In most cases, discrimination is much better than would be expected with the level of hearing loss. Low speech discrimination scores prognosticate poorly for postsurgical hearing improvement. In cases of well-advanced lesions, and in lesions with vestibular symptoms, expect several variations from classic presentation. With advanced lesions, patients can present with no measurable hearing, in which case they are best identified by history. Family history of hearing loss, or gradually progressive hearing loss starting early in adult life, may be the only clue.
Previous audiograms help, especially if measurable hearing existed with previous air-bone gaps.
History of bone-conducting hearing aid use and clinical benefit from hearing aids, even with lack of measurable hearing improvement, supports the diagnosis. Tuning-fork response also is suggestive. Vestibular symptoms occasionally are present in patients with otosclerosis. Suggested mechanisms include end-organ or neural degeneration, or biochemical derangement in the perilymph by contact of the disease process. Diagnose endolymphatic hydrops before considering surgical treatment.