Tympanic membrane findings and Eustachian tube function after transtympanic plugging for the chronic patulous Eustachian tube.

Objective: To evaluate Eustachian tube (ET) function after Kobayashi plug surgery based on the tympanic membrane (TM) findings and active opening (AO) of the ET assessed with sonotubometry.

Subjects And Methods: A retrospective survey of medical records identified 74 ears of 66 patients with patulous ET (PET) received transtympanic insertion of the Kobayashi plug. Excluding the six ears (6 patients) with abnormal preoperative TM, sixty-eight ears of 60 patients were found to have normal TM preoperatively. Among these 68 ears, there were 51 ears in which sonotubometry was performed both before and after surgery to evaluate whether the AO of the ET was positive or not.

Results: Out of the 68 ears with normal preoperative TM, 52 ears (76.5%) were judged successful (sum of complete relief and significant improvement). The postoperative TM was normal in 41 ears (60.3%), while 27 ears (39.7%) had abnormal TM findings postoperatively. The success rate was 75.6% (31/41) in ears with normal postoperative TM, while it was 77.8% (21/27) in ears with abnormal TM. Success in maintaining normal postoperative TM was found in 45.6% (31/68) of the total ears treated. Out of the 51 ears in which sonotubometry was performed both before and after surgery, AO was preoperatively positive in 88.2% of the ears (45/51), while it was positive in 64.7% (33/51) postoperatively. In thirty-four ears with normal TM postoperatively, AO was positive in 24 ears (70.6%), while it was positive in 9 out of 17 ears (52.9%) with abnormal postoperative TM. The success rate was 70.6% (36/51) for the 51 ears in which AO was assessed both pre- and postoperatively, and it was 66.7% (22/33) in ears with positive AO postoperatively, while it was 77.8% (14/18) in ears without AO postoperatively. The incidence of ears either having normal postoperative TM or positive AO postoperatively was 84.3% (43/51). Abnormal postoperative TM findings without effectiveness were found in 8.8% (6/68).

Conclusion: The obstructive dysfunction of the ET is a calculated risk but did not occur in most ears after plugging with the Kobayashi plug. Therefore, routine insertion of the VT at the same time as the initial surgery is not recommended for PET cases that are adequately followed up.