Head and Neck Imaging

Mastoidectomy

surgical procedure for removal of chronic inflammatory disease (usually cholesteatoma) in the middle ear and mastoid. Several types of mastoidectomy can be distinguished, depending on the extent of resection:

a) closed cavity mastoidectomy: the external auditory canal is left intact.

  • simple (or cortical) mastoidectomy: the mastoid is only opened to a limited extent; this procedure is no longer performed for chronic inflammatory disease.

  • intact canal wall mastoidectomy, with removal of Koerners septum, allowing inspection of the middle ear structures (Fig.1).

    b) open cavity (radical) mastoidectomy: the external auditory canal is removed, the mastoid cavity communicates freely with the middle ear; the ossicles, apart from the stapes if possible, are removed (Fig.2). If the ossicles are preserved, the procedure is called a modified radical mastoidectomy.

    Postoperative imaging allows evaluation of the extent of soft tissue thickening in the surgical cavity. Such tissue thickening may correspond to granulation tissue (see granulation tissue ear), recurrent cholesteatoma, oedema or scar tissue. Using CT, a tissue-specific diagnosis is often not possible, though a convexly bordered mass suggests recurrent cholesteatoma (Fig. 1). A more specific diagnosis may be possible with MRI.

    Imaging is also useful in patients who have undergone surgery previously, but for whom no surgical report is available. CT clearly shows the type of surgery performed, and allows assessment of the bony margins of the cavity and the facial nerve canal. MRI is indicated when a soft tissue mass is seen underneath a tegmen defect, to exclude a postoperative meningocele or encephalocele (Fig.3).

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    Fig.2

    Coronal CT image of left temporal bone (a different patient but section anatomically identical to figure 1). The external auditory canal has been removed and the ossicular chain is absent: radical mastoidectomy. There are signs of labyrinthitis ossificans (calcifications in vestibule and calcific obliteration of superior semicircular canal; see also labyrinthitis.
    Mastoidectomy, Fig.1
    Mastoidectomy, Fig.2
    Mastoidectomy, Fig.3 (a)
    Mastoidectomy, Fig.3 (b)