Diagnostic Tests

In many patients with acute and chronic sinusitis, diagnosis and subsequent therapy can be based on the history and physical findings (Table 3). However, in a significant number of patients, signs and symptoms may be equivocal, and additional testing is required to make a diagnosis.

Table 2

Symptoms Suggestive of Sinusitis

• Acute disease

Persistence of upper respiratory infection symptoms, usually without fever, beyond 7-10 d Children: cough, nasal discharge

Adults: discolored nasal discharge, unilateral facial pain, headache, cough

• Persistent disease

Long-standing nasal congestion, thick postnasal drip, cough, facial fullness, sore throat, and hearing problems

Laboratory Tests

Cytological examination of freshly stained nasal secretions (using Hansel's or modified Wright-Giemsa medium) have been used by some physicians to evaluate both acute and chronic nasal complaints. However, although nasal neutrophils are generally prominent in cases of acute viral rhinitis or acute bacterial sinusitis, this is a nonspecific finding. Similarly, although nasal eosinophils are most commonly encountered in patients with allergic rhinitis or eosinophilic nonallergic rhinitis, the presence of eosinophils lacks sensitivity in detecting these conditions and has a poor negative predictive value.

The peripheral white blood count/differential and nasal swab cultures have no utility in determining the presence of infection or in accurately identifying pathogenic bacteria in sinusitis.

Imaging Studies

Although plain radiography has recently fallen out of favor in evaluating sinusitis, we feel that this technique continues to play a helpful role, particularly in children below the age of 5 yr. Although plain X-rays accurately visualize the maxillary and frontal sinuses (particularly the Water's occipitomental view), the ethmoid and sphenoid sinuses are difficult to assess.

Waters' view findings that are diagnostic of sinusitis include a sinus air-fluid level, sinus opacification, or severe mucosal thickening (>50% of antral diameter in children and >8 mm in adults). Plain films, particularly the Waters' view, are helpful in evaluating possible chronic sinusitis in young children, since the maxillary sinuses are usually the principal sinuses involved. In adults with chronic sinusitis, however, plain films may yield false-negative results because infection is limited to the ethmoid sinuses in up to 40% of cases.

Computed tomography (CT) provides a detailed view of all of the paranasal sinuses and the ostiomeatal complex regions. CT is most helpful in patients who have persistent or recurrent symptoms suggestive of sinusitis despite a prolonged trial of medical therapy. CT should be delayed if a viral upper respiratory infection has recently occurred, because 85% of patients have transient abnormalities on CT following a cold. CT of the sinuses should always be used judiciously because even the screening scan remains a relatively expensive test and does require sedation for most children younger than 8 yr of age.

Magnetic resonance imaging (MRI) is extremely sensitive in detecting subtle soft tissue abnormalities of the paranasal sinuses. For this reason it is the technique of choice in imaging suspected sinus neoplasms, fungal infections, and complicated infections that extend intracranially. MRI should not be used for routine diagnosis of sinusitis because

Table 3 Diagnosis of Sinusitis

Clinical symptoms usually suffice

Plain films may be helpful in young children (Waters' view)

• Persistent

Computed tomography is gold standard Plain films of limited utility it is very costly and does not adequately visualize the bony landmarks required for surgical planning.

Sinus ultrasound is rarely used as a diagnostic test because of its poor sensitivity and specificity in patients with both acute and chronic sinusitis.

Maxillary Aspiration and Culture

Referral should be made to an otolaryngologist for maxillary aspiration when acute sinusitis is associated with signs of severe toxicity (particularly in hospitalized or immu-nosuppressed patients) or is unresponsive to an adequate trial of appropriate antibiotics.

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