Francesco G. Fiorino

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.

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.

Middle Ear Mechanics in Subjects with Rheumatoid Arthritis

The incudo-malleolar and incudo-stapedial joints are true diarthroses and therefore may be subject to the same rheumatic lesions as any other articulation in the body. The existence of this involvement in rheumatoid arthritis (RA), however, is highly controversial. The present study investigates modifications of the mechanical properties of the middle ear in a group of subjects with RA by evaluating the resonance frequency obtained with multiple-frequency tympanometry (MFT). Thirty patients with RA, aged 20 to 68 years (mean age: 45.8 +/- 12.4 years), participated in the investigation. Their data were compared with those obtained in a control group of 48 age-matched subjects. Results obtained in both ears were examined in all subjects. The two groups displayed almost equal hearing levels with mean air conduction thresholds ranging from 10 to 22 dB HL. None of the subjects displayed an air-bone gap greater than 5 dB. Normal resonance frequency, calculated at the 95th percentile from the control group, ranged from 900 to 1250 Hz. Twelve rheumatoid arthritis patients (40 per cent) displayed abnormal resonance values. These findings were monolateral in 9 patients and bilateral in 3. Eleven out of 15 ears with abnormal multiple-frequency tympanometry data were characterized by an increase in resonance and 4 by a decrease. A correlation between abnormal resonance values and more aggressive RA was established. The results of this study suggest that rheumatoid arthritis may involve the incudo-malleolar and incudo-stapedial joints, altering the ossicular mechanics in response to static air pressure modifications. This does not impair sound conduction through the middle ear, but might reduce the protective mechanisms of the middle ear towards high static pressures.

Auditory brainstem implantation: the University of Verona experience.

OBJECTIVE: We sought to describe the advantages of the retrosigmoid-transmeatal (RS-TM) approach in the application of auditory brainstem implants (ABIs) in adults with monolateral and bilateral vestibular schwannoma (VS) and in children with cochlear nerve aplasia. STUDY DESIGN: We conducted a retrospective case review. SETTING: The study was conducted at the ENT Department of the University of Verona, Italy. PATIENTS: Six adult patients (5 men and 1 woman) with neurofibromatosis type 2 (NF2) were operated on for VS removal with ABI. An additional patient had a unilateral VS in the only hearing ear. Tumor size ranged from 12 to 40 mm. In addition, 2 children received ABIs for bilateral cochlear nerve aplasia. INTERVENTION: An RS-TM approach was used in all VS patients, and an RS approach was used in the subjects with cochlear nerve aplasia. After tumor excision, landmarks (VII, VIII and IX cranial nerves, choroid plexus) for the foramen of Luschka were carefully identified. The choroid plexus was then partially removed and the tela choroidea divided and bent back; the floor of the lateral recess of the fourth ventricle and the convolution of the dorsal cochlear nucleus became visible. In the 2 subjects with no cochlear nerve, the choroid plexus and VII and IX cranial nerves were used as landmarks. The electrode array was then inserted into the lateral recess and the correct position was monitored with the aid of electrically evoked auditory brainstem responses (EABR) and neural response telemetry (NRT). RESULTS: Correct implantation was possible in all patients. Auditory sensations were induced in all patients with various numbers of electrodes. Different pitch sensations could be identified with different electrode stimulation. CONCLUSIONS: We believe that the RS approach is the route of choice for patients who are candidates for ABI due to the easy and clear access to the cochlear nucleus area. This route avoids some of the drawbacks of the translabyrinthine approach, such as mastoidectomy, labyrinthectomy, sealing of the cavity and posterior fossa with abdominal fat, and contamination from the middle ear. For this reason, it is the route of choice in children with cochlear nerve aplasia or severe cochlear malformation and in adults with complete ossification of the cochlea or cochlear nerve disruption due to cranial trauma.

A dehiscent superior semicircular canal may be plugged and resurfaced via the transmastoid route.

Objective: To evaluate the results obtained in treating superior semicircular canal dehiscence by plugging and resurfacing the defect via the transmastoid approach. Patients: Six patients (30-70 yr old) who had disabling semicircular canal dehiscence syndrome underwent surgery. Intervention: After a wide mastoidectomy and skeletonization of the semicircular canals, a shell of bone covering the middle fossa lateral to the superior semicircular canal was removed. The exposed dura was gently retracted and the canal skeletonized. Bone dust mixed with fibrine glue and bone wax were pressed to plug the dehiscent portion of the canal, and a slice of cortical bone was inserted to resurface it. Main Outcome Measure: Recovery from vestibular and auditory symptoms was evaluated. Results: No intraoperative or postoperative complications occurred. Patients experienced an immediate relief of symptoms attributable to the dehiscence. Conclusion: A superior semicircular canal dehiscence may be plugged and resurfaced via the transmastoid approach, thus avoiding the more invasive middle fossa craniotomy.

Middle fossa versus retrosigmoid-transmeatal approach in vestibular schwannoma surgery: a prospective study.

Objective To compare the advantages, disadvantages, and results obtained with the middle fossa and retrosigmoid-transmeatal approaches during pure intracanalar vestibular schwannoma surgery in an attempt to preserve hearing. Study Design Prospective study of patients treated from 1998 to 2001. Setting Tertiary care referral center. Patients Patients with intracanalar vestibular schwannoma (size ranging from 4 to 12 mm), 25 operated on with the retrosigmoid-transmeatal technique and 25 via the middle fossa route. Main Outcome Measures Facial nerve and auditory function were examined at 1 year with both techniques. Auditory results were also evaluated as a function of tumor size, distance from the internal auditory canal fundus, and internal auditory canal enlargement. Results The results indicated no significant difference in facial nerve and auditory function results between the two techniques. The retrosigmoid-transmeatal approach, however, yielded better facial nerve function results at discharge. Postoperative hearing was better when the distance from the fundus was greater than 3 mm, when the size of the vestibular schwannoma was equal to or less than 7 mm, and when the internal auditory canal enlargement was less than 3 mm. Conclusions The middle fossa approach does not afford any particular advantages over the retrosigmoid-transmeatal approach in terms of auditory results. Facial nerve function is less satisfactory in the short term, when the middle fossa route is used, but can be improved by decompression and gentle displacement of the facial nerve in its labyrinthine portion.