Mastoidectomy

There are 4 methods of dealing with mastoid pathology.

•  Exteriorization operation: the classic radical & modified radical mastoidectomy.

•  Obliteration: Muscleplasty

•  Combined approach tympanoplasty: Air-containing mastoid cavity with preservation of the posterior canal wall & posterior tympanotomy.

•  Posterior canal reconstruction.

•  Exteriorization: the classic radical & modified radical mastoidectomy.

In the old days, without the use of an operating microscope, the surgeon could not be sure of complete excision of the cholesteatoma so the mastoid had to be exteriorized. The posterior wall of the ear canal is removed & the skin of the ear canal is incised & turned down over the facial ridge to help line the mastoid cavity, thus removing the barrier between the external ear canal & the mastoid cavity, & exteriorizing it. With this technique, before healing can occur skin has to creep & line the entire mastoid cavity giving rise to granulations & healing by secondary Intention). If infection occurs, hypertrophic granulations may develop over which epithelium will not creep, resulting in secretion of more discharge which accumulates and causes more hypertrophic granulations to develop, till the vicious circle results in a complete breakdown of the whole lining and a persistently discharging mastoid cavity develops. (Fig 4). If any endothelium has not been eliminated (as in a well pneumatized mastoid) when the skin lines the cavity, the endothelium is not aerated so it will secrete mucous which will cause discharge and the same vicious cycle. A large cavity may not be self-cleaning and desquamated epithelium and wax accumulations have to be removed six monthly by an E.N.T. Surgeon. If this is not done, epithelium may break down underneath the wax accumulations, produce granulations and the vicious circle starts again. In the best hands in the world, in 20% of cases the discharge did not stop with this technique. The reservoir of air is absent, so the patient is very susceptible to eustachian catarrh, & an initial good hearing result may be affected by a bad cold & serous otitis media. In short, this operation renders the ear safe from the risk of intracranial complications, but as far as hearing improvement and stopping the discharge are concerned, the results are unsatisfactory.

B. Obliterative Technique-Muscleplasty.

In order to reduce the size of the mastoid cavity, pedicled muscle flaps may be swung in to obliterate the cavity. There are five disadvantages:

•  If any epithelium is buried, a cholesteatoma may form underneath the muscle and may burst into the brain.

•  If any endothelium is buried ( in well pneumatized mastoid, it may be impossible to remove
all the endothelium from perilabyrinthine cell) it will secrete mucus as it is not aerated. The accumulated mucus will cause discomfort & may periodically discharge.

•  After some years, parts of the muscle atrophy and retraction pockets may from.

•  The reservoir of air in an air containing mastoid is absent, so the patient is very susceptible to Eustachian catarrh and an initial good hearing result may be affected by a bad cold & serous otitis media.

•  The healing here also is by secondary intention, as the skin has to creep over the whole muscles mass.

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