tailieunhanh - Ebook Manual of otologic surgery: Part 2

Part 2 book “Manual of otologic surgery” has contents: Alternative approaches to the cochlea, unroofing the epitympanum, canal wall down (radical cavity), skeletonizing the facial nerve, labyrinthectomy, endolymphatic sac dissection, internal auditory canal, middle fossa approach (anterior transpetrosal/subtemporal approach). | 6 Alternative Approaches to the Cochlea Finding a patent cochlea may be very challenging in postmeningitic patients with labyrinthis ossificans. A myriad of cochlear drill out procedures including access to the scala vestibuli and mid/apical cochleostomies have been described. Scala Vestibuli Approach Landmarks • Facial recess • Facial nerve tympanic segment • Round window • Oval window niche • Stapedial tendon • Long process of the incus • Incudostapedial joint • Tensor tympani muscle Due to pathophysiological mechanisms that are not fully understood, the process of postmeningitic ossification of the inner ear often starts in the lateral semicircular canal, then reaches the scala tympani and finally affects both scalae in a basal to apical progress pattern. Whereas the status of the lateral SCC serves as an important marker for early detection of ossification by MRI, the fact that the scala vestibuli is often spared from ossification initially renders it an important alternative route for electrode insertion. After the scala tympani is drilled open for a few millimeters and no lumen can be found, a scala vestibuli approach is performed: The incus and stapes suprastructure are removed. The footplate of the stapes is left in place. © Springer-Verlag Wien 2015 C. Arnoldner et al., Manual of Otologic Surgery, DOI 31 32 6 Alternative Approaches to the Cochlea Fig. A tympanomeatal flap is raised and an atticotomy is performed to visualize the middle ear structures. After removal of the incus and stapes suprastructure, a scala vestibuli cochleostomy is drilled in the anterior niche of the oval window (RW round window, FP footplate, asterisk facial nerve, dashed line indicates area of scala vestibuli cochleostomy) Fig. Scala vestibuli cochleostomy and electrode insertion seen through facial recess (RW round window, FP footplate) Landmarks • Facial recess • Facial nerve tympanic segment • Round window • Oval window niche •