title: [Morphologic feature and cochlear implant surgical approach for cochlear modiolus deficiency].
abstract: OBJECTIVE
  To review the classification of cochlear modiolus deficiency and decision on surgical approach for above case,in order to provide mastery for cochlear implant (CI) indication.
  
  
  METHODS
  Basing on temporal bone HRCT pre-operation, CI subjects with modiolus deficiency were defined as following groups: (1) deficiency caused by cochlear dysplasia (Mondini malformation); (2) deficiency caused by dysplasia of cochlear and vestibule (Common cavity malformation); (3) deficiency caused by absence of internal acoustic meatus fundus (IP-III malformation). Three types of surgical approach were utilized: type I, electrode array was introduced through facial recess, enlarged the round window, type II, opened the surface of chchlea, electrode array was introduced through facial recess, fenestration on posterior promontory and then inserted around lateral wall of inner-cochlear cavity. type III, electrode array was introduce through fenestration of lateral semicircular canal and then placed close to the bony wall of common cavity.
  
  
  RESULTS
  One hundred and sixty-six cochlear modiolus deficiency cases were identified into 3 groups as following: 135 Mondini malformation cases into group a, 18 common cavity malformation cases into group b, and 13 IP-III malformation cases into group c. Surgical approach: type I were used in 136 cases (123 Mondini cases and 13 IP-III cases), while approach type II in 12 cases (12 Mondini cases), and approach type III in 18 cases (18 common cavity cases). Income post-operation of CI: For group a (Mondini malformation), post-activation mean hearing threshold in sound field was 65 dB, speech recognition score is 95% (single finals test) and 25% (signal initials test), while it was 80 dB, 60% and 0 for group b (Conmon cavity malformation), and it was 55 dB, 100% and 45% for group c (IP-III malformation).
  
  
  CONCLUSIONS
  The income of speech recognition score for cochlear modiolus deficiency was relatively poor, group b was worst and group c was best, while group a moderate.
authors.forename: Daoxing
authors.initials: D
authors.lastname: Zhang
mesh_terms: D003051:Cochlea / Q000002:abnormalities* / Q000601:surgery; D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D004423:Ear; D007758:Ear, Inner / Q000002:abnormalities; D005260:Female; D006801:Humans; D008297:Male; D011184:Postoperative Period; D012405:Round Window, Ear / Q000601:surgery; D012665:Semicircular Canals / Q000601:surgery; D013067:Speech Perception; D013701:Temporal Bone; D014722:Vestibule, Labyrinth / Q000002:abnormalities