Accessing the stapedius muscle via novel surgical retrofacial approach during cochlear implantation surgery: Intraoperative results on feasibility and safety.

Human stapedius muscle (SM) can be directly and safely accessed via retrofacial approach, opening new approaches to directly measure the electrically evoked stapedius reflex threshold (eSRT). The measurement of the SM activity via direct surgical access represents a potential tool for objective eSRT fitting of cochlear implants (CI), increasing the benefit experienced by the CI users and leading to new perspectives in the development of smart implantable neurostimulators. 3D middle-ear reconstructions created after manual segmentation and related SM accessibility metrics were evaluated before the CI surgery for 16 candidates with assessed stapedius reflex. Retrofacial approach to access the SM was performed after facial recess exposure. In cases of poor exposition of SM, the access was performed anteriorly to the FN via drilling of the pyramidal eminence (PE). The total access rate of the SM via both the retrofacial and anterior approach of the FN was 100%. In 81.2% of cases (13/16), the retrofacial approach allowed to access the SM on previously categorized well exposed (8/8), partially exposed (4/5), and wholly concealed (1/3) SM with respect to FN. Following intraoperative evaluation in the remaining 18.8% (3/16), the SM was accessed anteriorly via drilling of the PE. Exposure of SM with respect to the FN and the sigmoid sinus's prominence was a predictor for the suitable surgical approach. The retrofacial approach offers feasible and reproducible access to the SM belly, opening direct access to electromyographic sensing of the eSRT. Surgical planner tools can quantitatively assist pre-surgical assessment.

The Value of Electrically Evoked Stapedius Reflex in Determining the Maximum Comfort Level of a Cochlear Implant.

BACKGROUND: One of the most important steps for good user performance with a cochlear implant (CI) is activation and programming, aimed at determining the dynamic range. In adults, current levels are determined by psychophysical measures. In babies, small children, or individuals with multiple disorders, this procedure requires techniques that may provide inconsistent responses because of auditory inexperience or the age of the child, making it a very difficult process that demands the collaboration of both the patient and the family. PURPOSE: To study the relationship between the electrically evoked stapedius reflex threshold (ESRT) and maximum comfort level for stimulating electrodes (C-level) in postoperative CI users. RESEARCH DESIGN: Cross-sectional analytical observational case series study. STUDY SAMPLE: We assessed 24 patients of both sexes, aged between 18 and 68 yr, submitted to CI surgery. INTERVENTION: Otoscopy and immittance. Next, an implant speech processor connected to an Itautec® computer containing the manufacturer's software (custom sound Ep 3-2) was used, as well as an AT 235h probe inserted into the ear contralateral to the CI to capture the stapedius reflex, obtaining electrically evoked stapedius reflex thresholds. DATA COLLECTION AND ANALYSIS: Data from the last programming, defining C-levels for each electrode studied, were extracted from the databank of each patient. The manual decay function of the AT 235h middle ear analyzer was used to observe ESRT response in a same window for a longer response capture time. Electrodes 22, 16, 11, 6, and 1 were tested when active, with the aim of using electrodes over the entire length of the CI, and ESRT was considered present when compliance was ≥0.05 ml. Stimuli, in current units, were always initiated at 20 cu above the C-level. The analysis of variance parametric test, Tukey's honest significant difference test, the t-test, Wilcoxon nonparametric test, and the Kolmogorov-Smirnov test examined whether significant relationships existed between these other factors. RESULTS: The results demonstrate that all the electrodes selected for the study exhibited higher mean reflex threshold values than their mean C-level counterparts. However, there was no significant difference between them, for electrodes 1, 6, 11, and 16. The data provided allow the use of ESRT to define C-level values and make it possible to stipulate a correction factor ranging between 6 and 25.6 electrical units. CONCLUSION: The use of electrically evoked stapedius reflex thresholds can help the team in charge of programming CIs, making the process faster and safer, mainly for infants, small children, or individuals with multiple disorders.

On the origin of ear clicks during deglutition or pressure equalization.

