Experimental Simulation of Clinical Borderline Situations in Temporal Bone Specimens After Ossiculoplasty.

OBJECTIVES: One reason for insufficient hearing improvement with a distinct air-bone gap after ossiculoplasty with implantation of partial or total ossicular replacement prostheses can be the dislocation or minimal shifting of the prosthesis. The aim of this study was the simulation of common clinical borderline situations with minimal shifting of the prosthesis in temporal bone specimens after ossiculoplasty. It was furthermore the goal to identify these specific situations through imaging by cone beam computed tomography (cbCT) and direct visual inspection using the operation microscope. Additionally, the functional status was evaluated using laser-Doppler vibrometry (LDV). DESIGN: We used a total of four temporal bone specimens for this study. A reconstruction with a partial ossicular replacement prostheses was performed in three specimens and with a total ossicular replacement prostheses in one specimen, with good initial acoustic properties. Subsequently, one specific type of prosthesis failure was simulated in each specimen, respectively, by minimally shifting, tilting, or bending the prostheses from their initial positions. These changes were introduced step-by-step until a borderline situation just short of complete acoustic decoupling was reached. Each step was examined using both LDV and cbCT and observed through the operation microscope. RESULTS: LDV was able to quantify the mechanic function of the ossicular chain after most of the manipulation steps by demonstrating the effect of any shifting of the prosthesis on the middle ear transfer function. However, in some situations, the middle ear transfer function was better with a visually more advanced failure of the prosthesis. In addition, cbCT showed most of the steps with excellent resolution and was able to delineate changes in soft tissue (e.g., cartilage covering). CONCLUSION: cbCT seems to be a promising imaging technique for middle ear problems. As cbCT and LDV exhibited slightly different advantages and disadvantages regarding the demonstration of borderline situations, the combination of both techniques allowed for a more precise evaluation of middle ear reconstructions. Knowledge of the specific characteristics of these methods and their possible combination might help otologists and otosurgeons to refine indications for revision surgery and improve their personal patient counseling.

Cochlear implantation for hearing rehabilitation in single-sided deafness after translabyrinthine vestibular schwannoma surgery.

The aim of the study was to investigate the option of cochlear implantation (CI) in resultant single-sided deafness associated with unilateral translabyrinthine resection of sporadic vestibular schwannoma (VS). This is a retrospective study performed at Tertiary Care Academic Centre. Following extensive counselling regarding the potential for delayed CI, translabyrinthine VS resection was performed and an intracochlear placeholder was inserted to allow later CI in 11 patients who showed intraoperative microscopic confirmation of preserved cochlear nerve anatomy. Follow-up magnetic resonance imaging (MRI) and promontory testing were performed 1 year after surgery to confirm the absence of VS recurrence and viable cochlea. Confirmed CI candidates underwent a second procedure where the placeholder was removed and the CI inserted (4/11). Preimplant unaided and CI-aided evaluations at 12 and 24 months were performed for subjective and objective hearing outcomes. Tinnitus suppression was also measured for implant on and off effects. Available audiological data for three patients demonstrated significant hearing benefits for 'speech from deaf/implanted side, noise from the normal-hearing side' in all three patients and localisation ability improved for 2/3 patients. Subjective findings presented similar results. For the two patients with preimplant tinnitus, complete suppression occurred during active CI. CI is beneficial for hearing rehabilitation and tinnitus reduction in SSD patients with remaining viable cochlear nerve after translabyrinthine VS surgery. Counselling on the risks of intracochlear placeholder insertion and the inherent limitations for ongoing MRI investigations of VS recurrence is essential.

Prospects and limitations of different registration modalities in electromagnetic ENT navigation.

