RESUMO
OBJECTIVES: Finding a resolution of middle ear effusion using myringotomy, or dry tap (DT), is relatively common, but its clinical outcome is confounded by general anesthesia (GA). The confounding effect of GA and a time delay can be removed because laser myringotomy can be completed under topical anesthesia, which is a routine procedure for otitis media with effusion (OME) before GA in our clinic. DT without GA would clarify the clinical outcome, and the percentage of recurrence for OME after DT would be clinically relevant. The objectives of the present study are (1) to clarify the clinical nature of DT without including the confounding effect of GA and a time delay and (2) to determine if OME recurs when a ventilation tube (VT) is not used for DT. METHODS: The control group consisted of 308 children who received an unilateral myringotomy due to a natural resolution in the contralateral ear. The experimental group consisted of 296 children who had a bilateral myringotomy, and a ventilation tube was not inserted for DTs after laser myringotomy under topical anesthesia. The rate of DT and the recurrence rate of OME without tube insertion was the main outcome measure. RESULTS: In the control group, which showed a natural resolution, the rate of DT was 16.9% (52/308) of patients, and DT was more common in non-B tympanometry, which only had a recurrence rate of 17.3% (9/52). In the study group, 3.7% of patients showed unilateral DT (UDT) with contralateral positive effusion, and 5.4% of patients showed bilateral DTs (BDTs). BDT showed a non-B tympanometry pattern and a low rate of recurrence (25.0%), which was similar to the control group. UDT showed a B-type tympanometry in 81.8% of the patients, and the recurrence rate was significantly higher (68.2%; 15/22) than the BDT and control patients. BDT or DT with signs of natural resolution showed a low rate of OME recurrence regardless of tympanometry, and thus, patients do not need a VT. CONCLUSIONS: DT was not rare even without GA and the associated time delay, and DT was more common in the children that showed a natural resolution. However, microscopy and tympanometry was imperfect to predict dry tap, and thus, the surgeon needs to be prepared for individualized management of DT. UDT with B-type tympanometry and contralateral persistent effusion frequently recurred without tubes, and thus, VT for UDT appeared to be necessary.