Introduction

Congestion of the nasal lining (mucosa) and the paranasal sinuses is one of the most common reasons people visit their general practitioner. The membranes lining the nasal cavity and sinuses are confluent. Sinus inflammation rarely occurs without nasal inflammation and congestion; hence, the process is considered a single entity rhinosinusitis.

In this article, we consider rhinosinusitis associated with sinus infections. Inflammation of the nose and sinuses is most frequently caused by the common cold virus, with inflammation lasting up to 12 weeks. A small number of patients may go on to develop bacterial infections of the sinuses.

The National Institute for Health and Care Excellence (NICE) projects the one-year prevalence of sinusitis to range from 6% to 15% in the United Kingdom, making it one of the most common upper airway infections.

Anatomy and physiology of the sinuses

The nose functions to warm and humidify air and is part of the body's immune defences against pathogens and irritants.

The nasal cavity is a roughly cylindrical space stretching from the nostrils to the upper part of the back of the throat (the nasopharynx), divided in the middle by the nasal septum. The walls of the nasal cavities (one on either side of the nasal septum) are bony ridges known as the turbinates (also called nasal conchae). The spaces between the turbinates are known as meatal recesses.

Figure 1. Nose and nasal cavities. ReneeWrites. Wikimedia Commons [Internet]. Available from: Wikimedia Commons

Connected to the nasal cavity are the paranasal sinuses, mucosa-lined air spaces within the skull bones, which drain into the nose via a series of channels that mainly open up into the middle meatal recess to allow sinus drainage.¹

No one knows for sure the exact function of the paranasal sinuses, but they have a role in warming and humidifying the air inhaled through the nose. Like the nose, paranasal sinuses are rich in immune cells that help fight the entry of pathogens and irritants. They may also decrease the overall weight of the skull and help with vocal resonance.

Sinuses are divided into:

• Frontal sinuses (in the forehead, above the eyes)
• Maxillary sinuses (below the eyes in the upper part of the cheek)
• Ethmoid air cells (above the nose)
• Sphenoid sinuses (lie just underneath the pituitary gland)

The mucosal lining of the sinuses is continuous with the mucosal lining of the nose and is similarly affected by airborne pathogens and irritants.¹

Causes of nasal congestion

Nasal congestion (a blocked, runny nose) is caused by a wide variety of factors. Common causes are: ²

• Allergies, including hay fever (seasonal allergic rhinitis), pets, and animal dander
• Infections (viral, bacterial, fungal)
• A foreign body in the nose (usually seen in young children)
• Dry air
• Hormonal changes
• Pollution, tobacco smoke
• Acute rhinosinusitis
• A deviated nasal septum
• Vaso-motor rhinitis
• Nasal polyposis
• Abuse of nasal decongestants (rhinitis medicamentosa), cocaine

Sinus infections (sinusitis)

Expert groups in the United States of America (USA) and Europe have developed classifications of sinusitis to categorise different types of sinus inflammation with a view to a unified consensus on management. While they differ slightly, both classify acute rhinosinusitis as lasting up to 12 weeks.

The American system classifies rhinosinusitis into the following four subtypes:³

• Acute rhinosinusitis: Sudden onset of symptoms lasting up to four weeks with complete resolution of symptoms
• Subacute rhinosinusitis: a continuation of acute rhinosinusitis lasting up to 12 weeks
• Recurrent acute rhinosinusitis: four or more episodes of acute sinusitis, each lasting seven days or more in a one-year period
• Chronic rhinosinusitis: Signs and symptoms of sinusitis persisting for more than 12 weeks

The European classification recognises acute rhinosinusitis to exhibit symptoms such as nasal congestion, blockage, and runny nose (rhinorrhoea) with facial pain lasting up to 12 weeks. The classification subdivides sinusitis into:⁴

• Viral acute rhinosinusitis (usually due to common cold) exhibits symptoms lasting up to 10 days
• Post-viral acute rhinosinusitis exhibits symptoms lasting for more than 10 days (but less than 12 weeks) or worsening after a five-day period
• Bacterial acute rhinosinusitis presents three or more of the following:
  • Fever greater than 38 degrees
  • Unilateral (one-sided) symptoms like coloured one-sided nasal discharge 
  • Elevation in blood C-reactive protein (CRP) levels or erythrocyte sedimentation rate (ESR) (markers of inflammation)
  • “Double-sickening” refers to the phenomenon whereby symptoms become more severe after initial improvement or symptoms that last more than 10 days

Antibiotics are commonly prescribed to treat acute rhinosinusitis, even when most cases can be managed without antibiotics or complex investigations. Therefore, the updated classifications can avoid unnecessary antibiotic prescriptions and use.

