Marco Carner

Treatment of mixed hearing losses via implantation of a vibratory transducer on the round window

Early clinical findings are reported for subjects implanted with the Vibrant Med-El Soundbridge® (VSB) device. The present criteria for the VSB, limiting its application to patients with normal middle ear function, have been extended to include patients with ossicular chain defects. Seven patients with severe mixed hearing loss were implanted with the transducer placed onto the round window. All had undergone previous surgery: six had multiple ossiculoplasties, and one had the VSB crimped on the incus with unsuccessful results. Round window implantation bypasses the normal conductive path and provides amplified input to the cochlea. Post-operative aided thresholds of 30 dB HL were achieved for most subjects, as compared with unaided thresholds ranging from 60–80 dB HL. Aided speech reception thresholds at 50% intelligibility were 50 dB HL, with most subjects reaching 100% intelligibility at conversational levels, while unaided thresholds averaged 80 dB HL, with only one subject reaching 100% intelligibility. These results suggest that round window implantation may offer a viable treatment option for individuals with severe mixed hearing losses who have undergone unsuccessful ossiculoplasties.

Cochlear Implantation at under 12 months: Report on 10 Patients†

Objectives: There is growing evidence that early application of a cochlear implant in children affected by profound congenital hearing loss is of paramount importance for the development of an adequate auditory performance and language skills. For these reasons and as a result of advances in audiologic diagnosis and an enhanced awareness of the safety of cochlear implants, the age of implantation has substantially decreased over recent years. Children aged as little as 12 months are now being implanted in some centers. On the basis of our experience with very young children, we believe that the date of implantation may be further reduced to only 4 to 6 months of age.

Auditory brainstem implant (ABI): new frontiers in adults and children.

Previous studies have considered only patients with neurofibromatosis type 2 (NF2) older than 12 years as candidates for an auditory brainstem implant (ABI). Our study expands the potential criteria to include both children and adult subjects with other cochlear or cochlear nerve malfunctions who either would not benefit at all from a cochlear implant (eg, cochlear nerve aplasia or avulsion) or whose benefit was or would be severely compromised (eg, cochlear ossification, cochlear fracture). STUDY DESIGN: In our department, over the period from April 1997 to September 2002, 29 patients, 20 adults and 9 children, were fitted with ABIs. Their ages ranged from 14 months to 70 years. Thirteen subjects had tumors, 10 NF2 and 3 solitary vestibular schwannoma, and 16 patients had a variety of nontumor (NT) cochlear or cochlear nerve diseases. A retrosigmoid-transmeatal approach was used in T and a retrosigmoid approach in NT patients. The electrode array was inserted into the lateral recess of the fourth ventricle and correct electrode positioning was monitored with the aid of electrically evoked auditory brainstem responses (EABRs). RESULTS: Correct implantation was achieved in all patients. No complications were observed due to implantation surgery or related to ABI activation or long-term use. Auditory sensations were induced in all patients with various numbers of electrodes (from 5 to 15). Different pitch sensations were identifiable with different electrode stimulation. Closed-set word recognition, open-set sentence recognition, and speech tracking scores achieved by the patients are reported in detail. The auditory performance of the patients showed significantly better outcomes than controls (Multicentric European clinical investigations on ABI with NF2). CONCLUSION: We have shown that the indications for the ABI can be extended to include NT patients with severe cochlear and/or cochlear nerve abnormalities. The degree of auditory benefit varies as a function of the underlying pathological conditions, with NT subjects exhibiting significantly better outcomes than the T patients.

Outcomes in nontumor adults fitted with the auditory brainstem implant: 10 years' experience.

Objectives: Recently, open-set speech recognition performance has been observed with electric stimulation of the brainstem in some nontumor (NT) patients. These outcomes require that we reevaluate the criteria for patient selection and the rationale for expanding the application for the auditory brainstem implant (ABI) to NT adult patients with profound hearing loss. This study presents results from up to 10 years in adults, with analysis based on cause. Materials and Methods: In our Department, from April 1997 to September 2007, ABIs have been implanted in 112 patients (83 adults and 29 children) with tumor (T) and NT disorders. Of the 112 patients, 15 have previously had a cochlear implant elsewhere with no sound detection. This article presents speech recognition results from the 80 patients (32 neurofibromatosis type 2 and 48 NT) who had achieved at least 1-year follow-up. The retrosigmoid approach was used in all NT patients, and the retrosigmoid-transmeatal approach was used in all T patients. Results: All patients had a functioning implantation, and no complications were observed during the operation, activation, or long-term use of the ABI. At the most recent follow-up, NT adults scored from 10 to 100% in open-set speech perception tests (average, 59%), and T patients scored from 5 to 31% (average, 10%). The differences between these results are statistically significant (p = 0.0007). The best performance was observed in patients who lost their nerve VIII from head trauma or severe ossification. Lowest performance (although still highly beneficial to the patient) was observed in patients with neurologic disorders, neuropathy, and cochlear malformations. Conclusion: Our experience clearly indicates that the ABI is an effective tool for hearing rehabilitation in patients with profound hearing loss who cannot be fitted with cochlear implants.

