In vitro and in vivo pharmacokinetic study of a dexamethasone-releasing silicone for cochlear implants.

Cochlear implants have been widely used for patients with profound hearing loss and partial deafness. Residual low-frequency hearing, however, may deteriorate due to insertion trauma and tissue response around the electrode array. The present study investigated in vitro and in vivo release of dexamethasone from silicone used for cochlear implant electrode carriers. The in vitro experiment involved an apparatus simulating the inner ear fluid environment in humans. Release from two sizes of silicone films (200 µm × 1 mm × 10 mm and 500 µm × 1 mm × 10 mm), each loaded with 2 % dexamethasone, and was measured for 24 weeks. In the in vivo experiment, silicone rods loaded with 2 or 10 % dexamethasone, respectively, were implanted into the scala tympani of guinea pigs. Perilymph concentrations were measured during the first week after implantation. The results showed that dexamethasone was released from the silicone in a sustained manner. After a burst release, perilymph concentration was similar for silicone incorporated with 2 and 10 % dexamethasone, respectively. The similar pharmacokinetic profile was found in the in vitro experiment. The period of sustained drug delivery was maintained for 20 weeks in vitro and for 1 week in vivo. The results of the present study suggest that drugs like dexamethasone are released in a controlled manner from silicon electrode carriers of cochlear implants. Further studies will identify optimal release profiles for the use with cochlear implants to improve their safety and long-term performance.

Effects of a dexamethasone-releasing implant on cochleae: A functional, morphological and pharmacokinetic study.

AIM: This study evaluated the impact of a dexamethasone-releasing silicone implant on hearing function preservation, cochlear morphology and perilymph pharmacokinetics after cochlear implantation. METHODS: Guinea pigs were implanted unilaterally with silicone rods containing either 2% dexamethasone (DEXA group, n = 18) or no dexamethasone (control group, n = 17). Auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAEs) were measured preoperatively and over 6 months postoperatively. Cochlear histology using standard hematoxylin and eosin (H&E) staining and tumor necrosis factor (TNF)-alpha staining was performed 1 month postoperatively. Twenty-two guinea pigs were involved in the pharmacokinetic study, and real-time drug concentrations in perilymph were investigated using high-performance liquid chromatography (HPLC). The Mann-Whitney U test (1-tailed) was used for statistical analyses. RESULTS: ABR and DPOAE testing demonstrated decreased hearing function immediately postoperatively followed by a progressive hearing loss within the first day postoperatively. There was almost no observable hearing improvement in the control group from 1 week to 6 months postoperatively, but hearing levels in the DEXA group improved gradually from 1 week to 12 weeks. Hearing loss in the DEXA and control group was 5.0 ± 3.4 dB and 21.7 ± 5.3 dB, respectively at a 16-kHz stimulus frequency 6 months postoperatively. The difference in threshold shifts was present throughout all measured frequencies, and it was significant at 4-24 kHz. The morphological study revealed new fibrosis formation in the scala tympani, which encapsulated the implanted electrode. TNF-alpha positive staining in the cochleae of the DEXA group was less evident than the control group. The pharmacokinetic study revealed a peak perilymph concentration 30 min postoperatively and sustained dexamethasone release at least 1 week postoperatively. CONCLUSION: Cochlear implants that incorporate dexamethasone can release drug chronically in the inner ear and induce significant long-term recovery and preservation of auditory function after implantation.

Optimization of the Frequency Ratios for DPOAEs and Its Application in the Measurement of Normal and Hearing Loss Ears / 听力学及言语疾病杂志

Objective To optimize the f2/f1 frequency ratios for DPOAEs and to evaluate the effects in the measurement of normal and hearing loss ears .Methods Seven of 18 guinea pigs were randomly selected and DPOAE measurements were performed ,using the L2 stimulus levels of 25 ,40 and 60 dB SPL ,L1 = 0 .46 L2 +41 dB SPL .The stimulus frequency f2 ranged from 1 to 16 kHz ,and the f2/f1 ratio ranged from 1 .1 to 1 .5 .The maxi-mum DPOAEs (Ldp ) were determined and the corresponding f2/f1 ratios were used as the parameters for DPOAE measurement .The inner ears of all the 18 animals were operated unilaterally .One week later ,They were divided in-to 2 groups(A and B) and DPOAE measurements were performed with the optimal f2/f1 ratio in group A and with the fixed f2/f1 ratio in group B separately .Results When f2 ranged from 1~2 kHz ,the optimal f2/f1 ratio rose from 1 .25 to 1 .44 ;then it reduced to 1 .17 when f2 was 8 kHz .When f2 ranged from 8~16 kHz ,the optimal f2/f1 ratio rose slightly to 1 .24 .Compared with the fixed f2/f1 ratio in group B ,using the optimal f2/f1 ratio in group A could determine more precise DPOAEs in the operated ears ,especially in the f2 range from 1~4 kHz .Conclusion Using optimal f2/f1 ratios can promote the sensibility for the DPOAE measurements .