To explore the origin of clicking sounds in the ear during deglutition or other pharyngeal movements, which are interpreted differently in the literature. Experimental study at a tertiary referral centre. Acoustic phenomena during a forced opening test of the Eustachian tube (ET) were studied in a temporal bone model. Additionally, in vivo experiments were carried out in healthy volunteers for ruling out movements of the ossicular chain or the drumhead as potential causes of clicks. Thus, acoustic recordings were performed parallel to stapedius or tensor reflex measurements or pneumatic video endoscopies of the tympanic membrane. Obviously the acoustic signals (clicks) appear when the tube opens, which could be visualized and acoustically recorded during forced opening tests in temporal bone experiments. Middle ear muscle contractions with movements of the tympanic membrane did not cause any click events. Together with the results of a previous paper (9) we interpret the clicks as disruptions of fluid or mucus films covering the mucosa during the ET opening. The final goal of our studies is to use such clicks as indicators of ET openings in a new tube function test, which has to be elaborated.

[The clinical application of objective hearing monitoring technology in cochlear implants].

OBJECTIVE: Compare the clinical characteristics and application value between elcetrically evoked stapedius responses and neural response telemetry. METHOD: Select number 1, 7, 11, 17, 22 electrodes from 21 cochlear implanting nucleus 24R cochlear implants, using NRT3.0 software provided by Cochlear corporation to test the threshold of elcetrically evoked stapedius responses and neural response telemetry during operation and subjective psychological physical test after operation repectively named elcetrically evoked stapedius responses threshold, electrically evokded compound aciton potentials threshold, and T-levels. Respectively study the correlations of ESRT, ECAP threshold, and T-levels. RESULT: The detection rates of ESRT, NRT, and T-levels were 96.19%, 93.33%, 100%. The mean thresholds of ESRT were 206.61 +/- 10. 74, 208.48 +/- 13.64, 205.52 +/- 14. 63, 203.76 +/- 12.97, 199.50 +/- 11.19; The mean thresholds of NRT were 184.11 +/- 6.35, 188.55 +/- 11.70, 187.00 +/- 12.29, 181.85 +/- 13.22, 179.00 +/- 10.50; The mean thresholds of T levels were 145.48 +/- 18.66, 148.62 +/- 8.22, 146.62 +/- 18.08, 142.52 +/- 13.11, 140.33 +/- 13.68. The mean thresholds of ESRT in each electrode were rather greater than that of T-levels. There is a high degree of consistency in the mean thresholds of ES RT, NRT and T-levels. The test time, test means, unilaterally detection rate during operation, ESR is better than NRT. All the electrodes were set as observation objects, the correlation of ESRT and NRT is 0.69, the correlation of NRT and T is 0.62, and the correlation of ESRT and T is 0.39. CONCLUSION: The application of elcetrically evoked stapedius responses and neural response telemetry during operation can rapidly estimate wether the implant is in good condition and the pathway is normal. Rather than neural response telemetry, elcetrically evoked stapedi us responses is more flexible, convienient, accurate and visual, while it is more objective superiority after operation especially for young children for the former detector.

Would an endosteal CI-electrode make sense? Comparison of the auditory nerve excitability from different stimulation sites using ESRT measurements and mathematical models.

UNLABELLED: Regarding potential endosteal cochlear implant electrodes, the primary goal of this paper is to compare different intra- and extra-cochlear stimulation sites in terms of current strengths needed for stimulating the auditory nerve. Our study was performed during routine cochlear implantation using needle electrodes for electric stimulation and by visually recording electrically elicited stapedius reflexes (ESRT) as a measure for the stimulus transfer. Of course this rather simple setup only allows rough estimations, which, however, may provide further arguments whether or not to proceed with the concept of an endosteal electrode. In addition, a mathematical model is being developed. In a pilot study, intra-operative electric stimuli were applied via a needle electrode commonly used for the promontory stimulation test. Thus, stapedius reflex thresholds (ESRTs), electrically elicited via the needle from different points inside and outside the cochlea served as indicators for the suitability of different electrode positions towards the modiolus. Tests were performed on 11 CI-recipients. In addition, the extension of electrical fields from different stimulation sites is simulated in a mathematical cochlea model. In most patients ESRT measurements could be performed and evaluated. Thus an "endosteal" stimulation seems possible, although the current intensities must be higher than at intraluminal stimulation sites. Moreover, our model calculations confirm that the extension of electric fields is less favourable with increasing distance from the electrode to the ganglion nerve cells. In terms of hearing, the concept of an endosteal electrode should only be promoted, if its superiority for hearing preservation can be proven, e.g. in animal experiments. However, for other indications like the electric suppression of tinnitus, further research seems advisable. LEVELS OF EVIDENCE: N/A.

