Chronic Rhinosinusitis

Q: What is the difference between CRSwNP and CRSsNP?

CRSwNP is CRS with nasal polyps — bilateral inflammatory polyps, often with prominent smell loss and a good response to steroids. CRSsNP is CRS without polyps. Confirming which one a patient has is a specific guideline recommendation because it changes treatment.

Chronic rhinosinusitis by the guideline definition: the ≥12-week symptom criteria, why objective evidence is mandatory, the polyp vs non-polyp split, the role of CT and the Lund–Mackay score, and the medical-then-surgical treatment ladder.

Chronic rhinosinusitis (CRS) is symptomatic inflammation of the nasal cavity and paranasal sinuses lasting 12 weeks or more. It is a diagnosis defined by criteria rather than by clinical impression. What sets it apart from a run of common colds is not only how long the symptoms last, but a specific symptom set and, above all, objective evidence of inflammation. Symptoms on their own are not enough to make the diagnosis.

Definition and diagnostic criteria

By the widely used EPOS 2020 and AAO-HNS criteria, CRS requires all of the following:

Duration: symptoms for ≥12 weeks.
Symptoms: two or more, at least one of which is nasal blockage/obstruction/congestion or nasal discharge (anterior or posterior drip) — with or without facial pain/pressure, and with or without reduction or loss of smell.
Objective evidence of inflammation. This is the step that is easy to skip and shouldn’t be: the AAO-HNS guideline (Rosenfeld et al., 2015) states a clinical diagnosis of CRS must be confirmed with objective documentation of sinonasal inflammation, obtained by anterior rhinoscopy, nasal endoscopy, or CT. Symptoms alone are not enough — many conditions mimic them.

Two phenotypes

CRS is split by the presence or absence of nasal polyps, and the guideline recommends confirming polyp status in every patient:

CRS with nasal polyps (CRSwNP) — bilateral, grey, translucent inflammatory polyps in the middle meatus/ethmoids. (A unilateral polyp or mass is a red flag — think antrochoanal polyp, inverting papilloma, or malignancy, and biopsy.)
CRS without nasal polyps (CRSsNP) — mucosal inflammation without polyps.

This split matters because it steers treatment (polyps respond to steroids; smell loss is more prominent) and prognosis.

Contributing factors

CRS is a common endpoint of several processes: allergic rhinitis, impaired mucociliary clearance, anatomical obstruction of the drainage pathways (e.g. a narrowed ostiomeatal complex), microbial colonisation, systemic inflammatory disease (e.g. granulomatosis with polyangiitis), and immune disorders. The guideline specifically flags asthma, cystic fibrosis, immunodeficiency, and ciliary dyskinesia as conditions to look for, because they change management.

Investigations

Nasal endoscopy — inspects the ostiomeatal complex, confirms polyps/pus/oedema, and excludes tumour.
CT of the paranasal sinuses — the imaging study of choice to confirm the extent of disease; severity is commonly quantified with the Lund–Mackay score (Lund & Mackay, 1993). Note the guideline caveat: do not image routinely for acute rhinosinusitis unless a complication or alternative diagnosis is suspected.
Allergy / immune testing — where an underlying hypersensitivity or immunodeficiency is suspected.

Management

The order is medical first, surgical for the refractory — CRS is an inflammatory disease, so the mainstays are anti-inflammatory.

Medical

Saline irrigation — reduces crusting and symptom burden; a low-cost cornerstone.
Intranasal corticosteroids — standard first-line anti-inflammatory therapy (the guideline recommends saline irrigation, topical intranasal steroids, or both for symptom relief).
Short courses of oral corticosteroids — used to shrink nasal polyps and reduce swelling.
Antibiotics — for a bacterial component; in refractory cases, culture-directed (common organisms include Staphylococcus aureus and Pseudomonas aeruginosa).
Not antifungals — the AAO-HNS guideline recommends against topical or systemic antifungal therapy for CRS.

Surgical — Functional Endoscopic Sinus Surgery (FESS)

Indicated when CRS is refractory to adequate medical therapy, or causes obstructive anosmia.
Goal: remove polyps and disease and open the natural sinus drainage pathways, restoring mucus clearance and, importantly, making the sinuses accessible to post-operative topical rinses and sprays. Surgery enables medical therapy rather than replacing it.

Complications

Orbital (usually from acute exacerbation) — preseptal cellulitis, orbital cellulitis, subperiosteal abscess, orbital abscess, and cavernous sinus thrombosis.
Intracranial — spread through valveless veins to intracranial structures (meningitis, abscess).
Mucocele — an obstructed, expanding sinus.
Of surgery — infection, CSF leak, meningitis, pneumocephalus, seizures, and orbital injury.

Frequently Asked Questions

How is chronic rhinosinusitis different from recurrent colds or acute sinusitis? By duration and objective evidence. CRS requires symptoms for at least 12 weeks plus confirmed inflammation on nasal endoscopy or CT — not symptoms alone. Acute rhinosinusitis resolves within weeks and is usually diagnosed clinically; CRS is a persistent inflammatory disease that must be objectively documented.

Why isn’t a diagnosis of CRS made on symptoms alone? Because nasal blockage, discharge, facial pressure, and smell loss are non-specific and overlap with allergic rhinitis, migraine, and other conditions. Guidelines require objective evidence of sinonasal inflammation (anterior rhinoscopy, nasal endoscopy, or CT) precisely so that patients aren’t mislabelled and treated for the wrong thing.

What is the difference between CRSwNP and CRSsNP? CRSwNP is CRS with nasal polyps — bilateral inflammatory polyps, often with prominent smell loss and a good response to steroids. CRSsNP is CRS without polyps. Confirming which one a patient has is a specific guideline recommendation because it changes treatment.

Does chronic rhinosinusitis always need surgery? No. First-line treatment is medical: saline irrigation and intranasal corticosteroids, with short oral steroid courses for polyps and culture-directed antibiotics when infected. FESS is reserved for disease that is refractory to adequate medical treatment or causing obstructive anosmia, and it works partly by making ongoing topical treatment more effective.

What is the Lund–Mackay score? A widely used system for grading the severity of sinus disease on CT by scoring the opacification of each sinus group and the ostiomeatal complex. It gives an objective, reproducible measure of disease extent for diagnosis, research, and pre-operative planning.