MASTOIDECTOMY & EPITYMPANECTOMY Tashneem Harris & Thomas Linder

OPEN ACCESS ATLAS OF OTOLARYNGOLOGY, HEAD & NECK OPERATIVE SURGERY MASTOIDECTOMY & EPITYMPANECTOMY Tashneem Harris & Thomas Linder Chronic otitis media, with or without cho- to describe the different types of mastoid- lesteatoma, is one of the more common ectomy as summarized in Table 1. indications for performing a mastoidectomy. Mastoidectomy permits access to re- Table 1: Types of mastoidectomy move cholesteatoma matrix or diseased air cells in chronic otitis media. Mastoidec- Canal wall up Canal wall down tomy is one of the key steps in placing a mastoidectomy mastoidectomy cochlear implant. Here a mastoidectomy Combined approach Radical mastoidectomy allows the surgeon access to the middle ear Intact canal wall Modified radical through the facial recess. A complete mastoidectomy mastoidectomy mastoidectomy is not necessary; therefore, Closed technique Open technique the term anterior mastoidectomy is often Front-to-back mastoidectomy used (anterior to the sigmoid sinus). A Atticoantrostomy mastoidectomy is often an initial step in Open mastoidoepitympanec- lateral skull base surgery for tumours tomy involving the lateral skull base, including vestibular schwannomas, meningiomas, One of the problems is that the termino- temporal bone paragangliomas (glomus logy does not in fact entail specific infor- tumours), and epidermoids or repair of mation about what was done either to the CSF leaks arising from the temporal bone. middle ear or the mastoid. It is the authors’ preference to use the terms open/closed Definition of Cholesteatoma mastoidoepitympanectomy and to state separately whether a tympanoplasty or Cholesteatoma is a chronic middle ear in- ossiculoplasty was done e.g. left open fection with squamous epithelium and mastoidoepitympanectomy and tympano- retention of keratin in the middle ear and/ plasty type III. or temporal bone with progressive bone erosion. A middle ear atelectasis does not The most commonly used terms for canal retain keratin, although it also reveals skin wall down mastoidectomy are radical or in the middle ear space due to the retrac- modified radical mastoidectomy. The clas- tion pocket. sical radical mastoidectomy is not fav- oured by the authors as it results in a large Aims of Cholesteatoma Surgery cavity which frequently discharges and therefore does not satisfy the ultimate goal • Eradication of disease and preventing of mastoid surgery which includes having residual disease a “trouble free” cavity. • Improving middle ear ventilation and preventing recurrent disease The method of open and closed mastoido- • Creating a dry, self-cleansing cavity epitympanectomy as described in this text • Reconstitution of the hearing mecha- is standard. Common to both open and nism closed mastoidoepitympanectomy is the bony work involving the mastoid cavity. It Types of Mastoidectomy involves first identifying the important landmarks (= skeletonization = leaving a The terminology around mastoid surgery is thin shelf of bone covering the important not uniform. In fact, several terms are used structure) before removing the disease and maximum exposure for complete Epitympanotomy: Partial removal of the exenteration of the disease. lateral wall of the attic to expose the head of the malleus and incus in order to remove A closed technique, keeping the posterior soft tissue pathology in the epitympanum; canal wall in place and working transcanal the ossicles are left in place (following a proper canalplasty) and trans- mastoid (with or without posterior tympan- Epitympanectomy: Removal of the lateral otomy) is suggested in moderately pneum- wall of the attic, with removal of the incus atized and ventilated ears with sufficient and head of malleus and with exenteration exposure to remove the disease. and exteriorisation of supralabyrinthine cells Open mastoidoepitympanectomy involves complete exenteration of the mastoid air Cortical mastoidectomy: Also referred to cell system (e.g. retrosigmoid, retrofacial, as simple mastoidectomy, it entails exen- perilabyrinthine) and the epitympanum teration of the mastoid air cells and is (removal of incus and malleus head, performed most commonly for acute mas- exenteration of the supralabyrinthine and toiditis supratubal cells) and is indicated in poorly pneumatized and ventilated ears with Posterior tympanotomy: Drilling away of limited access and exposure. It requires the bone between the pyramidal (mastoid) skeletonization of the facial nerve along segment of the facial nerve, and the lateral the mastoid segment to lower the posterior bony canal and chorda tympani resulting in canal wall to the facial nerve (still covered access to the middle ear from the mastoid. by bone). The mastoid area behind the Posterior tympanotomy may be done for facial