[The objective method for recording stapedial reflex during surgery for cochlear implantation].

The purpose of the present study was to develop a method for the objective registration of the stapedial reflex at the contralateral ear during cochlear implantation surgery on the affected one. The excessive pressure in the middle ear (up to 500 daPa) was compensated by the administration of an additional air volume (1 liter) into the AA220 impedance meter pneumatic circuit. A syringe was used to measure variations of pressure in the new pneumatic circuit. Eight of the 12 patients demonstrated coincident visual and objective reflex thresholds. In the remaining 4 patients, the visually apparent stapedial reflex thresholds proved higher than those obtained objectively by the standard procedure of impedancemetry. It is concluded that the objective registration of the stapedial reflex excludes the effect of subjective factors interfering with its estimation and provides the possibility for comparative intra- and postoperative studies using one and the same instrument.

Acoustic stapedius reflex function in man revisited.

OBJECTIVE: The objective of this study was to examine the role of the acoustic stapedius reflex in the protection of speech recognition from the upward spread of masking arising from low-frequency background noise. DESIGN: Speech recognition scores were measured for nine control participants (19-34 years) and six patients with transected stapedius tendons poststapedotomy (39-57 years) as a function of the amplitude of a low-frequency masker, presented at nominal signal to noise ratios of +5 dB, -5 dB, and -15 dB. All participants had pure-tone hearing thresholds in the normal range. Continuous high-pass noise was present in all conditions to avoid ceiling effects; this reduced performance in quiet to approximately 85% for all participants. Scores were measured for soft and loud nonsense syllables (average third octave band levels of 35 and 65 dB SPL), so that a comparison of the low-frequency noise masking functions at the two levels would provide information about the effects of the reflex on speech intelligibility in noise. A third group of nine control participants (19-22 years) listened in the presence of a low-frequency masker gated to come on 1 sec before stimulus onset, to reduce the likelihood of reflex adaptation. The Speech-Intelligibility Index was used to quantify the amount of speech information available in each condition. RESULTS: Patients with transected tendons performed more poorly than control participants as a function of Speech-Intelligibility Index in all conditions, even at levels that were too soft for reflex activation. This could be because of postsurgical differences in sensitivity, the more advanced age of poststapedotomy group, or differences in medial olivocochlear inhibition. For loud speech, patient performance fell nearly linearly with increases in the low-frequency masker, but control participants' performance declined little as the signal to noise ratio declined from +5 to -5 dB, and then fell rapidly as the ratio declined to -15 dB. This plateau in the masking function did not occur for the patients. Masking functions obtained with the gated low-frequency masker were either highly similar or poorer to those obtained with a continuous masker, suggesting that the use of a continuous low frequency masker did not result in significant reflex adaptation. CONCLUSIONS: The stapedius reflex appears to offer some protection from the upward spread of masking of speech by background low-frequency noise at moderate levels, but not at high levels.

Evaluation of muscle hyperactivity of the grimacing muscles by unilateral tight eyelid closure and stapedius muscle tone.

Muscle hyperactivity of grimacing muscles, including the orbicularis oculi and corrugator supercilii muscles that cause crow's feet and a glabellar frown line with ageing, cannot be accurately evaluated by surface observation. In 71 subjects, this study investigated the extent to which grimacing muscles are innervated by the bilateral motor cortices, whether the corticofacial projection to the grimacing muscles affects the facially innervated stapedius muscle tone by measuring static compliance of the tympanic membrane, and whether unilateral tight eyelid closure with contraction of the grimacing muscles changes static compliance. Unilateral tight eyelid closure and its subsequent change in the contralateral vertical medial eyebrow position revealed that motor neurons of the orbicularis oculi and corrugator supercilii muscles were innervated by the bilateral motor cortices with weak-to-strong contralateral dominance. The orbicularis oculi, corrugator supercilii, and stapedius muscles innervated by the bilateral motor cortices had increased muscle hyperactivity, which lowered the vertical medial eyebrow position and decreased the static compliance of the tympanic membrane more than those innervated by the unilateral motor cortex. Unilateral enhanced tight eyelid closure with contraction of the grimacing muscles in certain subjects ipsilaterally decreased the static compliance with increased contraction of the stapedius muscle, which probably occurs to immobilise the tympanic membrane and protect the inner ear from loud sound. Evaluation of unilateral tight eyelid closure and the subsequent change in the contralateral vertical medial eyebrow position as well as a measurement of the static compliance for the stapedius muscle tone has revealed muscle hyperactivity of grimacing muscles.

