Morphology of a columellaform stapes.

A columellaform stapes found in male patient 18 years old with a conductive hearing loss, has been examined by SEM and light microscopy. The ossicle was smaller than a normal stapes. The head was linked to the base by a crural plate, probably formed by the fusion of the material of the two crura. Microscopy showed a slightly less interwoven structure of the fibrillar bone present mainly at the cranial aspect of the crural plate. Honeycomb-like bone was confined to the caudal part of the crural plate. Microscopy revealed a cavity in the centre of the stapes at the transition between the base and the plate. During surgery, a bony structure was found linking the posterior side of the head of the stapes to the pyramidal eminence. Post-operative audiograms revealed improved hearing with some residual conductive loss of about 10 dB. This case illustrates that a columellaform stapes may occur without forming part of a syndrome.