18 Tympanosclerosis
Holger Sudhoff
Tympanosclerosis presents as white tissue changes within the tympanic mem- brane and in the middle ear. It is composed of calcified hyaline collagen. The lack of blood vessels may lead to necrosis of the underlying bone. Steinbach found varying degrees of tympanosclerosis in 10 % of 2000 cases with chronic ear disease, 1.4 % of which were seen in cases of cholesteatoma. Tympanoscle- rosis may be found behind an intact tympanic membrane. Small plaques are harmless and can be disregarded. Large incrustations in the tympanic mem- brane remnants should be removed because the avascular material may pre- vent the integration of the graft. It can affect the ossicular chain especially the head of the malleus and the incus in the epitympanum. Mobilization is not advisable because refixation often occurs. The head of the malleus should be resected and the incus removed. For reconstruction the incus can be placed between the stapes if mobile. If the stapes is immobilized by tympanosclerosis it can sometimes be removed under high magnification. In extensive disease, however, the surgeon should be careful not to perforate the footplate or to luxate the stapes, which sometimes is extremely vulnerable due to bone destruction underneath the tympanosclerotic layers. Since the tympanoscle- rotic masses interrupt the vascular supply, the underlying bone may become necrotic. In extreme situations the promontorial bone covering the basal coil of the cochlea may be lifted off when large tympanosclerotic masses are removed. Tympanosclerosis on the stapes footplate is more common. The underlying footplate may be thin or even replaced by fibrous tissue. In these cases a prosthesis placed on the footplate may perforate through it.
Two-stage surgery is necessary. Since the prognosis for hearing improve- ment in extensive tympanosclerosis is not good, and the ear is safe after the first operation, a second stage surgery for hearing improvement must be dis- cussed with the patient if the contralateral ear hears is normal. The option of hearing aids should be discussed as well with the patient.
Chapter18 98