Intra- and postoperative electrically evoked stapedius reflex thresholds in children with cochlear implants.

OBJECTIVES: The aim of this study was to investigate whether there is a significant correlation between intra- and postoperative electrically evoked stapedius reflex thresholds (eSRTs) in children with cochlear implants. METHODS: Sixty-five pediatric cochlear implant users were included in this study. All patients had congenital prelingual hearing loss. The round window approach was used in all patients. The eSRTs were intraoperatively measured using the 1st, 3rd, 6th and 12th electrodes of the cochlear implant. The measurements taken during the first fitting of the device were taken again one month after surgery. We used paired-sample t-tests to determine the correlation between intra- and postoperative eSRTs. RESULTS: The eSRT analysis revealed a statistically significant difference between the intra- and postoperative thresholds. A correlation analysis did not reveal any correlation between intra- and postoperative eSRTs. CONCLUSION: Intraoperative eSRT measurements were unable to predict early postoperative eSRTs.

How reliable is visual assessment of the electrically elicited stapedius reflex threshold during cochlear implant surgery, compared with tympanometry?

OBJECTIVES: To assess the reliability of visually assessed thresholds of the electrically elicited stapedius reflex, recorded during cochlear implant surgery, compared with intra-operative tympanometric threshold assessment. Intra-operatively recorded electrically elicited stapedius reflex thresholds vary considerably, and differ from those measured post-operatively by means of impedance changes (i.e. using tympanometry). Thus, any confounding effect of different intra-operative techniques and visual assessment inaccuracies should be excluded. METHODS: Both techniques (i.e. visual observation and tympanometry) were performed intra-operatively in six patients, and threshold values were compared. RESULTS: Recorded electrically elicited stapedius reflex thresholds were very similar for both techniques. Visually assessed thresholds were slightly higher in some cases and lower in others, compared with tympanometric thresholds. DISCUSSION: There was almost no difference between reflex thresholds measured with the two different techniques under the same intra-operative conditions. Therefore, we conclude that differences between intra- and post-operative thresholds are not due to the use of different measuring techniques. The main reason for such differences is probably the influence of intra-operative narcotics on reflex thresholds.

Vestibular schwannoma: when to look for it?

OBJECTIVES: (1) To compare audiometric parameters in patients with vestibular schwannoma and in those with asymmetric hearing loss from other causes; and (2) to assess proposed screening criteria by comparing published protocols. METHODS: Audiometric data from 199 vestibular schwannoma patients and 225 non-tumour patients were compared. Eight screening protocols were tested on these 424 patients. RESULTS: Vestibular schwannoma and non-tumour patients with little or no hearing loss in the unaffected ear were inseparable; however, vestibular schwannoma patients with hearing loss in the unaffected ear had greater audiometric asymmetry, compared with non-tumour patients with the same pattern of hearing loss. The sensitivity of screening protocols varied from 73 to 100 per cent; parallelism was observed between sensitivity and screening rate. CONCLUSION: As regards vestibular schwannoma screening protocols, the best compromise between sensitivity and screening rate was offered by a criterion comprising either: (1) > or =20 dB asymmetry at two neighbouring frequencies, or unilateral tinnitus, or (2) > or =15 dB asymmetry at two frequencies between 2 and 8 kHz.

[Study of the relationship of stapedial reflex thresholds induced during cochlear implant surgery and the highest hearing comfort of paediatric patients]. / Estudio de la correlación entre los umbrales del reflejo estapedial inducido durante la cirugía del implante coclear y la máxima comodidad auditiva del paciente pediátrico.

