Acoustic reflexes: should we be paying more attention?

OBJECTIVE: The clinical audiology test battery often involves playing physically simple sounds with questionable ecological value to the listener. In this technical report, we revisit how valid this approach is using an automated, involuntary auditory response; the acoustic reflex threshold (ART). DESIGN: The ART was estimated four times in each individual in a quasi-random ordering of task conditions. The baseline condition (referred to as Neutral) measured the ART following a standard clinical practice. Three experimental conditions were then used in which a secondary task was performed whilst the reflex was measured: auditory attention, auditory distraction and visual distraction tasks. STUDY SAMPLE: Thirty-eight participants (27 males) with a mean age of 23 years were tested. All participants were audiometrically healthy. RESULTS: The ART was elevated when a visual task was performed at the same time as the measurements were taken. Performing an auditory task did not affect the ART. CONCLUSIONS: These data indicate that simple audiometric measures widely used in the clinic, can be affected by central, non-auditory processes even in healthy, normal-hearing volunteers. The role of cognition and attention on auditory responses will become ever more important in the coming years.

Evaluation of outcome of acoustic reflex tests in patients with type 2 diabetes mellitus: a cross-sectional study.

PURPOSE: Type 2 diabetes mellitus (T2DM) may induce micro-vascular and macro-vascular changes that can lead to neuropathic changes which may affect the auditory pathway resulting in hearing loss. The study aims to evaluate the outcome of ipsilateral and contralateral acoustic reflex (AR) parameters and reflex decay tests (RDT) in patients with T2DM, and the relationship between average AR parameters, and duration and control of T2DM. METHODS: An analytical cross-sectional study was conducted in a tertiary care setup in 126 subjects which included 42 subjects with T2DM between 30 and 60 years of age, age-matched with 84 non-diabetic subjects. The subjects were evaluated for pure tone average (PTA), speech identification score (SIS), AR parameters [acoustic reflex threshold (ART), acoustic reflex amplitude (ARA), acoustic reflex latency (ARL)] and RDT. RESULTS: The subjects with T2DM showed increased PTA in both ears when compared to the subjects with no disease. No significant difference was found in the SIS between both groups. There was no significant difference in the ART and ARL between the two groups. There was a significant difference in the ipsilateral and contralateral ARA at 500 Hz, 1000 Hz and broadband noise (BBN) when compared between the diabetic and non-diabetic groups. No significant difference was found between average AR parameters and duration and control of T2DM. CONCLUSION: T2DM increases hearing thresholds and reduces ipsilateral and contralateral AR at lower frequencies and BBN. Duration and control of T2DM do not affect the AR parameters.

The effect of cochlear implant age and duration of intervention on ESRT in children with cochlear implant.

OBJECTIVE: To study the effect of cochlear implant age and duration of the intervention (auditory rehabilitation post-cochlear implantation) on ESRT in children with cochlear implants. METHODS: A total of 90 pre-lingual cochlear implant users were included. For the measurement of ESRTs the recipient's processor was connected to the programming pod and electrode numbers 22, 11 and 3 (apical, middle and basal), respectively, were activated to give stimulation sequentially and elicit deflection as a response. RESULTS: There were significant differences in the measured T, C and ESRT levels with respect to the duration of the intervention (auditory rehabilitation post-cochlear implantation) and cochlear implant age obtained at p < 0.05*, 0.01**. DISCUSSION: The differences in the T, C and ESRT levels after continued device usage and after attending auditory rehabilitation sessions post-cochlear implantation are subjected to optimal benefit from implantation during the critical period. CONCLUSION: The differences in T, C and ESRT levels can be utilised clinically to study the importance of duration of cochlear implant device usage and the importance of auditory rehabilitation post-cochlear implantation in children with cochlear implantation.

Study of auditory pathways in type 1 diabetes mellitus through brainstem auditory evoked potentials and contralateral acoustic reflex.

PURPOSE: To investigate the functionalities of the neural pathways through the auditory evoked potentials of the brainstem and the contralateral stapedial acoustic reflexes in normal-hearing individuals with type 1 diabetes mellitus, in order to detect possible alterations in the central auditory pathways. METHODS: This is a cross-sectional study with a comparison group and a convenience sample, consisting of 32 individuals with type 1 diabetes mellitus and 20 controls without the disease. All subjects had hearing thresholds within normal limits and type A tympanometric curves. The acoustic reflex arc and brainstem auditory potentials were investigated. Statistical analyses were performed using the SPSS 17.0. The Chi-square test, Student´s t-test, and Multiple linear regression were used. RESULTS: The auditory thresholds of the acoustic reflex were statistically lower in the group with the disease at frequencies of 0.5 kHz and 1.0 kHz in the left ear (p=0.01 and p=0.01, respectively). The absolute latencies III and V of the auditory potentials of the brainstem in the right ear and V in the left ear were increased in subjects with type 1 diabetes mellitus (p=0.03, p=0.02 and p=0.03, respectively). CONCLUSION: The findings suggest that subjects with type 1 diabetes mellitus are more likely to present alterations in the central auditory pathways, even with auditory thresholds within normal limits.

Effects of preloads on middle-ear transfer function and acoustic reflex in ossiculoplasty with PORP.

