ACUTE & CHRONIC SINUSITIS

Saturday, August 16, 2008

Essentials of Diagnosis

• Fever, facial pain or pressure, headache, purulent nasal or postnasal discharge (PND), cough.

• Tenderness over the sinuses, PND, other signs of complications may be seen such as meningismus or periorbital cellulitis.

• Leukocytosis in some cases, sinus or blood cultures may be positive for S pneumoniae, H influenzae, or other bacteria.

• CT scan is a very sensitive method of detecting sinusitis.

General Considerations

Inflammation of the pseudostratified epithelium of the sinuses may occur as a result of an infection, allergy, toxin, or an autoimmune disorder. The paranasal sinuses (maxillary, ethmoid, frontal, and sphenoid) are sterile under normal conditions. Any one or all of them may become infected resulting in inflammation and edema of the pseudostratified epithelium that leads to an increase in tenacious secretions and the symptoms of acute sinusitis. The maxillary sinus is most commonly involved because its ostium is located at the highest part of the medial wall of the sinus. This leads to inadequate drainage and pooling of excess secretions, increased tenacity of secretions, and a drop in oxygen tension creating a more favorable environment for bacterial growth. Acute sinusitis occurs in all ages.

Infectious sinusitis may be bacterial, fungal, or viral. A large percent of acute sinusitis results from viral infection of the sinuses with or without bacterial superinfection. The latter is more symptomatic and patients are more likely to present to the physician. Episodes of sinusitis that occur all year round may be associated with allergies, polyps, or swimming.

The microbiology of acute bacterial sinusitis is similar to that of otitis media (Box 9-14). S pneumoniae and H influenzae account for > 50% of the sinusitis cases. Other pathogenic bacteria include M catarrhalis, a- and ß-hemolytic streptococci, S aureus, C pneumoniae, anaerobic bacteria, and occasionally gram-negative bacteria such as the Enterobacteriaceae or P aeruginosa. The ß-lactamase-producing H influenzae and M catarrhalis and intermediate or PRSP have proportionally increased in the microbiology of sinusitis and have important implications for management of sinusitis. Anaerobic bacteria, such as Peptostreptococcus, Fusobacterium, or Prevotella species, are implicated in ~ 8-10% of cases of acute sinusitis. These are usually polymicrobial and result from contiguous spread from the roots of the teeth.

Patients with craniofacial fractures have a higher incidence of sinusitis. P aeruginosa is a frequent cause of sinusitis in HIV-positive and in cystic fibrosis patients and must be considered in a patient who fails empirical antibiotic therapy that does not include antipseudomonal activity. S aureus is slightly more common in frontal or sphenoidal sinusitis. Fungi such as Aspergillus spp., Zygomycetes (Mucor spp.), and Pseudallescheria spp., among others, can occur in normal hosts or in immunocompromised hosts. Aspergillus sinusitis may occur in normal hosts or present as an allergic syndrome. Zygomycetes infection is more common in people with diabetes (particularly during acidosis), neutropenic patients, and patients on deferoxamine treatment. Viruses such as rhinovirus, influenza virus, adenovirus, coronavirus, and occasionally CMV, among others, account for sinusitis that presents with the primary rhinitis or upper respiratory tract infection syndrome. Coinfections of viruses and bacteria have a higher rate of prolonged duration of symptoms. Recurrent sinusitis may occur as a result of allergies, enlarged adenoids (especially in children), anatomic obstruction such as septal deviation, polyps, tumors, or craniofacial abnormalities, congenital primary or acquired immunodeficiency syndromes, or coexisting disease such as cystic fibrosis, asthma, or gastroesophageal reflux disease.

Chronic sinusitis, infection of the paranasal sinuses for 3 mo or more, may occur in patients with persistently impaired sinus drainage, immunodeficiency, or inadequately treated previous sinusitis episodes. The microbiology of chronic sinusitis is difficult to interpret with previous antibiotic use. However, chronic sinusitis is more often polymicrobial in etiology. There is a higher incidence of S aureus; anaerobes such as Peptostreptococcus, Fusobacterium, or Prevotella species (25-80%); gram-negative bacilli, such as P aeruginosa; and fungi in chronic sinusitis as compared with acute bacterial sinusitis.

Clinical Findings

A. Signs and Symptoms. The symptoms may vary with the severity, cause of the infection and presence of complications. Acute uncomplicated bacterial sinusitis presents with high fever, facial pain, headache, and nasal discharge predominantly. Nasal discharge or PND is purulent and may have a foul smell. Cough secondary to the PND may be present. A more common presentation is sinusitis associated with a viral upper respiratory tract infection. The course is usually milder and presents with "flulike" symptoms such as myalgias, rhinorrhea, and sore throat.

