Congenital Stapes Anomalies with Normal Eardrum

OBJECTIVES A non-progressive and conductive hearing loss with normal eardrum, but no history of trauma and infection, is highly suggestive of a congenital ossicular malformation. Among ossicular anomalies, stapes anomaly is the most common. The purpose of this study is to describe patterns of stapes anomaly and to analyze its surgical outcome with special reference to its patterns. METHODS We conducted a retrospective case review. The subjects comprised 66 patients (76 ears) who were decisively confirmed by the exploratory tympanotomy as congenital stapes anomalies without any anomalies of the tympanic membrane and external auditory canal. The preoperative and postoperative audiological findings, temporal bone computed tomography scan, and operative findings were analyzed. RESULTS There were 16 anomalous patterns of stapes among which footplate fixation was the most common anomaly. These 16 patterns were classified into 4 types according to the status of stapes footplate. Successful hearing gain was achieved in 51 out of 76 ears (67.1%) after surgical treatment. CONCLUSION Footplate fixation was usually bilateral, whereas stapes anomalies associated with other ossicular anomaly were usually unilateral. The success of the surgical treatment of stapes anomaly might depend on its developmental status of the footplate. Stapes anomalies were detected without any fixed patterns, therefore, it is quite possible to detect a large variety of patterns in future.