Olivier Sterkers

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°, 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 (≤80 dB HL at 125 and 250 Hz; ≤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.

Consensus statements on the BAHA system: where do we stand at present?

After more than 25 years of clinical experience, the BAHA (bone-anchored hearing aid) system is a well-established treatment for hearing-impaired patients with conductive or mixed hearing loss. Owing to its success, the use of the BAHA system has spread and the indications for application have gradually become broader. New indications, as well as clinical applications, were discussed during scientific roundtable meetings in 2004 by experts in the field, and the outcomes of these discussions are presented in the form of statements. The issues that were discussed concerned BAHA surgery, the fitting range of the BAHA system, the BAHA system compared to conventional devices, bilateral application, the BAHA system in children, the BAHA system in patients with single-sided deafness, and, finally, the BAHA system in patients with unilateral conductive hearing loss.

Factors Affecting Auditory Performance of Postlinguistically Deaf Adults Using Cochlear Implants: An Update with 2251 Patients

Objective: To update a 15-year-old study of 800 postlinguistically deaf adult patients showing how duration of severe to profound hearing loss, age at cochlear implantation (CI), age at onset of severe to profound hearing loss, etiology and CI experience affected CI outcome. Study Design: Retrospective multicenter study. Methods: Data from 2251 adult patients implanted since 2003 in 15 international centers were collected and speech scores in quiet were converted to percentile ranks to remove differences between centers. Results: The negative effect of long duration of severe to profound hearing loss was less important in the new data than in 1996; the effects of age at CI and age at onset of severe to profound hearing loss were delayed until older ages; etiology had a smaller effect, and the effect of CI experience was greater with a steeper learning curve. Patients with longer durations of severe to profound hearing loss were less likely to improve with CI experience than patients with shorter duration of severe to profound hearing loss. Conclusions: The factors that were relevant in 1996 were still relevant in 2011, although their relative importance had changed. Relaxed patient selection criteria, improved clinical management of hearing loss, modifications of surgical practice, and improved devices may explain the differences.

Results from a European clinical investigation of the Nucleus multichannel auditory brainstem implant.

Objective This study was designed to investigate the perceptual benefits and potential risks of implanting the Nucleus® multichannel auditory brainstem implant. Design Between September 1992 and October 1997 a total of 27 subjects received a Nucleus 20- or 21-channel Auditory Brainstem Implant (ABI). All subjects involved in the trial had bilateral acoustic tumour as a result of neurofibromatosis type 2 (NF2) resulting in complete dysfunction of the VIIIth nerve. The study used each subject as their own control without a preoperative baseline because residual hearing, if existing, was destroyed at surgery by tumour removal. A battery of speech tests was conducted to evaluate each patient’s performance and communication abilities. Tests were conducted, where possible, in the auditory-only, visual-only, and auditory-visual conditions at 3 days postoperatively (baseline), at 3-mo intervals for the first year and every 12 mo thereafter. A subjective performance questionnaire was administered together with an extensive neurological examination at each test interval. Results 27 subjects involved in this trial were successfully implanted with a Nucleus ABI. One subject died 2 days postoperatively due to a lung embolism unrelated to the device. Twenty-six subjects underwent device activation and all but one patient received auditory sensation at initial stimulation (96.2%). On average 8.6 (±4.2) of the available 21 electrodes were used in the patients’ MAPs. Performance evaluation measures showed that the majority of users had access to auditory information such as environmental sound awareness together with stress and rhythm cues in speech that assist with lipreading. Although most subjects did not achieve any functional auditory-alone, open-set speech understanding, two subjects from this series (7.4%) did receive sufficient benefit to be able to use the ABI in conversation without lipreading. Conclusions Although the medical risks and surgical complexity associated with ABI device implantation are far greater than those for a cochlear implant, the clinical results from this trial show that the Nucleus multichannel ABI is capable of providing a significant patient benefit over risk ratio for subjects suffering loss of hearing due to bilateral retrocochlear lesions.

Pre-, Per- and Postoperative Factors Affecting Performance of Postlinguistically Deaf Adults Using Cochlear Implants: A New Conceptual Model over Time

Objective To test the influence of multiple factors on cochlear implant (CI) speech performance in quiet and in noise for postlinguistically deaf adults, and to design a model of predicted auditory performance with a CI as a function of the significant factors. Study Design Retrospective multi-centre study. Methods Data from 2251 patients implanted since 2003 in 15 international centres were collected. Speech scores in quiet and in noise were converted into percentile ranks to remove differences between centres. The influence of 15 pre-, per- and postoperative factors, such as the duration of moderate hearing loss (mHL), the surgical approach (cochleostomy or round window approach), the angle of insertion, the percentage of active electrodes, and the brand of device were tested. The usual factors, duration of profound HL (pHL), age, etiology, duration of CI experience, that are already known to have an influence, were included in the statistical analyses. Results The significant factors were: the pure tone average threshold of the better ear, the brand of device, the percentage of active electrodes, the use of hearing aids (HAs) during the period of pHL, and the duration of mHL. Conclusions A new model was designed showing a decrease of performance that started during the period of mHL, and became faster during the period of pHL. The use of bilateral HAs slowed down the related central reorganization that is the likely cause of the decreased performance.