A safety evaluation of dexamethasone-releasing cochlear implants: comparative study on the risk of otogenic meningitis after implantation.

CONCLUSION: Dexamethasone released from a cochlear implant seems not to enhance the risk for postoperative infections. OBJECTIVE: Dexamethasone has a positive impact on hearing preservation for electric acoustic stimulation (EAS). Due to their antiproliferative and immunosuppressive properties, steroids may enhance the risk of postoperative infections. A comparative study was performed to evaluate the risk of pneumococcal meningitis after implantation of dexamethasone-eluting cochlear implants. METHODS: Thirty guinea pigs were implanted with non-eluting (n = 15) or dexamethasone-eluting (n = 15) cochlear implant electrode dummies. After 5 weeks, animals were exposed to a virulent strain of Streptococcus pneumoniae. The two groups were compared based on the meningitis rate. Animals were observed for 5 days for signs of meningitis. Meningitis was verified by clinical outcome as well as by pleocytosis and presence of bacteria in cerebrospinal fluid. Results were confirmed by histological examination of brains and cochleae, clinical findings and culture. RESULTS: There was no significant difference in meningitis risk between the two groups. In the group with non-eluting implants, 3 of 15 animals developed meningitis, while in the group with dexamethasone-eluting implants 4 of 15 showed signs of meningitis. In this study dexamethasone-releasing implants did not significantly increase the risk of postoperative pneumococcal otogenic meningitis.

Assessment of the subjective benefit of electric acoustic stimulation with the abbreviated profile of hearing aid benefit.

CONCLUSION: This study demonstrates that electric-acoustic stimulation (EAS) significantly decreases the subjective impairment in speech perception. OBJECTIVES: To assess the subjective benefit of EAS over the first 12 months after EAS fitting using the Abbreviated Profile of Hearing Aid Benefit (APHAB). METHOD: Twenty-three EAS users, implanted with either the PULSAR(CI)(100) FLEX(EAS) provided with the DUET EAS processor or the COMBI40+ Medium provided with the TEMPO+ speech processor, were included. Electric stimulation was activated about 1 month postoperatively; ipsilateral acoustic stimulation was added 2 months thereafter. EAS benefit was measured preoperatively with only a hearing aid and postoperatively at EAS fitting and then 3, 6 and 12 months after EAS fitting using the APHAB. RESULTS: Subjects reported significant improvements in the global score with a mean decrease in impairment from 74% preoperatively to 45% after 3 months of EAS use. Furthermore, clinical relevance was demonstrated in multiple subscales between preoperative and first fitting reflecting a true benefit of EAS with a probability of 95%.

Protection of inner ear function after cochlear implantation: compound action potential measurements after local application of glucocorticoids in the guinea pig cochlea.

BACKGROUND: Cochlear implant users with residual hearing often benefit greatly from simultaneous electric and acoustic stimulation. However, implantation can cause trauma to the inner ear, resulting in poorer hearing postoperatively. We investigated whether a single local injection of glucocorticoids can reduce hearing loss in long-term implanted guinea pigs. METHODS: Three groups of animals underwent bilateral surgery. One ear was implanted with an electrode, and the contralateral ear received a cochleostomy only. A single dose of the glucocorticoids triamcinolone or dexamethasone, or of artificial perilymph was infused into cochleae via cochleostomy. Compound action potentials were measured before and after application and for 3 months postoperatively. Tissue growth was measured as the percentage of the total area of the scala tympani that was obliterated. RESULTS: Ears subjected to cochleostomy only and treated with glucocorticoids demonstrated a mild hearing loss. In the implanted ears, both glucocorticoids preserved hearing at least temporarily. The volume of tissue growth within the scala tympani was not reduced, and there was no relation between the amount of tissue and hearing loss. CONCLUSIONS: Both glucocorticoids show a potential benefit for hearing preservation in implanted ears. Glucocorticoid therapy may be useful to protect residual hearing during cochlear implantation.

