OVERVIEW

What is Acute Rhinosinusitis?

Due to the anatomical relationship between the nose and sinuses, acute rhinitis often coexists with sinusitis. Therefore, many scholars prefer the term "rhinosinusitis." For consistency, the term "rhinosinusitis" in this article is equivalent to "sinusitis."

We generally classify sinusitis with a duration of ≤30 days as acute rhinosinusitis (ARS). The primary pathogens of ARS are viruses, referred to as acute viral rhinosinusitis (AVRS), followed by bacteria, known as acute bacterial rhinosinusitis (ABRS).

From an anatomical and pathophysiological perspective, colds and influenza-like illnesses often overlap with AVRS. Studies show that 68% of healthy children with colds exhibit mucosal thickening, edema, and inflammation in the paranasal sinuses. Thus, distinguishing AVRS from colds or influenza-like illnesses is challenging.

We also recognize that most cases of ABRS are secondary to acute nasal inflammatory conditions such as colds, influenza-like illnesses, or allergic rhinitis.

Given the close relationship between AVRS and ABRS, this topic discusses them together.

SYMPTOMS

What are the clinical manifestations of acute viral rhinosinusitis (AVRS) and acute bacterial rhinosinusitis (ABRS)? Are there any significant differences?

There are no highly reliable clinical criteria to distinguish AVRS from ABRS.

In fact, all ARS cases, whether viral or bacterial, can present with nasal congestion, nasal obstruction, increased nasal discharge, cough (especially at night), and sore throat. Other possible symptoms include fever, fatigue, reduced or loss of smell, ear pressure or fullness, headache, and bad breath. A small number of patients may experience eustachian tube dysfunction, manifesting as ear pain, ear fullness or pressure, hearing loss, or tinnitus.

Most AVRS cases last 7–10 days, with symptoms peaking between days 3–6. Symptoms improve after 7–10 days, even if not completely resolved.

Although fever is more common in children with AVRS compared to adults, most AVRS cases do not involve fever. Even if fever occurs, it usually subsides within 3 days.

In contrast, ABRS symptoms tend to be more severe and may include:

• High fever (≥ 39°C) lasting more than 3 days, accompanied by persistent nasal symptoms.
• Symptoms persisting for more than 10 days without improvement.
• A biphasic pattern, where symptoms worsen again after initial improvement.

Can the consistency of nasal discharge (watery vs. purulent) distinguish between bacterial and viral infections in acute rhinosinusitis?

The consistency of nasal discharge—whether watery or purulent—cannot reliably differentiate AVRS from ABRS. ABRS may present with watery, thin nasal discharge, while AVRS can also produce thick, purulent mucus.

What complications can acute bacterial rhinosinusitis cause? When should special attention be given?

Untreated ABRS may lead to the spread of inflammation to the orbit or intracranial structures, potentially causing complications such as periorbital or orbital cellulitis, septic cavernous sinus thrombosis, meningitis, brain abscess, or intracranial abscess.

The following signs require immediate attention:
• Periorbital/orbital swelling or proptosis;
• Persistent headache and vomiting;
• Altered level of consciousness;
• Focal neurological deficits;
• Meningeal signs (including neck stiffness, Kernig's sign, Brudzinski's sign, etc.);
• Impaired eye movement, vision changes, or papilledema.

CAUSES

Why is bacterial rhinosinusitis more common in children?

It is currently understood that conditions like colds and influenza-like illnesses can lead to secondary ARBS. The incidence in non-hospitalized adults is approximately 0.5%–2.0%, while in children, it is about 6%–13%.
Three key factors determine whether sinusitis occurs: patency of the sinus ostia, ciliary function, and characteristics of sinus secretions.
Generally, only the ethmoid and maxillary sinuses are present at birth. The ethmoid sinuses become aerated shortly after birth.
The maxillary sinuses aerate by age 4. The sphenoid sinuses develop by age 5 and reach their final size by age 12. The frontal sinuses develop between ages 6–8 and fully mature by adolescence.
In 1%–4% of adults, the frontal sinuses fail to develop. About 80% of adults have bilateral frontal sinuses, while the rest exhibit unilateral hypoplasia. Compared to adults, children have narrower sinus openings.

Thus, when AVRS occurs, children are more prone to poor sinus drainage, often leading to secondary bacterial infections.

What are the risk factors for acute rhinosinusitis in adults?

Older age, smoking, air travel, exposure to atmospheric pressure changes (e.g., deep-sea diving), swimming, asthma, allergic rhinitis, dental diseases, and immunodeficiency can all increase the likelihood of acute rhinosinusitis in adults.

