Surgical Procedure

Intraoperative facial nerve monitoring is useful in the transcanal removal of cholesteatoma, particularly as one approaches the level of the drum. The anterior atticotomy may be performed using an endaural (preferred) or postauricular incision. It is necessary to have wide exposure of the external auditory canal. The tympanomeatal flap is extended anterior to the short process of the malleus, at the 2 o'clock position in a right ear and the 10 o'clock position in a left ear (Fig. 7-1). Depending on the extent of middle ear involvement, the tympanomeatal flap may be folded inferiorly or removed completely, ensuring adequate exposure of the pathology. The skin of the anterior and inferior canal may be elevated lateral or medial depending on the surgeon's preference.

Tympanomeatal Flap Incisions

Canal skin incision 6 to 2 o'clock

FIGURE 7-1 For the anterior atticotomy, the tympa-nomeatal flap is extended anterior to the short process of the malleus. In a right ear the tympanomeatal flap is made circumferentially around the posterior canal from the 6 o'clock position to the 2 o'clock position.

Canal skin incision 6 to 2 o'clock

FIGURE 7-1 For the anterior atticotomy, the tympa-nomeatal flap is extended anterior to the short process of the malleus. In a right ear the tympanomeatal flap is made circumferentially around the posterior canal from the 6 o'clock position to the 2 o'clock position.

The ear canal is circumferentially enlarged with straightening of the anterior canal wall to expose the anterior drum and annulus. The posterior canal wall is thinned until air cells are seen through a thin layer of bone. Do not drill into the mastoid air cells, as this may lead to postoperative drainage. The roof or the canal is elevated to the level of the tegmen. The tegmen is followed medial to the scutum and lateral attic wall. The tympanic membrane and short process of the malleus are guides to the depth of bone removal. The scutum, the lateral attic wall, is thinned using a diamond or polishing bur rotating away from the malleus, clockwise in a left ear and counterclockwise in a right ear. The egg-shelled lateral attic wall is elevated away from the choles-teatoma sac and the heads of the malleus and incus, which are 0.5 to 1 mm medial to the lateral attic wall2 (Fig. 7-2). With removal of the scutum, cholestea-toma is exposed in the attic from the fossa incudis, the aditus, and forward to the protympanum, above the eustachian tube.

Once the drum is elevated, the incudostapedial joint is separated and the incus removed. Cholestea-toma is dissected from the epitympanum. The head of the malleus is amputated to access disease in the protympanum.

Greater exposure of the oval window, posterior middle ear, and sinus tympani can be obtained by removing the posterior annulus and medial bony

Protympanum

FIGURE 7-2 The tegmen is followed medial to the level of the drum and short process of the malleus with thinning of the scutum and posterior canal wall. The scutum and posterior canal wall are egg-shelled and then elevated away from the cholesteatoma and ossicles. Cholesteatoma is exposed in the middle ear and epitym-panum from the aditus, the fossa incudis, forward to the protympanum, above the eustachian tube.

FIGURE 7-2 The tegmen is followed medial to the level of the drum and short process of the malleus with thinning of the scutum and posterior canal wall. The scutum and posterior canal wall are egg-shelled and then elevated away from the cholesteatoma and ossicles. Cholesteatoma is exposed in the middle ear and epitym-panum from the aditus, the fossa incudis, forward to the protympanum, above the eustachian tube.

canal wall back to the vertical facial nerve. The pyramidal segment of the facial nerve, superior to the oval window and the chordae tympani nerve, serves as a guide to the vertical facial nerve (the lateral genu of the facial nerve is approximately 1 to 3 mm posterior to the tympanic annulus at the fossa incudis and up to 8 mm posterior to inferior tympanic annulus).9 The technique for safely removing the posterior annulus is with the drill rotating away from the stapes, clockwise in a right ear and counterclockwise in a left ear. Strokes with the drill are from inferior to superior, toward the stapes. This reduces the risk of the drill running into the stapes and facial nerve.5 With anterior thinning of the posterior canal wall and removal of the annular rim, wide exposure of the middle ear and attic are obtained (Fig. 7-3).

Cholesteatoma is dissected out of the aditus, epitympanum, and middle ear using blunt dissection with a small sponge. Stapes instrumentation and higher magnification may be necessary to dissect cholesteatoma from a mobile stapes. After removing all visible cholesteatoma, the middle ear and tympanic membrane are reconstructed. The aditus is obliterated with bone, cartilage, or muscle to prevent secondary retraction pocket formation.3 The epitympanum is lined with fascia to create a smooth cavity (Fig. 7-4).

Epitympanic Retraction
FIGURE 7-3 The surgical defect after removal of cholesteatoma, incus, and head of the malleus allows wide exposure of the epitympanic and middle ear spaces. The mastoid antrum and posterior tympanum recesses may be inspected for residual disease using 30-degree and 70-degree 4-mm nasal endoscopes.

If the cholesteatoma extends beyond the aditus into the mastoid antrum, the anterior atticotomy may be extended to an anterior-posterior mastoi-dectomy by combining the transcanal approach with an intact canal wall and complete simple mastoi-dectomy. Care must be taken not to thin the posterior canal wall, which has been thinned on its anterior surface.10,11 If there is a long history of chronic ear problems or a sclerotic mastoid with extensive

Modified Radical Mastoidectomy Pics

fascia

FIGURE 7-4 Reconstruction of the tympanic membrane and ossicular chain is performed. The aditus is obliterated with free conchal cartilage graft, to prevent secondary retraction pocket formation. The epitympanum is lined with fascia to promote reepithelialization.

fascia

FIGURE 7-4 Reconstruction of the tympanic membrane and ossicular chain is performed. The aditus is obliterated with free conchal cartilage graft, to prevent secondary retraction pocket formation. The epitympanum is lined with fascia to promote reepithelialization.

cholesteatoma, the transcanal anterior atticotomy is converted to a modified radical mastoidectomy with tympanoplasty, by removing the posterior canal wall.12 The attico-antrostomy where the atticotomy is extended posterior to the antrum is not recommended, because of a frequently draining cavity and problems with postoperative care due to a deep mastoid antrum with exposed mucosa.

Over time, 15% of patients develop a secondary mastoid cholesteatoma from retraction pocket formation. Should this occur and there is good postoperative hearing, a Bondy modified radical mastoidectomy may be performed without disturbing the middle ear.

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