Otosclerosis

Otosclerosis, usually an hereditary disorder, causes abnormal bone to be formed around the stapes footplate, preventing its normal movement. Conductive deafness then results. More rarely, the bone of the cochlea is affected and results in sensorineural deafness. 54 CLINICAL FEATURES OF OTOSCLEROSIS 1 Usual onset in second and third decades. 2 Two-thirds give a family history. 3 Two-thirds are female.The gene is not sex-linked but pregnancy may make the deafness worse. Not many men get pregnant, so more females present for treatment! 4 Deafness may be unilateral or bilateral. 5 Paracusis is often present—the patient is able to hear better in noisy surroundings. 6 Tinnitus is often present—it may not be relieved by operation. 7 The tympanic membranes are normal. 8 Tuning fork tests show the deafness to be conductive. 9 Cochlear impairment may be present. 10 Audiometry. Air conduction impaired. Bone conduction initially normal but deteriorates as the disease progresses. Box 12.1 Clinical features of otosclerosis. TREATMENT Stapedectomy First performed in 1956, stapedectomy is an elegant solution to the problem. The middle ear is exposed (Fig. 12.1), the stapes superstructure is removed and the footplate perforated. A prosthesis of stainless steel or Teflon in place of the stapes is attached to the long process of the incus with its distal end in the oval window (Fig. 12.2). The patient is usually discharged the following day and should refrain from strenuous activity for at least a month. Stapedectomy may result in total loss of hearing in the operated ear, and patients should be made aware of such risk before operation. Hearing aids and lip-reading Modern hearing aids are of great benefit to patients with conductive deafness and have the advantage of causing no risk to the patient’s hearing. A hearing aid should always be offered to a patient as an alternative to surgery. If the disease is progressing rapidly and profound deafness seems likely, instruction in lip-reading should never be neglected at a stage when the patient still has usable hearing.

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