What pathogens cause acute viral rhinosinusitis (AVRS)?

Viruses responsible for colds and influenza-like symptoms often also cause AVRS. Confirmed pathogens include:

• Rhinoviruses;
• Coronaviruses;
• Influenza virus;
• Parainfluenza virus;
• Respiratory syncytial virus;
• Adenovirus;
• Metapneumovirus;
  Some studies also suggest enteroviruses and the recently discovered bocavirus may be causative. Due to overlapping pathogens and symptoms, distinguishing AVRS from colds or influenza-like illnesses is challenging.

What pathogens cause acute bacterial rhinosinusitis (ABRS)?

Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis are the most common pathogens causing acute bacterial rhinosinusitis.
Compared to adults, children have a higher proportion of Moraxella catarrhalis infections (over 20%). In adults, Streptococcus pneumoniae and Haemophilus influenzae account for 75%, while Moraxella catarrhalis comprises about 5%.
Adults harbor a broader range of bacteria. For instance, anaerobic bacteria and Staphylococcus aureus are present in some adult ARBS cases. Odontogenic infections often involve anaerobic bacteria.

DIAGNOSIS

How is acute rhinosinusitis diagnosed?

It is generally confirmed based on specific clinical manifestations and signs.

What tests are needed to diagnose acute rhinosinusitis?

Examinations mainly include imaging and microbiological tests, which are primarily performed when complications such as intracranial or intraocular infections are suspected, namely:

• Imaging tests: CT or MRI of the head (including sinuses). These can identify the specific location of abscesses and inflammation.
• Microbiological tests: For patients suspected of having intracranial infection spread or other severe complications, sinus puncture or endoscopic sampling for culture is appropriate. However, these are generally not useful for viral rhinosinusitis.

What diseases should acute rhinosinusitis be differentiated from?

Depending on clinical manifestations and pathogens, acute rhinosinusitis needs to be distinguished from acute fungal sinusitis, the common cold, etc. Additionally, for patients with single symptoms, it should also be differentiated from other diseases with similar manifestations, such as:

• Facial pain – Multiple conditions may cause facial pain, including neuralgia, temporomandibular joint disorders, cancer pain, or carotidynia.
• Headache – Frontal sinus pain may have various headache etiologies, including migraines, tension-type headaches, and cluster headaches.

TREATMENT

Which department should I visit for acute rhinosinusitis?

Acute rhinosinusitis often presents with nasal symptoms similar to a cold or flu, so patients typically visit general internal medicine or respiratory medicine. Of course, those with a confirmed diagnosis can also go to the otolaryngology department.

What are the treatment methods for acute viral rhinosinusitis?

Most AVRS cases resolve spontaneously. A few may carry a risk of secondary ABRS. The goal of treatment is symptom relief:

• Ibuprofen or acetaminophen is commonly used to reduce fever and pain.
• Saline nasal irrigation and intranasal corticosteroids help relieve mucosal inflammation and improve sinus drainage.
• Antihistamines and decongestants may alleviate runny nose and congestion, but they have notable side effects. For example, the benefits of antihistamines and decongestants for children under 6 are insufficient to outweigh the risks, so they are not recommended. Adults should not use nasal decongestants for more than 3 days.

What are the treatment options for acute bacterial rhinosinusitis?

ABRS may lead to severe complications. However, contrary to common belief, most ABRS cases resolve spontaneously within 2 weeks without treatment.

Considering the risk of serious complications, antibiotic treatment is still recommended for ABRS. Amoxicillin is the first-line choice, while amoxicillin-clavulanate is preferred for children.

Azithromycin is not recommended due to its high risk of resistance. For patients with confirmed penicillin allergies, doxycycline, levofloxacin, or moxifloxacin can be alternatives.

Although systemic corticosteroids may improve symptoms, their side effects make this therapy inadvisable. Intranasal corticosteroids, however, can help relieve symptoms with acceptable side effects.

Patients with severe complications should receive treatment based on the causative pathogen and related conditions.

DIET & LIFESTYLE

What should patients with acute rhinosinusitis pay attention to in daily life?

• Patients with chronic rhinitis should receive standardized and active treatment to reduce the risk of secondary ABRS.

• To minimize the risk of colds and flu-like illnesses, frequent handwashing, a varied diet, and regular exercise should be adopted to boost immunity.

PREVENTION

Can acute rhinosinusitis be prevented? How to prevent it?

The best and strongest preventive measure for acute rhinosinusitis is vaccination. Vaccinations such as the flu vaccine can reduce the risk of viral infections. Meanwhile, pneumococcal and Haemophilus influenzae vaccines can lower the risk of ABRS.