Electric-acoustic stimulation of the auditory system: a review of the first decade.

Electric-acoustic stimulation (EAS) was developed for individuals with a profound hearing loss in the high frequencies and a substantial residual low-frequency hearing (LFH). For this group of candidates, conventional hearing aids often neither provided sufficient amplification nor were they considered suitable for cochlear implantation due to the possible destruction of residual hearing capabilities. With EAS, combining electric stimulation with an ipsilateral acoustic stimulation, preservation of residual LFH and the development of a new speech processor uniting both strategies became essential. Over the last years, EAS has developed further and advanced in electrode design and surgery techniques. This paper summarizes the history of EAS and acknowledges the tremendous work of the many research groups who contributed to the success of EAS.

Combined electric acoustic stimulation with the PULSARCI(100) implant system using the FLEX(EAS) electrode array.

CONCLUSION: This study demonstrates that electric acoustic stimulation (EAS(®)) using the FLEX(EAS) electrode is a successful treatment method for preservation and stability of low frequency hearing, and results in significant improvements in speech perception. OBJECTIVES: Low frequency hearing preservation and stability following EAS surgery with the MED-EL PULSARCI(100) implant using the FLEX(EAS) electrode and a combined processor in a multicentre setting, and the efficacy and benefits of EAS over time were evaluated. METHODS: Eighteen subjects with normal to moderate hearing loss in the low frequencies and severe to profound hearing loss in the high frequencies were implanted with the FLEX(EAS) electrode. Implantation was performed by different surgeons at three participating centres using either the cochleostomy or the round window approach. Preoperatively, hearing was measured; a battery of speech perception tests and the subjective benefit questionnaire were administered. These tests were subsequently repeated: first at EAS fitting, which was due 3 months after surgery, and then again 3, 6 and 12 months after EAS fitting. RESULTS: Hearing could be preserved in all subjects. Speech understanding showed significant improvement in all tests over time with the EAS condition outperforming the cochlear implant-only condition at all intervals. These considerable effects were also reflected in the subjective benefit outcome.

Influence of a totally open oval window on bone conduction in otosclerosis.

OBJECTIVE: The aim of this study was to evaluate changes in bone conduction thresholds before, during and after total stapedectomy. STUDY DESIGN: Prospective clinical study. METHODS: In 27 ears of 26 patients undergoing stapedectomy under local anesthesia, bone conduction was measured before surgery, during surgery under open oval window conditions, and after the insertion of a steel wire connective tissue prosthesis. Statistical data analysis was performed on the audiometric results. RESULTS: Under open oval window conditions, bone conduction hearing was found to be improved between 500 and 2000 Hz, but not at 4000 Hz. After insertion of the prosthesis, an additional improvement was evident at 500 and 1000 Hz, but a loss was seen at 2000 and 4000 Hz. CONCLUSION: This is the first investigation reported in which audiometry was performed under open oval window conditions during stapes surgery. Our results demonstrate that at least part of the preoperative bone conduction hearing loss in otosclerosis must be of mechanical, but not of sensorineural origin, as already suspected by Carhart. The fixed footplate suppresses cochlear micromechanics mainly at frequencies between 500 to 2000 Hz. Furthermore, the loss in bone conduction hearing at 2000 and 4000 Hz after insertion of the prosthesis indicates that rather than the surgical procedure of total removal of the footplate, other factors such as the handling of the prosthesis or its mechanical properties after insertion cause high-frequency hearing loss after stapes surgery.

Combined aesthetic and functional reconstruction of ear malformations.

