Mechanisms of cholesteatoma formation following stapedectomy.

Poststapedectomy cholesteatoma is uncommon. We report a patient with bilateral cholesteatomas, each following an initially successful stapedectomy for conductive hearing loss due to stapedial fixation from otosclerosis. A revision right stapedectomy done in 1972 was complicated 4 years later by prosthesis extrusion and cholesteatoma. An extensive left cholesteatoma occurred 7 years after stapedectomy in 1977 and required a radical mastoidectomy. The etiology of poststapedectomy cholesteatoma in this patient was probably chronic eustachian tube dysfunction and negative middle ear pressures. The initial right cholesteatoma occurred following prosthesis extrusion, which is presumed to have been the portal of entry of squamous epithelium into the middle ear. The later-occurring left poststapedectomy cholesteatoma represented progression of an attic retraction pocket. Both of these complications were likely secondary to negative middle ear pressure. In addition to eustachian tube dysfunction, other proposed etiologies for poststapedectomy cholesteatoma formation include prosthesis extrusion independent of negative middle ear pressure, unrecognized presence of squamous epithelium in an oval window fat graft, an inverted tympanomeatal flap due to improper positioning, and a marginal perforation from a disrupted anulus. Poststapedectomy cholesteatoma is a rare phenomenon, but does occur. The preoperative exclusion of patients with eustachian tube dysfunction and proper surgical techniques should reduce this complication.