Hearing restoration with auditory brainstem implant in three children with cochlear nerve aplasia.

Objective To verify the possibility of auditory habilitation in children with aplasia and hypoplasia of the cochlear nerve by direct electrical stimulation of the cochlear nuclei with an auditory brainstem implant. Study Design Retrospective case review. Setting Study conducted at the Ear, Nose, and Throat Department of the University of Verona, Italy. Patients Three children, aged 4, 3, and 2 years, respectively, with severe bilateral cochlear malformations and cochlear nerve aplasia have received an auditory brainstem implant at this institution in the past 2 years. Intervention The classic retrosigmoid approach was used. Correct positioning of the electrodes was evaluated using electric auditory brainstem responses and neural response telemetry. Before the patients were discharged, high-resolution computed tomography with a bone algorithm reconstruction technique was performed to evaluate electrode placement. The auditory brainstem implant was activated 30 to 60 days after implantation. Results No postoperative complications were observed. To date, 21, 18, and 8 electrodes, respectively, have been activated in the three children. The first patient, 12 months after activation, had achieved good environmental sound awareness, good speech detection, and some speech recognition. The second child, 8 months after activation, had achieved good environmental sound awareness and moderate speech detection. The third patient, 1 month after activation, had obtained good environmental sound awareness. Conclusion This study indicates that auditory brainstem implantation is technically feasible in children with cochlear nerve aplasia. The early results suggest the possibility of achieving auditory habilitation with auditory brainstem implantation in this population.

Auditory brainstem implant as a salvage treatment after unsuccessful cochlear implantation.

Objective: The present article investigates on an individual basis the performance achieved with the auditory brainstem implant in patients who had been treated unsuccessfully with a cochlear implant. Study Design: An intrasubject comparison between results achieved with the cochlear implant and the auditory brainstem implant is reported. Setting: Tertiary referral care. Patients: Five subjects were fitted with an auditory brainstem implant in our department because of the poor results achieved with cochlear implants. Two were children, one with bilateral cochlear nerve aplasia and one suffering from auditory neuropathy. Three were adults with complete cochlear ossification. Intervention: A retrosigmoid approach was used in all subjects. Electrically evoked auditory brainstem responses and neural response telemetry were used to monitor electrode positioning. Results: No complications were observed due to implantation surgery or related to activation or long-term use of the auditory brainstem implant. Auditory sensations were induced in all patients with varying numbers of electrodes (from 9–16). In all three adults, the cochlear implant did not allow either word/sentence discrimination or speech tracking, whereas the auditory brainstem implant permitted discrimination of two- or three-syllable words with scores from 85 to 100%. In the two adults with a follow-up of 5 and 6 months after auditory brainstem implant activation, the open-set sentence recognition scores (auditory-only mode) were 70% and 100%, respectively, and the speech-tracking scores were 27 and 40 words/min, respectively. One patient with a follow-up of only 3 months scored 0% in both sentence recognition and speech tracking. The two children who had achieved no hearing ability with the cochlear implant were already able to detect sounds and words as early as 2 months after activation of the auditory brainstem implant and are showing progressive improvement in their performance. Conclusion: Auditory brainstem implantation may be a very powerful rehabilitative treatment after cochlear implant failure. The possibility of using the auditory brainstem implant as first-choice therapy in some categories of deaf patients (e.g., subjects with auditory neuropathy or cochlear ossification) who are currently treated with cochlear implantation is discussed.

Auditory Brainstem Implant in Posttraumatic Cochlear Nerve Avulsion

Patients aged over 12 years with neurofibromatosis type 2 are considered candidates for an auditory brainstem implant (ABI). This study extends the indication criteria of ABI to subjects with profound hearing loss due to damaged cochleas and/or cochlear nerves (CNs) following head injuries. In our department, over the period from April 1997 to November 2002, 32 patients, 23 adults and 9 children, were fitted with ABIs. Their ages ranged from 14 months to 70 years. These patients were suffering from a variety of tumor (13 subjects) and nontumor CN or cochlear diseases (19 subjects). Six patients, 5 adults and 1 child, had profound hearing loss following head injury. Their mean age was 25 years (range: 16–48 years). Five were male and 1 female. The retrosigmoid approach was used in all 6 patients. The electrode array was inserted into the lateral recess of the fourth ventricle and correct electrode positioning was monitored with the aid of electrically evoked auditory brainstem responses and neural response telemetry. Correct implantation was achieved in all patients. No complications were observed due to implantation surgery or related to ABI activation and stimulation of the cochlear nuclei. At activation, an average of 9.8 electrodes (range 5–13) were switched on without side effects. One to 6 electrodes were activated in the following sessions after time periods ranging from 2 to 16 months. All patients achieved auditory-alone-mode closed-set word recognition scores ranging from 40 to 100%; 3 had auditory-alone-mode open-set sentence recognition scores of 60–100%; 2 of these even had speech-tracking performance scores of 38 and 43 words, respectively, showing an ability to engage in normal conversation and converse over the phone. The present study demonstrates that the ABI is a useful rehabilitation instrument in subjects with damaged cochleas and/or CN avulsion following head injury who are unamenable or poorly responsive to auditory rehabilitation using cochlear implants.

