The nasal mucosa is best visualized after application of a topical vasoconstrictive agent, such as oxymetazoine, and use of a nasal speculum. One approach to the exam should include notice of the color, edema, character of nasal secretions, presence of polyps, and structure of the nasal septum.

Purulent discharge from the middle meatus is highly predictive of bacterial sinusitis. Palpation for tenderness of both the maxillary and frontal sinuses are helpful. Because a small proportion of cases of maxillary sinusitis may be caused by tooth infection, one should also check for maxillary teeth tenderness by tapping with a tongue blade.

Transillumination of the sinuses is an additional diagnostic test, and is limited to the frontal and maxillary sinuses, as other sinuses are too distal to examine. To examine the maxillary sinus, a light source is placed over the infraorbital rim, and light transmission is observed through the hard palate. The utility of this test is debatable .

Imaging of the sinuses is usually reserved to confirm the diagnosis, if history and physical are equivocal, or if conventional treatment has failed. Modalities include plain radiograph, CT, ultrasound, and MRI. Plain X-rays come in several views.

The Caldwell (anterior-posterior), Waters (occipito-mental), and lateral films provide views of the frontal sinus, maxillary, and sphenoid sinuses, respectively. Unlike the CT scan, the ethmoid sinus is not well visualized. Significant opacification or mucosal thickening and air-fluid level are all signs of disease.

However, there is no ability to predict the response to antibiotics based on the radiographic extent of disease. MRI is best used to evaluate soft tissue structures, and can distinguish between inflammatory and malignant disease. MRI is also useful to determine the extent of the complications of sinusitis, such as intracranial or orbital involvement.

Ultrasound, although limited, is an alternative technique to evaluate the maxillary and frontal sinuses without exposure to ionizing radiation. This is an especially viable option for pregnant women. CT is the modality of choice, and is better able to evaluate the ethmoid sinuses compared with plain X-ray.

CT is also much better than MRI for evaluation of boney structures. The ability to visualize detailed anatomy is helpful in preoperative planning. However, CT is unable to distinguish between viral or bacterial sinusitis. In one study, 31 healthy adult volunteers with ‘‘a fresh common cold,’’ 71% of whom described nasal or head congestion, underwent CT sinus imaging early on in their illness.

Of the patients with congestion, 100% had an abnormality in one or more of their sinuses, compared with 56% of those who did not have congestion. Fourteen subjects returned for repeat imaging, and without interim antibiotics, 79% of the subjects showed either resolution or marked improvement.

In addition, a significant number of patients have incidental mucosal changes on CT, in the absence of symptoms. Moreover the extent of mucosal changes on CT does not correlate with severity of symptoms. Identification of the pathologic organism is best done through maxillary sinus aspiration.

After sterilization of the puncture site, usually through the lateral wall of the inferior meatus, contents of the maxillary sinus are aspirated. The invasive nature of this procedure often limits its use. As a less invasive approach, endoscopically obtained cultures of the middle meatus, may be a possible surrogate.

However, the same organisms have been found to colonize the middle meatus in healthy children, as those with sinusitis, so the mere presence of the organism does not prove infection. In adults, good correlation has been shown between endoscopically obtained cultures of the middle meatus, and those of direct antral culture.

The diagnosis of sinusitis is usually made on clinical grounds, which include both the history and physical examination and, if appropriate, diagnostic procedures. Symptoms of acute sinusitis often overlap with those of other diagnosis, such as allergic rhinitis and the common cold.

Several studies have attempted to determine the relationship between the signs and symptoms of sinusitis, and benchmarks such as sinus puncture, CT, plain X-ray, and ultrasound. In a primary care clinic in Norway, 201 patients with a clinical diagnosis of acute sinusitis underwent CT scan.

Of these patients, 63% met the clinic’s definition of acute sinusitis by having either an air fluid level or total opacification. The presence of two phases of illness, purulent rhinorrhea, erythrocyte sedimentation rate greater than 10 mm, and purulent secretion noted in the nasal cavity, were all independently associated with acute sinusitis.

And a combination of three out of four of these criteria gave a specificity of 81% and a sensitivity of 66%. Williams and colleagues conducted a study of adult men who presented to a primary care clinic with either rhinorrhea, facial pain, or a self-suspected diagnosis of sinusitis, and compared their symptoms to findings of sinusitis on X-ray.

The overall prevalence of sinusitis was 38%. They found the following symptoms were most sensitive: presence of colored discharge, cough, and sneezing with a sensitivity of 72%, 70%, and 70%, respectively. However, not surprisingly, the specificity of these symptoms was much less (52%, 44%, and 34% respectively).

The most specific symptom (93%) was maxillary toothache; however, this was found in only a small subset of patients. Van Duijn and colleagues reported a study of European patients who presented to their primary care providers.

They compared an algorithm of five symptoms, which included preceding common cold, purulent rhinorrhea, pain on bending, unilateral maxillary pain, and pain in teeth, to findings on ultrasound, a technique primarily used in Europe. Even with this set of criteria, the proportion of correct diagnosis was a little over one half.

In this study, the most sensitive indicator was history of preceding cold (85%), and most specific indicator was pain in teeth (83%). Perhaps the gold standard for the diagnosis of sinusitis is the finding of purulent material through maxillary sinus aspiration.

In marked contrast to the studies discussed previously, Hansen and colleagues found no independent association between purulent aspirate and the following symptoms:

• preceding upper respiratory tract infection
• maxillary pain, tenderness of maxillary sinus
• maxillary toothache
• purulent nasal discharge
• and visualization of purulent material on the posterior wall of the pharynx.

In summary, there are no signs and symptoms of sinusitis that are both highly sensitive and specific. Most will agree that if symptoms persist beyond 7 to 10 days, a diagnosis of bacterial sinusitis should be entertained. Although rare, complications of acute sinusitis can occur through direct, local extension.

With antibiotic treatment, complications occur with an estimated frequency of 1 per 10,000 cases. Clinical presentation may include facial edema, cellulitis, orbital, visual, and meningeal involvement. In these cases, aggressive treatment, which may include surgical intervention, is warranted.

Unfortunately, clinical criteria to diagnose chronic sinusitis, as well as the predictive value of these criteria, are sorely lacking. Historically, the diagnosis of chronic sinusitis was based on several clinical symptoms, similar to the presentation of acute sinusitis, although often less dramatic.

However, none of these symptoms are specific to sinusitis. In particular, headache, as the sole presenting symptom, is not likely chronic sinusitis. On the other hand, nasal endoscopy is useful.

Evidence of nasal secretions, nasal polyps, and deformation of the middle meatus have been shown to distinguish patients with extensive sinus disease, as defined by CT image criteria, compared with either the control group or to those with limited disease.

Plain X-rays are often insufficiently sensitive to diagnose chronic sinusitis and do not provide the anatomic detail required for preoperative evaluation. Although CT is recommended, this alone is still not evidence enough to make the diagnosis.

CT should be performed at least 2 weeks after an upper respiratory infection, and more than 4 weeks after treatment of acute bacterial sinusitis, to evaluate underlying chronic disease. Therefore it is recommended that a combination of clinical signs and symptoms, nasal endoscopy, and CT be used to make the diagnosis of chronic sinusitis.