Sinusitis

Symptoms of rhinitis and sinusitis are often very similar and even difficult to differentiate in many cases. Sinusitis implies inflammation of the mucosa of one or more of the paranasal sinuses. This usually coexists with rhinitis and is actually more accurately referred to as rhinosinusitis. Studies have shown that CT scans of patients with uncomplicated viral upper respiratory infections (URIs) have mucosal thickening and opacification of the sinuses. For this reason, most URIs are technically considered viral rhinosinusitis. In most cases, these changes resolve with time and symptomatic treatment. The terms rhinosinusitis or sinusitis are typically used when a bacterial infection of the sinuses is suspected. About 5% of viral URIs will progress to bacterial rhinosinusitis. An estimated 20 million cases of bacterial sinusitis occur in the United States annually, accounting for 9% and 21% of all pediatric and adult antibiotic annual prescriptions, respectively (Sinus Partnership, 2004).

Inflammatory conditions of the paranasal sinuses cause significant socioeconomic impact annually, secondary to considerable medical expense and missed workdays. Chronic sinusitis can be quite debilitating. Studies have shown that quality-of-life scores of patients with chronic sinusitis are often similar to those of other, more severe conditions (CHF, COPD). Chronic sinusitis can also exacerbate coexisting medical conditions, most notably reactive airway disease.

Sinusitis represents one of the most common disorders requiring antibiotic treatment in adults. The challenge to the clinician in evaluating the patient with possible sinusitis is to differentiate viral URI, allergic rhinitis, and even a migraine headache, which do not require antibiotics, from bacterial sinusitis, which does respond to antibiotic treatment. There still seems to be a public perception that antibiotics hasten recovery from the common cold. Some physicians prescribe antibiotics in these situations, not wanting to disappoint the patient and seeing no significant risk. In fact, evidence suggests that there is a greater likelihood of harming rather than benefiting the patient with inappropriate use of antibiotics (Scott and Orzano, 2001). The emergence of bacteria highly resistant to broad-spectrum antibiotics has forced the medical community to modify its behavior regarding the treatment of URIs. Antibiotics should not be prescribed unless a bacterial infection is certain or at least probable. The patient should be educated about the rationale for this and usually responds favorably.

The underlying cause of most cases of sinusitis is muco-ciliary dysfunction and sinus obstruction. The maxillary sinuses, anterior ethmoid sinuses, and frontal sinuses all drain through small ostia that converge into a small channel called the ostiomeatal unit, which then empties into the middle meatus, beneath the middle turbinate . Obstruction at the ostiomeatal unit leads to obstruction of these sinuses and secondary infection. The posterior ethmoid sinuses and sphenoid sinuses are usually affected later. Sinusitis most often follows a viral URI or an episode of allergic rhinitis. Mucosal edema, impaired local immunity, and ciliary dysfunction lead to impaired sinus drainage and mucus stasis, followed by bacterial infection. Less frequently, sinusitis can result from direct bacterial contamination from an infected tooth or trauma.

Sinusitis is classified into acute (symptoms up to 3 weeks), subacute (symptoms from 3 to 6 weeks), and chronic (symptoms longer than 6 weeks) cases. Cases of acute sinusitis that clear completely only to develop again quickly are referred to as recurrent acute sinusitis. Although the types of sinusitis share many characteristics, there are several critical differences in pathogenesis and treatment.

The most important risk factor for the development of sinusitis is rhinitis (e.g., viral, allergic). Other risk factors include anatomic abnormalities (abnormality within the sinuses, septal deviation, choanal atresia, foreign body, adenoid hypertrophy), nasal polyps (which can also occur secondary to chronic sinusitis), conditions of local or systemic immunodeficiency, cystic fibrosis, primary ciliary dysfunction (Kartagener's syndrome), secondary ciliary dysfunction (cigarette smoking, nasal decongestant abuse, cocaine abuse), gastroesophageal reflux disease (GERD), systemic inflammatory conditions (sarcoidosis, Wegener's granulo-matosis), dental disease, and nasal or sinus tumors. Any of these conditions can mimic or cause rhinosinusitis. Further workup or referral is indicated if a patient continues to struggle with nasal or sinus symptoms despite medical therapy.

