Multicentre investigation on electrically evoked compound action potential and stapedius reflex: how do these objective measures relate to implant programming parameters?

OBJECTIVES: The aims of this study were to collect data on electrically evoked compound action potential (eCAP) and electrically evoked stapedius reflex thresholds (eSRT) in HiResolution(TM) cochlear implant (CI) users, and to explore the relationships between these objective measures and behavioural measures of comfort levels (M-levels). METHODS: A prospective study on newly implanted subjects was designed. The eCAP was measured intra-operatively and at first fitting through neural response imaging (NRI), using the SoundWave(TM) fitting software. The eSRT was measured intra-operatively by visual monitoring of the stapes, using both single-electrode stimulation and speech bursts (four electrodes stimulated at the same time). Measures of M-levels were performed according to standard clinical practice and collected at first fitting, 3 and 6 months of CI use. RESULTS: One hundred seventeen subjects from 14 centres, all implanted unilaterally with a HiResolution CII Bionic Ear(®) or HiRes 90K(®), were included in the study. Speech burst stimulation elicited a significantly higher eSRT success rate than single-electrode stimulation, 84 vs. 64% respectively. The NRI success rate was 81% intra-operatively, significantly increasing to 96% after 6 months. Fitting guidelines were defined on the basis of a single NRI measurement. Correlations, analysis of variance, and multiple regression analysis were applied to generate a predictive model for the M-levels. DISCUSSION: Useful insights were produced into the behaviour of objective measures according to time, electrode location, and fitting parameters. They may usefully assist in programming the CI when no reliable feedback is obtained through standard behavioural procedures.

Optimizing fitting in children using objective measures such as neural response imaging and electrically evoked stapedius reflex threshold.

OBJECTIVE: To study over time correlations between Compound Action Potential measured through Neural Response Imaging (NRI) and electrically Evoked Stapedius Reflex Thresholds (eSRT) and psychophysical measurements to develop guidelines for using those objective measures to optimize HiRes programs in patients implanted with Advanced Bionics CII-Bionic Ear or a HiRes90K cochlear implants. PATIENTS: Fifteen pediatric subjects, all implanted with a CII-Bionic Ear or a HiRes90K. INTERVENTIONS: NRI was measured on 4 electrodes intraoperatively at first fitting and after 3, 6, and 12 months of use. eSRT recordings were performed intraoperatively with SoundWave speech bursts. Subjects were fitted using the SoundWave defaults. Relationships between NRI thresholds (tNRI), eSRT, and most comfortable levels (M) are presented. MAIN OUTCOME MEASURES: Intraoperative eSRT, and intraoperative and postoperative tNRI at each fitting session. Auditory performance measured by Categories of Auditory Performance and Meaningful Auditory Integration Scale. RESULTS: First fitting Ms are 97% of intraoperative tNRI; stable Ms (12 months of implant use) are equal to 115% of 12 months' tNRI and to 76% of intraoperative eSRT on average across the electrode array with great intersubject variability. CONCLUSION: The results show that single-channel tNRI and eSRT values can be clinically useful for programming cochlear implants in children, although this should be done with caution as there is considerable interpatient variability.

Local anesthesia for middle ear surgery.

The adequacy of anesthesia and comfort during surgery was assessed for 100 consecutive patients undergoing middle ear surgery using local anesthesia, both by the patients themselves and by the surgeon. The possibility of inducing an iatrogenic facial weakness was also evaluated. Both the surgeon and the majority of patients were pleased with the quality of anesthesia and little adverse effects occurred as a consequence of local anesthesia itself.