Symptoms and clinical presentation

The symptoms of rhinosinusitis are: 

• Nasal congestion and blockage
• Runny nose (rhinorrhoea)
• Coloured nasal discharge (particularly in bacterial acute rhinosinusitis)
• Facial pain in the sinus region
• Loss of sense of smell (anosmia)
• Less specific symptoms: 
• Headache
• Bad breath (halitosis)
• Fatigue
• Malaise
• Dental pain
• Cough
• Earache

In children, cough is considered significant, particularly in younger children who may not be able to describe post-nasal purulence (dripping of nasal secretions down the throat) but may respond to it with a cough.⁵ 

Examinations that help diagnose rhinosinusitis

Examination may reveal:⁶

• Facial swelling, particularly in the area surrounding your eye socket
• Tapping over the sinuses may elicit tenderness
• Shining a pen torch in the region of the sinuses may show abnormal transillumination. Normally, light may be seen passing through the air-filled sinuses, which may be absent in sinusitis
• An anterior rhinoscopy (examination of the nose through the nostrils) may reveal:
  • Inflamed, swollen mucosa
  • Purulent (a fluid indicating infection) discharge
  • Causes of nasal obstruction, such as a deviated nasal septum or nasal polyps 

Diagnosis

Acute rhinosinusitis can be diagnosed clinically in primary care (general practice) settings or the emergency room. The diagnosis is based on the patient's medical history and exam results and does not require any diagnostic tests.

The vast majority of cases will have a viral cause (usually the common cold) and will be self-limiting. Nevertheless, diagnostic tests may be performed for the following reasons including:⁴

• To confirm the exact cause (viral or bacterial) and eradicate doubts
• Distinguish sinusitis from other differential diagnoses
• Eliminate the chances of complicated infections, such as fungal sinusitis, especially in immunocompromised individuals (e.g., with HIV or undergoing chemotherapy)

Nasal endoscopy

Usually performed by an ENT (ear, nose, and throat) specialist, a rigid nasendoscopy is a procedure that allows examination of the inside of the nose, including examination of the “osteomeatal complex”, the area of the nose into which the sinuses drain.

Purulent (pus) discharge from the middle meatus of the nose around the osteomeatal complex, signs associated with chronic rhinosinusitis, including nasal polyposis, or other nasal structural abnormalities may be seen.

Swabs for bacterial culture can be taken under endoscopic vision if pus is seen coming from the middle meatus.⁷

Imaging techniques: plain X-ray and CT scan of the sinuses

Plain X-rays of the sinuses may detect opacification (cloudy or hazy) of the frontal, maxillary, or sphenoid sinuses. However, plain X-rays are not routinely recommended as they do not adequately image the ethmoidal sinuses or the osteomeatal complex, in which most sinus disease occurs.

A sagittal (lengthways sliced) CT scan of the sinuses is the investigation of choice for imaging the sinuses and can demonstrate thickening of the sinus mucosal lining, opacification of the sinuses or fluid within the sinuses, and distortion of the sinus anatomy.

Additionally, in chronic sinusitis, where surgery is a treatment option, CT is required to provide the surgeon with a map of the patient’s sinuses as anatomy differs from person to person. Imaging is not routinely performed in acute sinusitis but has an important role in the evaluation of chronic sinusitis.⁸

Allergy testing

In chronic sinusitis, when the suspected cause is allergy, skin-prick allergy testing may help in deciding on treatment, as nasal topical steroids and antihistamines may be of benefit. In acute viral rhinosinusitis with a clear clinical history, allergy testing offers no benefit.

