Otosclerosis is a condition where the stapes (or piston), the last of the 3 middle ear bones, becomes stuck. This prevents transmission of sound into the inner ear and causes a conductive hearing loss. This is a progressive condition, and can affect both ears. This is the result of a very localised abnormality in bone turnover, that does have a familial tendency, and can be exacerbated by pregnancy. It can be unilateral or bilateral, and can often in the later stages also cause nerve damage.
This diagnoses is strongly considered when examination of ear is normal, there has been little in the way of previous ear infections, and with the presence of a conductive hearing loss.
Treatment options come down to the decision between surgery and an hearing aid. The success rates for surgery are high, but are accompanied by a very low risk of worsening the hearing. An extensive discussion is required before making a decision in this regard.
Stapedectomy, or the creation of a small hole through the base of the stapes and insertion of an artificial piston is a very effective way of restoring hearing. The patient however must be counselled that there is an approximately 1% chance of neural hearing damage as the result of surgery.
This surgery is at the challenging end of the spectrum for an otologist. The critical point of surgery is creation of a hole or (stapedotomy) through the base of the stapes. This hole measures only 0.5mm in diameter, and through this a piston is placed. At St Vincent’s Hospital we have the advantage of a KTP laser, which minimises trauma to the inner ear during this step of surgery.
An intra-operative photo of a left ear, where a o.4mm diameter Nitinol Piston has been inserted through the stapedectomy hole. The laser in then used to fasten (or crimp) the piston onto the incus to allow transmission of sound into the inner ear.
As mentioned the otosclerotic process can also cause sensorineural hearing loss. Whilst this does not affect the success of surgery in terms of correcting the conductive hearing loss, the expectations in terms of returning the hearing to normal must be tempered. There is also evidence that especially if the sensorineural hearing loss is progressive treatment with fluoride or 3rd generation bisphosphonates should be considered.