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Objectives/hypothesis: To evaluate the hearing performance with cochlear implants (CIs) in patients who were 70 years or older at the time of implantation (geriatric patients) and compare it with the performance in younger adults., Study Design: Individual, retrospective, cohort study., Methods: A cohort of 1,005 postlingually deafened adults was selected for this study. According to their age at the time of cochlear implantation, patients were divided into four age groups: group 1, 18 to 39 years; group 2, 40 to 59 years; group 3, 60 to 69 years; and group 4, 70 years and older). The test battery was composed of four standard German speech tests: Freiburger Monosyllabic Test, Speech Tracking Test, and Hochmair-Schulz-Moser (HSM) Sentence Test in quiet and in 10 dB noise., Results: Geriatric patients showed a similar learning curve as the younger adults in the first 2 years after implantation. The direct comparison of speech perception in the Freiburger Monosyllabic Test, Speech Tracking Test, and HSM Test in quiet revealed no differences between the average performance of the geriatric patients and younger adults. However, in the HSM Test in noise, the performance of the geriatric group was significantly lower than the younger adults., Conclusions: Geriatric CI patients have a similar learning curve to younger adults, and in speech tests in quiet they show a comparable performance. However, their performance is significantly lower in noisy surroundings. This may be due to the central presbycusis in patients older than 70 years and should be taken into account in postoperative fitting of these patients. Further prospective studies are required to evaluate the role of special rehabilitation methods and cognitive training to improve the speech perception in noise in geriatric CI patients., (Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.)

Objectives/hypothesis: To evaluate the effect of technological advances in the past 20 years on the hearing performance of a large cohort of adult cochlear implant (CI) patients., Study Design: Individual, retrospective, cohort study., Methods: According to technological developments in electrode design and speech-processing strategies, we defined five virtual intervals on the time scale between 1984 and 2008. A cohort of 1,005 postlingually deafened adults was selected for this study, and their hearing performance with a CI was evaluated retrospectively according to these five technological intervals. The test battery was composed of four standard German speech tests: Freiburger monosyllabic test, speech tracking test, Hochmair-Schulz-Moser (HSM) sentence test in quiet, and HSM sentence test in 10 dB noise., Results: The direct comparison of the speech perception in postlingually deafened adults, who were implanted during different technological periods, reveals an obvious improvement in the speech perception in patients who benefited from the recent electrode designs and speech-processing strategies. The major influence of technological advances on CI performance seems to be on speech perception in noise., Conclusions: Better speech perception in noisy surroundings is strong proof for demonstrating the success rate of new electrode designs and speech-processing strategies. Standard (internationally comparable) speech tests in noise should become an obligatory part of the postoperative test battery for adult CI patients., (Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.)

We used multifrequency tympanometry to provide middle ear mechanics after implantation of different implantable hearing aids. A total of 34 patients were included in the investigation; 19 of them were fitted with the Otologics system and 15 with the MED-EL Vibrant Soundbridge system. With the Otologics recipients, measurements were made preoperatively and both two months and at least 12 months postoperatively. Measurements involving the MED-EL patients were taken at least 12 months postoperatively. For all measurements, the non-implanted contralateral side was used as a control. Preoperatively, the resonance frequency of the Otologics patients was 904.3 +/- 218.2 Hz for the implanted side and 907.1 +/- 161.8 Hz for the non-implanted side. Postoperatively, a significant increase (p < 0.01) compared with the preoperative value and the control side was observed after two months: 1111.3 +/- 234.7 Hz, as opposed to 823.8 +/- 274.5 Hz on the contralateral side. After 12 months, the resonance point was restored to approximately the preoperatively measured values: 975 +/- 55.3 Hz (implanted side) and 901.3 +/- 207.1 (control side). The resonance frequency in the Symphonix patients, as measured after at least 12 months (on average, 35 months), was 1006.3 +/- 269.5 Hz on the non-implanted side and 900.1 +/- 249.3 Hz on the implanted side. It is apparent that the resonance frequency on the implanted side was higher than on the control side, although the difference was not significant (p = 0.496). Monitoring following the implantation of active hearing systems is therefore recommended in order that conclusions can be drawn regarding the adequacy of the coupling of the actuation driver to the ossicular chain.

The auditory midbrain implant (AMI), which is designed for stimulation of the inferior colliculus (IC), is now in clinical trials. The AMI consists of a single shank array (20 contacts) and uses a stimulation strategy originally designed for cochlear implants since it is already approved for human use and we do not yet know how to optimally activate the auditory midbrain. The goal of this study was to investigate the effects of different pulse rates and phase durations on loudness and pitch percepts because these parameters are required to implement the AMI stimulation strategy. Although each patient was implanted into a different region (i.e. lateral lemniscus, central nucleus of IC, dorsal cortex of IC), they generally exhibited similar threshold versus phase duration, threshold versus pulse rate, and pitch versus pulse rate curves. In particular, stimulation with 100 mus/phase, 250 pulse per second (pps) pulse trains achieved an optimal balance among safety, energy, and current threshold requirements while avoiding rate pitch effects. However, we observed large differences across patients in loudness adaptation to continuous pulse stimulation over long time scales. One patient (implanted in dorsal cortex of IC) even experienced complete loudness decay and elevation of thresholds with daily stimulation. Comparing these results with those of cochlear implant and auditory brainstem implant patients, it appears that stimulation of higher order neurons exhibits less and even no loudness summation for higher rate stimuli and greater current leakage for longer phase durations than that of cochlear neurons. The fact that all midbrain regions we stimulated, which includes three distinctly different nuclei, exhibited similar loudness summation effects (i.e. none for pulse rates above 250 pps) suggests a possible shift in some coding properties that is affected more by which stage along the auditory pathway rather than the types of neurons are being stimulated. However, loudness adaptation occurs at multiple stages from the cochlea up to the midbrain.

