Influence of stimulus presentation rate on intraoperative ECAP thresholds in cochlear implant users.

OBJECTIVE: The objective is to evaluate the influence of the presentation rate on intraoperative ECAP thresholds in cochlear implant users. DESIGN: The design was data on the ECAP thresholds (t-NRT) as well as the behavioural T- and C-levels have been collected in CI patients of a quaternary otologic referral centre. Measurements of the tNRT thresholds were performed intraoperatively for 250 Hz and 80 Hz presentation rates and correlated to the stabilised T- and C-levels measured at the 5th fitting session, 4-6 months after surgery. STUDY SAMPLE: There was a study sample of 35 consecutive CI patients. All patients were users of the Nucleus 24RECA (Freedom) or Nucleus CI512 cochlear implants with the Contour Advance-of-Stylet electrode. RESULTS: The result showed that the t-NRT thresholds were higher for the 250 Hz pulse rate typically used during the intraoperative stimulation under general anaesthesia than for the 80 Hz rate used typically during the postoperative fitting sessions. This difference was more pronounced for the basal electrodes where it exceeded 10 current levels (CL). Pearson's correlation coefficients between the t-NRT-measurements and the stabilised T- and C-levels r ranged between 0.34 and 0.47. CONCLUSION: In conclusion, the magnitude of the ECAP thresholds (t-NRT) recorded intraoperatively depends significantly on the stimulus presentation rate.

Postimplantation changes of electrophysiological parameters in patients with cochlear implants.

OBJECTIVE: To evaluate the postoperative changes of the basic electrophysiological and psychophysical parameters in cochlear implant (CI) patients: the impedance of the electrode contacts, the electrically-evoked compound action potential (ECAP) thresholds and the T/C levels. STUDY DESIGN AND SETTING: Retrospective case review in a quaternary otologic referral centre. MATERIALS AND METHODS: Data on the impedance of the electrode contacts, the ECAP thresholds and the T/C levels were collected in 20 consecutive CI patients divided into 2 groups. Group 1 comprised 10 prelingually deaf children implanted before the age of 18 months, and group 2 comprised 10 postlingually deaf adults (average age of 58 years). All patients were users of the Nucleus 24RECA (Freedom, Contour advance off-stylet electrode) CI. RESULTS AND CONCLUSIONS: (1) The mid-portion and the apical electrodes showed a decrease in the impedance values between the 1st and the 6th postoperative months and stabilization in the later course. Impedance of the most basal electrodes grew during the first postoperative months and stabilized later on, but remained higher than the impedance of the mid-portion and the apical electrodes. (2) The neural response telemetry threshold values tended to decrease within the first 3 months after surgery to reach a plateau afterwards. (3) The behavioural threshold levels remained generally stable, except for the basal electrodes where a decrease could be observed. The hearing comfort levels showed an increase during the first 6 months of the implant use and remained stable afterwards.

Cochlear Implantation in Single-Sided Deafness and Asymmetric Hearing Loss: 12 Months Follow-up Results of a European Multicenter Evaluation.

People with single-sided deafness (SSD) or asymmetric hearing loss (AHL) have particular difficulty understanding speech in noisy listening situations and in sound localization. The objective of this multicenter study is to evaluate the effect of a cochlear implant (CI) in adults with single-sided deafness (SSD) or asymmetric hearing loss (AHL), particularly regarding sound localization and speech intelligibility with additional interest in electric-acoustic pitch matching. A prospective longitudinal study at 7 European tertiary referral centers was conducted including 19 SSD and 16 AHL subjects undergoing cochlear implantation. Sound localization accuracy was investigated in terms of root mean square error and signed bias before and after implantation. Speech recognition in quiet and speech reception thresholds in noise for several spatial configurations were assessed preoperatively and at several post-activation time points. Pitch perception with CI was tracked using pitch matching. Data up to 12 months post activation were collected. In both SSD and AHL subjects, CI significantly improved sound localization for sound sources on the implant side, and thus overall sound localization. Speech recognition in quiet with the implant ear improved significantly. In noise, a significant head shadow effect was found for SSD subjects only. However, the evaluation of AHL subjects was limited by the small sample size. No uniform development of pitch perception with the implant ear was observed. The benefits shown in this study confirm and expand the existing body of evidence for the effectiveness of CI in SSD and AHL. Particularly, improved localization was shown to result from increased localization accuracy on the implant side.

Audiological outcomes after cochlear implantation in a patient with Melnick-Needles syndrome.

This is the first report on a successful cochlear implantation in a patient suffering from the Melnick-Needles syndrome (MNS). This case study presents an MNS patient with peri-lingual profound hearing loss, implanted at the age of 38. MNS is a rare X-linked genetic bony dysplasia characterized by skeletal and facial abnormalities. Various soft tissue defects and hearing loss have also been described in MNS; however, this is the first report on bilateral inner ear malformation as a phenotypic feature of MNS. At 15 months after cochlear implantation there was 91% speech identification in open-set monosyllabic CVC test. In noise, the results obtained with the CVC lists were the following: 67% for SNR +15 dB, 52% for SNR +10 dB and 36% for SNR +5 dB. The patient is able to discriminate the differences in all 22 phoneme pairs in the APE phoneme discrimination test. This allows the patient to obtain significant communication ability through the telephone. Conclusions are as follows. 1) Bilateral inner ear malformations and bilateral profound perceptive hearing loss possibly belong to the phenotypic features of MNS. 2) Cochlear implant is potentially a good functional solution for patients suffering from MNS and profound hearing loss. 3) Exceptionally good results on auditory performance have been obtained in this MNS patient with peri-lingual profound hearing loss and almost 36 years duration of deafness.