Inner Ear Anomalies and Risk for Stapedectomy

Objective 1) Quantify the anatomic relationships within the vestibule of temporal bones with known inner ear malformations that are relevant to stapes surgery complication rates. 2) Evaluate for pathologic evidence of stapes complications in temporal bones with structural inner ear malformations that have undergone stapes surgery. Method Sensorineural hearing loss after primary stapes surgery is rare. Histologic examinations in these cases have identified hydrops formation, scala media atrophy, adhesion formation, and perilymph fistula. The study is a pathologic review of the National Temporal Bone Database for cases of inner ear malformations with and without otosclerosis. Results The database contains 7,490 subjects with greater than 12,000 temporal bone specimens from 16 institutions. Database queries yielded 122 examples of structural inner ear malformations not related to chronic ear disease or malignancy. Of these, 10 had pathologic evidence of otosclerosis, and 6 of these had stapes surgery performed. Though retrospective and with malformations diagnosed postmortem, the clinical record of this group noted no operative complications. Only 1 of these 6 patients had documented worsening of hearing from the first to last clinical visit. Four of 6 patients had documented hearing improvement. Conclusion The decision to perform stapes surgery in patients with known inner ear malformations has been dictated by surgical dogma in the past. This review may lend histopathological evidence to loosen those criteria, though more rigorous clinical testing is needed.