nerve is later obliterated with a the following reasons: muscle flap to keep the volume of the final • As part of a closed mastoidoepitympa- cavity low and avoid discharging ears. nectomy (combined approach) when removing cholesteatoma The other method of “canal wall down” • To remove pus from the region of the mastoidectomy is front-to-back mastoidec- round window in acute bacterial or tomy. Surgeons may elect this approach viral otitis media with sensorineural when it has been decided in advance that hearing loss the canal wall will be taken down e.g. with • To provide access to the promontory or a sclerotic mastoid. The principles of this round window in cochlear implant sur- method are that one follows the disease, gery and access to incus or round i.e. the mastoid is only opened as far as the window with insertion of the Vibrant extent of the disease. The only problem Soundbridge with this approach is that one must be certain that there are no more mastoid cells Closed mastoidoepitympanectomy with present as incomplete exenteration will tympanoplasty: This includes a canalplas- cause a discharging cavity. ty, mastoidectomy, epitympanectomy, (posterior tympanotomy) and tympano- Surgical Terminology plasty. The external bony canal is pre- served. The drawback of this approach is Canalplasty: Enlargement of the external the limited view into the anterior epi- ear canal while avoiding injury to the tem- tympanum and the sinus tympani in cases poromandibular joint anteriorly and the of limited pneumatisation and cholestea- mastoid air cells posteriorly (Video) toma formation 2 Open mastoidoepitympanectomy (with Applied Anatomy obliteration): This involves the radical exenteration of the tympanomastoid tracts Knowledge of middle ear and temporal with exteriorisation of the surgical cavity bone anatomy is vital to understanding the and lowering of the posterior bony canal concepts of surgical management. It is wall to the level of the skeletonised facial imperative to practise the surgery and learn nerve. In order to reduce the size of the the 3-dimensional temporal bone anatomy cavity, especially with moderately-well in a temporal bone laboratory. The impor- pneumatised mastoids, the mastoid tip is tant landmarks and structures will be high- removed and a myosubcutaneous occipital lighted with the surgical steps. flap is created to reduce the size of the cavity. Meatoplasty is routinely performed. Preoperative assessment Open/Closed Mastoidoepitympanectomy History Age is not a limiting factor as children Patients with chronic ear disease frequen- behave equally well with open MET’s as tly have a longstanding history of hearing do adult patients! loss or chronic otorrhoea. It is important to establish whether there is a history of Deciding whether to do open or closed previous surgery. Foul smelling otorrhoea cavity mastoidoepitym-panectomy may is a clear hint of cholesteatoma. depend on the factors listed in Table 2. Otomicroscopy Factor Closed MET Open MET Extent of Limited Large cholestea- This is an important means to determine disease toma Primary surgery the presence of cholesteatoma and it helps with sufficient Labyrinthine to define the extent of disease. The ear space fistula should be thoroughly cleaned of secretions Other complica- and debris. Findings may include a retrac- tions tion pocket with accumulation of keratin in the attic or in the posterosuperior quadrant Recurrent cholesteatoma of the tympanic membrane, granulation after previous tissue or a polyp (Figures 1 & 2). A polyp closed MET “signals” an underlying cholesteatoma. Pneumatisation Good Poor pneumatisation pneumatisation Aeration Air in middle Glue in middle Pneumatic otoscopy ear and mastoid ear air cells Granulation tissue This should be routinely performed to in mastoid air determine the presence of a positive fistula cells response. A negative response however Bleeding does not exclude a fistula. Follow-up Good 5-year Poor 5-year follow-up follow-up Audiology anticipated anticipated Table 2: Indications for closed vs. open Pure tone audiometry should be obtained cavity mastoidoepitympanectomy (MET) with air and bone conduction, and also speech reception thresholds should be 3 determined. These should be done within 3 HRCT (0,5mm cuts) is invaluable for both months of surgery. for diagnosis and surgical planning. Pre- operative counselling is mandatory with any surgical procedure. Information gained from the CT scan enables the surgeon to discuss in detail with the patient what the surgical goals and risks of the surgery are, as well as the possibility of a staged procedure and follow-up routine. Diagnostic value of HRCT • Specificity is poor with mass lesions which may include granulation tissue, secretions, cholesterol granuloma or a

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