Bones of the skull

Acute Sinusitis

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Rhinosinusitis is a disease characterised by inflammation of the paranasal sinuses and nasal cavity. Since sinusitis is so commonly accompanied by inflammation in the nasal cavity, it is preferable to refer to β€œrhinosinusitis” as opposed to considering it a separate entity.

Rhinosinusitis is categorised according to its duration. Acute rhinosinusitis (ARS) lasts up to 4 weeks, while chronic rhinosinusitis (CRS) persists for more than 12 weeks.1Β Sinusitis persisting between 4 and 12 weeks is termed subacute sinusitis.Β 

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Aetiology and risk factors

ARS may be further subdivided based on its aetiology into bacterial (ABRS) or viral rhinosinusitis (AVRS). Most cases of ARS have a viral aetiology.2Β The most common viral causes of ARS include:

  • Rhinovirus
  • Influenza virus
  • Parainfluenza virus

ABRS most commonly occurs as a secondary infection of inflamed paranasal sinuses, either following a viral illness or another method which impairs the physiological clearance mechanisms and promotes bacterial stasis.

Such factors may include physical obstruction (for example, due to individual anatomy), immunodeficiency, illnesses which impair ciliary clearance (cystic fibrosis, Kartagener syndrome), and allergic or non-allergic rhinitis.3

Bacterial pathogens that most commonly cause ABRS include:1

  • Streptococcus pneumoniae
  • Haemophilus influenza
  • Staphylococcus aureus
  • Moraxella catarrhalis

Clinical features


Recent clinical guidelines describe three cardinal symptoms of ARS.1 These include purulent nasal discharge, facial pressure and nasal obstruction.4 The combination of these symptoms is highly specific for ARS, though the absence of this triad does not preclude ARS. Other symptoms can include:

  • Fever
  • Fatigue
  • Headache
  • Ear pressure

Although there are no validated symptoms that reliably differentiate between AVRS and ABRS5, 6, the two have different clinical courses. AVRS typically has a shorter and milder course, with symptoms lasting between 7 and 10 days2, 7-10. In contrast, ABRS is more likely to last beyond 10 days. Additionally, ABRS often presents with a β€œbiphasic” pattern of illness. This pattern is characterised by a period of recovery, followed by a worsening of symptoms.

Clinical examination

Diagnosis of ARS relies on the patient history more so than the clinical examination, since physical signs are not always present and may be nonspecific. Of the physical signs that may be present, the most specific for the diagnosis of ARS is purulent discharge in the nasal cavity or posterior pharynx. However, other signs that may be evident on examination include:

  • Facial swelling
  • Palpable cheek tenderness
  • Facial redness

Differential diagnoses

Minor upper respiratory conditions may resemble ARS, including the common cold, allergic and non-allergic rhinitis. However, facial pain and purulent nasal discharge are unlikely to present in any of these illnesses.

Additionally, the common cold and rhinitis are more likely to feature sneezing as opposed to ARS. The common cold may also present with throat pain, which is unlikely to occur in acute sinusitis.

Aside from these differentials, another cause of facial pain that may mimic ARS is cluster headache or migraine. Although neither of these typically present with facial pain, the retro-orbital pain of a cluster headache may be confused for frontal, ethmoidal or maxillary sinus pathology.

However, cluster and tension headaches are unlikely to present with acute tenderness over the paranasal sinuses, or purulent nasal discharge. Both of these conditions also have characteristic temporal patterns, neither of which are similar to acute rhinosinusitis.

Cluster headaches classically present in short (30-60 minutes) episodes of excruciating unilateral pain, often multiple times in one day.

Migraine headaches usually have a protracted course (over multiple hours) and may be accompanied by additional features such as photophobia, phonophobia, nausea, vomiting and visual aura.

Overall, the symptomatology of ARS is unique, and the presence of all three cardinal symptoms is sufficient for a clinical diagnosis.


Since the diagnosis of ARS relies on clinical features, the utility of investigations is limited to situations where the clinician is unsure of the diagnosis or suspects a complicated infection.

Laboratory investigations

For cases of complicated ABRS unresponsive to initial antibiotic therapy, nasal cultures can help to identify the causative agent.


Experts dispute the role of imaging studies in ARS. It is generally not recommended to request imaging in cases of suspected ARS unless the clinician suspects either a complicated infection or an alternate diagnosis.1Β In these cases, a CT scan with contrast can help to reveal intracranial or orbital involvement.


