14 Cholesteatoma Surgery
Holger Sudhoff, Henning Hildmann
Introduction
History in the case of cholesteatoma is often non-specific. Patients may com- plain of periodic or constant aural and often fetid discharge. Pain is unusual.
The degree of hearing loss is highly variable. A cholesteatoma may develop insidiously for some time without otorrhoea and may be detected incidentally during an ear examination. Involvement of the vestibular system, auditory sys- tem or facial nerve will cause vertigo, sensorineural hearing loss, tinnitus, or facial palsy. Intracranial complications are extremely rare in the absence of premonitory signs and symptoms. However, in children these prodromi might pass unnoticed.
Diagnosis is made under the otomicroscope after secretions have been aspi- rated and the external canal and tympanic membrane have been cleaned.
Endoscopic evaluation can be useful and surgical exploration. Exploration may be necessary. With a typical epitympanic or attic cholesteatoma, a perfo- ration (usually peripheral) can be seen in the tympanic membrane. Polyps,
Fig. 14.1
Cholesteatomas are epidermal inclusion cysts of the middle ear or mastoid.
In the case of a retraction pocket cholesteatoma, the “cyst” opens into the external auditory canal developing from a retraction pocket (Fig. 14.1). The cyst contains desquamated debris (principally keratin) from their keratiniz- ing, squamous epithelial lining. Cholesteatomas of the temporal bone may be congenital or acquired. Acquired cholesteatomas are the consequence of otitis media with effusion (OME) or acute otitis media (AOM) or both. An under- standing of the pathogenesis and pathophysiology of aural cholesteatoma is particularly important because it is the destructive nature of this entity that is responsible for much of the morbidity associated with chronic otitis media.
The propensity of cholesteatomas to erode bone and the lack of effective, non- surgical management add importance to the understanding of this disease.
Any squamous epithelium in the middle ear with the possibility of destruc- tion of the surrounding structures and intracranial life threatening complica- tions must be considered to be a cholesteatoma.
A cholesteatoma consists of layers of keratin in a cavity lined by squamous epithelium, called matrix, and the underlying subepithelial connective tissue, called perimatrix. It is mainly confined to the middle ear but may also occur in other areas such as the skull base, meninges, brain and temporal bone. Choles- teatoma gradually expands as a result of progressive exfoliation of keratinous material and causes complications by eroding surrounding structures. Within the middle ear, bony erosion may result in hearing loss, vestibular dysfunc- tion, facial nerve palsy and intracranial complications. Due to its pathogene- sis, cholesteatoma can be divided into congenital and the much more frequent acquired cholesteatoma.
There are four basic theories of the pathogenesis of acquired aural choleste- atoma: (1) invagination of the tympanic membrane (retraction pocket choles- teatoma), (2) basal cell hyperplasia, (3) epithelial ingrowth through a perfora- tion (the migration theory), and (4) squamous metaplasia of middle ear epi- thelium. Recently, Sudhoff and Tos proposed a combination of the invagina- tion and basal cell theories as an explanation for retraction pocket cholestea- toma formation [1]. The loss of self cleaning will result in a transition from the retraction to the expansion stage of cholesteatoma (Fig. 14.2).
Fig. 14.2
Acquired cholesteatomas of the middle ear are divided into:
1. Attic cholesteatoma, originating from Shrapnell’s membrane and extend- ing primarily into the attic.
2. Sinus cholesteatoma, originating from the posterosuperior retraction of pars tensa and extending primarily into the tympanic sinuses. From here it may extend along the prominence of the facial nerve, medial to the incus body, into the posterior attic and antrum, while the anterior part of the tympanic cavity and the anterior attic are not involved.
3. Tensa-retraction cholesteatoma, originating from an entirely retracted pars tensa, draping over the posterior and anterior walls of the tympanic cavity, extending from here into the hypotympanic cells and tubal orifice.
Furthermore it may extend, medially to the malleus folds, towards the posterior and anterior attic.