The symptoms of sinusitis may last longer than a viral syndrome and ~ 60% of these patients will have positive sinus cultures. Headache is common and may be frontal, temporal, vertex, or retro-orbital depending on the sinus involved. Sphenoidal sinusitis predominantly causes a vertex headache. Eustachian tube blockage caused by local edema and nasopharyngeal secretions may cause the sensation of "blocked ears." Patients may give a history of a predisposing condition such as sneezing or nasal itching with allergies. History of recurrent sinusitis or sinopulmonary disease, arthritis, and other organ disorders is important to identify immunodeficiencies and noninfectious etiologic diagnosis. Chronic sinusitis symptoms are occasional headaches, fatigue, irritability, low-grade temperature, facial pressure, and PND.

In acute uncomplicated bacterial sinusitis, there is severe tenderness overlying the affected sinuses. There may be swelling, erythema, and induration of the overlying area. Cloudy, yellow-to-green purulent drainage is noted. Intranasal examination should be conducted to attempt identifying the site of purulent discharge. Percussion examination of teeth should be done in patients with unilateral sinusitis or with a history of dental pain. Patients may have signs resulting from complications of sinusitis such as erythema, edema, and proptosis in orbital cellulitis. Purulent discharge and elevated temperature may be the only signs of acute sinusitis. Transillumination of the maxillary sinuses may demonstrate the presence of fluid.

B. Laboratory Findings. Acute sinusitis is usually associated with leukocytosis of > 10,000 cells/mm3. The sedimentation rate may be elevated. Cultures obtained by sinus puncture are regarded as the standard for an accurate microbiologic diagnosis and yield bacteria in ~ 60% of cases. Bacterial growth of > 105 colony-forming units (CFU)/mL suggests an etiologic role of those specific bacteria whereas growth of < 105 CFU/mL may represent contamination. Sinus puncture is recommended in patients who are severely ill; have intracranial or orbital complications, compromised immune systems, nosocomial sinusitis; or are not responding to standard empirical therapy. Newer endoscopic methods of collection of secretions are technically more difficult than puncture, especially from the maxillary antrum because of the location of its ostium. Endoscopic cultures obtained from the middle meatus may be contaminated with nasal secretions. In comparison with sinus puncture cultures, endoscopic cultures have a sensitivity of 65% and specificity of 40%, but this increases when evaluated specifically for S pneumoniae, H influenzae, and M catarrhalis.

C. Imaging. Standard radiography is useful for evaluating frontal and maxillary sinusitis with an anterior-posterior and Waters' view. Ethmoid sinuses are poorly seen on plain x-rays and difficult to interpret. Although standard radiography is less sensitive than CT, it may still be helpful in acute disease or determining bony erosion. The presence of air-fluid levels, opacification, and mucosal thickening is suggestive of acute disease. The coronal CT scan is a very sensitive imaging technique for sinus disease and is the imaging method of choice for accurate assessment. Findings on CT scan may include typical air-fluid levels that have a good correlation with acute bacterial sinusitis. Other findings such as membrane thickening, presence of polyps, and anatomic variations predisposing to or complicating sinusitis may help in defining the disease. Magnetic resonance imaging of the sinuses is also very sensitive in identifying mucosal disease. Both CT and magnetic resonance imaging are sensitive in detecting a fungus ball in the sinuses. Intracranial complications will require evaluation of the head with CT, especially if there are focal neurologic findings, or lumbar puncture for cell count, chemistry, and culture, and susceptibilities in a patient presenting with meningitis.

Differential Diagnosis

Patients with noninfectious sinusitis such as that related to Wegener's granulomatosis, tumors, or allergic rhinitis may present with signs and symptoms similar to those of infectious sinusitis.

Complications

The proximity of the orbits to the sinuses accounts for orbital complications. Orbital complications include periocular edema, orbital cellulitis, abscess, and further extension into the cavernous sinus leading to cavernous sinus thrombosis. Infection of the bone by direct spread or septic thrombophlebitis may occur. Frontal bone osteomyelitis and subperiosteal abscess cause a swelling and doughy feeling of the frontal bone called Pott's puffy tumor. Intracranial extension results in meningitis or epidural, subdural, or brain abscess. The incidence of these complications has declined, but they present as medical emergencies and require immediate attention. Cough or bronchitis from aspiration of postnasal drainage into the respiratory tract may also occur.

