Introduction
Rhinosinusitis, characterized by infl ammation of the maxillary and ethmoid sinuses, accounts for about 25
million offi ce visits annually in the United States. It is the fi fth most common reason physicians prescribe
antibiotics. For practical purposes, sinusitis and rhinosinusitis are interchangeable terms, although many
experts now prefer the latter because the nasal structures that are contiguous with the paranasal sinuses are
also invariably infl amed along with the sinuses.

Etiology and Pathogenesis
The normal sterility of the sinuses is maintained by continuous mucociliary clearance. A variety of physiologic and
anatomic abnormalities can lead to loss of patency of the sinus ostia and the ostiomeatal complex, the region of
common sinus drainage in the anterior middle meatus. This mechanism is thought to be common to the pathogenesis of most cases of bacterial sinusitis , both acute and chronic. Although viral upper respiratory infection
(URI) is the most common antecedent, allergic and vasomotor rhinitis can also predispose to bacterial sinusitis.
Anatomic factors that may play a role include deviated nasal septum and enlarged, pneumatized nasal turbinates
(concha bullosae). Nasal polyps arising in the presence of chronic inflammation in the sinuses may also lead to more
infection. Foreign bodies such as nasotracheal and nasogastric tubes are signifi cant in the hospitalized patient.
Cigarette smoking and certain intranasal drugs can impair ciliary action, predisposing to sinusitis. Any of these
conditions may increase edema at the sinus ostia or impair clearance from the sinuses. A relatively distinct pathogenetic mechanism is the occasional extension of a dental abscess into the maxillary sinuses that may spread into adjacent sinuses.
Cultures obtained by maxillary sinus puncture, as well as endoscopically directed cultures obtained from the
middle meatus, show that the most common bacterial pathogens, if present, are Streptococcus pneumoniae and
Haemophilus influenzae; however, other streptococci and Moraxella catarrhalis are sometimes isolated.
In patients with uncontrolled diabetes, neutropenia, or other immune-compromised states, pathogens such as
Aspergillus, Rhizopus (Mucor), Candida, Alternaria, Pseudomonas, Nocardia, Legionella, atypical mycobacteria, and
certain parasites are unusual but important etiologic considerations.
Nosocomial sinusitis associated with nasotracheal or nasogastric tubes is frequently polymicrobial. In
this setting, Staphylococcus aureus, enteric gram-negative bacteria, and anaerobes, particularly anaerobic streptococci and Bacteroides, may be present.

Culture studies of chronic rhinosinusitis reveal a different bacteriology. Anaerobes have been associated with
some cases of chronic rhinosinusitis, although their pathologic role is unclear. Similarly unclear is the high rate of
coagulase-negative staphylococcus as well as S. aureus frequently isolated in the presence of frank purulence. In the
setting of previous surgery, cultures reveal a greater prominence of gram-negative bacteria, including Pseudomonas
aeruginosa, in up to 30% of cases. Recent studies have suggested several different associated
mechanisms that may contribute to the development of chronic rhinosinusitis, distinguishing it from acute
disease and suggesting novel treatment modalities. Theories suggested include staphylococcal superantigen, chronic osteitis, biofilms, and an abnormal response to the presence of fungus in the nose.
Clinical Presentation
Patients with a “common cold” (viral rhinosinusitis or URI) usually have some combination of the following
symptoms: sneezing, rhinorrhea, congestion, facial pressure, postnasal drip, hyposmia or anosmia, sore throat,
cough, ear fullness, fever, and myalgia. Color of the mucus discharge is not an accurate indicator of bacterial infection.

There is considerable overlap in the presentation between viral and bacterial rhinosinusitis. A prolonged (>10 days)
“cold” with congestion and facial pain, with or without purulent drainage, raises the probability of bacterial
involvement. Some patients report a biphasic illness. Fever may be present, but is not typical. Some patients may have subacute (lasting 4 to 12 weeks) or chronic (lasting more than 12 weeks) symptoms.
The clinical exam may reveal facial tenderness, whereas anterior rhinoscopy may identify edema of the inferior
turbinates and possibly the presence of polyps or mucopurulence. The value of transillumination in routine
clinical decision making is probably limited at best. Serious life-threatening complications of sinusitis are
uncommon but can occur and require rapid intervention. The bony orbits are surrounded by the paranasal sinuses;
consequently, orbital infection can result from sinusitis, particularly ethmoid sinusitis with extension through the
lamina papyracea in children. A swollen upper lid may be the initial sign, followed by ptosis, chemosis, proptosis, and ophthalmoplegia. Anterior spread of infection from the frontal sinus can lead to osteomyelitis of the frontal bone, which presents with headache, fever, and a palpable doughy edema of the frontal bone called Pott’s puffy tumor.
Retrograde migration of septic thrombi along venous channels from infection in the posterior sinuses, including
the sphenoid sinus, can lead to thrombophlebitis of the cavernous sinus. Presenting fi ndings include fever, toxicity,
chemosis, proptosis, and cranial nerve palsies involving nerves III (oculomotor), IV (trochlear), and VI (abducens).
Cavernous sinus thrombosis may quickly become bilateral because of spread through the intercavernous communications.
Extension to the meninges or brain parenchyma can occur directly or through venous channels and can lead to epidural or subdural abscess, frontal lobe abscess, or meningitis.
Immune-compromised individuals, including diabetic patients, are at risk for invasive fungal infection of the
sinuses primarily with species of Aspergillus and Mucor.
Differential Diagnosis
Viral URI, allergic rhinitis, vasomotor (nonallergic) rhinitis, chronic use of topical nasal decongestants (rhinitis
medicamentosa), and deviated nasal septum are the most common diagnostic considerations in patients with sinus
complaints.
Less common causes of sinusitis include vasculitis or granulomatous disorders (Wegener’s granulomatosis,
Churg-Strauss, sarcoidosis), tumor, cerebrospinal fluid leak, drug-induced vasomotor rhinitis (from cocaine, prazosin, and angiotensin-converting enzyme inhibitors), foreign body, and certain hormonal conditions (hypothyroidism, pregnancy). Some patients with “sinus” may also be manifesting symptoms of migraine (with or without aura).

