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Background
Sinusitis is a common disorder that affects over 30 million individuals each year in the United States and approximately 90 % of these patients will visit their physician to seek treatment. Symptoms of sinusitis can include nasal congestion, purulent nasal discharge, maxillary tooth discomfort, cough, headache, fever, malaise, and facial pain or pressure that is worsened by bending forward.
The gold standard for the diagnosis of acute bacterial sinusitis is the recovery of bacteria in high density from the cavity of a paranasal sinus. However, sinus aspiration is an invasive, time-consuming, and potentially painful procedure that should only be performed by an otolaryngologist. It is not a feasible method of diagnosis for the primary care practitioner and is not recommended for the routine diagnosis of bacterial sinus infections in children.
The American Academy of Pediatrics Clinical Practice Guideline on the Management of Sinusitis for children, aged 1 to 21 years (2001), has not taken a position on the use of ultrasound as a diagnostic measure of uncomplicated sinusitis. The guidelines stated that imaging (either radiographs, computed tomography [CT] or magnetic resonance imaging [MRI]) can serve only as confirmatory measures of sinus disease in patients whose clinical histories are supportive of the diagnosis.
The American Academy of Allergy, Asthma and Immunology published parameters on the diagnosis and management of sinusitis (Spector et al, 1998), stated that computed tomography is the preferred imaging technique for pre-operative evaluation of the paranasal sinuses and that ultrasonography has limited utility, but may be applicable in pregnant women and for determining the amount of retained secretions.
In a Cochrane review of 57 randomized trials, Ahovuo-Saloranta et al (2008) evaluated clinical response to antibiotic therapy to control or antibiotics from different classes for acute sinusitis. The methods used to establish a diagnosis of acute sinusitis were: clinical examination, radiograph, computed tomography, fiber-optic examination, or culture taken by nasal swab or sinus puncture. None of these trials reported using ultrasound to establish a diagnosis of acute sinusitis.
The Agency for Health Care Policy and Research (AHCPR) evidence report (Lau et al, 1999) on the Diagnosis and Treatment of Acute Bacterial Rhinosinusitis stated: "Compared with sinus puncture, the reference standard for diagnosing acute bacterial rhinosinusitis, sinus radiography has moderate sensitivity (76 %) and specificity (79 %). Sinus ultrasonography has similar test characteristics, but the results are more variable and the procedure is not commonly used in the United States. Limited evidence suggests that diagnoses based on clinical criteria may be as accurate as those using sinus radiography."
The American College of Radiology (ACR) task force on appropriateness criteria and its expert panel (McAlister et al, 2000) have developed criteria for determining appropriate imaging examinations for the diagnosis and treatment of sinusitis in the pediatric population. The ACR guidelines recommended: (i) the diagnosis of acute and chronic sinusitis should be made clinically, not on the basis of imaging findings alone; (ii) when acute sinusitis is diagnosed and appropriately treated, no imaging studies are indicated if full clinical resolution occurs; (iii) patients with acute sinusitis persisting after 10 days of appropriate therapy, or with chronic sinusitis, and in whom imaging evaluation is desired, should undergo coronal CT scans of the sinuses regardless of their age; and (iv) the use of plain films in the evaluation of sinusitis should be discouraged unless exceptional circumstances warrant it.
In addition, the ACR gave paranasal sinus ultrasound an appropriateness rating of 1 to 2 on a scale of 1 to 9 for 8 variant presentations (1 being the least appropriate). The task force reports that control studies using ultrasound of the sinuses have shown that this modality lacks sufficient sensitivity and specificity and is not recommended.
The German Agency for Health Technology Assessment (Perleth et al, 1999) conducted a systematic review and meta-analysis of the diagnosis of acute maxillary sinutitis in adults. The assessment concluded that x-rays in patients with suspected sinusitis appears to be the most accurate diagnostic method. The assessment found that ultrasound was less accurate and depends more on the examiner.