The diagnosis of sinusitis is initially clinical. Imaging and cultures are not initially indicated (Reider, 2003). In 1996 the Task Force on Rhinosinusitis sponsored by the American Academy of Otolaryngology-Head and Neck Surgery developed diagnostic criteria for sinusitis. The signs and symptoms of sinusitis are divided into major and minor. Major signs and symptoms include facial pain and pressure, nasal congestion and obstruction, nasal discharge, discolored posterior discharge, anosmia or hyposmia, fever (acute only), and purulence on intranasal examination. Minor signs and symptoms include headache, otalgia or ear pressure, halitosis, dental pain, cough, fever (nonacute), and in children, fatigue and irritability. The diagnosis of sinusitis is probable if the patient has two or more major factors or one major and two or more minor factors. A suggestive history is indicated by the presence of one major factor or two minor factors.

Microbiology of sinusitis varies according to its chronic-ity. Acute sinusitis is most often initially viral. If symptoms persist, the likelihood of bacterial infection increases. Bacteria most often involved in acute sinusitis are Pneumococcus spp., Haemophilus influenzae, and Moraxella catarrhalis, with beta-lactamase production common in all these. Chronic sinusitis is caused by the same bacteria as in acute sinusitis, but anaerobic bacteria, Pseudomonas spp., and staphylococci become involved more often. The incidence of antibiotic-resistant bacteria, including MRSA and multidrug-resistant Pneumococcus, seems to be increasing. Polymicrobial infections are not uncommon.

Sinusitis can also be caused by fungi. Invasive fungal sinusitis (caused most often by Aspergillus or Mucor spp.) can be seen in patients with impaired immune function and poorly controlled diabetes. It is life threatening even with aggressive medical and surgical treatment. Much more common is a more indolent fungally mediated sinusitis. Allergic fungal sinusitis is seen in patients with normal immune function. This is often seen in association with nasal polyps and is thought to be the result of an aberrant immune response to the fungus rather than a true infection. Patients do not always have type I hypersensitivity to fungi. Secondary bacterial infection is often associated with this problem.

Rarer causes of sinusitis are secondary to mycobacterial or parasitic infection.

Complications of Sinusitis

Most cases of sinusitis would resolve with or without medical treatment. Sinusitis is usually treated, however, to avoid potential complications and hasten recovery. The proximity of the paranasal sinuses to the orbits and brain potentially allows infection to spread to these locations. Orbital and CNS involvement of sinusitis can lead to loss of vision and can be life threatening and therefore requires early recognition and treatment. Table 19-6 lists the potential complications of sinusitis and treatment recommendations. A high degree of clinical suspicion is required in cases of possible complicated sinusitis, especially in young children. Patients with a recent URI who present with periorbital erythema, vision change, increasing or severe headache, high fever, or altered mental status require urgent evaluation and treatment. Ophthalmologic, infectious diseases, and ENT consultations are obtained in cases of orbital complication. Periorbital and

Table 19-6 Complications of Sinusitis

Complication

Physical Findings

Treatment

Periorbital cellulitis

Periorbital erythema, edema

Antibiotics: PO or IV

Orbital cellulitis

Erythema, edema, proptosis ± vision loss

IV antibiotics, close observation

Orbital abscess

Erythema, edema, proptosis ± vision loss

IV antibiotics + drainage, FESS

Cavernous sinus thrombosis

Erythema, edema, proptosis + vision loss

IV antibiotics + FESS

Meningitis

Headache, altered mental status, nuchal rigidity, fever

IV antibiotics ± FESS

Intracranial abscess

Headache, altered mental status, high fever

IV antibiotics + drainage, FESS

Mucocele or pyocele

Facial swelling ± fever ± pain

Drainage

FESS, Functional endoscopic sinus surgery.

orbital cellulitis usually can be managed with intravenous antibiotics. The more severe orbital complications, however, usually require drainage procedures in combination with IV antibiotics. Surgical drainage also allows cultures to be obtained. Recovery from orbital complications is usually complete with prompt and aggressive treatment. Permanent vision impairment can occur even after appropriate treatment.

