A wide shave is performed, and the incision is made 1.5 cm posterior to the postauricular sulcus. Patient preparation and draping are performed as for a routine tympanomastoidectomy. Because the limits of the tumor are not visible through the tympanic membrane, CT provides an assessment of the extent of tumor involvement. Preoperative CT evaluation is crucial before this approach is undertaken. The tumor may extensively involve the middle ear and mastoid, but has arisen from the glomus tympanicum body and does not involve the jugular bulb. The mastoid–extended facial recess approach is used for tympanomastoid glomus tumors. Brackmann, in Otologic Surgery (Third Edition), 2010 Mastoid–Extended Facial Recess Approach MRI has been more useful in following patients with complex skull base epidermoids because of altered anatomy (such as a rerouted facial nerve), it is desirable to avoid a second look. The senior author has had several recent cases where early recurrences were missed on MRI and later found at revision surgery. However, the inability of MRI sequences to identify small residual disease limits its usefulness in routine postoperative surveillance. The apparent diffusion coefficient (ADC) value is significantly lower in cholesteatoma that noncholesteatoma, 29 and when combined with DWI, this technique can be useful to identify residual or recurrent cholesteatoma.
15,28 Cholesteatoma will demonstrate restricted diffusion (bright) on DWI. Improved imaging techniques include non–echo-planar diffusion-weighted MRI (DWI) that improves sensitivity and specificity to identify cholesteatoma down to 3 to 5 mm in size ( Fig. Cholesteatomas are immediate to hyperintense on T2W ( Fig. MRI demonstrates isointensity to hypointensity on T1W ( Fig. MRI may be beneficial in these patients if clinical suspicion remains high. When fluid or inflammatory tissue fills the middle ear, the contour of the cholesteatoma is obscured, limiting the use of CT. Axial and coronal oblique sections through the middle ear will demonstrate thinning or absence of bone covering the lateral canal and flattening of the medial wall of the epitympanic recess due to erosion of the normal protuberance of the lateral canal. The ampullated limb of the lateral semicircular canal is the most common site of fistula formation. A labyrinthine fistula can result from involvement of the medial wall of the middle ear ( Fig. 135.22), lateral extension with erosion of the outer cortex or EAC, or medial extension along a perilabyrinthine air cell tract to involve the petrous apex. Posterior extension into the mastoid air cells leads to erosion of the bony trabeculae, with disease progression leading to mastoid contraction and obliteration ( Fig. Erosion of the lenticular process of the incus and stapes superstructure, as well as enlargement of the attic, aditus, and mastoid antrum, are also common. Lateral displacement and erosion of the ossicular chain is characteristic of an epitympanic cholesteatoma ( Fig.
27Īcquired cholesteatomas typically develop in the epitympanum, first eroding the scutum and ossicles ( Fig. 25,26 Posterior extension of the congenital cholesteatomas may demonstrate widening of the antrum with obstruction of the mastoid air cells. As these lesions enlarge, they may enlarge to fill the entire middle ear, eroding the ossicles, fallopian canal, tegmen, or otic capsule ( Fig. HRCT without contrast enhancement will demonstrate a homogeneous soft tissue lesion, classically in the anterior tympanum adjacent to the eustachian tube ( Fig. Congenital cholesteatomas are found behind an intact tympanic membrane can be limited to the anterior tympanum some may fill the entire tympanum and extend into the mastoid. Regardless, cholesteatomas do have specific radiologic characteristics that may aid in the diagnosis and formulation of a management option. The diagnosis of an acquired cholesteatoma in a previously unoperated patient is based on history and examination, not radiology. Although some clinicians advocate for the routine use of imaging in all operative cases, others feel that imaging should be reserved for those undergoing surgery in an only hearing ear or in those patients in whom a complication of cholesteatoma is suspected. There is controversy regarding the role imaging plays in the evaluation of cholesteatoma.
Flint MD, FACS, in Cummings Otolaryngology: Head and Neck Surgery, 2021 Middle Ear and Mastoid
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