BACKGROUND: Surgery for major malformations of the outer and middle ear involves aesthetic as well as functional aspects. Whereas reconstruction of the auricle with autogenous rib cartilage is well established and has shown favorable results, functional repair using classic reconstructive techniques is possible only in a limited group of patients and the outcome is often unsatisfactory. Active middle ear implants (MEI) offer a promising alternative to reconstructive surgery. METHOD: Fifteen patients with ear malformations underwent implantation of an active middle ear implant (Soundbridge), with or without concomitant reconstruction of the auricle. The vibrating element, the floating mass transducer (FMT), was coupled either to the round window, stapes, oval window or incus, according to each individual's anatomical middle ear situation. Aesthetic as well as functional outcomes were evaluated. RESULTS: Implantation could be integrated into aesthetic reconstruction of the auricle without complications. In 14/15 patients, a satisfactory functional result could be achieved (< 30 dB pure-tone audiometry). Neither facial nerve palsy nor inner ear hearing loss was observed after implantation. CONCLUSION: The versatile form of the FMT of the Soundbridge allows for adaptation of the coupling procedure to the individual anatomical situations. Implantation of a Soundbridge MEI is a valuable option for functional reconstruction of the malformed ear, which may offer more consistent and reliable results than classic reconstructive surgery.

Torque measurements of the ossicular chain: implication on the MRI safety of the hearing implant Vibrant Soundbridge.

HYPOTHESIS: Is the human ossicular chain stabile enough to withstand the torque of a Vibrant Soundbridge middle ear hearing implant in the magnetic field of a 1.5 T magnetic resonance imaging (MRI) system? BACKGROUND: The Vibrant Soundbridge is a semi-implantable hearing device in which a tiny electromechanical transducer, called floating mass transducer (FMT), is clipped to the ossicular chain within the middle ear. The FMT contains a permanent magnet, which can generate a torque when exposed to a static magnetic field of MRI systems. Since the transducer is routinely attached to the long process of the incus, this torque could affect or even disrupt the ossicular chain. This study investigates the likelihood of a middle ear injury by an FMT in an MRI system. METHODS: Torque measurements were performed on 10 unpreserved human temporal bones. A brass fork was attached to the long process of the incus via a posterior tympanotomy, and a defined torque was applied by a calibrated torque meter. The torque was increased stepwise until an injury of the middle ear was observed. RESULTS: The mean torque at which the middle ear was injured was 4.3 mN.m +/- 1.7 mN.m. The lowest value measured was 1.5 mN.m, and the highest was 6.5 mN.m. CONCLUSION: Even the lowest torque measured is more than 1.5 times higher than the "worst-case" torque affecting the FMT during a 1.5 T MRI examination. The torque on an FMT crimped to the long process of the incus should therefore not harm the human middle ear.

Testing the diagnostic value of electrical ear canal stimulation in cochlear implant candidates by functional magnetic resonance imaging.

Prior to cochlear implant (CI) surgery in children, the integrity of the auditory pathway is sometimes assessed by electrical ear canal stimulation (ECS). However, the evaluation of reactions as auditory is subjective. To test the prognostic value of ECS, functional magnetic resonance imaging (fMRI) was performed during ECS vicariously in 18 adult CI candidates. Activation of the primary auditory cortex was detected in 9 of 16 cases when auditory sensations during ECS occurred, and tended to be more bilaterally distributed in CI candidates than in normal-hearing controls. ECS sensations only tended to correlate with fMRI activations. However, solely frequency discrimination during electrical stimulation predicted CI outcome, but neither other auditory sensations nor fMRI activations did so satisfactorily, which limits the diagnostic value of these measures. Instead, preoperative residual hearing (nonamplified and amplified) was a robust predictor for CI benefit.

Spontaneous bilateral necrosis of the tongue: a manifestation of giant cell arteritis?

Giant cell arteritis is a chronic vasculitis, which involves large- and medium-sized branches of the arteries originating from the aortic arch. This disease is a diagnostic challenge with a wide range of clinical symptoms and findings due to different affected vessels. Classic symptoms are temporally located headache, thickened temporal artery and jaw claudication. Furthermore, visual symptoms like diplopia or loss of vision can occur. The tongue has an excellent blood supply and ischemic ulceration due to giant cell vasculitis is usually unilateral and rarely described in literature. We present a patient with a spontaneous bilateral tongue necrosis and are convinced that this extraordinary case must be deemed to be a manifestation of giant cell arteritis, although it does not completly satisfy the usually used diagnostic criteria formulated by the American College of Rheumatology.

Unspecific parotitis can be the first indication of a developing Wegener's granulomatosis.

