Head and Neck Imaging

Stapedectomy

surgical procedure to correct the conductive hearing loss caused by stapes fixation; it is most commonly performed in patients with fenestral otosclerosis. During this procedure, the superstructure (head and crurae) of the stapes is removed, a small hole is drilled in the stapedial footplate, and a prosthesis is attached to the long process of the incus and inserted in the hole in the footplate; alternatively, a part of the stapedial footplate is resected, the prosthesis is inserted in the defect, and the remaining defect is closed with some tissue. The prosthesis transmits the ossicular vibrations to the intralabyrinthine fluid. Stapedial prostheses exist in various materials and thicknesses, and may be difficult to see on CT-images. The tip of the device should be located at the level of the oval window (Fig.1). Subluxation of the tip is a reason for failure of the procedure. Another reason for recurrent conductive hearing loss is pressure necrosis of the long process of the incus, at the site where the prosthesis is fixed. Postoperative vertigo may be caused by inward displacement of the prothesis, protruding into the vestibule; such an event can be detected by CT. Postoperative vertigo may also be caused by serous labyrinthitis, usually a self-limiting condition. However, in some cases there may be leakage of perilymph into the middle ear; such a perilymphatic fistula may cause severe vertigo and sensorineural hearing loss (Fig.2).

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Fig.1

a-c. Adjacent 1 mm thick axial CT images of right temporal bone. Stapedial prosthesis (arrowhead) is seen between the tip of the long incudal process (i) and the stapedial footplate (fp). Area of fenestral otosclerosis can be seen anterior and caudal to the footplate.
Stapedectomy, Fig.1 (a)
Stapedectomy, Fig.1 (b)
Stapedectomy, Fig.1 (c)
Stapedectomy, Fig.2 (a)
Stapedectomy, Fig.2 (b)
Stapedectomy, Fig.2 (c)
Stapedectomy, Fig.2 (d)