8.12\ Atticotomy

8.12.1\ Discussion

Atticotomy, also known as epitympanectomy, consists of removing the bone of the lateral attic wall (scutum) in order to provide visualization of the attic contents and aditus ad antrum (Fig. 8.51). This procedure is most often used to treat attic cholesteatoma or fixation of the ossicular heads. Often, but not always, the body of the incus and head of the malleus are resected during atticotomy if they are involved with disease or if wider surgical exposure is needed. Atticotomy may be applied as a stand-alone procedure through the

external auditory canal, or it may be part of a more extensive combined approach that additionally involves canal wall-up mastoidectomy. Canal wall defects that result from atticotomy can easily be reconstructed with auricular cartilage or soft tissue grafts, but rarely these defects are intentionally left open if the surgeon intends to exteriorize part or all of the attic into the external auditory canal. Following atticotomy, CT or MRI may be performed to evaluate for the presence of recurrent cholesteatoma. Atticotomy is sometimes difficult to distinguish from autoatticotomy where long-standing negative middle ear pressure or cholesteatoma has generated an atticotomy defect.

8.13\ Eustachian Tube Occlusion

Procedures

8.13.1\ Discussion

A patulous Eustachian tube can cause autophony and a sense of ear fullness. Intolerable symptoms can be treated via fat, Teflon, or hydroxyapatite injection into the Eustachian tube and surrounding soft tissues in order to create mass effect upon an incompetent tubal valve. Alternatively, the Eustachian tube can be occluded using Silastic tubes (Fig. 8.52). Injected hydroxyapatite appears

as streaky or focal hyperattenuation on CT (Fig. 8.53). The material can resorb over time. Injected Teflon appears mildly hyperattenuating on CT and sometimes incites a foreign body reaction, which results in an encapsulated granuloma after 3–6 months following injection (Fig. 8.54). Such lesions can also appear intensely hypermetabolic on PET. Other complications include inadequate occlusion of the Eustachian tube and breakage or migration of the catheters and plugs, which can lead to recurrent symptoms and impingement upon the ossicles (Figs. 8.55 and 8.56).

Fig. 8.54  Teflon injection with granuloma formation. Coronal CT image shows a hyperattenuating mass in the left nasopharyngeal region. Biopsy confirmed the presence­ of foreign body reaction. (Courtesy of Juan Small MD)

Fig. 8.56  Displaced transtympanic Eustachian tube plug. Axial CT image shows the soft attenuation plug (arrow) within the mesotympanum, abutting the ossicular chain, rather than within the Eustachian tube orifice

8.14\ Mastoidectomy and Mastoid

Obliteration

8.14.1\ Discussion

There are two main types of mastoidectomy: canal wall-up mastoidectomy (also called intact canal wall mastoidectomy) in which the native bony external auditory canal is preserved (except for perhaps a partial atticotomy defect) or canal wall-down mastoidectomy in which the superior and posterior segments of the bony canal wall are resected such that the mastoidectomy cavity and portions of the middle ear are thereby rendered exteriorized into the external auditory canal. Canal wall-down mastoidectomy can be further divided into radical and modified radical mastoidectomy based on whether or not the entire middle ear space is exteriorized with the ossicles removed (radical) or the middle ear space is par-

tially maintained via tympanic membrane reconstruction (modified radical) (Figs. 8.57, 8.58, 8.59, 8.60, and 8.61). Sometimes, the surgeon chooses to obliterate all or part of the mastoid cavity or exteriorized attic with fascia, bone chips, cartilage, or soft tissue rotational flaps in order to reduce the postoperative risk of having a high-maintenance chronically unstable canal wall-down mastoid cavity (Figs. 8.62 and 8.63). Thin-section CT and MRI are the most useful modalities for evaluating patients with potential complications following mastoidectomy. In particular, T2-weighted turbo spin echo and gradient echo sequences with multiplanar reformats are best suited for evaluating the middle ear structures, while high resolution T2-weighted steady state sequences are optimal for imaging the inner ear. The use of T1-weighted sequences without and with contrast is recommended for an overall assessment.

Fig. 8.57  Partial canal wall-up mastoidectomy. Axial CT image shows that the lateral cortex of the mastoid has been resected. The mastoid air cells are otherwise nearly intact. Sometimes a limited mastoidectomy such as this is performed to drain a mastoid abscess

Fig. 8.58  Canal wall-up mastoidectomy. Axial CT image shows an intact posterior wall of the external auditory canal (EAC) and an air-filled mastoid bowl (*). Sometimes the mastoid cavity can lack aeration after canal wall-up mastoidectomy if the lateral soft tissues scar inward to fill the cavity

Fig. 8.59  Canal wall-down mastoidectomy. Axial CT image shows resection of the posterior wall of the external auditory canal, such that the mastoid bowl (*) communicates with the external auditory canal

Fig. 8.60  Radical mastoidectomy. Axial CT image shows the absence of the ossicles, but preservation of the facial nerve, which has been skeletonized (arrow) as it courses through the mastoid bowl

Fig 8.61  Modified radical mastoidectomy. Coronal CT image shows the repositioned right tympanic membrane margin overlying the horizontal semicircular canal and resection of the mastoid air cells

Fig. 8.62  Mastoid obliteration with fat graft. Axial CT image shows fat graft present within the mastoidectomy bowl (*). Sometimes fat is used to obliterate a mastoid cavity even if it is a canal wall-up procedure if a cerebrospinal fluid leak is present