Antral proof puncture

Antral proof puncture involves puncturing the maxillary sinus via the inside of the nose (in the region of the inferior meatus) with a cannula. This invasive procedure is often used to wash out the sinuses and diagnose bacterial sinusitis (by culturing bacteria from the maxillary sinus washings). Though a “gold standard” for diagnosis, this procedure is now considered obsolete.

Management and treatment

Managing nasal congestion, common cold, or acute rhinosinusitis

At least 50 percent of all cases will be caused by the rhinovirus (common cold). Other respiratory viruses may be responsible, including adenovirus, influenza, and  SARS-CoV-2 (responsible for COVID-19). The following are evidence-based recommendations for the treatment of acute rhinosinusitis associated with the common cold:

• Symptomatic treatment: paracetamol and non-steroidal anti-inflammatory drugs (NSAIDs), e.g., ibuprofen
• Second-generation antihistamines may reduce symptoms in the first two days 
• Nasal decongestants: These are known to have a small symptomatic effect in adults, not children. Use should be limited, ideally three days, no more than 7-10 days due to risk of rebound symptoms on stopping 
• Probiotics and zinc: if given within 24 hrs of the onset of symptoms 
• Ipratropium bromide nasal spray for runny nose (rhinorrhoea) 

The following are not recommended: antibiotics, topical nasal corticosteroids, echinacea, and homeopathy. In post-viral acute rhinosinusitis, the continued use of nasal decongestants or second-generation antihistamines is not recommended.⁹

Managing bacterial acute rhinosinusitis

Bacterial acute rhinosinusitis is managed with the following:

• A broad-spectrum antibiotic, preferably a beta-lactam antibiotic such as amoxicillin or amoxicillin with clavulanic acid, is the first-line antibiotic of choice if the individual is not allergic to it
• Second- or third-generation cephalosporin or macrolides such as clarithromycin are suitable alternatives
• There is some evidence that oral corticosteroids may reduce facial pain 

Managing fungal rhinosinusitis

Fungal rhinosinusitis is rare. It is subdivided into invasive and non-invasive forms (which have further subclassifications).

Invasive fungal rhinosinusitis occurs in mucormycosis, affecting individuals with uncontrolled diabetes or Aspergillus infections in those with AIDS. Both are destructive diseases that require emergency surgery. In non-invasive fungal rhinosinusitis, surgery is both therapeutic and diagnostic.¹⁰

Surgical interventions

Functional endoscopic sinus surgery (FESS) is performed for chronic rhinosinusitis. Surgery is performed with the aid of endoscopic vision through the nostrils to open up the sinus drainage and remove diseased tissue from the sinus lining.

Surgery is rarely a treatment for acute rhinosinusitis, the exception being recurrent acute rhinosinusitis. If an individual has a good supportive clinical history, a limited FESS procedure (middle meatal antrostomy and anterior ethmoidectomy) may be beneficial.

Surgery to correct nasal deformity, such as a deviated nasal septum or to remove nasal polyps may improve nasal congestion associated with these abnormalities.¹¹

Complications and when to see a doctor?

Severe complications from acute bacterial sinusitis are uncommon but can be serious. These include infections spreading to the eyes (orbital complications), brain (intracranial complications), and surrounding bones (osseous complications).

Key signs of bacterial sinusitis include high fever, symptoms lasting over 10 days, worsening after initial improvement ("double-sickening"), or one-sided facial pain.

• Orbital cellulitis can cause swelling and vision issues, sometimes requiring emergency surgery
• Intracranial infections like meningitis or brain abscesses may present with severe headaches, confusion, or neurological symptoms
• Bone infections (osteomyelitis) can occur if the bacteria spread to the skull

Though most sinus infections resolve on their own, symptoms of bacterial infection should be evaluated by a doctor, as antibiotics may be needed.¹²

Summary

Inflammation of the nose and sinuses due to acute infection is a common problem, with most cases being caused by the common cold virus (rhinovirus). Evidence-based guidelines suggest that antibiotic prescriptions and investigations are unnecessarily overused. A small number of patients develop sinusitis caused by acute bacterial infection of the sinuses, requiring the prescription of antibiotics. Very rarely, serious complications affecting the structures surrounding the sinuses can arise from acute bacterial sinusitis, including orbital cellulitis, meningitis, and brain abscesses, which require specialist care.