The CNS complications require neurosurgical, ENT, and infectious diseases consultation. High-dose IV antibiotics are administered. Surgical drainage of the sinuses is sometimes recommended to treat the nidus of the infection and identify the exact pathogen. Recovery from CNS complications is more variable and depends on the patient's age and medical history, severity of the infection, and response to treatment.

Although not always complicated infections, sphenoid and frontal sinusitis deserve special mention. In some cases, drainage of the frontal sinuses is compromised. Chronic and recurrent frontal sinusitis can lead to both intracranial and ophthalmologic complications if untreated. Large mucoceles or mucopyeloceles can also form within the frontal sinus, causing disfigurement and diplopia. These conditions usually require surgical drainage. Similarly, sphenoid sinusitis can rarely be aggressive. The carotid artery and optic nerves traverse the lateral walls of the sphenoid sinuses. The sphenoid sinus occupies a space inferior and anterior to the cranial vault. Acute or long-standing sphenoid sinusitis can progress to CNS or eye complications, or both. If frontal or sphenoid sinus involvement is noted on CT scan, ENT evaluation is usually indicated.

Medical Treatment of Acute Sinusitis

Treatment of acute sinusitis is almost always medical. Medical treatment of sinusitis, in general, is intended to restore normal mucociliary function, eradicate infection, and improve patient symptoms. Treatment to restore mucociliary function is critical and is as important as antibiotic treatment.

Improved mucociliary function allows the patient's local immunity to function better and often leads to resolution of the infection.

The patient's medical history, including allergies, must be considered. Patients with poorly controlled hypertension or coronary artery disease may not tolerate decongestants. In acute cases of sinusitis, mucociliary function can be improved by a combination of medications, including oral or topical decongestants (topically for less than 3 days), mucolytics (guaifenesin), and nasal toilet (saline mist or irrigations). Nasal saline irrigations are available over the counter or can be homemade. Both 0.9% isotonic saline and hypertonic saline irrigations are extremely beneficial. Nasal steroids are not indicated for acute sinusitis but may decrease symptoms and hasten recovery in some patients. Antihistamines are usually not helpful, unless there is a strong allergic component, and can actually be counterproductive by increasing mucus viscosity and mucosal dryness. Oral steroids are usually not indicated in acute sinusitis, but they may be helpful in select patients.

This leaves the practitioner with the responsibility of using good clinical judgment to appropriately prescribe antibiotics to treat acute sinusitis. Antibiotics are empirically chosen based on the expected pathogens and local antibiotic-resistance patterns. The high incidence of beta-lactamase-pro-ducing strains of H. influenzae and M. catarrhalis and the penicillin-resistant pneumococci must be considered. More prudent use of antibiotics seems to have resulted in a plateau of the emergence of antibiotic resistance of these pathogens. MRSA seems to be more common, however, especially in chronic sinusitis.

According to Cochrane Collaboration recommendations for treatment of acute sinusitis, antibiotics provide a minor improvement in simple, acute (uncomplicated) sinus infections. However, 8 of 10 patients improve without antibiotics within 2 weeks. The small benefit gained may be overridden by the negative effects of antibiotics, both on the patient and on the population in general. For acute sinusitis confirmed by radiology or nasal endoscopy, current evidence is limited but supports the use of intranasal steroids for acute sinusitis as a monotherapy or as an adjuvant therapy to antibiotics. Clinicians should weigh the modest but clinically important benefits against possible minor adverse events when prescribing therapy.

Many antibiotics are indicated for the treatment of acute bacterial rhinosinusitis. In addition, there are antibiotics that do not have Food and Drug Administration (FDA) approval for treatment of sinusitis but are still appropriately used.

