What are the diagnostic criteria and treatment options for sinusitis?

Sinusitis Diagnosis

Diagnose acute sinusitis clinically when patients present with persistent upper respiratory symptoms lasting less than 4 weeks, particularly when they have purulent rhinorrhea, facial pain, and poor response to decongestants. 1

Clinical Diagnostic Criteria

The diagnosis of sinusitis is primarily clinical and does not require imaging in uncomplicated cases. 1, 2

Five key clinical findings are the strongest predictors of acute bacterial sinusitis:

• Maxillary toothache 2
• Poor response to decongestants 2
• History of colored nasal discharge 2
• Purulent nasal secretion on examination 2
• Abnormal transillumination (only negative findings are useful) 2

Additional symptoms supporting the diagnosis include:

• Postnasal drainage 1
• Anosmia 1
• Nasal congestion 1
• Headache 1
• Fever 1
• Cough 1

Classification by Duration

Classify sinusitis by symptom duration to guide management: 1

• Acute: <4 weeks 1
• Subacute: 4-8 weeks 1
• Chronic: ≥8 weeks 1
• Recurrent: ≥3 episodes per year 1

When to Order Imaging

Do not order imaging for straightforward acute sinusitis. 1, 2

Order CT imaging only when: 1

• Diagnosis is uncertain (intermediate probability) 2
• Symptoms persist despite adequate treatment 1
• Chronic sinusitis evaluation (≥8 weeks of symptoms) 1
• Suspected complications 1
• Pre-surgical planning 1

For CT imaging, order coronal sinus CT with extra cuts through the ostiomeatal complex to clarify disease extent and location. 1

Plain radiography has limited utility—air-fluid levels and complete opacification are specific but only present in 60% of cases. 3

Distinguishing Viral from Bacterial Sinusitis

Suspect bacterial sinusitis when:

• Symptoms persist beyond 10 days without improvement 4
• Symptoms worsen after initial improvement within 10 days (double-worsening pattern) 4
• Unusually severe symptoms in the first 3-4 days with high fever and purulent discharge for 3+ consecutive days 4

Viral upper respiratory infections typically resolve within 7-10 days. 5

Red Flags Requiring Immediate Evaluation

Return immediately or refer urgently if patients develop: 4

• Orbital complications: eye pain, swelling, visual changes, periorbital edema or erythema 4
• Neurological complications: severe headache, altered mental status, neck stiffness 4
• High fever with severe headache 6

Chronic Sinusitis Diagnosis

Chronic sinusitis requires both:

• Symptoms persisting ≥8 weeks 1
• Abnormal CT or MRI findings 1

Common pitfall: Chronic sinusitis may be noninfectious (chronic hyperplastic eosinophilic rhinosinusitis) and will not respond to antibiotics. 1 These patients present with vague or insidious symptoms and require a different treatment approach. 1

When to Evaluate for Underlying Factors

Evaluate for underlying risk factors in patients with: 1

• Recurrent sinusitis (≥3 episodes per year) 1
• Chronic sinusitis 1
• Treatment failures 1

Workup should include:

• Testing for IgE sensitization to inhalant allergens (allergic rhinitis) 1
• Assessment for anatomic abnormalities 6
• Consider nasal-sinus biopsy if suspected neoplasia, fungal disease, or granulomatous disease 1

When to Refer to Specialists

Refer to allergist-immunologist for: 1

• Recurrent sinusitis (≥3 episodes/year) requiring evaluation of inflammation, allergy, immunodeficiency, and anatomic abnormalities 1
• Chronic or recurrent sinusitis associated with otitis media, bronchitis, bronchiectasis, or pneumonia 1
• Suspected immunodeficiency 6

Refer to otolaryngology for: 1

• Structural abnormalities 1
• Nasal polyps 1
• Consideration for surgical intervention 6