MICROTYMPANOMETRY, MICROSCOPY AND TYMPANOMETRY IN EVALUATING MIDDLE-EAR EFFUSION PRIOR TO MYRINGOTOMY

Objective. To determine the accuracy of a hand-held microtympanometer (Microtymp, Welch Allyn) used by a general practitioner when compared with findings at myringotomy. Method. Independent preoperative assessm ent of children's ears using microtympanometry by a general practition er, microscopy and pneumatic otoscopy by a specialist otologist and im pedance bridge tympanometry by a specialist audiologist were performed and compared with findings at myringotomy. Subjects. Fifty children ( 100 ears) on the waiting list for bilateral myringotomies and ventilat ion tube insertion for recurrent acute otitis media or otitis media wi th effusion. Results. Microscopy with pneumatic otoscopy had a 90.9% s ensitivity and a 92.9% specificity in detecting middle ear effusions. Impedance bridge tympanometry had a 94.4% sensitivity and a 71.8% spec ificity if type B and C2 were combined to predict middle ear effusion. Microtympanometry had 100% sensitivity and 75% specificity if type B and C tympanograms were combined; if type B tympanograms alone were us ed, a sensitivity of 83.4% and specificity of 75% in predicting middle ear effusions was obtained. Conclusion. The Microtymp is a useful ins trument in general practice for assessment of middle ear effusions as no ears with fluid were missed in this study if type B and C tympanogr ams were considered abnormal. The Microtymp would also be useful as a screening instrument by suitably trained personnel.