Electrode Selection and Speech Understanding in Patients With Auditory Brainstem Implants.

OBJECTIVES: The objective of this study was to evaluate whether speech understanding in auditory brainstem implant (ABI) users who have a tumor pathology could be improved by the selection of a subset of electrodes that were appropriately pitch ranked and distinguishable. It was hypothesized that disordered pitch or spectral percepts and channel interactions may contribute significantly to the poor outcomes in most ABI users. DESIGN: A single-subject design was used with five participants. Pitch ranking information for all electrodes in the patients' clinic maps was obtained using a pitch ranking task and previous pitch ranking information from clinic sessions. A multidimensional scaling task was used to evaluate the stimulus space evoked by stimuli on the same set of electrodes. From this information, a subset of four to six electrodes was chosen and a new map was created, using just this subset, that the subjects took home for 1 month's experience. Closed-set consonant and vowel perception and sentences in quiet were tested at three sessions: with the clinic map before the test map was given, after 1 month with the test map, and after an additional 2 weeks with their clinic map. RESULTS: The results of the pitch ranking and multidimensional scaling procedures confirmed that the ABI users did not have a well-ordered set of percepts related to electrode position, thus supporting the proposal that difficulty in processing of spectral information may contribute to poor speech understanding. However, none of the subjects benefited from a map that reduced the stimulation electrode set to a smaller number of electrodes that were well ordered in place pitch. CONCLUSIONS: Although poor spectral processing may contribute to poor understanding in ABI users, it is not likely to be the sole contributor to poor outcomes.

Cochlear implantation in children with auditory neuropathy spectrum disorders.

AIM: To present the outcomes of cochlear implantation (CI) in children with auditory neuropathy spectrum disorders (ANSD). MATERIALS AND METHODS: The pre- and post-CI hearing outcomes in children with ANSD were retrospectively evaluated. Performance was assessed with categories of auditory performance (CAP) and the Manchester spoken language development scale (MSLDS). RESULTS: Full data were available in 27 implanted children with ANSD with average age at implantation 35.4 months (range 19-68 months). Nine children were implanted bilaterally, while 13 were bimodal. The pre-CI CAP and MSLDS scores were 2.5 (range 0-5) and 2.5 (range 0-6), while the post-CI scores 5.8 (range 2-9) and 7.7 (range 3-10), respectively. CONCLUSIONS: Although the outcome of CI in children with ANSD might vary, it is favourable in most of the cases. CI seems a justified hearing rehabilitation option for children with ANSD and limited benefits from conventional hearing aids.