INTRODUCTION AND GOALS: We have studied the relationship between the minimum stapedial reflex thresholds induced by means of the intra-operative stimulation of the cochlear implant and the post-operative thresholds of highest auditory comfort level. METHODS: We have assessed the maximum auditory comfort at the end of the first and second quarters following activation of the cochlear implant, by which time the strategy for codification of the stimuli and the programming map are considered to be already stable. The study was carried out at our cochlear implants unit. All the patients in the study had bilateral sensorineural deafness of varying aetiology and, following our standardized battery of diagnostic tests, were considered to be good candidates for cochlear implant. All aspects of the surgical technique were kept the same in order to be able to compare the results better. All members of the study were fitted with at least one Nucleus Freedom implant with Contour Advance Electrode. RESULTS: This study has been carried out on 24 cochlear implants placed in 22 patients younger than 14 years old. CONCLUSIONS: After assessing our experience, we can conclude that, in the Nucleus Freedom with Contour Advance Electrode cochlear implant, there is a positive statistical relationship between the levels of acoustic reflex induction obtained at the peri-operative stage and the levels of maximum auditory comfort, as determined by behavioural observation techniques for each of the different electrodes, in children up to 14 years old.

[Analysis of the mechanical-acoustic features of the middle ear after stapedial surgery both with and without stapes muscle preservation]. / Estudio de las características mecanoacústicas del oído medio sometido a cirugía estapedial con y sin conservación del tendón del estribo.

INTRODUCTION AND OBJECTIVE: Stapes replacement surgery performed in cases of otosclerosis alters various anatomical (ossicular, ligament, and tendon) elements of the middle ear affecting their physical properties. The goal of our work is to determine which of the surgical techniques applied during otosclerosis most respects the mechanical-acoustic features of the middle ear. PATIENTS AND METHOD: We analyzed the audiological and admittance results of 100 patients who underwent various stapedial replacement techniques and compared them to 20 otologically healthy subjects. RESULTS: The audiological results obtained are similar in the different surgical techniques compared. However, those techniques in which the stapedial muscle tendon is preserved offer similar hearing resonance frequencies post intervention as healthy ears, which was not found to be the case in the remaining techniques evaluated. CONCLUSIONS: We feel that the stapedial tendon should be preserved during otosclerosis surgery as the mechanical-acoustic features of the ear are thus better conserved, leading to enhanced language recognition in noisy environments.

[Electrically evoked stapedius reflex threshold and its clinical contribution of cochlear implantations].

OBJECTIVE: To investigate and measure the electrically evoked stapedius reflex threshold (ESRT) and the maximum comfortable level (MCL), the feasibility of using objective index of the fitting of speech processor was evaluated. METHODS: The relationship of ESRT and MCL was conducted by measuring the ESRT and MCL of 28 Medel Combi 40 + cochlear implant users from August 2003 to April 2006. RESULTS: The incidence of ESRT of 10 patient during operation was 78.3% (94/120), and the incidence 3 months after the operation was 82.5% (99/120). The incidence of ESRT in 3 patients with Large vestibular aqueduct syndrome was 47.2% (17/36). The ESRT and MCL of each electrode of those 28 patients after operation were compared, the result was shown as following: (1) 247 electrodes' MCL were greater than ESRT; (2) 14 electrodes' MCL were equal to ESRT; (3) 46 electrodes' MCL were smaller than ESRT. The average of ESRT after operation was (677.1 +/- 109.8) cu, the average of MCL was (732.3 +/- 114.8) cu. ESRT was smaller than MCL (t = 11.37, P < 0.05). CONCLUSIONS: The cochlear implantations must be in normal working condition when ESR was positive. ESRT is a useful method to map the fitting of speech processor.

Estudo comparativo entre nível de desconforto e reflexo acústico em trabalhadores / Comparative study between the level of discomfort and the acoustic reflex in workers

TEMA: estudo comparativo do nível do desconforto e do limiar do reflexo acústico em trabalhadores. OBJETIVO: observar o comportamento auditivo por meio da avaliação da atividade da contração do músculo estapédio e do nível de desconforto em pessoas expostas e não expostas a ruído ocupacional, com intuito de identificar alguma influencia do ruído no comportamento da contração do músculo estapédio e na sensibilidade auditiva. MÉTODO: o estudo foi desenvolvido no Serviço Social da Indústria - SESI Ceará. Foram selecionados 103 adultos com audição normal, de ambos os sexos, na faixa etária de 18 a 45 anos distribuídos em três grupos: G1 com 41 adultos expostos a ruído que utilizavam EPIA, G2 com 32 adultos expostos a ruído que não utilizavam EPIA e G3 composto por 30 adultos não expostos. Os indivíduos foram submetidos à avaliação audiológica, tendo sido analisado o LRA e ND nas freqüências de 500Hz, 1000Hz, 2000Hz, 3000Hz, 4000Hz e WN. A análise estatística foi realizada por meio dos testes de Mann Whitney, Wilcoxon e Kruskal com nível de significância em 5 por cento. RESULTADOS: não houve diferença estatística significante entre os LRA obtidos nos três grupos, com valores médios de 93 a 103dBNA; o LRA foi significantemente menor que o ND, tendo valores médios para ND variando de 111 a 119dBNA no G1, de 113 a 120dBNA no G2 e 106 a 114dBNA no G3; o ND é maior nos indivíduos do grupo G1 seguidos pelos grupos G2 e G3. CONCLUSÕES: o ruído não determina alterações no comportamento do LRA; o ND é aumentado pela exposição ao ruído ocupacional; o ND é maior que o LRA de 10 a 25dB.

