progress to bacterial infection. Typical organisms include Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.
Other Causes:
Fungal sinusitis (rare, more in immunocompromised or chronic sinusitis).
Allergic rhinosinusitis (associated with atopy).
Anatomic abnormalities (e.g. nasal polyps, septal deviation) predispose to chronic or recurrent disease.
Clinical Presentation
Typical Symptoms
Nasal congestion/obstruction
Mucopurulent nasal discharge (anterior/posterior)
Facial pain/pressure (often worsens on bending forward)
Hyposmia or anosmia (reduced/absent smell)
Cough (especially in children, from postnasal drip)
Malaise, low-grade fever (in acute cases)
Differentiating Viral from Bacterial
It is often challenging; however, pointers to possible bacterial sinusitis include:
Symptoms >10 days without improvement.
Severe symptoms (e.g. high fever ≥39°C, significant purulent nasal discharge/facial pain) lasting ≥3–4 consecutive days at the beginning of illness.
Double-worsening (initial improvement in viral URTI followed by a sudden worsening of symptoms).
However, many “bacterial” presentations can still resolve spontaneously. Clinical judgment is key.
Red Flags and Complications
Orbital cellulitis (especially from ethmoid sinusitis): Eye pain, redness, proptosis, diplopia, or restricted eye movements.
Intracranial spread: Meningitis, intracranial abscess, or cavernous sinus thrombosis. Signs might include severe headache, altered mental status, focal neurological signs, or neck stiffness.
Osteomyelitis (e.g. frontal bone).
Severe/persistent pain not responding to usual treatment.
Unilateral nasal polyps or bleeding suspicious for neoplasm.
Any suspicion of these complications mandates urgent specialist referral and imaging.
Investigations
Clinical diagnosis is paramount; imaging is rarely required for uncomplicated acute sinusitis.
Plain sinus X-rays are generally not recommended (poor sensitivity and specificity).
CT sinus may be indicated if:
Suspicion of orbital, intracranial, or other complications
Persistent or recurrent sinusitis not responding to treatment
Suspected neoplasm, fungal infection, or anatomical abnormality needing surgery
Nasal endoscopy is for ENT specialists in certain chronic or complicated scenarios.
Microbiology (nasal swabs) typically not done in straightforward acute sinusitis (poor correlation). Endoscopic sinus aspirate for culture can be considered in selected complicated or refractory cases by ENT.
Management of Acute Sinusitis
General Principles
Most acute sinusitis is viral: supportive management is usually sufficient.
Watchful waiting: For mild-moderate symptoms, guidelines commonly advise to observe for up to 7 days before considering antibiotics, unless “red flags” are present.
Symptomatic treatment:
Analgesics (paracetamol, NSAIDs) for pain/fever.
Nasal saline irrigation: Helps clear secretions, improves nasal patency.
Intranasal corticosteroids (e.g. budesonide, fluticasone) can reduce inflammation and improve symptoms, especially if there is an allergic component or significant nasal inflammation.
Nasal decongestants (topical oxymetazoline/xylometazoline) may provide short-term relief. Limit use to <5 days to avoid rebound congestion (rhinitis medicamentosa). Oral decongestants have limited benefit and can cause systemic side effects.
Antibiotic Therapy
Indications to Start Antibiotics:
Severe symptoms (high fever ≥39°C and purulent nasal discharge/facial pain) for at least 3–4 days.
Symptoms not improving for ≥10 days.
Double-worsening pattern (after initial improvement).
High-risk patients (e.g. immunocompromised) or red flag signs.
First-line Antibiotics:
Amoxicillin (500 mg–1 g every 8 hours in adults; or child-appropriate dosing) is typically first line.
Amoxicillin + Clavulanic Acid if no response to amoxicillin alone, or risk factors for resistance (e.g. recent antibiotic use, comorbidities, severe infection).
Duration of Antibiotic Course: Usually 5 days for a first course (adults), can be extended to 7 days if response is suboptimal. Child courses may vary slightly. For complicated sinusitis, longer durations (e.g. 10–14 days) may be considered.
Penicillin-allergic Patients:
Mild allergy: a cephalosporin (e.g. cefuroxime, cefprozil) may be used if no immediate (Type I) hypersensitivity.
Immediate (Type I) hypersensitivity: use a macrolide (e.g. clarithromycin) or doxycycline (for adults).
Adjunct Therapy
Intranasal corticosteroids: Evidence suggests they can improve symptoms in acute sinusitis, especially beneficial for patients with allergic rhinitis or prominent nasal inflammation.
Oral corticosteroids: Generally not routine for uncomplicated acute sinusitis; can be considered short-term in severe inflammation or nasal polyposis, on specialist advice.
Antihistamines: May help in allergic rhinosinusitis but can thicken secretions; not routinely recommended for non-allergic sinusitis.
Management of Chronic Sinusitis
Chronic rhinosinusitis (>12 weeks) is a more complex condition often associated with nasal polyps, allergic components, or anatomical variants. Mainstays include:
Intranasal corticosteroids long-term
Nasal saline irrigation regularly
Managing comorbidities (allergic rhinitis, asthma, etc.)
Intermittent antibiotic courses for acute exacerbations
Surgery (Functional Endoscopic Sinus Surgery – FESS): For patients with persistent symptoms despite optimal medical therapy, or with complications/anatomical obstructions.
Referral Indications
Red flags suggestive of complication (orbital, intracranial, or bony involvement).
No improvement or recurrent episodes despite appropriate medical therapy.
Suspected nasal polyps or mass.
Chronic sinusitis requiring surgical intervention.
Suspected immunodeficiency or unusual pathogens.