Ioannidis and Lau (2001) reported on the results of a systematic evidence review of diagnostic modalities for acute sinusitis in children and adolescents. The authors stated that the reference standard for the diagnosis of acute uncomplicated bacterial sinusitis is sinus aspiration and culture; this is infrequently used because it is invasive, cumbersome to perform and time-consuming. Included studies using other diagnostic parameters (e.g., clinical presentation, plain film and ultrasound) were compared to assess concordance rather than proof of diagnostic accuracy. The authors identified one study that found that 68 of 72 sinuses with ultrasonographic abnormalities yielded fluid on aspiration. The conclusions that can be drawn from the study were limited, however, because aspiration was not attempted in any control group without ultrasonographic abnormalities. In addition, cultures of the aspirate from 59 sinuses yielded microbial pathogens in less than 50 % of the cases (26 out of 59). The authors reported that the only study to compare ultrasonography with plain film radiography and sinus fluid abnormalities, among children with a clinical picture of sinusitis, found very low concordance between these diagnostic techniques.
In a guideline on appropriate antibiotic use in sinusitis endorsed by the Centers for Disease Control and Prevention, American Academy of Family Physicians, the American College of Physicians-American Society of Internal Medicine, and the Infectious Diseases Society of America (Snow et al, 2001), radiography is not recommended for the diagnosis of acute sinusitis. The guideline recommended that clinicians rely on duration of illness (at least 7 days) and severity of symptoms to make an accurate diagnosis of sinusitis. These guidelines make no recommendation for the use of paranasal sinus ultrasound in the diagnosis of either acute or chronic sinusitis.
Neher (2003) systematically reviewed the evidence supporting the use of various imaging studies in acute sinusitis. The author stated that "[t]here is no role for imaging in the diagnosis of acute sinusitis. For patients who have persistent symptoms, or those for whom surgery is being considered, some guidelines suggest that coronal CT scan of the paranasal sinuses be considered." The author noted that the great variability of test performance of diagnostic ultrasound in acute sinusitis, citing a systematic evidence review by Varonen et al (2000). Neher noted that, since the cost of diagnostic ultrasound is similar to that of a sinus CT, ultrasound is not indicated in the diagnostic evaluation of the sinuses. Nether concluded that "[a]ccurate diagnosis of acute sinusitis in both children and adults depends on the history and clinical examination of the patient." The author explained that, "[w]hile the clinical signs and symptoms of acute sinusitis are often difficult to distinguish from viral upper respiratory infection, such an assessment remains the best approach to diagnosing acute sinusitis."
Triulzi and Zirpoli (2007) stated that the diagnosis of both acute as well as chronic rhinosinusitis in the pediatric population should be made clinically, and not on the basis of imaging findings alone. Plain radiography may be used as a screening method for various pathological conditions of sinuses, but CT remains the study of choice for the imaging evaluation of acute and chronic rhinosinusitis. In acute sinusitis, CT is indicated in patients with symptoms persisting after 10 days of appropriate therapy and in patients with suspected complications (especially in the brain and in the orbit). In addition to CT scanning, magnetic resonance imaging of the sinuses, orbits, and brain should be performed whenever extensive or multiple complications of sinusitis are suspected. In chronic sinusitis, CT scanning is the "gold standard" for the diagnosis and the management, because it also provides an anatomical road map, when surgery is necessary. Nuclear medicine studies and ultrasound are rarely indicated in acute and chronic rhinosinusitis.
Varonen et al (2003) conducted a randomized controlled clinical study to compare antibiotics and placebo in patients with clinically diagnosed acute maxillary sinusitis, and to study whether sinus ultrasound examination would help to detect those patients who benefit from antibiotic therapy. The study included 150 adult patients with a clinical diagnosis of sinusitis at nine primary care sites in Finland. Subjects received antibiotics or placebo for one week after diagnosis; all patients were examined with sinus ultrasound after randomization. The authors found that only half of patients with a clinical diagnosis of acute maxillary sinusitis had sinusitis in ultrasound examination.
A review on management of acute sinusitis in Drug and Therapeutics Bulletin (2009) stated that ultrasound is only of moderate value, adds little to radiology, and is seldom used in the management of acute sinusitis. Furthermore, the University of Michigan Health System's clinical guideline on "Acute rhinosinusitis in adults" (2011) did not mention the use of ultrasonography for the diagnosis of rhinosinusitis.
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