The Sinus and Allergy Health Partnership (2004) made the following comprehensive recommendations regarding the treatment of acute rhinosinusitis:

1. A bacterial infection should be suspected if symptoms of a viral URI do not improve after 10 days, or if symptoms worsen after 5 to 7 days.

2. Antibiotic resistance is common. Specifically, intermediate resistance of Streptococcus pneumoniae to penicillin (PCN) is 15%, and complete resistance is estimated at 25%. Resistance of S. pneumoniae and Haemophilus influenzae to trimethoprim-sulfamethoxazole (TMP-SMX) is common, as is resistance of S. pneumoniae macrolides. Beta-lactamase production of H. influenzae and Morax-ella catarrhalis is 30% and 100%, respectively.

3. Selection of an antibiotic should be based on severity of symptoms, whether the patient has received an antibiotic in the last 4 to 6 weeks, and the response to current antibiotic therapy after 72 hours. Mild symptoms include rhinorrhea and fatigue. Moderate symptoms include congestion, low-grade fever, and facial pain.

4. The widespread use of fluoroquinolones for mild sinusitis may promote resistance to this class of antibiotics.

5. Antibiotic choices for adults with mild disease and no recent antibiotics include amoxicillin (1.75-4 g/day, with or without clavulanate), cefpodoxime proxetil, cefuroxime axetil, or cefdinir. TMP-SMX, doxycycline, azithromycin, erythromycin, and clarithromycin may be considered in PCN-allergic patients, but the failure rate may be as high as 20% to 25%. Failure of therapy should prompt reevaluation of the patient or a switch in therapy.

6. Antibiotic choices for adults with moderate disease or with mild disease who have received recent antibiotics include amoxicillin-clavulanate (4 g/day) or a respiratory fluoroquinolone (levofloxacin or moxifloxacin). Ceftriaxone (1-2 g parenterally for 5 days) or combination therapy for gram-positive and gram-negative bacteria may also be considered. Failure of therapy should prompt reevaluation of the patient, CT scan, endoscopy with culture, or a switch in therapy.

7. Antibiotic choices for children with mild disease and no recent antibiotics include amoxicillin (90 mg/kg/ day, with or without clavulanate), cefpodoxime proxetil, cefuroxime axetil, or cefdinir. TMP-SMX, doxycycline, azithromycin, erythromycin, and clarithromycin may be considered in PCN-allergic patients (especially immediate type I hypersensitivity), but the failure rate may be as high as 20 to 25%. If the patient has a true type I hypersensitivity to beta-lactams, desensitization, sinus culture, CT scan, or other intervention may be necessary. Less severe reaction may allow use of another beta-lactam antibiotic. Failure of therapy should prompt reevaluation of the patient or a switch in therapy.

8. Antibiotic choices for children with moderate disease or with mild disease who recently received antibiotics include amoxicillin-clavulanate (90 mg/kg/day). Cefpodoxime proxetil, cefuroxime axetil, or cefdinir may be used if there is a nonsevere PCN allergy (rash). Cefdinir is preferred because of high patient acceptance. Ceftriaxone (50 mg/kg/day parenterally for 5 days) or combination therapy for gram-positive and gram-negative bacteria may also be considered. Failure of therapy should prompt reevaluation of the patient, CT scan, endoscopy with culture, or a switch in therapy.

As recurrence or severity of the infection increases, broader-spectrum antibiotics are indicated. Macrolides, fluoroquino-lones, augmented penicillins, and cephalosporins are useful in these cases. Culture-directed antibiotic treatment may be indicated in more refractory cases. Obtaining a culture usually requires an ENT referral, because simply swabbing the nasal cavity is not reliable. Cultures can be obtained from an endoscopically guided middle meatus swab. Maxillary sinus aspiration can also be done but is more invasive and not much more accurate than a middle meatal culture. Adjunctive treatment to help improve mucociliary function becomes more important as recurrence increases.

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