The present study examined electromagnetic tracking technology for ENT navigation. Five different registration modalities were compared and navigation accuracy was assessed. Four skull models were individually fabricated with a three-dimensional printer, based on patients' computer tomography datasets. Individual silicone masks were fitted for skin and soft tissue simulation. Five registration modalities were examined: (1) invasive marker, (2) automatic, (3) surface matching (AccuMatch), (4) anatomic landmarks, and (5) oral splint registration. Overall navigation accuracy and accuracy on selected anatomic locations were assessed by targeting 26 titanium screws previously placed over the skull. Overall navigation accuracy differed significantly between all registration modalities. The target registration error was 0.94 ± 0.06 mm (quadratic mean ± standard deviation) for the invasive marker registration, 1.41 ± 0.04 mm for the automatic registration, 1.59 ± 0.14 mm for the surface matching registration, and 5.15 ± 0.66 mm (four landmarks) and 4.37 ± 0.73 mm (five landmarks) for the anatomic landmark registration. Oral splint registration proved itself to be inapplicable to this navigation system. Invasive marker registration was superior on most selected anatomic locations. However, on the ethmoid and sphenoid sinus the automatic registration process revealed significantly lower target registration error values. Only automatic and surface registration met the accuracy requirements for noninvasive registration. Particularly, the automatic image-to-world registration reaches target registration error values on the anterior skull base which are comparable with the gold standard of invasive screw registration.

Cochlear implantation in children with single-sided deafness: does aetiology and duration of deafness matter?

For adult patients with single-sided deafness (SSD), treatment with a cochlear implant (CI) is well established as an acceptable and beneficial hearing rehabilitation method administered routinely in clinical practice. In contrast, for children with SSD, CI has been applied less often to date, with the rationale to decide either on a case-by-case basis or under the realm of clinical research. The aim of our clinical study was to evaluate the longitudinal benefits of CI for a group of children diagnosed with SSD and to compare their outcomes with respect to patient characteristics. Evaluating a pool of paediatric SSD patients presenting for possible CI surgery revealed that the primary aetiology of deafness was congenital cochlear nerve deficiency. A subgroup of children meeting the CI candidacy criteria for the affected ear (the majority with acquired hearing loss) were enrolled in the study. Preliminary group results suggest substantial improvements in speech comprehension in noise and in the ability to localise sound, which was demonstrated through objective and subjective assessments after CI treatment for the group, with results varying from patient to patient. Our study shows a trend towards superior outcomes for children with acquired hearing loss and a shorter duration of hearing loss compared to congenitally deafened children who had a longer duration of SSD. This indicates an interactive influence of the age at onset, aetiology and duration of deafness upon the restoration of binaural integration and the overall benefits of sound stimulation to two ears after CI treatment. Continued longitudinal investigation of these children and further studies in larger groups may provide more guidance on the optimal timing of treatment for paediatric patients with acquired and congenital SSD.

Binaural integration of periodically alternating speech following cochlear implantation in subjects with profound sensorineural unilateral hearing loss.

In cochlear implant (CI) recipients with unilateral hearing loss (UHL) and normal hearing (NH) in the contralateral ear, the central auditory system receives signals of different auditory modalities, i.e. electrically via the CI ear as well as acoustically via the NH ear. The present study investigates binaural integration of bimodal stimulation in the central auditory system of 10 CI subjects with UHL by applying a modified version of the Rapidly Alternating Speech Perception (RASP) test to characterise speech recognition ability under monotic and dichotic listening arrangements. Subsequently, the results for each monotic and dichotic test condition were compared to quantify the binaural benefit from CI usage. The study results demonstrate significantly improved speech recognition under dichotic compared to monotic listening conditions, providing evidence that there is binaural integration of acoustically and electrically transmitted speech segments in the central nervous system at brainstem and cortical levels. In contrast to more commonly used tests of binaural integration, such as localisation, the RASP test provides the clinical option to investigate binaural integration involving structures at the cortical level.

European multi-centre study of the Nucleus Hybrid L24 cochlear implant.

