Observations on Bilateral Symmetry of the Stapedial Footplate Lesion and Narrowing of the Oval Window Niche in Otosclerosis

Abstract

We consider whether patients with bilateral otosclerosis who have surgery on their second ear show symmetry in the degree of severity of their footplate otosclerosis. The severity of the stapedial otosclerotic lesion and the degree of narrowing of the oval window niche by exostoses were recorded for each ear of 269 patients who elected to undergo operation on the second ear. The severities and similarities of the otosclerotic lesion affecting the oval window niche were compared between the ears. The majority of oval window niches were normal in width in both ears. A niche narrowed to less than 0.8 mm in diameter was rare and tended to affect both ears (5.6% first ears and 5.95% second ears; chi2 = 134.6 on 4 df, p < .0001). The degree of footplate otosclerosis was classified and amalgamated into 3 broad categories: minor (47.2%), moderate (21.6%), and severe (31.2%). A high degree of bilateral symmetry of the stapedial footplate lesion was found (chi2 = 162.2 on 4 df; significant at .0001 level). The findings at the oval window of the first ear in regard to the severity of otosclerotic involvement of the stapes footplate and narrowing of the niche by exostoses do allow a fair prediction of the pathological findings in the second ear, if that ear is suitable for stapes surgery and the patient elects to have an operation. The surgeon is forewarned of possible difficulties and technical challenges if an operation has been performed on the first ear.