Radioanatomy of cochlear and stapedial otosclerosis

Otospongiosis of the otic capsule is a primary focal disease, which can be reproduced by both conventional multidirectional tomography and computed tomography. The final stage of otospongiosis, otosclerosis has a complete different appearance in radiography. When the otospongiosis focus is located at the oval window a progressive conductive hearing loss will result, which in its final stage will have the character of otosclerosis with fixation of the stapes in the oval window. The radiographic diagnosis with either conventional multidirectional tomography or CT is more or less pathognomonic and will easily confirm the audiologic examinations results. The diagnosis of otospongiosis by computed tomography is advantageous to conventional tomography. With both methods high resolution technique is mandatory for safeguarding both diagnosis and evaluation of the extent of the lesion. Minor otospongiotic or otosclerotic lesions of the oval window with fixation of the footplate are still a challenge to high resolution radiographic imaging. In most cases stapedial otosclerosis is advantageously diagnosed by otoscopy and audiometry. High resolution radiographic imaging is a valuable confirmative method to corroborate clinical diagnoses and differentiating the disease from other conditions based on other morphologic lesions.