Since the majority of cases of ARS are viral in origin and will improve within 10 days, symptomatic relief is the mainstay of treatment.1Β Symptomatic relief may include oral analgesics, saline nasal irrigation or intranasal corticosteroids. If patients do not feel any improvement after 10 days or feel worsening of symptoms at any time, treat them as a presumed case of ABRS.

In immunocompetent patients with ABRS, watchful waiting for 7 days may be more prudent than early antibiotic use. However, if these patients do not improve within 7 days or experience worsening of symptoms at any time, prescribe appropriate antibiotics. Current guidelines for empiric management of ABRS recommend amoxicillin first-line.

Clinicians managing patients with ABRS should have a low threshold for referral to an ENT service, as complications may develop rapidly and be particularly devastating. However, clinicians can manage the vast majority of patients with ARS through symptomatic treatment and watchful waiting if secondary infection occurs.


Although the majority of ABRS cases are uncomplicated, complications may cause significant morbidity. The severity of these complications is due to the proximity between the paranasal sinuses and other intracranial structures, including the orbit, cavernous sinus and meninges. The following symptoms may be present in patients with a complicated bacterial infection:

  • Severe headache
  • Visual changes
  • Periorbital oedema
  • Altered mental status

Key points

  • Acute rhinosinusitis (ARS) describes inflammation of the paranasal sinuses and nasal cavity lasting under 4 weeks.
  • Cases of ARS are classified as having a bacterial or viral aetiology.
  • Acute viral rhinosinusitis (AVRS) is very common and should improve within 10 days, but a small number of patients develop a secondary bacterial infection (ABRS).
  • The cardinal symptoms of ARS are purulent nasal discharge, nasal congestion and facial pain or fullness.
  • Investigations are not warranted in most cases of ARS unless the clinician suspects a complicated infection or an alternative diagnosis.
  • Symptomatic treatment with analgesics and saline irrigation is sufficient for the majority of patients with AVRS.
  • In otherwise healthy patients with ABRS, watchful waiting over 7 days may avoid unnecessary antibiotic prescription.
  • Complications of ARS are rare but may cause high morbidity.


  1. Rosenfeld RM, Piccirillo JF, Chandrasekhar SS, Brook I, Ashok Kumar K, Kramper M, Orlandi RR, Palmer JN, Patel ZM, Peters A, Walsh SA & Corrigan MD (2015). Clinical Practice Guideline (Update): Adult Sinusitis. Otolaryngology–Head and Neck Surgery 152, S1-S39.
  2. Rosenfeld RM (2016). Acute Sinusitis in Adults. New England Journal of Medicine 375, 962-970.
  3. Scheid DC & Hamm RM (2004). Acute bacterial rhinosinusitis in adults: part I. Evaluation. Am Fam Physician 70, 1685-92.
  4. Meltzer EO & Hamilos DL (2011). Rhinosinusitis diagnosis and management for the clinician: a synopsis of recent consensus guidelines. Mayo Clin Proc 86, 427-43.
  5. Chow AW, Benninger MS, Brook I, Brozek JL, Goldstein EJ, Hicks LA, Pankey GA, Seleznick M, Volturo G, Wald ER & File TM, Jr. (2012). IDSA clinical practice guideline for acute bacterial rhinosinusitis in children and adults. Clin Infect Dis 54, e72-e112.
  6. Young J, De Sutter A, Merenstein D, van Essen GA, Kaiser L, Varonen H, Williamson I & Bucher HC (2008). Antibiotics for adults with clinically diagnosed acute rhinosinusitis: a meta-analysis of individual patient data. Lancet 371, 908-14.
  7. Axelsson A & Runze U (1976). Symptoms and signs of acute maxillary sinusitis. ORL J Otorhinolaryngol Relat Spec 38, 298-308.
  8. Axelsson A & Runze U (1983). Comparison of subjective and radiological findings during the course of acute maxillary sinusitis. Ann Otol Rhinol Laryngol 92, 75-7.
  9. Berg O & Carenfelt C (1988). Analysis of symptoms and clinical signs in the maxillary sinus empyema. Acta Otolaryngol 105, 343-9.
  10. Williams JW, Jr., Simel DL, Roberts L & Samsa GP (1992). Clinical evaluation for sinusitis. Making the diagnosis by history and physical examination. Ann Intern Med 117, 705-10.


Sarah Vreugde MBBS PhD

Associate Professor of OtorhinolaryngologyΒ 

Queen Elizabeth Hospital, Adelaide


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