Magnetic resonance imaging and audiologic assessment of middle ear effusions in patients with nasopharyngeal carcinoma before radiation therapy.

OBJECTIVE: The aim of this study was to assess the performance of clinical methods, viz. otoscopy, pure-tone audiometry, and tympanometry in diagnosing middle ear effusions (MEEs) using magnetic resonance imaging as a reference standard. STUDY DESIGN: A retrospective study of 46 patients with newly diagnosed nasopharyngeal carcinoma was performed comparing clinical evaluation and audiometry results with magnetic resonance imaging findings obtained before radiation therapy. RESULTS: Twenty-two (25%) of the temporal bones imaged had both MEE and mastoid effusions, 24 (27%) had only middle ear fluid, and 29 (33%) had mastoid fluid alone. The sensitivity for tympanometry, audiometry, and otoscopy in detecting fluid in the middle ear was 96%, 92%, and 80%, respectively. Although tympanometry was most sensitive in diagnosing MEE, there was no statistically significant difference when comparing the overall accuracy of pure-tone audiometry air-bone gap and tympanometry (p = 0.7, chi-square test). Flat curve tympanograms (type B) only achieved a sensitivity of 45% but were of high specificity (92%). Forty-nine percent with negative pressure tympanograms (mean air pressures > -100 daPa) had no MEE. CONCLUSIONS: Using magnetic resonance imaging as a reference standard, tympanometry is the most sensitive audiologic test in detecting the presence of MEE. The overall accuracy of tympanometry, pure-tone audiometry air-bone gap, and otologic examination was, however, not significantly different.