In an unusual course of Wegener's granulomatosis (WG), a 71-year-old woman presented a 3-week history of unilateral painful parotid swelling unresponsive to antiphlogistic and antibiotic treatment. Following lateral parotidectomy with unspecific inflammatory histopathological findings, the patient developed disturbance of wound healing and high recurrent fever. Control chest X-ray showed several pulmonary round lesions. Immunologic testing for antinuclear cytoplasmatic antibodies (ANCA) was positive and CT navigated puncture revealed pronounced necrotic vasculitis of small arteries and veins. Consequently, systemic WG was diagnosed and specific immunosuppressive therapy was started. Long-term follow-up of 6 months showed a decline in the ANCA course, full remission of the presented symptoms and prevention of renal manifestations. Isolated inflammatory parotid enlargement can be the initial symptom of systemic WG and should be considered as differential diagnosis, especially when nondiagnostic histopathological results are obtained. Early testing for c-ANCA supplies valuable information and therefore should be prompted when additional symptoms occur. Once diagnosed as WG, appropriate therapy is able to prevent progression to severe clinical courses.

Comparison of musical activities of cochlear implant users with different speech-coding strategies.

Speech coding might have an impact on music perception of cochlear implant users. This questionnaire study compares the musical activities and perception of postlingually deafened cochlear implant users with three different coding strategies (CIS, ACE, SPEAK) using the Munich Music Questionnaire. Overall, the self-reported perception of music of CIS, SPEAK, and ACE users did not differ by very much.

Outcomes in adults implanted with the FLEXsoft electrode.

CONCLUSION: Achieving deep insertions, as well as good speech perception results, the FLEXsoft electrode array allows for some preservation in subjects with measurable low frequency hearing, even after a period of time. This opens the door for future research in electrode design, hearing preservation research and drug delivery systems. OBJECTIVES: The FLEXsoft electrode is designed to be atraumatic to the structures of the cochlea during deep insertion of a cochlear implant electrode. This paper reports on the surgical and functional outcomes in implantations with the FLEXsoft electrode array. PATIENTS AND METHODS: Twenty-three adult subjects received a FLEXsoft electrode array and were assessed on speech perception tests (monosyllables, sentences in quiet and in noise), a subjective questionnaire (Nijmegen Cochlear Implant Questionnaire) and a pure-tone audiogram. Results at 1, 3, 6 and 12 months post first fitting were compared to scores from the preoperative interval. RESULTS: Surgery was uneventful in all cases, the surgical handling was satisfactory and correct position of the electrode was achieved in all cases. Hearing could be preserved (as determined by the audiogram) in half of the subjects who had measurable audiograms preoperatively at the 1 month test interval, and in a quarter of subjects after 12 months of device use, despite deep insertion of the electrode. Speech perception scores showed significant improvement over time, as did quality of life scores, and were comparable to results with the standard electrode array as used in the COMBI 40+ and PULSARCI100.

Application of a corticosteroid (Triamcinolon) protects inner ear function after surgical intervention.

HYPOTHESIS: Opening of the inner ear during stapes surgery or cochlear implantation may result in trauma to inner ear structures and possible hearing loss. The dual aim of the present study was to evaluate the effectiveness of locally applied Triamcinolon* to protect the inner ear against surgically induced trauma and to exclude possible ototoxic effects. METHODS: In an animal model (guinea pig), a corticosteroid (Triamcinolon) was topically applied to the inner ear, either by extracochlear application and diffusion through the round window membrane or by direct intracochlear application via a cochleostomy. Physiological effects of the steroid were investigated by monitoring the hearing of steroid treated animals in comparison to control animals treated with Ringer solution instead of Triamcinolon. Thresholds as well as input/output functions (I/O function) of compound action potentials (CAPs) in response to auditory stimuli were determined before the cochleostomy and at specific intervals up to 4 weeks after application of Triamcinolon. RESULTS: Extracochlear application of Triamcinolon induced only minor shifts of mean CAP thresholds but significantly increased mean maximal amplitudes of I/O function 14 d after application. No detrimental effects on cochlear function were noted; thus, indicating absence of ototoxicity for extracochlear application in the concentrations used. After the surgical trauma of cochleostomy, CAP thresholds increased by 12.5 dB directly after surgery and by 15.8 dB at day 3. Amplitudes of CAPs diminished. Intracochlear application of Triamcinolon resulted in significantly enhanced recovery of CAP thresholds and amplitudes of I/O function from initial loss over a period of 4 weeks. CONCLUSIONS: From these results, we conclude that extracochlear topical application of Triamcinolon has no ototoxic effect in the concentrations that were used and that intracochlear application supports an increased recovery of cochlear functions after surgical trauma. Furthermore, the results indicate a protective effect of corticosteroids, partially preventing progressive loss of hearing after cochleostomy over a period of 4 weeks. Intracochlear application of Triamcinolon may be useful to prevent hearing loss after surgical intervention on the inner ear; however, clinical safety and efficacy remain to be proven in clinical studies.

