Rhinosinusitis is a concomitant inflammation of the mucosal surfaces of the nose and paranasal sinuses (Figure 1). The condition is very common and is estimated to affect 16% of the adult population annually in the U.S.1 We would expect similar numbers in Canada, where chronic rhinosinusitis is more frequent in women than in men, and this sex difference is consistent across age groups. The prevalence increases with age but levels off after 60. In women -- but not in men -- the incidence has been found to be higher in the eastern regions and among native Canadians as compared to immigrants and those living in central or western Canada. Cigarette smoking and low income are associated with a higher occurrence of rhinosinusitis in both sexes, but there's no relationship with alcohol consumption or a lack of regular exercise.2

What causes sinusitis?
The etiologic factors are wide and varied, and can be congenital or acquired. Hereditary causes include ciliary dyskinesias, cystic fibrosis, cleft palate and immunoglobulin deficiencies. Acquired causes range from infections, allergy, environmental pollutants, trauma and barotraumas, to iatrogenic mechanisms such as dental procedures and nasogastric intubation.

The common theme is a failure of normal mucociliary clearance. This promotes stagnation and subsequent colonization by bacterial pathogens, which further reduces mucociliary function. The initial insult may be fairly innocuous -- a viral infection or severe and persistent rhinitis may be enough to trigger the chain of events necessary for the development of acute rhinosinusitis. This is especially true if anatomic variants, prior trauma or ciliary dyskinesias are present. Mucosal congestion and edema, an acidic intrasinus pH and negative intraluminal pressure due to obstruction of the sinus ostia all spark a vicious cycle of ciliary dysfunction, stagnation of secretions and poor lymphatic drainage. These conditions promote an anaerobic environment and subsequent bacterial overgrowth.

When do you suspect it?
Rhinosinusitis can be acute, subacute, recurrent acute or chronic. The diagnosis in the office setting isn't always straightforward. Patients frequently attribute almost all types of facial pain to their sinuses. The differential diagnosis may include dental pain, mid-face tension headaches, migraine, temporomandibular joint dysfunction and trigeminal neuralgia, among others. If the individual presents with facial pain, you should seek a history that corroborates a sinus etiology. A premorbid event, such as an upper respiratory tract infection, increases the probability of sinusitis. Symptoms such as green nasal discharge, heaviness, congestion or throbbing in the sinuses, a vertex headache, fever, hyposmia and maxillary alveolar pain make acute rhinosinusitis most likely. A specific inquiry regarding migraine or neck complaints may raise the suspicion for alternative causes of the pain, as would a history of lancinating pain or aches that occur, for example, in cold weather. An acute sinus headache is, in fact, very rare.3

Acute rhinosinusitis, by definition, settles completely within 4 weeks -- from onset to resolution. Subacute rhinosinusitis will present with similar features as acute rhinosinusitis, but episodes typically last from 4-12 weeks, followed by complete resolution. Chronic rhinosinusitis is defined by a green nasal discharge present on most days, and is associated with facial heaviness, throbbing or congestion in the region of the paranasal sinuses -- without complete resolution in a 3-month period. Three or more episodes of acute rhinosinusitis in a year constitute recurrent acute rhinosinusitis.4

What are the offending pathogens?
The initial insult in acute or subacute rhinosinusitis is likely to be a viral upper respiratory infection. Typical viruses are the rhinovirus, coronavirus, influenza A or B, parainfluenza, respiratory syncytial virus, adenovirus and enterovirus.5 Bacterial infections are unlikely to be the cause of a common cold. Inflammation and congestion occurs not only in the nasal passages, but also within the sinuses themselves. Indeed, the distinction between the mucosal surfaces of the nose and sinuses is an artificial one, which explains the use of the term rhinosinusitis.

Mucous stasis, viral immunosuppression and secondary bacterial colonization promote a purulent discharge along with the other symptoms already mentioned. Bacterial pathogens are those normally associated with upper respiratory tract infections -- Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis are the most likely candidates (see Figure 2). Staphylococcus aureus is unusual, as are fungal infections. Anaerobes may be prevalent in chronic rhinosinusitis.

