Slowly progressive conductive hearing loss results. Frequency, as mentioned above, is thought to be decreasing secondary to measles vaccination. Otosclerosis is inherited in an autosomal dominant pattern with incomplete penetrance. Women are two times more likely to develop the disease than are men. Otosclerosis generally is limited to the Caucasian population.
Reports implicate the measles virus by gene activation.
The lesion is a pleomorphic replacement of normal bone with spongiotic or sclerotic bone. The histiologic disease progresses in stages. Bony resorption and replacement with new spongy bone characterize early lesions. Osteolytic osteocytes appear at the leading edge of the lesion, and sheets of connective tissue can be seen replacing the bone. Formation of dense sclerotic bone in areas of previous resorption signifies the late phase of otosclerosis.