Influence of anaesthetic agents on transient evoked otoacoustic emissions and stapedius reflex thresholds.

This aim of this study was to determine the effect of anaesthetic agents on stapedius reflex (SR) thresholds and transient evoked otoacoustic emissions (TEOAE). Fifty patients who were scheduled for operation and who had normal hearing were included in the study. All were given midazolam for premedication and propofol for induction. Anaesthesia was maintained in five different ways in each group of 10 patients. Groups I-IV received inhalational anaesthesia: group I received 70 per cent N2O plus 30 per cent O2, group II sevoflurane, group III desflurane and group IV halothane. Group V received total intravenous anaesthesia with propofol plus sufentanil. The SR and TEOAE of the patients were measured four times: on the day before surgery (first measurement), after premedication (second measurement), after induction of anaesthesia (third measurement) and during maintenance of anaesthesia (fourth measurement). Midazolam significantly increased ipsilateral and contralateral SR thresholds and decreased TEOAE wave reproducibility. Propofol significantly increased only the SR thresholds. The other anaesthetic agents significantly increased only the contralateral reflex thresholds. Of these, the highest increase was seen after sevoflurane and the lowest after halothane. The changes in TEOAE wave reproducibility due to anaesthetic agents used for maintenance were not significant. We concluded that midazolam premedication may affect audiological evaluation with SR and TEOAE tests, and sevoflurane should not be used when it is necessary to measure SR under general anaesthesia.

Identificação de sentenças sintéticas (SSI) e reflexo acústico contralateral / Synthetic sentence identification (SSI) and contralateral acoustic stapedius reflex

TEMA: estudo da relação do reflexo acústico contralateral na habilidade auditiva de fechamento auditivo. OBJETIVO: analisar a identificação do sinal de fala em presença de sons competitivos em sujeitos com ausência do reflexo acústico contralateral. MÉTODO: aplicação do teste de identificação de sentenças sintéticas (SSI) nas condições mensagem competitiva contralateral (SSI-MCC), na relação sinal-ruído de 0 e -40dB e mensagem competitiva ipsilateral (SSI-ICM), na relação sinal-ruído de 0, -10, -15 e -20dB, em 43 adultos-jovens (grupo A = 21 sujeitos com presença do reflexo acústico contralateral em todas as freqüências pesquisadas e grupo B = 22 sujeitos com ausência do reflexo na freqüência de 500Hz, em todas as freqüências pesquisadas ou ainda em algumas das freqüências pesquisadas, mas que incluísse 500Hz), de ambos os sexos sem queixas auditivas, otológicas ou de aprendizagem. RESULTADOS: o limiar do reflexo acústico esteve acima de 100dB NA em 59 por cento dos indivíduos do grupo B e em 14 por cento dos indivíduos do grupo A, todos os indivíduos apresentaram desempenho de acordo com o padrão de normalidade sugerido pela literatura especializada para o teste SSI, o desempenho do grupo B no teste SSI-ICM foi inferior ao grupo A em todas as relações sinal-ruído utilizadas, embora a diferença não tenha sido estatisticamente significante, o grupo B que apresentou limiar do reflexo acústico superior a 100dB NA ou ausência do reflexo acústico também foi o que apresentou pior desempenho no teste SSI. CONCLUSAO: a ausência do reflexo acústico contralateral parece interferir na identificação do sinal de fala na presença de ruídos competitivos.

Influence of EEG monitoring on intraoperative stapedius reflex threshold values in cochlear implantation in children.

