Otosclerotic involvement of the cochlear capsule can be limited to a small portion of the basal turn adjacent to the anterior margin of the oval window or it can spread into the basal turn and other areas of the cochlea. The radiographic appearance of the otosclerotic lesion varies according to the stage of maturation of the disease. In the demineralizing or spongiotic stage, the normally sharp outline of the capsule becomes interrupted and can disappear. The demineralization of the capsule causes a loss of the normal differential density between the lumen of the cochlear coils and the capsule. A typical sign of cochlear otosclerosis is the formation of a double-ring effect caused by the confluence of spongiotic fossae (figures 1, 2). [1]
From the Department of Radiology, Louisiana State Medical School, New Orleans (Dr. Palacios), and the Department of Radiology and Otolaryngology, University of Illinois Medical Center, Chicago (Dr. Valvassori).
Reference
(1.) Valvassori GE. Otosclerosis and bone dystrophies. In: Valvassori GE, Mafee MF, Carter BL, eds. imaging of the Head and Neck. New York: Thieme Medical Publishers, 1995:143-56.
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