How do you make the diagnosis?
The gold standard of diagnosis is sinonasal endoscopy and guided microbial culture of pus (see Figure 3). This kind of procedure isn't always feasible in the office setting, however, in which case the history should provide enough of a clue to point towards the most probable cause of symptoms. A history shorter than 7-10 days is likely to represent a viral pathogenesis. If symptoms have been present longer than that, you should suspect secondary bacterial infection. Anterior rhinoscopy, using an otoscope, will reveal congestion and rhinorrhea, possibly pus emanating from the middle meati, anatomic variants and perhaps polyposis. To facilitate this diagnostic procedure, you can begin with topical decongestion -- permitting adequate time for it to work. You'll find that the mucosa overlying the inferior turbinate shrinks, enabling a clearer appreciation of the middle meatus and any pathology related to it. More detailed endoscopic examination in the office setting is probably not feasible.

What's the existing therapy?
When the patient presents early on in the course of the disease, you should manage the illness sympathetically and according to symptoms. Simple analgesics, saline irrigations and decongestants are good options for early therapy.6 Antihistamines have no role, unless there's an atopic predilection. There's also no place for antibiotics during the early stages of disease, due to the risks of resistance and selection of more virulent bacterial strains. In the short term, topical intranasal steroids will offer little symptomatic relief.

If symptoms of acute rhinosinusitis are confirmed and persist beyond 7 days, you may be dealing with a bacterial super-infection. In this case, an empiric choice of antibiotic therapy may serve to shorten the duration of the illness. We recommend amoxicillin 500 mg 3 times daily as a first-line treatment. In penicillin-allergic patients, clarithromycin 500 mg twice daily is appropriate. The optimal duration of therapy isn't known, but a 10-14 day course of antibiotics is reasonable and acceptable to patients.4 Others recommend treatment until the patient is free of symptoms and then for an additional 7 days.7 In either case, patients should be encouraged to complete the antibiotic course even if symptoms resolve early.

What's next when first-line therapy fails?
Not infrequently, a course of oral antibiotics combined with decongestants and simple analgesics will fail to completely resolve an episode of acute rhinosinusitis. Under these circumstances, there may be persistent discomfort in the distribution of the paranasal sinuses, discharge (either from the nostrils or as a post-nasal drip), headache or nasal congestion. In such a case, begin by reviewing your diagnosis. Are the symptoms still consistent with rhinosinusitis? If the answer is still "yes," then therapy may need to be modified accordingly.

Consider second-line antibiotics in any of the following situations: if symptoms fail to improve after a 72-96 hour timeframe; if you suspect either frontal or sphenoid sinusitis; if antibiotics have been prescribed in the preceding 3 months; or in the presence of systemic immunosuppression or other chronic comorbidities. In these instances, a second-generation cephalosporin, an oral beta-lactam, a macrolide or a fluoroquinolone are all good options. Any of these antibiotic classes is a reasonable choice, but it's important that the best drug in its class is selected and prescribed at an optimal therapeutic dose (see Table 1).4 This should reduce the risk of progression to subacute or chronic rhinosinusitis.

Do you recommend corticosteroids?
Topical intranasal corticosteroids have been shown to be a useful adjunct in the management of protracted rhinosinusitis. Their action is anti-inflammatory, and it isn't known whether they penetrate the nasal mucosa or act on target cells. Their low systemic activity supports a theory of local action on the nasal mucosa, which is thought to modulate inflammatory cells and their mediators. Corticosteroid-induced inhibition of IgE-dependent release of histamine has also been postulated, but remains unproven.

The systemic bioavailability of intranasal steroids is often a concern and varies between formulations. It's best practice to prescribe the lowest dose that will control symptoms without causing adverse systemic effects; also make sure you choose a method of delivery and a regimen that's convenient and likely to encourage compliance.

The value of topical saline irrigations can't be overstated. They enhance mucociliary function due to the beneficial effects of humidification, pH restoration and thinning of secretions. There will likely be an improvement in symptoms of rhinosinusitis and, quite possibly, a reduction in the use of medication in those who use saline irrigation compliantly and on a regular basis.

