Lateral Ossicular Chain Problems

Although surgical lasers have improved the safety and ease of tissue removal from the oval window, lateral chain problems continue to complicate revision stapes surgery. Abnormalities of the incus and malleus include erosion of the long process of the incus and incus/malleus fixation.

Pathology of the lateral ossicular chain in most cases of revision stapes surgery is due to necrosis of the long process of the incus. In our experience, necrosis of the incus is usually encountered in cases with a lateralized wire prosthesis that becomes firmly adherent to the edge of the oval window or in small fenestra cases with a displaced platinum ribbon/Teflon piston prosthesis. A less frequently encountered, but equally difficult, lateral ossicular chain problem is attic fixation of the incus and/or malleus. This finding requires removal of the incus and, if also fixed, the malleus neck is cut.

In patients with incusor necrosis attic fixation, the prosthesis is removed as discussed previously. The eroded incus is disarticulated from the malleus and removed from the attic with a large right-angle hook. Using the argon laser, the connective tissue in the oval window is removed to the level of the endos-teum to create a new fenestra. The fenestra is covered with either a vein or a perichondrial graft. This graft is necessary to prevent migration of the new prosthesis into the vestibule. In cases of previous total stapedectomy, ossicular reconstruction is accomplished using a Brackmann modified total ossicular prosthesis covered with tragal cartilage. The Brackmann prosthesis is trimmed to a total length of the distance from the fenestra to the edge of the scutum. The prosthesis is packed in place to prevent either lateral or medial displacement. The platform of the prosthesis is covered with tragal cartilage to prevent the prosthesis from contacting the tympanic membrane. In cases of small fenestra, ossicular reconstruction is performed with a Causse malleus to footplate prosthesis. This prosthesis has a narrow shaft that is more suited to a small fenestra.48 The Causse prosthesis is trimmed to a total length of the distance from the long process of the malleus to the fenestra. The Causse prosthesis is placed on a vein graft over the fenestra to prevent medial displacement of the prosthesis.

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