tailieunhanh - Ear Surgery - part 10

Hình 12,5 ốc tai của con mèo sau khi transection nội sọ của dây thần kinh ốc tai. Là tổng số lỗ của các loại tế bào hạch xoắn ốc để chỉ các tế bào hạch loại II (II) và các sợi ly tâm (đầu mũi tên) trong các kênh rạch Rosenthal. Các cơ quan Corti (OC) đã bổ sung bình thường của tế bào cảm giác và hỗ trợ | 114 Chapter 12 Cochlear Implant Surgery Fig. Cochlea of cat after intracranial transection of the cochlear nerve. There is total loss of type I spiral ganglion cells leaving only type II ganglion cells II and efferent fibers arrowhead in Rosenthal s canals. The organ of Corti OC has normal complement of sensory and supporting cells 12 large then the exposure is generous and removal of the fallopian canal wall is not necessary. However with small FR removal of fallopian canal wall and the posterior bony ear canal may be required to gain exposure of the RWN. The FN is at some risk but should be preserved using careful surgical technique. If the exposure of the RWN still not possible using the above modifications in FR exposure then the cochleostomy may be created further up the basal turn of cochlea for insertion of the prosthesis. The implanted cochlea is x-rayed after surgery and before discharge to confirm the depth of insertion and the absence of kinking which may negatively affect activation of the prosthesis. In the rare instance where the scala tympani cannot be accessed because of anatomical or pathological ossification reasons the prosthesis may be inserted through the oval window into the scala vestibuli. There is a greater incidence of vestibular labyrinth trauma with the latter. However if vestibular symptoms persist and are disabling postoperatively then ablation of residual vestibular function with intratympanic gen-tamycin may be effective. Transcanal Approach to Round Window Niche Veria Operation Insertion of the CI prosthesis may be accomplished without mastoidectomy and posterior tympanotomy 2 3 . In this procedure an endaural exposure of the middle ear is provided with tympanomeatal flap to permit the cochleostomy. A bony tunnel is drilled from a recess in the outer cortex above the suprameatal spine. This tunnel takes a direct path just beneath the surface of the posterior bony ear canal into the epitympanum. The prosthesis is then .