What role does imaging play?
In addition to endoscopic evaluation, imaging of the paranasal sinuses now plays a vital role in the diagnosis and management of sinonasal disorders. Standard sinus x-rays include the Waters' view, Caldwell view, lateral view and submentovertex view. In the case of rhinosinusitis, these projections may show a complete opacification or air-fluid level in one or more of the sinuses. Partial opacification or mucosal thickening are less useful diagnostic criteria because they're both too non-specific. Unfortunately, plain sinus views are limited in their ability to accurately and consistently diagnose paranasal sinus disease, even when interpreted by radiologists.8

Plain sinus films have almost exclusively been replaced by computed tomography (CT) in the tertiary care setting. CT provides a superior means of confirming pathology and the anatomy of the paranasal sinuses (see Figure 4). The scanners that are in use today are quick and expose the patient to much lower doses of radiation than the old ones. They also allow for multiplanar reformatting, providing the otolaryngologist with a three-dimensional image of the paranasal sinuses. It's important to interpret a CT scan in the context of the history and examination because there may be incidental mucosal changes in about 30% of the asymptomatic population, so a CT could yield "false positives." In contrast, a normal CT in a patient with facial pain should prompt the physician to make an alternative diagnosis.

Magnetic resonance imaging (MRI) provides insights into the soft tissue pathology, but does so at the expense of bony anatomy. It's less useful to the otolaryngologist when dealing with inflammatory sinonasal conditions, and should be reserved for suspected neoplastic conditions, particularly those involving the anterior skull base or the orbit.

When should you refer?
Seek the opinion of an otolaryngologist if an acute case doesn't resolve with treatment or if symptoms worsen despite adequate intervention. Recurrent acute sinusitis should also be referred to a specialist since this condition severely affects the quality of life and productivity of a patient. In addition, all cases of suspected frontal sinusitis and isolated sphenoiditis should probably get a second opinion, given the propensity to develop complications. If you detect any signs of potential complications, refer immediately. Red flags include symptoms of acute sinusitis with a swollen or red eye, a displaced globe, double vision, ophthalmoplegia, an inability to assess vision, a reduced visual acuity or colour discrimination, severe unilateral or bifrontal headache, frontal swelling, evidence of meningitis or focal neurologic signs. Under these circumstances, an endoscopic evaluation is mandatory, and symptoms can be alleviated by prompt intravenous antibiotic therapy and decongestion. More serious complications are investigated with CT, and targeted surgery in an acute situation may prevent blindness and death. The approach is most often multi-disciplinary and may require the intervention of an ophthalmologist or neurosurgeon.

What can surgical intervention achieve?
Should rhinosinusitis fail to respond to optimal medical therapy, targeted surgery to the sinuses may help (see Figure 5). Surgery has evolved over the past decades and now comprises minimally-invasive, endoscopic-assisted techniques. The aim of such a procedure should be to restore physiologic sinus drainage pathways, remove disease, allow ventilation of the paranasal sinuses, and to facilitate the delivery of topical medications.

Patients are advised at the outset that surgical intervention is intended to complement medical therapy, and not to replace it. A decision to proceed requires commitment from both parties, particularly in the immediate post-operative period when frequent outpatient visits and debridement of the sinus cavities are necessary to ensure the best results. Edema and consequent congestion usually take several weeks to subside. The nasal passages are kept clear with regular saline douches. Maximal benefit occurs around 3 months after surgery.

What does the future hold?
The management of rhinosinusitis has greatly improved over the past decade. A better understanding of the disease process, combined with superior pharmacotherapy and the development of enhanced, minimally-invasive surgical techniques has increased the quality of life of those suffering from the disease. Currently, state-of-the-art computer-assisted image-guided navigation systems allow those experienced in their use to get an unparalleled view of sinus anatomy in real time. This advancement has extended the earlier limitations of sinus surgery where anatomic landmarks weren't obvious -- particularly in revision cases.

Biofilms, i.e. dense bacterial colonies, and their possible association with chronic rhinosinusitis are an area of intense study at the moment.9 Acute infections are thought to occur when showers of these bacteria break free from their colony. If this theory holds true, antibiotic regimens will need to be appropriately tailored, since current prescribing practices may be woefully inadequate for penetration and eradication of the biofilm. Alternatively, biofilms may call for earlier surgical intervention.

The most significant advances in the management of rhinosinusitis, though, will come from an appreciation that the nasal and sinus mucosa is a continuation of the mucosa of the lower respiratory tract. A better understanding of lower respiratory disease and its management will facilitate a more comprehensive approach to treating rhinosinusitis. This will undoubtedly entail a close collaboration between sinus surgeons, other otolaryngologists, respiratory physicians, microbiologists and researchers in the field of airway disease. The future is very exciting.