Acute rhinosinusitis

Overview

Inflammation of the nasal cavity and one or more paranasal sinuses lasting <12 weeks. Vast majority are viral and self-limiting - antibiotic stewardship is the central clinical theme.

Presentation

•Cardinal features: nasal blockage, nasal discharge (anterior or posterior), facial pain/pressure, hyposmia/anosmia

•Maxillary sinusitis: cheek pain or toothache, worse on bending forward

•Frontal sinusitis: frontal headache, tenderness beneath supraorbital ridge

•Symptoms follow viral URTI and peak around days 2-3; discoloured discharge alone does NOT reliably indicate bacterial infection

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'Double sickening' - initial improvement then deterioration - is the classic exam trigger for bacterial superinfection and is a direct indication for antibiotics.

Investigations

•Clinical diagnosis - investigations not routinely required in primary care

•CT sinuses - if complications suspected (orbital/intracranial), recurrent episodes, or pre-surgical planning

•MRI - preferred over CT for soft tissue delineation when intracranial or orbital complication suspected

Management

•Viral/mild: analgesia, intranasal saline irrigation, intranasal corticosteroids (e.g. mometasone) for symptom relief; watchful waiting

•Bacterial superinfection (first-line antibiotic): phenoxymethylpenicillin

•Routine ENT referral: recurrent acute rhinosinusitis (≥4 episodes/year), nasal polyps, suspected anatomical abnormality, failure of medical management after 3 months

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2-week wait referral to ENT for persistent unilateral symptoms (obstruction, discharge, epistaxis, facial swelling) - may represent sinonasal malignancy.

Complications

•Orbital cellulitis - most common serious complication; periorbital oedema, proptosis, chemosis, restricted eye movement; vision-threatening if untreated

•Subperiosteal/orbital abscess - pus between orbital wall and periosteum; urgent IV antibiotics ± surgical drainage

•Intracranial extension - meningitis, epidural/subdural empyema, cerebral abscess; rare but life-threatening

•Pott's puffy tumour - doughy forehead swelling; indicates frontal bone osteomyelitis

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The ethmoid sinuses are separated from the orbit only by the thin lamina papyracea - this explains why orbital complications are the most common serious sequelae of acute rhinosinusitis.

Bacterial vs Viral Features

Distinguishing viral from bacterial rhinosinusitis

Feature	Viral	Bacterial
Course	Improving by days 7-10	Double sickening or symptoms >10 days
Fever	Low-grade or absent	Higher fever (≥38°C)
Discharge	Clear or discoloured (unreliable)	Persistent thick purulent
Facial pain	Mild, diffuse	Localised, severe, unilateral
Antibiotics	Not indicated	Indicated

Red Flags - Urgent Hospital Referral