Functional middle ear reconstruction: experience with prostheses and tissue graft.

The transmission of sound to the internal ear passes across the tympanic membrane to vibrate the ossicle chain formed by the malleus, incus and stapes. Movements of the stapes footplate set up complex wave formation within the cochlear fluids to excite the sensory nerve endings of the organ of Corti. Microsurgery for the relief of middle ear deafness has been progressively developed since 1946 and is concerned with the restoration of this collection of sound by an intact flexible ear drum and transmission of oscillation across the middle ear by a free, mobile chain of ossicles. Otosclerosis is a deafness of genetic origin caused by bony overgrowth immobilizing the stapes footplate and is treated with a 95% success rate by selective stapedectomy and fenestration of the footplate. A prosthesis or one limb of the stapes is attached on to the incus and inserted into the fenestration, often with the use of using a tissue graft as a sealing membrane. Over twenty years' experience has originated many differing contours and materials for the stapes prosthesis--in scale some 4 mm or 5 mm in length and 0.3 mm to 0.8 mm in diameter--which will be illustrated and discussed. These prostheses lie deep within a healthy tympanic cavity, and it is most exceptional for a prosthesis to detach or extrude. In our large series subsequent reexploration usually reveals a prosthesis sheathed in mucosa without visible foreign body reaction.