Contraindications to the small hole stapedectomy.

A small hole stapedectomy with an unprotected piston is contraindicated in an ear subjected to excessive pressure changes whether these are excessive fluid pressure changes which occur in the inner ear or excessive air pressure changes in the middle ear. Excessive fluid pressure changes in the inner ear may be the result of an overly patent aqueduct of the cochlea or a permeable internal auditory canal. These excessive fluid pressure changes may produce fistulas or a dilated blister around the piston called a tented piston. Excessive air pressure changes in the middle ear will produce excessive excursions of the tympanic membrane which may result in vertigo or a dislocated piston.