OBJECTIVES: To investigate the preservation of residual hearing in subjects who received the Nucleus Hybrid L24 cochlear implant. To investigate the performance benefits up to one year post-implantation in terms of speech recognition, sound quality, and quality of life. DESIGN: Prospective, with sequential enrolment and within-subject comparisons. Post-operative performance using a Freedom Hybrid sound processor was compared with that of pre-operative hearing aids. STUDY SAMPLE: Sixty-six adult hearing-impaired subjects with bilateral severe-to-profound high frequency hearing loss. RESULTS: Group median increase in air-conduction thresholds in the implanted ear for test frequencies 125-1000 Hz was < 15 dB across the population; both immediately and one year post-operatively. Eighty-eight percent of subjects used the Hybrid processor at one year post-op. Sixty-five percent of subjects had significant gain in speech recognition in quiet, and 73% in noise (≥ 20 percentage points/2 dB SNR). Mean SSQ subscale scores were significantly improved (+ 1.2, + 1.3, + 1.8 points, p < 0.001), as was mean HUI3 score (+ 0.117, p < 0.01). Combining residual hearing with CI gave 22-26 %age points mean benefit in speech recognition scores over CI alone (p < 0.01). CONCLUSIONS: Useful residual hearing was conserved in 88% of subjects. Speech perception was significantly improved over preoperative hearing aids, as was sound quality and quality of life.

Device setting modifications for 3D flatpanel imaging in skull base surgery.

To evaluate the image quality and clinical implementation after setting modification of a three-dimensional isocentric C-arm fluoroscopic image intensifier system combined with a digital flatpanel detector as a new tool for sinus and petrous bone surgery. Image acquisition was performed using two cadaveric heads. Experimental design was oriented to the clinically sensible intraoperative setup. Different tube currents and orbital movements of the C-arm system were evaluated for image quality by three otolaryngological surgeons using predetermined landmarks. Modification of the X-ray intensity did not attain statistically significant values compared to the X-ray-intensity predetermined by producer (12.0-18.5 mA, p > 0.05) for either sinus or for petrous bone scans. Elliptical orbital movement resulted in significantly superior image quality than data sets acquired by circular orbital movement (3.194 vs. 2.809, p < 0.0001). New C-arm systems with 3D-capabiltity offer a promising tool for intraoperative near real-time image guidance. Image quality of the skull base can be improved significantly with optimized system settings.

The value of moderate dose escalation for re-irradiation of recurrent or second primary head-and-neck cancer.

BACKGROUND: Treatment for local and locoregional recurrence or second head-and-neck (H&N) cancers after previous radiotherapy is challenging, and re-irradiation carries a significantly increased risk for radiotherapy-related normal tissue toxicities and treatment failure due to a radioresistant tumor phenotype. Here, we analyzed re-irradiation management and outcomes in patients with recurrent or second primary H&N carcinoma using state-of-the-art diagnostic procedures and radiotherapy techniques. METHODS: Between 2010 and 2019, 48 patients with recurrent or second primary H&N carcinoma received re-radiotherapy at the University of Freiburg Medical Center and were included in this study. Overall survival (OS) and progression-free survival (PFS) were calculated with the Kaplan-Meier method, and univariate Cox-regression analyses were performed to assess the effects of clinico-pathological factors on treatment outcomes. Acute and chronic treatment-related toxicities were quantified using the Common Terminology Criteria for Adverse Events (CTCAE v4.03). RESULTS: Thirty-one patients (64.6%) received definitive and 17 (35.4%) adjuvant radiotherapy. Simultaneous chemotherapy was administered in 28 patients (58.3%) with cetuximab as the most commonly used systemic agent (n = 17, 60.7%). After a median time of 17 months (range 4 months to 176 months) between first and second radiotherapy, patients were re-irradiated with a median of 58.4 Gy and a treatment completion rate of 87.5% (n = 42). Median OS was 25 months with a 1-year OS amounting to 62.4%, and median PFS was 9 months with a 1-year PFS of 37.6%. Univariate analyses demonstrated that both a lower rT-status and a radiotherapy boost were associated with improved OS (p < 0.05). There was a trend towards superior OS for patients who received > 50 Gy (p = 0.091) and who completed the prescribed radiotherapy (p = 0.055). Five patients (10.4%) suffered from at least one grade 3 toxicities, while 9 patients (27.3%) experienced chronic higher-grade toxicities (≥ grade 3) with one (3.0%) grade 4 carotid blowout and one (3.0%) grade 4 osteoradionecrosis. CONCLUSION: Re-irradiation of recurrent or second primary H&N cancer with modern radiation techniques such as intensity-modulated radiotherapy resulted in promising survival rates with acceptable toxicities compared to historical cohorts. Increased re-irradiation doses, utilization of a radiotherapy boost and completion of the re-irradiation treatment were found to result in improved survival.

