Rhinosinusitis: Acute and Chronic

Introduction

Rhinosinusitis is inflammation of the nasal mucosa and one or more paranasal sinuses, and is one of the most common reasons for a primary care consultation and for antibiotic prescribing, appropriate or not.¹ It is classified by duration into acute (symptoms lasting less than 12 weeks) and chronic (12 weeks or more), which have different underlying mechanisms and different management.

The great majority of acute cases are viral and self-limiting, and the central management message mirrors that of acute otitis media: antibiotics benefit only a small minority and should be reserved for those most likely to have bacterial infection or to be at risk of complications.

Diagnostic criteria and classification

Rhinosinusitis is diagnosed clinically when a patient has nasal blockage or congestion, or nasal discharge (anterior or postnasal drip), together with facial pain/pressure or a reduction or loss of smell, for the relevant duration.²

Aetiology and risk factors

Acute rhinosinusitis is most often triggered by a viral upper respiratory tract infection, with mucosal oedema obstructing the sinus ostia and impairing normal mucociliary drainage. A minority of cases become secondarily infected with bacteria, principally Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis.¹

Chronic rhinosinusitis is multifactorial, involving persistent mucosal inflammation that may be driven by allergy, structural obstruction, or, in nasal polyp disease, a Type 2 inflammatory process closely linked to asthma. Odontogenic sinusitis, arising from a dental infection or extraction affecting the maxillary sinus floor, is an important and sometimes overlooked cause of unilateral maxillary symptoms.

• Allergic rhinitis and asthma (particularly relevant to nasal polyp disease)
• Smoking
• Nasal septal deviation or other structural abnormality
• Nasal polyps
• Dental infection or recent dental work (odontogenic sinusitis)
• Swimming and diving
• Immunodeficiency
• Primary ciliary dyskinesia or cystic fibrosis, impairing mucociliary clearance

Clinical features

Patients report nasal blockage, purulent nasal discharge (anterior or as a postnasal drip causing cough or throat clearing), facial pain or pressure - classically worse on bending forward - and a reduced or absent sense of smell. Acute bacterial rhinosinusitis is more likely with fever, severe unilateral facial pain, and a "double sickening" pattern of initial improvement followed by deterioration.^1,2

Chronic rhinosinusitis presents with the same core symptoms persisting beyond 12 weeks, often with a more prominent and troublesome loss of smell, particularly when nasal polyps are present. Ask about asthma and aspirin sensitivity, since the combination of asthma, nasal polyps and aspirin-exacerbated respiratory disease (Samter's triad) is a recognised and important association.

Examination

Anterior rhinoscopy may show mucosal oedema, erythema, purulent discharge or visible polyps. Palpate over the frontal and maxillary sinuses for tenderness. Nasal endoscopy, performed in secondary care, gives a much more detailed view of the middle meatus, where pus or polyps are best seen, and is a routine part of the chronic rhinosinusitis work-up.²

Always assess the eyes and periorbital region - visual acuity, pupillary responses, eye movements, and any proptosis or periorbital swelling - given the proximity of the ethmoid sinuses to the orbit and the risk of orbital complications.

Differential diagnosis

• Allergic rhinitis: clear discharge, sneezing and itchy, watery eyes, without significant facial pain
• Dental abscess: localised dental pain and tenderness, sometimes with facial swelling
• Migraine or tension-type headache: headache without nasal symptoms
• Temporal arteritis: in an older patient with headache, jaw claudication and raised inflammatory markers
• Sinonasal tumour: unilateral, persistent symptoms, sometimes with bleeding or facial numbness - a red flag rather than a differential to dismiss

Investigations

Uncomplicated acute rhinosinusitis is a clinical diagnosis and needs no imaging.¹ Plain sinus X-rays are not recommended and add little useful information. CT of the paranasal sinuses is reserved for chronic rhinosinusitis being considered for surgery, or when a complication is suspected, and provides detailed anatomical mapping of the sinuses and ostiomeatal complex.

Allergy testing (skin prick or specific IgE) is useful in chronic rhinosinusitis with a suspected allergic component. MRI or contrast CT is added urgently if orbital or intracranial extension is suspected.

Management of acute rhinosinusitis

Most cases are viral and resolve within 2-3 weeks without antibiotics. First-line management is analgesia, nasal saline irrigation, and, for symptoms persisting beyond 10 days, a high-dose intranasal corticosteroid for up to 2 weeks, which reduces mucosal oedema and improves symptoms.¹

Antibiotics are not routinely recommended, as most patients improve without them and the risk of side effects and antimicrobial resistance outweighs a modest benefit. Consider a back-up or immediate antibiotic (phenoxymethylpenicillin first line, or doxycycline in penicillin allergy) for patients with symptoms lasting more than 10 days who are systemically very unwell, at high risk of complications, or showing a "double sickening" pattern.³

Management of chronic rhinosinusitis

First-line treatment is a combination of intranasal corticosteroids and saline nasal irrigation, continued for at least 3 months before assessing response, since chronic mucosal inflammation takes time to settle.² A short course of oral corticosteroids can be used for severe nasal polyp disease to reduce polyp size, and a prolonged low-dose macrolide antibiotic course is sometimes used for its anti-inflammatory (rather than purely antimicrobial) effect in selected patients.

Patients who fail an adequate trial of medical therapy, particularly those with nasal polyps causing persistent obstruction or anosmia, are referred for functional endoscopic sinus surgery (FESS), which widens the sinus drainage pathways and removes polyps under endoscopic guidance. Biologic therapies (e.g. targeting IL-4/IL-13 or IgE pathways) are increasingly used for severe nasal polyp disease refractory to surgery, particularly alongside coexisting severe asthma.

Complications

Complications arise from local spread of infection through the thin bony walls surrounding the sinuses, and are the reason rhinosinusitis is occasionally an emergency rather than a routine primary care problem:¹

• Orbital complications: spread from the ethmoid sinuses causes preseptal (periorbital) cellulitis, or, more seriously, orbital cellulitis with proptosis, painful eye movements and reduced visual acuity, which can progress to abscess and permanent visual loss if untreated
• Intracranial complications: meningitis, extradural or subdural abscess, and cavernous sinus thrombosis, from spread through the posterior sinus walls
• Pott's puffy tumour: osteomyelitis of the frontal bone with a subperiosteal abscess, presenting as a boggy frontal swelling
• Mucocele: a chronically obstructed, mucus-filled, expanding sinus that can erode into the orbit or anterior cranial fossa over time

Red flags

Prognosis

Acute rhinosinusitis usually resolves within 2-3 weeks, most of it without antibiotics, and complications are rare in immunocompetent patients who are appropriately monitored. Chronic rhinosinusitis follows a more variable course; many patients achieve good long-term control with intranasal corticosteroids and saline irrigation, while others, particularly those with nasal polyps and coexisting asthma, need surgery or biologic therapy to control symptoms.²