Fenestration of the Oval Window and Interposition

Abstract

A total of 145 cases operated on by the authors at the Otolaryngological University Clinic in Turku are presented. The following were the most important points in the operation: intubation anesthesia, endaural incision, tympanotomy, fracturing of the crura from the footplate, total removal of the plate, sealing of the window with a graft of temporal muscle fascia, repositioning of the crura or replacement of the stapes with a polyethylene tube, and turning of the tympanic membrane and the meatal skin back into place.

The results showed that the air-bone gap closed in 89 % of all cases. In 10.3% the gap remained from 11–20 db, and in 0.7% from 21–30 db. In 12 cases (8.2 %) hearing receded to the preoperative level. The impairment invariably occurred within the first six months of the operation. It was caused either by too short crura, which no longer formed a firm bridge between the incus and the window as the fascia graft contracted, or by reossification of the window in those cases in which it could not initially be opened completely because of the large size of the otosclerotic focus. No reossification of the window was seen in the cases in which complete opening had been possible. There were no complications in the form of deaf ears. Two late degenerations occurred.

The authors consider that fenestration of the oval window with interposition of the crura or a polyethylene tube is the best of the currently used operations for otosclerosis. Covering of the window with a graft of temporal muscle fascia is a simple and very satisfactory method.