title: Auditory brainstem implant: part I. Auditory performance and its evolution over time.
abstract: OBJECTIVE
  Evaluation of auditory performance and its evolution over time in patients with the auditory brainstem implant.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Tertiary referral center.
  
  
  METHODS
  Between May 1996 and April 2000, 14 patients with neurofibromatosis type 2 underwent implantation with a multichannel auditory brainstem implant. Auditory performance data were obtained in 13 patients who had used their device on a regular daily basis for 1 to 41 months (average 19 months). Hearing evaluation was based on the results of four tests (vowel confusion, consonant confusion, Freiburger numbers, and speech-tracking test), which were performed with and without lip-reading at regular intervals after device activation.
  
  
  RESULTS
  12 patients received auditory sensation through the auditory brainstem implant immediately after device activation. In one patient, because of postoperative electrode migration, device activation was not successful. In this case, after the electrode array was repositioned, activation was successful. The results of the audiovisual mode 2 weeks after device activation revealed a lip-reading enhancement above the chance level in about 50% of the patients in the vowel confusion and speech-tracking tests and in 70% of the patients in the consonant confusion test. Lip-reading enhancement improved within the first 6 months and then entered a plateau phase, which was more prominent in the monosyllabic vowel and consonant tests. In the auditory alone mode, more than half of the patients showed their first positive result in the vowel test 3 months after device activation, but it took about 6 months until half of the patients revealed a result above the chance level in the consonant and Freiburger numbers tests. Open set speech recognition in the auditory alone mode (in the speech-tracking test) was not common and happened relatively late (within 1 year or later).
  
  
  CONCLUSIONS
  Although auditory sensation appeared immediately after device activation, a period of 6 months was necessary for relearning and adaptation of the central auditory system to the altered form of auditory information presented by the auditory brainstem implant.
authors.affiliation: Department of Otolaryngology, Medical University of Hannover, Carl Neuberg-Strasse 1, D-30625 Hannover, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Lenarz
authors.forename: M
authors.initials: M
authors.lastname: Moshrefi
authors.forename: C
authors.initials: C
authors.lastname: Matthies
authors.forename: C
authors.initials: C
authors.lastname: Frohne
authors.forename: A
authors.initials: A
authors.lastname: Lesinski-Schiedat
authors.forename: A
authors.initials: A
authors.lastname: Illg
authors.forename: U
authors.initials: U
authors.lastname: Rost
authors.forename: R D
authors.initials: RD
authors.lastname: Battmer
authors.forename: M
authors.initials: M
authors.lastname: Samii
mesh_terms: D000328:Adult; D019929:Cochlear Implantation; D003638:Deafness / Q000175:diagnosis* / Q000209:etiology / Q000601:surgery; D004868:Equipment Failure; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016518:Neurofibromatosis 2 / Q000150:complications; D010700:Phonetics; D011446:Prospective Studies; D019736:Prostheses and Implants; D012720:Severity of Illness Index; D013067:Speech Perception / Q000502:physiology*