Treatment

Therapy of acute bacterial sinusitis includes symptomatic care along with an appropriate antibiotic regimen (Box 9-15). It may be helpful to stratify patients by the severity of symptoms. Patients who present with complicated sinusitis with evidence of intracranial or orbital extension should be hospitalized, undergo immediate appropriate diagnostic tests, and start on a parenteral empirical antibiotic regimen. Therapy should be guided by diagnostic sinus fluid aspiration. The recommended empirical antibiotic regimen in complicated sinusitis should include vancomycin, which is active against intermediate and highly PRSP, and a high-dose, third-generation cephalosporin (ie, cefotaxime or ceftriaxone) with activity against other usual pathogens. Empirical therapy should continue until culture and susceptibility results from sinus aspiration are available. Surgical consultations should be sought for possible drainage procedures. The increasing incidence of intermediate and highly PRSP and ß-lactamase-producing organisms has led to a decrease in the efficacy of amoxicillin for sinusitis.

Current recommendations for empirical antimicrobial therapy for acute uncomplicated bacterial sinusitis include amoxicillin/clavulanate or oral cephalosporins such as cefuroxime for 10 d. Other efficacious antibiotics include cefprozil, cefaclor, loracarbef, or cefpodoxime. TMP-SMX achieved 95% cure rates in older sinusitis studies; however, it is less effective against GAS and S pneumoniae.

Alternative antibiotics include macrolides such as clarithromycin (15 mg/kg/d for children, 500 mg every 12 h in adults) or azithromycin. Erythromycin has poor activity against H influenzae and is not recommended. Newer fluoroquinolones, such as levofloxacin or gatifloxacin (not approved for use in children and adolescents < 18 y old), have good activity against PRSP and are approved for use in adults with upper respiratory tract infections. TMP-SMX, cephalosporins or macrolides could be used for penicillin allergic patients. Odontogenic sinusitis treatment should include anaerobic coverage with either a ß-lactam/ß-lactamase inhibitor combination or the alternative regimen should include clindamycin or metronidazole. Fungal sinusitis requires aggressive surgical debridement along with parenteral or oral antifungal therapy.

Supportive measures for symptomatic relief may be considered. Decongestants provide symptomatic improvement by decreasing the nasal edema and obstruction. Oral decongestants are preferred over topical ones to avoid rebound vasodilatation. Steroid inhalers are not recommended unless the patient has significant allergy history and symptoms. Most symptoms will resolve in 7-10 d. Indiscriminate use of antibiotics is strongly discouraged to prevent the emergence of resistant strains of bacteria, particularly if the symptoms are consistent with a viral upper respiratory tract infection.

Persistent symptoms after an appropriate course of treatment may result from retained secretions, resistant or unusual organisms, presence of allergies, or possible immunodeficiency. Recurrent bacterial sinusitis should prompt further evaluation of the paranasal anatomy; immunoglobulin levels; neutrophil function analysis; HIV serology; sinus aspiration; and cultures for aerobic and anaerobic bacteria, fungi, and mycobacteria. Sinus aspiration and lavage or other drainage procedures may be more efficacious in relieving symptoms in these patients. Sinus aspirate should be sent for aerobic and anaerobic bacterial, mycobacterial and fungal culture, and susceptibilities. Patients with chronic sinusitis may require retreatment with a second course of broad-spectrum antibiotics to include antimicrobial activity against S aureus and anaerobes. This could be achieved with amoxicillin/clavulanate or combination therapy of a cephalosporin with clindamycin or metronidazole given for 4-6 wk. Occasionally antipseudomonal therapy may need to be added particularly in patients with cystic fibrosis, patients who are hospitalized, or patients who are HIV positive. Acute or chronic sinusitis exacerbations should be treated similarly to acute sinusitis.

Prognosis

Most community-acquired bacterial sinusitis episodes respond well to antimicrobial therapy. Complicated sinusitis or sinusitis in an immunocompromised host may require aggressive treatment including surgery. Such patients may continue to have recurrences and the attendant morbidity. Mortality in sinusitis is related mostly to complications such as meningitis.

Prevention & Control

Proper hygiene measures such as handwashing can reduce the incidence of acute sinusitis by decreasing transmission of infectious particles between persons (Box 9-16). Simple actions like covering the mouth with a handkerchief or tissue when sneezing or coughing can prevent aerosol or droplet transmission. Active immunization with pneumococcal polysaccharide vaccine or influenza vaccine may further decrease the incidence of these infections.

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