Radiotherapeutic management of cervical lymph node metastases from an unknown primary site - experiences from a large cohort treated with modern radiation techniques.

PURPOSE: To analyze management and outcomes following (chemo)radiation therapy in patients with cervical lymph node metastases from an unknown primary site (CCUP) in a large single-center cohort. METHODS: Between 2008 and 2019, 58 patients with CCUP were treated with (chemo)radiation therapy at the University of Freiburg Medical Center and were included in this analysis. Overall survival (OS), locoregional progression-free survival (PFS) and distant metastasis-free survival (DMFS) were calculated using the Kaplan-Meier method. The use of diagnostic procedures and their impact on oncological outcomes was analyzed by Cox regression, and treatment-related toxicities were quantified. RESULTS: Median follow-up was 29.9 months (range 4.6-121.9). Twenty-one patients (36.2%) received definitive RT, 35 (60.3%) underwent adjuvant RT, and 2 (3.4%) were treated for oligometastatic disease. Concurrent chemotherapy was prescribed in 40 patients (69.0%). 89.6% of patients completed the prescribed RT, and 65.0% completed the prescribed simultaneous chemotherapy. Locoregional recurrence was observed in 7 patients (12.1%) and distant metastases in 13 cases (22.4%). OS was 81,1, 64.9% and 56,6% after 1, 3 and 5 years, respectively. Univariate analysis of age, gender, extracapsular spread, tumor grading, neck dissection, diagnostic utilization of 18F-fluorodeoxyglucose positron-emission tomography and concomitant chemotherapy showed no effect on OS (p > 0.05 for all), while smoking was significantly associated with decreased survival (p < 0.05). There was a trend towards impaired OS for patients with advanced nodal status (pN3) (p = 0.07). Three patients (5.2%) experienced grade 3 radiation dermatitis, and 12 (22.4%) developed grade 3 and 1 (1.7%) grade 4 mucositis. CONCLUSIONS: RT of the panpharynx and cervical lymph nodes with concurrent chemotherapy in case of risk factors demonstrated good locoregional control, but the metachronous occurrence of distant metastases limited survival and must be further addressed.

Speech Recognition in Noise in Single-Sided Deaf Cochlear Implant Recipients Using Digital Remote Wireless Microphone Technology.

BACKGROUND: Previous research in cochlear implant (CI) recipients with bilateral severe-to-profound sensorineural hearing loss showed improvements in speech recognition in noise using remote wireless microphone systems. However, to our knowledge, no previous studies have addressed the benefit of these systems in CI recipients with single-sided deafness. PURPOSE: The objective of this study was to evaluate the potential improvement in speech recognition in noise for distant speakers in single-sided deaf (SSD) CI recipients obtained using the digital remote wireless microphone system, Roger. In addition, we evaluated the potential benefit in normal hearing (NH) participants gained by applying this system. RESEARCH DESIGN: Speech recognition in noise for a distant speaker in different conditions with and without Roger was evaluated with a two-way repeated-measures design in each group, SSD CI recipients, and NH participants. Post hoc analyses were conducted using pairwise comparison t-tests with Bonferroni correction. STUDY SAMPLE: Eleven adult SSD participants aided with CIs and eleven adult NH participants were included in this study. DATA COLLECTION AND ANALYSIS: All participants were assessed in 15 test conditions (5 listening conditions × 3 noise levels) each. The listening conditions for SSD CI recipients included the following: (I) only NH ear and CI turned off, (II) NH ear and CI (turned on), (III) NH ear and CI with Roger 14, (IV) NH ear with Roger Focus and CI, and (V) NH ear with Roger Focus and CI with Roger 14. For the NH participants, five corresponding listening conditions were chosen: (I) only better ear and weaker ear masked, (II) both ears, (III) better ear and weaker ear with Roger Focus, (IV) better ear with Roger Focus and weaker ear, and (V) both ears with Roger Focus. The speech level was fixed at 65 dB(A) at 1 meter from the speech-presenting loudspeaker, yielding a speech level of 56.5 dB(A) at the recipient's head. Noise levels were 55, 65, and 75 dB(A). Digitally altered noise recorded in school classrooms was used as competing noise. Speech recognition was measured in percent correct using the Oldenburg sentence test. RESULTS: In SSD CI recipients, a significant improvement in speech recognition was found for all listening conditions with Roger (III, IV, and V) versus all no-Roger conditions (I and II) at the higher noise levels (65 and 75 dB[A]). NH participants significantly benefited from the application of Roger in noise for higher levels, too. In both groups, no significant difference was detected between any of the different listening conditions at 55 dB(A) competing noise. There was also no significant difference between any of the Roger conditions III, IV, and V across all noise levels. CONCLUSIONS: The application of the advanced remote wireless microphone system, Roger, in SSD CI recipients provided significant benefits in speech recognition for distant speakers at higher noise levels. In NH participants, the application of Roger also produced a significant benefit in speech recognition in noise.