Protecting the cochlea during stapes surgery: is there a role for corticosteroids?

The aim of the present study was to evaluate possible protective effects of corticosteroids on the inner ear after surgical trauma and to exclude any ototoxicity. A corticosteroid (triamcinolone, Volon A) was topically applied to the inner ear of guinea pigs, either by extracochlear application with permeation and diffusion through the round window membrane or by intracochlear application with direct infusion into the inner ear via a cochleostomy. Threshold and input/output functions of compound action potentials (CAPs) were determined before and after application of the corticosteroid. We found that extracochlear application of the corticosteroid induced insignificant mild shifts of mean CAP thresholds, but significantly increased mean maximal amplitudes of input/output function after the 14th day following application of the steroid. No detrimental effects on cochlear function were noted in the extracochlear group, indicating absence of ototoxicity with the concentrations used. In the intracochlear group, CAP thresholds and amplitudes of input/ output function recovered from partial hearing loss due to cochleostomy between 7 and 14 days after application of the steroid, whereas in controls without steroid application, no such recovery of hearing was detected. These results suggest that topical application of triamcinolone has no ototoxic effect and that it leads to increased recovery of cochlear functions after trauma in the guinea pig inner ear.

Round window stimulation with an implantable hearing aid (Soundbridge) combined with autogenous reconstruction of the auricle - a new approach.

BACKGROUND: Congenital malformations of the auricle are often combined with atresia of the outer ear canal and malformations of the ossicles, representing aesthetic as well as functional deficits. Optimal treatment should therefore address both aspects equally. This report describes a new approach, combining the reconstruction of the auricle with implantation of an active middle ear hearing aid, stimulating the round window membrane. METHOD: A 33-year-old male patient, with bilateral ear microtia, fibrous atresia of the external ear canals and malformation of the ossicles due to Treacher Collins-Franceschetti syndrome was included in the study. In stage one, the cartilage framework of the new auricle, made of autogenous rib cartilage, was fabricated and implanted. During stage two, the auricle was elevated, a retro-auricular sulcus was formed and a Vibrant MED-EL Soundbridge device was implanted. The transducer was coupled to the round window membrane. RESULTS: Both functional and aesthetical results were favourable. Aided thresholds were between 15 and 30 dB in the frequency range of 0.75-6 kHz, monosyllabic word understanding at 65 dB SPL increased from 0 to 80%. DISCUSSION: Combining aesthetic and functional rehabilitation, autogenous reconstruction of a new auricle together with the implantation of an active middle ear hearing aid, coupled to the round window membrane, is a promising new approach.

Ipsilateral electric acoustic stimulation of the auditory system: results of long-term hearing preservation.

OBJECTIVE: To evaluate long-term ipsilateral hearing preservation in patients who underwent cochlear implantation for the combined electric acoustic stimulation of the auditory system. METHODS: This was a prospective observational study conducted at a tertiary referral center. Twenty-three subjects were implanted with the MED-EL C40+ standard or C40+ medium electrode using an atraumatic surgical protocol via an anterior-inferior cochleostomy approach. The desired insertion depth was 18-24 mm or 360 degrees. All patients showed significant low-frequency hearing prior to surgery and monosyllabic word scores did not exceed 40% in the best aided condition. Pure-tone audiometry was performed prior to implantation and at distinct intervals after surgery. RESULTS: Nine patients (39.1%) showed complete pure-tone audiometric hearing preservation (0-10 dB) over an average of 29 months. Seven subjects (30.4%) showed partial preservation of residual hearing (hearing loss 15-40 dB) until an average of 25 months. Delayed loss of residual hearing was observed in 5 cases (21.7%) and 2 patients (8.6%) completely lost residual hearing during or immediately after surgery. Freiburger Monosyllabic word understanding scores in a group of patients with complete hearing preservation increased from 13.1% preoperatively to 75% in the electric acoustic stimulation condition. CONCLUSION: This study documents that complete and partial preservation of ipsilateral hearing after cochlear implantation can be achieved in about 70% of cases over an average period of 27.25 months when using 360 degrees electrode insertions.