Two cases of stapedial ankylosis due to superstructure fixation

Abstract

We report 2 cases of isolated stapes superstructure fixation. Case 1 presented with bilateral conductive hearing loss similar to otosclerosis. Intraoperative findings showed that the stapes superstructure was fixed to the bony facial canal by a bony bar. Stapes mobility was improved by resection of the ectopic bar. Case 2 presented with unilateral conductive hearing loss. Intraoperative findings indicated that the stapes superstructure was fixed by an elongated pyramidal eminence. Resection of the eminence improved stapes mobility.

Isolated stapes superstructure fixation is a rare entity. According to a literature review, four lesions have been identified; an ossified stapedius tendon, an elongated pyramidal eminence, fixation to the facial canal, and fixation to the promontory. These fixations can be either congenital or acquired. In case 1, an ectopic bony bar, of non-inflammatory origin, between the facial canal and stapes superstructure resulted in progressive hearing loss. In case 2, overdevelopment of the anlage of the pyramidal eminence caused congenital fixation of the stapes superstructure.