Objective: High-precision intraoperative navigation using high-resolution flat-panel volume computed tomography makes feasible the possibility of minimally invasive cochlear implant surgery, including cochleostomy. Conventional cochlear implant surgery is typically performed via mastoidectomy with facial recess to identify and avoid damage to vital anatomic landmarks. To accomplish this procedure via a minimally invasive approach--without performing mastoidectomy--in a precise fashion, image-guided technology is necessary. With such an approach, surgical time and expertise may be reduced, and hearing preservation may be improved., Interventions: Flat-panel volume computed tomography was used to scan 4 human temporal bones. A drilling channel was planned preoperatively from the mastoid surface to the round window niche, providing a margin of safety to all functional important structures (e.g., facial nerve, chorda tympani, incus)., Main Outcome Measures: Postoperatively, computed tomographic imaging and conventional surgical exploration of the drilled route to the cochlea were performed., Results: All 4 specimens showed a cochleostomy located at the scala tympani anterior inferior to the round window. The chorda tympani was damaged in 1 specimen--this was preoperatively planned as a narrow facial recess was encountered., Conclusion: Using flat-panel volume computed tomography for image-guided surgical navigation, we were able to perform minimally invasive cochlear implant surgery defined as a narrow, single-channel mastoidotomy with cochleostomy. Although this finding is preliminary, it is technologically achievable.

Background: The accuracy of navigation systems can be improved significantly by using high-resolution flat panel-based Volume Computed Tomography (fpVCT) so that new surgical therapeutic concepts become feasible. A navigation-guided minimally-invasive cochleostomy places highest requirements on the accuracy of intraoperative navigation., Methods: A flat-panel Volume Computed Tomograph (fpVCT) was used to scan four human temporal bones. The isometric voxel size was 200 microm. The preoperative planning was used to define an optimized drilling channel from the mastoid surface to the round window niche and the scala tympani providing a safety margin to critical anatomical structures such as facial nerve, chorda tympani, sigmoid sinus and posterior wall of auditory canal. The canal was drilled hand-operated with a navigated drill following the previously planned trajectory. Afterwards the drilled canal was imaged by fpVCT. Conventional dissection including mastoidectomy and posterior tympanotomy assured correct localization of the cochleostomy., Results: Path planning took an average of 54 minutes (range 35-85 minutes). Installation took an average of 16 minutes (range 14-19 minutes). The drilling procedure itself took an average of 7.75 min (range 5-12 minutes.) The RMSE-values varied between 0.1 and 0.2 mm (Table 1). All four specimens showed a cochleostomy located at the scala tympani anterior inferior to the round window. The chorda tympani was damaged in one specimen--this was preoperatively planned as a narrow facial recess was encountered. The time needed for planning and system-installation could be reduced continuously., Conclusions: This feasibility study demonstrates that using current image-guided surgery technology in combination with fpVCT allows drilling of a minimally invasive channel to the cochlea with loco typico cochleostomy. The necessary accuracy of intraoperative navigation can be achieved by use of fpVCT (technical accuracy between 0.1 and 0.2 mm). Our results demonstrate the feasibility of a navigation-guided minimally-invasive cochleostomy loco typico. While we are enthused by this preliminary work, we recognize the barriers which exist in translation to clinical application. These include surgical issues (e.g. control of unexpected bleeding) and electrode issues (e.g. development of insertion tools).

Hypothesis: Perimodiolar intracochlear electrodes with contacts facing towards the modiolus have limited current flow towards the outer wall of the cochlea and therefore, may reduce the occurrence of facial nerve stimulation (FN) in cochlear implant subjects., Background: Facial nerve stimulation is a well-known complication in cochlear implant treatment especially in the group of subjects with otosclerosis. The possible explanation of this side effect is a change of the electrical properties of the otosclerotic bone leading to leakage current and resulting in facial nerve stimulation., Methods: Four CI subjects who had been implanted with a Nucleus Mini22 device with a Nucleus Straight electrode between 9 to 12 years ago suffered from severe FN stimulation. Electrode contacts had to be switched off so that they could only use 4, 11, 13, and 15 electrodes of their usual set of 22. The switch off resulted in deteriorating speech understanding over time. Therefore, all subjects were reimplanted with a Nucleus 24R device with a Contour electrode. Preoperatively, the threshold of FN stimulation was obtained on all electrodes subjectively. Intraoperatively, FN stimulation thresholds were measured objectively with both, the old and the new device and were compared. NRT and SRT thresholds were also obtained with the reimplanted device to assure effective electrical stimulation of the auditory nerve., Results: In all four cases the postoperative fitting demonstrated no FN stimulation on all electrodes up to maximum comfortable level. The insertion of the Contour electrode array was complete in three cases, in one case the array could only be inserted partially similarly to the situation before the reimplantation. Speech perception tests showed a significant improvement in all subjects with the new device., Conclusion: Electrodes with modiolar facing contacts and perimodiolar position like the Nucleus Contour electrode reduce the possibility of facial nerve stimulation significantly due to more focused electrical stimulation.