DIFFICULT CASES OF COCHLEAR IMPLANTATION

Abstract

Background: In the recent  years, there  is a tendency to extend  the  indications  to cochlear implantation in patients  with inner and middle ear malformations, cochlea  ossificans and  Meniere's disease. In otosurgical practice, the cases are not uncommon when  cochlear  implantation is difficult after previous canal wall down mastoidectomy due to chronic suppurative otitis media.  Aim: To improve postoperative auditory performance of patients  with profound  sensorineural  hearing loss (deafness), complicated  by the inner or middle ear disorders, through the optimization of cochlear implantation surgical technique.  Materials and methods: We analyzed 42 patients  with profound  sensorineural  hearing  loss who underwent  cochlear  implantation, 12 of them  having cochlea  ossification  after  meningitis  (group  1), 19,  with  inner  ear  malformations   (group  2),  9, had underwent canal wall down mastoidectomy (group 3) and 2, with Meniere's disease (group 4). Surgical  techniques  varied  depending  on  the type of disorder. In all patients, implant  telemetry and  evoked  stapes  reflex registration  (if stapedium muscle was present) were performed. Postoperatively the mastoid cavity was controlled by  otomicroscopy.  Results: Stapes  reflex were obtained in 8 patients  from group  1. Number of from group 3 in whom of the proposed cochlear implantation technique was used, no long-term relapses of chronic suppurative otitis media were observed, the mastoid cavity could be visualized very well and graft survival was excellent. No cases of electrode array extrusion or protrusion were registered. Patients  with  Meniere's  disease  and bilateral  sensorineural  hearing  loss who  underwent  simultaneous  operations  (endolymphatic sac drainage  and cochlear implantation)  showed satisfactory results of audioverbal  rehabilitation and a marked reduction  of vestibular symptoms.  Conclusion: Surgical techniques proposed in this study  allow for insertion  of maximal  electrode numbers  into the spiral canal of a malformed and ossified cochlea. Formation  of bone  tunnels  for the active electrode  in the burred  cavity and its covering with autocartilage helps to prevent  any protrusion  and displacement of the electrode  in patients   who  had  previously  underwent canal wall down mastoidectomy. Simultaneous cochlear implantation and endolymphatic sac drainage is also considered  to be an adequate approach  to treatment of patients  with late  stage  Meniere's disease with profound bilateral sensorineural hearing loss.