A middle ear implant, the symphonix Vibrant soundbridge: Retrospective study of the first 125 patients implanted in France

Objective The Vibrant Soundbridge is an active semi-implantable middle ear implant for the rehabilitation of patients with a sensorineural hearing loss who are not able to derive adequate benefit from conventional hearing aids. A retrospective study was performed to assess the overall level of satisfaction of implanted patients and to investigate the potential determinants of postoperative success. Study Design A retrospective survey of audiological data from repeated measures and subjective data from self-assessment scales administered postoperatively was conducted to determine the degree of benefit and satisfaction for Vibrant Soundbridge implantees. Setting Twenty-one tertiary referral and teaching hospitals. Subjects The first 125 VSB implantees implanted in France between August 1997 and May 2001 were included in the study. Results No clinically significant change was observed for residual hearing postoperatively. Most patients (83%) reported they were either satisfied or very satisfied with the Vibrant Soundbridge. Analysis of correlation revealed a moderate correlation (Pearson coefficient r = 0.59) between the degree of benefit reported via the patient survey and the degree of benefit reported via the Glasgow Benefit Inventory. A moderate correlation (Pearson coefficient r = 0.66) was observed between speech comprehension scores in quiet for the preoperative unaided condition and the postoperative aided Vibrant Soundbridge condition. No correlation was observed between subjective reports of satisfaction postoperatively and performance on preoperative objective tests or patient characteristics. Conclusion The results indicate a high level of satisfaction with the VSB as a treatment of sensorineural hearing impairment in patients with a wide range of characteristics. Preoperative scores for unaided speech comprehension tests in quiet may be a potential indicator of success on aided Vibrant Soundbridge speech comprehension tests postoperatively but do not reflect patient satisfaction with the device reported on self-assessment scales.

PRESERVATION OF FACIAL, COCHLEAR, AND OTHER NERVE FUNCTIONS IN ACOUSTIC NEUROMA TREATMENT

Between March 1966 and September 1992, 1400 acoustic neuromas were treated in Paris, France, by surgical excision. The findings over the last 7 years are presented. The translabyrinthine approach has been used in more than 85% of cases. Where hearing preservation is attempted, the middle fossa approach has been adopted for intracanilicular tumors and the retrosigmoid approach for small tumors extending into the cerebellopontine angle, in which the fundus of the internal meatus is free of tumor. The main goal is to achieve a grade I or II result in facial function within 1 month of surgery. Results improved during 1991 after the introduction of continuous facial nerve monitoring and the use of the Beaver mini-blade for dissection of tumor from nerve. With these techniques, facial function at grade I or II at 1 month improved from 20% to 52% for large tumors (larger than 3 cm), from 42% to 81% for medium tumors (2 to 3 cm), and from 70% to 92% for small tumors (up to and including 2 cm extracanalicular). The facial nerve was at greater risk using the retrosigmoid or middle fossa approaches than by the translabyrinthine route. Since 1985, success in hearing preservation has changed little, with useful hearing being preserved in 38.2% of cases operated on by means of the retrosigmoid route and 36.4% of cases after the middle fossa approach. In older patients with good hearing and small tumors, observation with periodic MRI scanning is recommended. Despite earlier diagnosis, the number of patients suitable for hearing preservation surgery remains very limited and careful selection is required. Trigeminal nerve signs were present in 20% of cases preoperativey, in 10% postoperatively, and recovered spontaneously. Palsies of the other cranial nerves after surgery were much rarer and were as follows: sixth nerve (abducens), 0.5%; ninth nerve (glossopharyngeal), 1.4%; and tenth nerve (vagus), 0.7%. The importance of preservation of function of the nervus intermedius of Wrisberg is stressed. These results emphasize the advantages of the translabyrinthine approach, offering greater security to the facial nerve and lower morbidity.

