Mastoidectomy: Intact Canal Wall Procedure

Definitions

The common mastoid operations performed for chronic ear infections are defined in this section. The technical surgical variations peculiar to each surgeon do not alter the fundamental classification. The basic classifications have remained unchanged since 1974.

Evolution of Technique

Before the mid-1950s, there were two operations for chronic otitis media with cholesteatoma: radical mastoidectomy and modified radical mastoidectomy. These classic operations are still indicated but are performed infrequently. Their objectives are to create a safe ear by exteriorizing the disease and to preserve the hearing, if possible.

When Wullstein and Zollner introduced tympanoplasty, exenteration of the mastoid was the rule. Two complications eventually became apparent: moisture in the cavity had a deleterious effect on the full-thickness skin used to graft the tympanic membrane, and the narrowed middle ear space created in the classic types III and IV tympanoplasty was prone to collapse, nullifying any hearing improvement (see Chapter 14 ).

It became apparent that if satisfactory hearing results were to be obtained, some method of avoiding a narrow middle ear space would be necessary. Many investigators thought that the best way of solving this problem was by not creating an exteriorized cavity, but by reconstructing the tympanic membrane in a normal position, and then inserting some type of tissue or prosthetic device to reestablish the sound pressure transfer mechanism (see Chapter 14 ). Although this concept led to better hearing results, many complications developed over the years, some of which still occur.

The physicians at the House Ear Clinic began performing intact canal wall tympanoplasty with mastoidectomy in 1958, under the direction of William House. By 1961, more than half of all cholesteatoma cases were managed at the House Ear Clinic with an intact canal wall technique. Many revision operations were required to correct cholesteatoma recurrence resulting from retraction pockets. As a result, many physicians at the House Ear Clinic reverted to taking the canal wall down and then obliterating the cavity with muscle, based on a procedure suggested by Rambo. In 1963, 50% of cholesteatoma cases were managed this way.

By 1964, it was realized that the technique of obliteration did not eliminate the cavity and the complications involved. Additionally, the routine use of plastic sheeting through the facial recess in the intact canal wall procedure was reducing the number of cases requiring revision for retraction pockets (recurrent cholesteatoma). The percentage of cases managed by a canal wall-down technique gradually decreased to 10% in 1970. Subsequently, although there have been fluctuations, on average 15% to 30% of chronic ear surgery is managed by canal wall-down procedures.

Controversy

The controversy over intact canal wall versus canal wall-down procedures centers mostly on the safety of the operative procedure and safety over the ensuing years. The technical ability of the surgeon should also be considered. In surgery for aural cholesteatoma, whether intact canal wall or canal wall-down, judgment and technical ability are major factors in the outcome. Let us assume that the technical ability and judgment are superior in the two groups. Why is there a difference in opinion as to what is best for the patient?

Are hearing results a factor? Experienced otologic surgeons do not find much difference in the hearing results. Surgeons are very careful not to narrow the middle ear space (see Chapter 1 ) and to stage the operation almost as frequently as in an intact canal wall operation (see Chapter 18 ).

Is there a difference in the healing? Intact canal wall procedures, with lateral surface grafting (see Chapter 8 ), may take 6 to 8 weeks to heal. Open cavities frequently require 3 to 4 months and occasionally 6 to 8 months, and there is a small percentage that is never free of minor moisture.

What about residual and recurrent disease? Some surgeons would argue that a primary canal wall-down approach results in one operation, not two. Most experienced surgeons who use intact canal wall and canal wall-down procedures find little difference in the incidence of middle ear residual disease or disease left behind. They also find little difference in the incidence of staging the operation (see Chapter 18 ).

Recurrent cholesteatoma is a different matter. Recurrent cholesteatoma characteristically results from a posterosuperior retraction pocket, ^, which occurs only in intact canal wall procedures. Surgeons who have reported a 20% to 40% incidence of recurrent cholesteatoma have failed, with rare exceptions, to stage the operation when indicated (75% of the time) and have failed to use plastic sheeting through the facial recess, even when the operation was performed in one stage. Advocates of the intact canal wall procedure, surgeons who have had extensive experience, have an incidence of recurrent cholesteatoma of less than 5%.

When a cavity is created, it is usually necessary to clean (remove dead skin) every 6 to 12 months for the rest of the patient’s life. Patients who have undergone the intact canal wall procedure need to be seen by the physician only once every year. Precautions relative to not getting water in the ear are necessary 50% or more of the time in canal wall-down cases, depending on whether the cavity is healed, how large it is, whether an adequately sized meatus was created, and whether the cavity is round instead of bean-shaped. Finally, an adequately sized meatus is relevant. If one creates a meatus large enough to have a trouble-free ear and allow water in the ear, the size may pose a problem when fitting a hearing aid, if and when needed in future. The problem consists of obtaining a secure fit and preventing feedback. The behind-the-ear aid usually solves this problem and is the best aid for use in an ear that may have some drainage from a cavity.

Indications for Mastoidectomy

Mastoidectomy may be indicated in tympanoplasty surgery to eliminate disease, explore the mastoid to exclude disease, enlarge the air-containing middle ear–antral space, or occasionally to create temporary postauricular drainage (with a catheter) in patients with compromised eustachian tube complications or uncontrolled mucosal infection. The most common indication is the treatment of cholesteatoma and the associated infection.

What about physicians who recommend at least a cortical (“simple”) mastoidectomy in all tympanoplasties? The rationale seems to be that it is “good practice,” and that “it’s better to be safe than sorry.” There are also arguments, mentioned earlier, that this practice can increase the middle ear cleft space, and that this is a good idea if there is compromised eustachian tube function. The indication for mastoidectomy is based on the clinical history and the appearance of the ear in the physician’s office. The final decision is made during surgery. Radiographs and imaging studies play little part in making the diagnosis or the decision to perform the surgery but are helpful in cases with unusual anatomy or revision surgery.

Indications for Exteriorized Mastoid Cavity

We prefer not to create a cavity, but this may sometimes be necessary. That decision may be made preoperatively, but more often than not, the operation is begun as an intact canal wall procedure and the decision to exteriorize the mastoid made intraoperatively.