The benefits of sequential bilateral cochlear implantation for hearing-impaired children.

CONCLUSION: Sequential bilateral implantation offers listening advantages demonstrable on speech recognition in noise and for lateralization. Whilst the trend was for shorter inter-implant intervals and longer implant experience to positively impact binaural advantage, we observed no contraindications for binaural advantage. OBJECTIVE: To evaluate the benefits of sequential bilateral cochlear implantation over unilateral implantation in a multicentre study evaluating speech recognition in noise and lateralization of sound. SUBJECTS AND METHODS: Twenty children, implanted bilaterally in sequential procedures, had the following characteristics: they were native German-speaking, were3 years or older and had a minimum of 1 year inter-implant interval and had between 2 months and 4 years 7 months binaural listening experience. Binaural advantage was assessed including speech recognition in noise using the Regensburg modification of the Oldenburger Kinder-Reimtest (OLKI) and lateralization of broadband stimuli from three speakers. RESULTS: A significant binaural advantage of 37% was observed for speech recognition in noise. Binaural lateralization ability was statistically superior for the first and second implanted ear (p = 0.009, p = 0.001, respectively). Binaural experience was shown to correlate moderately with absolute binaural speech recognition scores, with binaural advantage for speech recognition and with binaural lateralization ability. The time interval between implants correlated in an inverse direction with binaural advantage for speech recognition.

Speech Perception in Quiet and Noise With an Off the Ear CI Processor Enabling Adaptive Microphone Directionality.

OBJECTIVE: To investigate the impact of the wearing position of an off-the-ear-processor (OTE) on speech perception in quiet and noise. PATIENTS: The study group consisted of 16 adult subjects with bilateral severe-to-profound sensorineural hearing loss, 2 of them unilaterally, and 14 bilaterally provided with cochlear implants. MAIN OUTCOME MEASURES: Speech perception in quiet and noise was measured for frontal presentation with the recipients behind-the-ear processor CP810 or CP910 and the OTE processor Kanso (Cochlear Limited, Sydney, Australia). Additionally, speech performance in noise with the OTE for spatially separated signal and noise sources was assessed. RESULTS: The recipients showed monosyllabic word recognition scores in quiet between 65 and 95% and speech reception thresholds in noise between 2.4 and -5.5 dB SNR with the OTE. For frontal presentation of speech and noise, application of the adaptive directional microphone (Beam) yielded a slight median decrement of 0.6 dB for the speech reception threshold compared with standard directionality. However, huge median improvements, ranging from -3.7 to -11.6 dB, for the three tested conditions with spatially separated sources (S0NIL, S0NCL, S0N180) were observed. CONCLUSION: The beamforming algorithm in the investigated OTE processor provides similar benefits as described in previous studies for behind-the-ear processors in conditions with spatially separated speech and noise sources. Adaptive microphone directionality can be successfully implemented in an OTE processor. The OTE processor's potential to increase usability, comfort, and cosmetics might not be compromised by a deterioration of speech performance.

Navigation accuracy after automatic- and hybrid-surface registration in sinus and skull base surgery.