A Multicenter Study of the Vibrant Soundbridge Middle Ear Implant: Early Clinical Results and Experience

Objective The Vibrant Soundbridge (VBS; Symphonix Devices, Inc., San Jose, CA, U.S.A.) is an active, semi-implantable, middle ear hearing device that directly drives the ossicular chain and is used in the treatment of patients with mild to severe sensorineural hearing loss. The benefits of the VBS and the effects of surgery were examined and compared with the preoperative aided condition in 25 patients with implants. Study Design Single-subject repeated-measures evaluations were performed with each patient acting as his or her own control. Objective audiologic measures and subjective questionnaires also were used. Setting Five tertiary referral and teaching hospitals. Subjects Adult patients had bilateral sensorineural hearing loss (average hearing loss, 56 dB; range, 33–80 dB). Twenty-one patients had worn a conventional hearing aid before surgery (11 binaurally, 10 monaurally). Four patients had not used a conventional hearing aid before surgery. Intervention Rehabilitative. Results No significant change in residual hearing after surgery was observed. Functional gain was significantly superior with the VBS. No significant differences were observed for aided speech recognition in quiet. A significant improvement in communication in various listening conditions was reported with the VBS as compared with conventional hearing aids. Conclusion The VBS surgical implantation procedure does not affect the residual hearing level in the implanted ear, nor does it present any unacceptable risk. Measurable benefit from the VBS in comparison with conventional amplification was demonstrated with regard to the provision of superior usable amplification and greater ease in communication in daily listening environments for the majority of patients.

Cardiovascular and Thromboembolic Risk Factors in Idiopathic Sudden Sensorineural Hearing Loss: A Case-Control Study

Objective: The pathogenesis of idiopathic sudden sensorineural hearing loss (ISSHL) remains unknown, but vascular involvement is one of the main hypotheses. The main objective of this study was to investigate the association between ISSHL and cardiovascular and thromboembolic risk factors. Study Design: Multicentric case-control study. Methods: Ninety-six Caucasian patients with ISSHL and 179 sex- and age-matched controls were included. Patients were evaluated on the day of the inclusion and 1 week, 3 weeks and 3 months later. Clinical information concerning personal and familial cardiovascular and thromboembolic risk factors and concerning the ISSHL was collected. Blood samples were collected for genetic analysis of factor V Leiden and G20210A polymorphism in the factor II gene. The severity of the hearing loss was classified as mild (21–40 dB), moderate (41–70 dB), severe (71–90 dB) and profound or total (>90 dB). Hearing improvement was calculated as a relative improvement of hearing thresholds using the contralateral ear as baseline. Results: Systolic blood pressure was higher in patients (130 ± 1.7 mm Hg) than in controls (124 ± 1.1 mm Hg, p = 0.003). The personal/familial history of cardiovascular events was also more prevalent in patients (p = 0.023 and p = 0.014, respectively), whereas no difference was found in the prevalence of personal cardiovascular risk factors (hypertension, diabetes mellitus, hyperlipidemia, smoking habits). There was no correlation between the audiogram type, the hearing outcome and the presence of cardiovascular risk factors. No significant difference was observed in the personal/familial history or in the presence of thromboembolic risk factors. The prothrombin and factor V mutations were uncommon in both patients and controls. The final hearing threshold was only correlated with the severity of the initial hearing loss (p < 0.001), but not influenced by the presence of vertigo, audiogram type, time elapsed from onset of ISSHL to hospitalization or failure of a previous oral therapy. Hearing stabilization was obtained at 21 days in 92% of patients. Conclusion: These results support the theory of vascular involvement as the etiology of some cases of ISSHL. The sole predictive factor of poor final hearing is the severity of the initial hearing loss.

Histamine and Betahistine in the Treatment of Vertigo Elucidation of Mechanisms of Action

The aim of this review is to provide clinicians with a picture of the mechanisms by which: (i) histamine and histaminergic agonists act on the vestibular system both peripherally and centrally; and (ii) histaminergic agonists and antagonists interfere with the recovery process after peripheral vestibular lesion. We have focused on betahistine, a structural analogue of histamine with weak histamine H1 receptor agonist and more potent H3 receptor antagonist properties, to review the currently available data on the role of the histaminergic system in the recovery process after peripheral vestibular deficits and the effects of histamine analogues in the clinical treatment of vertigo.This review provides new insights into the basic mechanisms by which betahistine improves vestibular compensation in animal models of unilateral vestibular dysfunction, and elucidates particularly the mechanisms of action of this substance at the level of the CNS.It is proposed that betahistine may reduce peripherally the asymmetric functioning of the sensory vestibular organs in addition to increasing vestibulocochlear blood flow by antagonising local H3 heteroreceptors. Betahistine acts centrally by enhancing histamine synthesis within tuberomammillary nuclei of the posterior hypothalamus and histamine release within vestibular nuclei through antagonism of H3 autoreceptors. This mechanism, together with less specific effects of betahistine on alertness regulation through cerebral H1 receptors, should promote and facilitate central vestibular compensation.Elucidation of the mechanisms of action of betahistine is of particular interest for the treatment of vestibular and cochlear disorders and vertigo.