4.2.1 Dealing with osseous tissue
Determining whether the resection of osseous tissue is necessary
requires particular attention during surgery. As the ossified tissue
forms a relatively static lesion, it may be retained if it does not
affect middle ear drainage or trigger secondary otitis media. However,
the osseous tissue will require attention if one of the following
occurs: (1) The osseous tissue occupies a relatively large volume and
obstructs the aditus ad antrum, resulting in local aeration and drainage
disorders of the middle ear; (2) in patients with middle ear
cholesteatoma or chronic otitis media, lesion tissue usually grows along
the gap between osseous and normal bone tissue, which necessitates the
grinding of osseous tissue to eliminate residual lesions.
When treating osseous tissue, there are several matters that require
attention. First, there are usually no clear boundaries that delineate
the osseous tissue. Hence, adequate exposure of bone is necessary for
removal. In the seven patients with EC-LSC investigated in the present
study, canal wall down mastoidectomy was adopted for the complete
saucerization of the surgical cavity to ensure adequate bone exposure.
Second, the bone density of the osseous tissue is generally lower than
that of the bony semicircular canals. Bone density should therefore be
carefully distinguished, and the osseous tissue should be ground in a
layer-wise manner during surgery. In some cases, the osseous tissue may
form a concealed gap with normal bone tissue. Once this gap is exposed,
the separation of osseous tissue from the normal structural surfaces can
be performed.