Diagnostic Approach
The clinical diagnosis of acute bacterial rhinosinusitis should generally be reserved for patients presenting with
sinus symptoms lasting more than 7 days, unilateral maxillary sinus pain or tenderness, and purulent nasal secretions.
Many of these patients will still have a viral etiology, and although antibiotics are often prescribed, many experts
believe watchful waiting is a reasonable option. Imaging tests such as plain radiography or computed
tomography (CT) are generally of limited utility in the initial evaluation of a patient with clinical rhinosinusitis.
Plain radiography is only moderately sensitive and specific for bacteriologically proven sinusitis. Sinus CT is a highly
sensitive test, but has poor specifi city, and does not distinguish between viral and bacterial inflammation. Maxillary
sinus radiographs of young adults with typical viral URI show mucosal abnormalities in about 40% of cases on the
seventh day of illness, and CT scans are abnormal in about 85% of similar cases.
The use of imaging in the initial evaluation of suspected sinusitis is more expensive and not much more effective
than other strategies, such as empiric antibiotic treatment of patients with reasonably high clinical likelihood of bacterial rhinosinusitis and symptomatic therapy for others. For these reasons, radiography is recommended only when initial therapy is ineffective, or for cases of recurrent or chronic rhinosinusitis. Furthermore, many ear, nose, and throat specialists fi nd nasal endoscopy to be more useful than imaging in refractory, recurrent, or otherwise complicated cases because of the ability to see and culture
purulent secretions.
Management and Therapy
Selection of Patients for Antibiotic Therapy
Most so-called cases of acute sinusitis diagnosed in general ambulatory practice are uncomplicated viral URIs. Even
when there is inflammation of the sinuses, bacterial and viral etiologies are diffi cult to distinguish on clinical
grounds. Although antibiotics are clearly overprescribed for this indication, their use can be justified in a subset of
patients with sinus complaints. Recent systematic reviews have examined the issue of antibiotic therapy for acute
rhinosinusitis. When considered in aggregate, placebocontrolled studies of clinical response show an absolute
benefit of about 15%, which means that about seven patients need to be treated for each patient who benefits.
The degree of benefi t is small, and most placebo-treated patients improve without antibiotic therapy. No serious
complications have been reported in sinusitis trials among patients who received placebo.
Given the increasing problem of antibiotic resistance, most experts advocate reserving antibiotics for patients.

Optimum Therapy
Antibiotic Treatment for Acute Bacterial Rhinosinusitis
Three recent meta-analyses have concluded that newer, broad-spectrum antibiotics are no more effective than
narrow-spectrum agents. When an antibiotic is prescribed, it should be the agent with the narrowest spectrum that is
active against the most common bacterial pathogens, S. pneumoniae and H. infl uenzae. Newer consensus guidelines
from the American Academy of Otolaryngology and the Centers for Disease Control and Prevention suggest that
amoxicillin with or without clavulanate and the cephalosporins cefpodoxime and cefuroxime appear to be as
effective as newer, more expensive agents when used as first-line therapies in patients who have not received an
antibiotic in the preceding 4 to 6 weeks. Trimethoprimsulfamethoxazole (TMP-SMX), doxycycline, and macrolides
are alternatives for penicillin-allergic patients. In those who have received recent antibiotic therapy, newer
quinolones may be appropriate. The optimal duration of therapy is unknown, but 7- to 14-day regimens are typically
used. In one study, 3 days of TMP-SMX was as effective as 10 days of therapy. Given the rapid increase of antibiotic
resistance among S. pneumoniae and H. infl uenzae, the clinician may also want to consider current recommendations for therapy against these organisms when making treatment decisions, particularly if the prevalence of resistant organisms or the risk for complications is high.