Canal wall down tympanomastoidectomy: the 'on-disease' approach for retraction pockets and cholesteatoma.

It is well known that cholesteatoma is three-dimensional; hence, we feel that its surgical management requires a three-dimensional approach in order to achieve the best curative and functional results. Retraction pockets are undeniably caused by chronic and recurrent eustachian tube obstruction. However, we found that the presence of a large mastoid antrum was an important, additional aetiological factor in the formation of a retraction pocket and its progression to cholesteatoma formation, with bone destruction and subsequent complications. Canal wall down tympanomastoidectomy--the 'on-disease' approach--is an innovative, three-dimensional technique based on universally accepted surgical principles. We modified the technique to ensure complete exposure and thereby eradication of the disease, with a resultant small cavity. Working in a three-dimensional field, we began drilling at the posterior meatal wall, lowering it while simultaneously widening the cavity as the mastoid was drilled to reach the antrum and the aditus. The bridge was lowered and the incus removed to completely expose the entire disease. The facial ridge was debulked and the temporalis fascia graft placed so as to simplify the middle-ear cleft. We present a comprehensive report of this technique, based upon 600 patients studied retrospectively over a five-year period. After one-year follow up, 546 patients had a dry, healed cavity. Canal wall down tympanomastoidectomy performed by the on-disease approach ensures complete eradication of the disease, with excellent curative as well as functional results.