OBJECTIVE: Computer-aided-surgery in ENT surgery is mainly used for sinus surgery but navigation accuracy still reaches its limits for skull base procedures. Knowledge of navigation accuracy in distinct anatomical regions is therefore mandatory. This study examined whether navigation accuracy can be improved in specific anatomical localizations by using hybrid registration technique. STUDY DESIGN: Experimental phantom study. SETTING: Operating room. SUBJECTS AND METHODS: The gold standard of screw registration was compared with automatic LED-mask-registration alone, and in combination with additional surface matching. 3D-printer-based skull models with individual fabricated silicone skin were used for the experiments. Overall navigation accuracy considering 26 target fiducials distributed over each skull was measured as well as the accuracy on selected anatomic localizations. RESULTS: Overall navigation accuracy was <1.0 mm in all cases, showing the significantly lowest values after screw registration (0.66 ± 0.08 mm), followed by hybrid registration (0.83± 0.08 mm), and sole mask registration (0.92 ± 0.13 mm).On selected anatomic localizations screw registration was significantly superior on the sphenoid sinus and on the internal auditory canal. However, mask registration showed significantly better accuracy results on the midface. Navigation accuracy on skull base localizations could be significantly improved by the combination of mask registration and additional surface matching. CONCLUSION: Overall navigation accuracy gives no sufficient information regarding navigation accuracy in a distinct anatomic area. The non-invasive LED-mask-registration proved to be an alternative in clinical routine showing best accuracy results on the midface. For challenging skull base procedures a hybrid registration technique is recommendable which improves navigation accuracy significantly in this operating field. Invasive registration procedures are reserved for selected challenging skull base operations where the required high precision warrants the invasiveness.

Perception of Interaural Phase Differences With Envelope and Fine Structure Coding Strategies in Bilateral Cochlear Implant Users.

The ability to detect a target signal masked by noise is improved in normal-hearing listeners when interaural phase differences (IPDs) between the ear signals exist either in the masker or in the signal. To improve binaural hearing in bilaterally implanted cochlear implant (BiCI) users, a coding strategy providing the best possible access to IPD is highly desirable. In this study, we compared two coding strategies in BiCI users provided with CI systems from MED-EL (Innsbruck, Austria). The CI systems were bilaterally programmed either with the fine structure processing strategy FS4 or with the constant rate strategy high definition continuous interleaved sampling (HDCIS). Familiarization periods between 6 and 12 weeks were considered. The effect of IPD was measured in two types of experiments: (a) IPD detection thresholds with tonal signals addressing mainly one apical interaural electrode pair and (b) with speech in noise in terms of binaural speech intelligibility level differences (BILD) addressing multiple electrodes bilaterally. The results in (a) showed improved IPD detection thresholds with FS4 compared with HDCIS in four out of the seven BiCI users. In contrast, 12 BiCI users in (b) showed similar BILD with FS4 (0.6 ± 1.9 dB) and HDCIS (0.5 ± 2.0 dB). However, no correlation between results in (a) and (b) both obtained with FS4 was found. In conclusion, the degree of IPD sensitivity determined on an apical interaural electrode pair was not an indicator for BILD based on bilateral multielectrode stimulation.

Erythropoietin to treat head and neck cancer patients with anaemia undergoing radiotherapy: randomised, double-blind, placebo-controlled trial.

BACKGROUND: Anaemia is associated with poor cancer control, particularly in patients undergoing radiotherapy. We investigated whether anaemia correction with epoetin beta could improve outcome of curative radiotherapy among patients with head and neck cancer. METHODS: We did a multicentre, double-blind, randomised, placebo-controlled trial in 351 patients (haemoglobin <120 g/L in women or <130 g/L in men) with carcinoma of the oral cavity, oropharynx, hypopharynx, or larynx. Patients received curative radiotherapy at 60 Gy for completely (R0) and histologically incomplete (R1) resected disease, or 70 Gy for macroscopically incompletely resected (R2) advanced disease (T3, T4, or nodal involvement) or for primary definitive treatment. All patients were assigned to subcutaneous placebo (n=171) or epoetin beta 300 IU/kg (n=180) three times weekly, from 10-14 days before and continuing throughout radiotherapy. The primary endpoint was locoregional progression-free survival. We assessed also time to locoregional progression and survival. Analysis was by intention to treat. FINDINGS: 148 (82%) patients given epoetin beta achieved haemoglobin concentrations higher than 140 g/L (women) or 150 g/L (men) compared with 26 (15%) given placebo. However, locoregional progression-free survival was poorer with epoetin beta than with placebo (adjusted relative risk 1.62 [95% CI 1.22-2.14]; p=0.0008). For locoregional progression the relative risk was 1.69 (1.16-2.47, p=0.007) and for survival was 1.39 (1.05-1.84, p=0.02). INTERPRETATION: Epoetin beta corrects anaemia but does not improve cancer control or survival. Disease control might even be impaired. Patients receiving curative cancer treatment and given erythropoietin should be studied in carefully controlled trials.