This classification, proposed by Tos for a better understanding of the patho- genesis, has become widely accepted. He classifies the pars tensa cholesteato- mas into sinus cholesteatomas originating from a posterior retraction and tensa retraction cholesteatomas developing from the anterior, inferior and posterior parts of the tympanic membrane. Such a classification is also impor- tant for the evaluation of the natural history, prognosis, surgical methods and results.
General Principles for Surgery
The basic goal of cholesteatoma surgery is the complete removal of the squa- mous epithelium to minimize the risk of recurrence. Cholesteatoma is a life- threatening disease due to its intracranial complications. Therefore it may be necessary to sacrifice even functionally important structures such as the audi- tory ossicles and even the inner ear in cases of extended disease. The first step is the complete removal of the epithelium. Only after complete removal is recon- struction to be planned. Comparable to tumour surgery, it is dangerous when
under favourable conditions. However, endoscopes are not routinely used in cholesteatoma surgery. Hopkin’s wide-angle endoscopes are intraoperatively useful for checking areas of epithelium which cannot be looked at with the microscope. If the site of inspection is clear, drilling for direct inspection and removal may not become necessary.
Surgical Steps
1. Incision. Generally, if work in the mastoid becomes necessary, a retroau- ricular incision is used. This approach allows extensive exposure of the mastoid according to the extent of the disease. A cavity can be reduced in size by removing the tip of the mastoid and the outer bone of the mastoid if required. Larger flaps for obliteration can be harvested. Only for smaller sinus cholesteatomas not extending into the mastoid is the endau- ral incision preferable.
2. The meatal flap is prepared as described above. In most cases it should be wider than in tympanoplasty for a central perforation. The incisions are made at 12 and 6 o’clock. Since drilling in the ear canal is necessary, we remove the posterior meatal skin and reimplant it at the end of the opera- tion as a free graft. This allows more space for drilling and prevents dam- age of the flap by the drill. Additionally it improves the overview and saves time. Ear canal widening is important in cases of narrow ear canals to facilitate the postoperative follow-up and care.
3. The ear canal is widened by drilling some of the bone free from the flap. If an overhanging anterior meatal wall obscures the vision, the skin must also be removed from the anterior wall for drilling until the anterior tympano- meatal angle is seen. This anterior tympanomeatal angle is a vulnerable area.
Whenever possible the epithelium must not be damaged to avoid blunting.
4. If the cholesteatoma extends into the attic, antrum or mastoid, it is usually followed and exposed by drilling until the sac can be looked at and removed. Only for or sinus cholesteatomas and tensa cholesteatomas con- fined to the middle ear might it be sufficient to widen the ear canal. If the epithelium invades the sinus tympani, the region cannot be completely
Fig. 14.3
Fig. 14.4
be done and the posterior wall is reconstructed with cartilage (Fig. 14.4).
For extended cholesteatomas the entire posterior wall should be removed, resulting in a mastoid cavity. This surgery and the problems associated with it are described below. The epithelium may also extend under the head of the malleus and the anterior epitympanum. This part can escape detection if the surgeon does not meticulously check this area. The defect is reconstructed with cartilage if the middle ear is aerated. The techniques and problems of reconstruction are described in Chap. 15, “Mastoid Cav- ity”.
6. Whenever possible the cholesteatoma sac should not be opened. Parts of the sac obscuring the surgical field, however, can be resected. If the sur- geon works underneath the epithelium within the perimatrix, he or she can be sure to remove the epithelium completely. The epithelium should not be torn out, but removed in continuity. This is especially difficult in invasive types of cholesteatoma where one cell needs to be cleaned after the other. The bony partitions between the cells are removed with a curette or a diamond burr. Smoothing of the denuded bone allows improved self-cleaning and accelerated healing.
7. The classical intact canal wall technique for the removal of cholesteatoma is only used in selected cases. The recurrence rate, especially in inexperi- enced hands, has been too high. We see an indication in patients with extensive mastoids. The procedure is described next in Chap. 15, “Mastoid Cavity”.
