Otospongiosis (otosclerosis): polytomographic and histologic correlation

The Temporal Bone Laboratory of Northwestern University Medical School has three sets of temporal bones from patients who had antemortem polytomographic examinations resulting in a diagnosis of otospongiotic involvement of the cochlea. One of these cases was thought to have been an example of pure cochlear otospongiosis. The other two cases were patients with clinical (stapedial) otospongiosis, and their polytomograms were interpreted as unilateral otospongiosis with involvement of the basal turn of the cochlea. In the first set of temporal bones, no otospongiosis was present. In the other two sets, the otospongiotic lesion did not involve the cochlea, and a contralateral otospongiotic lesion was present that had not been seen on the polytomograms. Caution must be exercised in the interpretation of subtle polytomographic changes noted in the cochlear capsule and restraint used in the X-ray diagnosis of pure cochlear otospongiosis until there is evidence of correlation with pathological material.