Quality control after cochlear implant surgery by means of rotational tomography.

OBJECTIVE: To investigate the intracochlear electrode position in using rotational tomography in adult cochlear implant patients. STUDY DESIGN: Retrospective. SETTING: Tertiary referral center. PATIENTS: Eighteen adult patients being implanted either with a Nucleus straight electrode array or a Contour electrode with a total of 22 implanted ears. Preoperative computed tomography had been without evidence for obliteration, ossification, or malformation of the cochlea. INTERVENTION: Rotational tomography. MAIN OUTCOME MEASURES: The intracochlear electrode position was evaluated with regard to scala tympani, scala vestibuli, and a dislocation from one scala to the other. The intraoperative procedure was compared with the electrode position by analyzing the operating reports. RESULTS: Preliminary results indicate, respectively, that there is a higher incidence of intracochlear trauma in using the Contour electrode array than expected with a more frequent dislocation of electrode arrays from scala tympani to scala vestibuli and that there is a higher rate of scala vestibuli insertions. CONCLUSIONS: The impact of these findings may influence further developments of electrode arrays as well as surgical techniques for implantation.

Preservation of residual hearing with cochlear implantation: how and why.

CONCLUSIONS: Hearing may be conserved in adults after implantation with the Nucleus Contour Advance perimodiolar electrode array. The degree of hearing preservation and the maximum insertion depth of the electrode array can vary considerably despite a defined surgical protocol. Residual hearing combined with electrical stimulation in the same ear can provide additional benefits even for conventional candidates for cochlear implantation. OBJECTIVES: We present preliminary results from a prospective multicentre study investigating the conservation of residual hearing after implantation with a standard-length Nucleus Contour Advance perimodiolar electrode array and the benefits of combined electrical and acoustic stimulation. MATERIAL AND METHODS: The subjects were 12 adult candidates for cochlear implantation recruited according to national selection criteria. A "soft" surgery protocol was defined, as follows: 1-1.2-mm cochleostomy hole anterior and inferior to the round window; Nucleus Contour Advance electrode array inserted using the "Advance-off-stylet" technique; and insertion depth controlled by means of three square marker ribs left outside the cochleostomy hole. These procedures had been shown to reduce insertion forces in temporal bone preparations. Variations in surgical techniques were monitored using a questionnaire. Pure-tone thresholds were measured pre- and postoperatively. Patients who still retained thresholds <90 dB HL for frequencies up to 500 Hz were re-fitted with an in-the-ear (ITE) hearing aid. Word recognition was tested in quiet and sentence perception in noise for the cochlear implant alone and in combination with an ipsilateral hearing aid. RESULTS: Hearing threshold level data were available for 12 patients recruited from 6 of the centres. Median increases in hearing threshold levels were 23, 27 and 33 dB for the frequencies 125, 250 and 500 Hz, respectively. These median increases include the data for two patients who had total loss of residual hearing due to difficulties encountered during surgery. "Cochlear view" X-ray images indicated that the depth of insertion varied between 300 and 430 degrees, despite modest variations in the length of the electrode inserted (17-19 mm). The insertion angle had some influence on the preservation of residual hearing at frequencies of 250-500 Hz. Six of the 12 patients retained sufficient hearing for effective use of an ipsilateral ITE hearing aid (< or = 80 dB HL at 125 and 250 Hz; < or = 90 dB HL at 500 Hz). Word recognition scores in quiet were improved from 10% to 30% with the cochlear implant plus ipsilateral hearing aid in 3 patients who had at least 3 months postoperative experience. Signal:noise ratio thresholds for sentence recognition were improved by up to 3 dB. Patients reported that they experienced greatly improved sound quality and preferred to use the two devices together.