Hearing habilitation with auditory brainstem implantation in two children with cochlear nerve aplasia.

Patients with aplasia and hypoplasia of the cochlear nerve have no chance of having their hearing restored by stimulating the periphery of the auditory system using the traditional cochlear implant. A possible approach to auditory rehabilitation may be direct electrical stimulation of the cochlear nuclei with an auditory brainstem implant (ABI). Recently, two children, aged 4 and 3 years, respectively, with bilateral severe cochlear malformations and cochlear nerve aplasia received an ABI. The present paper reports the technique and the preliminary results of this experience. The classic retrosigmoid approach was used. The correct position of the electrodes was estimated with the aid of EABRs and neural response telemetry (NRT). No postoperative complications were observed. High-resolution CT scans with a bone algorithm reconstruction technique were taken postoperatively to evaluate electrode placement before discharge. The ABI was activated 30 days after implantation in both patients. To date 16 and 13 electrodes, respectively, have been activated in the two children. Three months after activation the first patient had achieved good environmental sound awareness, good speech detection and some speech discrimination. The second child, 1 month after activation, had achieved good environmental sound awareness and moderate speech detection. To the best of our knowledge this is the first report of patients with hypoplasia of the cochlea and aplasia of the cochlear nerve, aged below 5 years and treated with an ABI.

TORP vs round window implant for hearing restoration of patients with extensive ossicular chain defect

Conclusions: Round window implant (RWI) with a floating mass transducer (FMT) may be suggested as the first choice in hearing rehabilitation for patients with chronic otitis media (COM) and extensive destruction of the ossicular chain. Objective: To investigate the pros and cons of the total ossicular replacement prosthesis (TORP) vs the RWI in restoration of hearing in patients with COM. Patients and methods: Thirty-eight patients with bilateral moderate to severe mixed or conductive hearing loss from COM without cholesteatoma and bilateral ossicular chain erosion (footplate residual) were alternately assigned to a titanium-TORP (T-TORP) and to RWI with the FMT of the Medel Vibrant Soundbridge (MVBS) located onto the RW niche. The therapeutic efficiency, preoperative vs postoperative air-conduction gain and speech recognition were investigated for the two groups and statistically analyzed at 36 months postoperatively. The following postoperative anatomic conditions were also evaluated for the two groups: 1) recurrence of infection, 2) retraction pocket, 3) extrusion rate, and 4) displacement of the prosthesis. Results: Good functional results and stability at 36 months were obtained with both procedures. The extrusion rates for T-TORP were low. So far no extrusion has been observed for RWI. Hearing results were statistically much better for RWI vs T-TORP for all investigated parameters.

Auditory results after vestibular nerve section and intratympanic gentamicin for Ménière's disease.

Objective: Hearing loss is a possible complication of vestibular neurectomy and intratympanic gentamicin administration in Ménières disease. The aim of this study was to compare the incidence of this complication with the two treatments. Study Design: Retrospective review. Setting: Tertiary referral center. Patients: The initial study population reviewed consisted of 24 patients receiving gentamicin injections and 209 patients undergoing vestibular nerve section. Comparison of data was performed among all 24 intratympanic gentamicin patients and the last 24 vestibular neurectomy patients operated on via the retrosigmoid approach. Interventions: Intratympanic gentamicin administration (26-156 mg) and retrosigmoid vestibular neurectomy. Main Outcome Measure: Auditory and vertigo results were evaluated according to the American Academy of Otolaryngology 1995 criteria. Results: The mean preoperative pure-tone average for patients undergoing vestibular nerve section was 48.5 dB, with a speech discrimination score of 85%. In these patients, the postoperative pure-tone average was 50.3 dB, and the speech discrimination score was 82%. Patients undergoing gentamicin injection had a mean pretreatment pure-tone average of 50.1 dB and a speech discrimination score of 87%. The posttreatment pure-tone average and discrimination score for the gentamicin group were 74.7 dB and 65%, respectively. The amount of postprocedure hearing loss was significantly greater in the gentamicin group (p = 0.03). Excellent control of vertigo (classes A and B) was obtained in 95.8% of the patients treated with vestibular nerve section and in 75% of the patients in the gentamicin group. Conclusion: Gentamicin administration and vestibular neurectomy are both effective for relieving vertigo in Ménières disease. The incidence of hearing loss is significantly higher after gentamicin injection.