Unexplained conductive hearing loss.

We report a series of unusual clinical cases which exhibit what we have referred to as unexplained conductive hearing loss. Audiometrically, these cases typically display mild to moderate conductive or mixed-type hearing loss and good word discrimination (80% to 100%). The otologic evaluations also lend support to the audiometric findings. When polytome roentgenograms were obtained thr results showed a normal inner ear system. Most often, the otologists' clinical impression was a fixed malleus or congenital stapes fixation, and exploratory tympanotomy with inspection of the ossicular chain was recommended. In each case, the ossicular chain was found to be intact. When the incudostapedial joint was separated the malleus and incus were seen to be mobile. Further, palpation of the stapes resulted in good round window reflexes. Possible explanations for this phenomenon are considered.