BACKGROUND: Cochlear implantation is a widely used means of treating deafness and severe hearing disorders. The surgical procedure includes inserting the cochlear implant electrode array into the cochlea and embedding the corresponding signal receiver in the mastoid bone behind the ear. Postoperative fitting of the externally worn speech processor is very important for successful use of the cochlear implant. For this purpose, electrically elicited stapedius reflex threshold values can be used. However, stapedius reflex threshold values measured intraoperatively are influenced by anaesthetics. The goal of this retrospective study was to find out whether electroencephalogram (EEG) control of anaesthesia produces more reliable reflex threshold values as a basis for the fitting of the speech processor. METHODS: Three groups of children, after surgery for cochlear implantation, were analysed with regard to the magnitude of intraoperative electrically elicited stapedius reflex threshold values and their deviations from postoperatively determined maximum comfortable levels (group 1: methohexital/remifentanil with EEG monitoring, n = 10; group 2: isoflurane/fentanyl with EEG monitoring, n = 9; group 3: isoflurane/fentanyl without EEG monitoring, n = 11). RESULTS: Children with EEG monitoring had significantly lower electrically elicited stapedius reflex threshold values and also significantly lower differences between intraoperative stapedius reflex threshold values and postoperatively determined maximum comfortable levels. CONCLUSIONS: Electroencephalogram monitoring in cochlear implantation is of considerable value in controlling anaesthesia and improving speech processor fitting based on more reliable intraoperative neurophysiological data.

Occupational exposure to noise decreases otoacoustic emission efferent suppression.

With the discovery of otoacoustic emissions (OAEs), the efferent cochlear system has become accessible for investigation in humans. Recently, it has been suggested that contralateral sound activated OAE efferent suppression may provide an early indication of auditory damage due to exposure to noise. In this study, OAE efferent suppression in normally hearing subjects, occupationally exposed to noise, was compared with respective effects in healthy, non-exposed subjects. The noise-exposed group exhibited higher mean hearing thresholds at frequencies 4, 6 and 10 kHz (p < 0.01) and lower-level transient-evoked otoacoustic emission (TEOAE) and distortion-product otoacoustic emission (DPOAE) at a frequency of 4 kHz (not significant). TEOAE efferent suppression was moderately decreased, whereas DPOAE efferent suppression was negligible, in the exposed group compared to non-exposed subjects. The results of the study suggest that OAEs, particularly DPOAE contralateral suppression, are likely to become a valuable method for assessing early hearing damage caused by exposure to noise.

Menière's disease in the elderly.

OBJECTIVES: To assess the prevalence, presentation, treatment, and evolution of Menière's disease in elderly patients (> or = 65 yr old). STUDY DESIGN: Retrospective clinical study and case report. SETTING: A neuro-otology referral center at the university hospital in Bern, Switzerland, and a neurotologic practice in Geneva, Switzerland. PATIENTS: Patients were selected from the hospital clinic and otolaryngologic practice registers. Among 8423 neurotologic checkups performed between 1988 and 1998, 432 (5.1%) patients had definite Menière's disease and 66 (15.3%) of these patients were > or = 65 years old. INTERVENTION: The files of these 66 patients were analyzed. RESULTS: Menière's disease in the elderly had 2 modes of presentation: reactivation of longstanding Menière's disease (40.9%) and de novo Menière's disease (59.1%), where the first dizzy spells, tinnitus, and hearing loss appeared after 65 years of age. Drop attacks occurred in 11.1 and 25.6% of the cases, respectively, and could be responsible for misdiagnosis of strokes of the brainstem. The patients were treated by mild antivertiginous drugs (betahistine, cinnarizine). Twenty-seven patients (41%) underwent surgery: transtympanic ventilation tubes (19 patients), sacculotomy (4 patients), vestibular neurectomy (3 patients), surgical labyrinthectomy (1 patient). The vertigo spells disappeared in 73.3 to 100% of the cases according to the type of surgery performed. CONCLUSION: Our study shows that Menière's disease in the elderly is not at all uncommon. It can appear as a de novo disease or as a reactivated longstanding disease. Drop attacks are more frequent than reported in general patient populations with Menière's disease and can mimic a stroke of the brainstem. Medical and surgical treatments have to be cautious because many of these elderly patients are fragile.