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.2

Patient experiencing severe vertigo a few hours after left stapedectomy, and complete unilateral deafness 1 day after the procedure. a. Axial T1-weighted spin-echo image of temporal bones shows slightly increased signal intensity in left labyrinth (arrows) compared to right. b. After administration of gadolinium, labyrinthine enhancement is seen: labyrinthitis (arrows). Enhancement in left middle ear and mastoid: secondary to recent surgery. c. Maximal intensity projection of thin axial T2-weighted fast spin-echo images shows normal high signal intensity in the right cochlea (c), vestibule (v) and semicircular canals. d. Signal loss in left vestibule, semicircular canals and part of the cochlea: presumably due to leakage of labyrinthine fluid into middle ear. (Figs. 2a-d courtesy by Bert De Foer, MD, Antwerp, Belgium)
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)