INTRODUCTION: Surgical outcomes in ossiculoplasty with partial ossicular replacement prostheses (PORPs) are greatly influenced by the amount of preload imposed on the PORP. In this study, the attenuation of the middle-ear transfer function (METF) was experimentally investigated for prosthesis-related preloads in different directions, with and without concurrent application of stapedial muscle tension. Different PORP designs were assessed to determine functional benefits of specific design features under preload conditions. METHODS: The experiments were performed on fresh-frozen human cadaveric temporal bones. The effect of preloads along different directions were experimentally assessed by simulating anatomical variance and postoperative position changes in a controlled setup. The assessments were performed for three different PORP designs featuring either a fixed shaft or ball joint and a Bell-type or Clip-interface. Further, the combined effect of the preloads towards the medial direction with tensional forces of the stapedial muscle was assessed. The METF was obtained via laser-Doppler vibrometry for each measurement condition. RESULTS: The preloads as well as the stapedial muscle tension primarily attenuated the METF between 0.5 and 4 kHz. The largest attenuations resulted from the preload towards the medial direction. The attenuation of the METF with stapedial muscle tension was reduced with concurrent PORP preloads. PORPs with a ball joint resulted in reduced attenuation only for preloads along the long axis of the stapes footplate. In contrast to the clip interface, the Bell-type interface was prone to lose coupling with the stapes head for preloads in the medial direction. CONCLUSIONS: The experimental study of the preload effects indicates a direction-dependent attenuation of the METF, with the most pronounced effects resulting from preloads towards the medial direction. Based on the obtained results, the ball joint offers tolerance for angular positioning while the clip interface prevents PORP dislocations for preloads in lateral direction. At high preloads, the attenuation of the METF with stapedial muscle tension is reduced, which should be considered for the interpretation of postoperative acoustic reflex tests.

Automated Adaptive Wideband Acoustic Stapedius Reflex Thresholds in Adults With Normal Hearing and Sensorineural Hearing Loss.

OBJECTIVES: This study compared the measurement of the acoustic stapedius reflex threshold (ART) obtained using a traditional method with that obtained using an automated adaptive wideband (AAW) method. Participants included three groups of adults with normal hearing (NH), mild sensorineural hearing loss (SNHL), or moderate SNHL. The purpose of the study was to compare ARTs for the three groups and to determine which method had the best performance in detecting SNHL. DESIGN: Ipsilateral and contralateral ARTs were obtained using 0.5, 1, and 2 kHz tonal activators, and broadband noise (BBN) activators on a traditional admittance system (Clinical) at tympanometric peak pressures (TPP) and on an experimental wideband system using an AAW method at both ambient pressure and TPP. ART data previously reported for 39 NH adults with a mean age of 47.7 years were compared with data for 25 participants with mild SNHL with a mean age of 63.8 years, and 20 participants with moderate SNHL with a mean age of 65.7 years. Differences in ARTs between the normal-hearing and SNHL groups for the three methods were examined using a General Linear Model Repeated-Measures test. A receiver operating characteristic curve (ROC) analysis was also used to determine the ability of an ART test to detect SNHL. RESULTS: For the 0.5 kHz activator condition, there were no significant group mean differences in ART between NH and SNHL groups for either ipsilateral or contralateral activator presentation modes for the Clinical or AAW methods. There were significant group mean differences for the 1 and 2 kHz tonal activators and BBN activator for both ipsilateral and contralateral modes with greater differences in ART between groups for the AAW method than the Clinical method. In these conditions, the mean ART was lower for the AAW tests relative to the Clinical test. The greatest difference between groups was for the ipsilateral AAW tests for the comparison of NH with moderate SNHL for the BBN activator. This difference was approximately 20 dB for the AAW tests and 8 dB for the Clinical test. The ROC analysis showed that the area under the ROC curve (AUC) increased with the frequency of the activator stimulus and with the degree of hearing loss and was maximal for the BBN activator for both the AAW and Clinical methods for both ipsilateral and contralateral presentations. CONCLUSIONS: For ipsilateral and contralateral ART tests for activator frequencies above 0.5 kHz and BBN, listeners with SNHL generally had elevated ARTs compared with those with NH. The AAW method resulted in greater differences between SNHL groups and NH than the Clinical method. The AUC for detecting SNHL also increased with activator frequency and degree of hearing loss and was greatest for the BBN activator for the AAW method in both the ambient and TPP conditions. The results are encouraging for the use of an AAW ART method for the assessment of individuals with SNHL.

Acoustic Reflex After Surgical Repair in Patients with Congenital Aural Atresia.

BACKGROUND: This study aimed to examine the plasticity of nerves indirectly by acoustic reflex after surgical repair of unilateral congenital aural atresia. METHODS: This study is a retrospective study including 80 patients who had undergone surgical repairs of congenital aural atresia before 18 years old and for whom acoustic reflex testing was performed postoperatively. Several variables correlated with acoustic reflex were analyzed to find factors affecting the presence of acoustic reflex. RESULTS: Among 80 patients, 44 were positive for acoustic reflex. As a result of multivariate analysis, good postoperative hearing (P = .017), younger age at surgery (P = .028), and the longer time interval between surgery and acoustic reflex test (P = .040) were revealed as factors affecting the acoustic reflex. CONCLUSION: Acoustic reflex was present in 55% of surgically managed patients with congenital aural atresia. The results of this study imply that the reflex arc of acoustic reflex may be restored after proper surgical reconstruction and prolonged use of reconstructed ear in patients with unilateral congenital aural atresia.

Audiology Clinical Practice Patterns in Acoustic Reflex Testing.

PURPOSE: Periodic reports of audiology clinical practice patterns, including acoustic reflex threshold (ART) protocols, provide insights into trends and assist in clinical decision making. Therefore, the purpose of this study was to examine audiologists' ART protocols, factors influencing audiologists' decision to test, and considerations for mentoring Doctor of Audiology (AuD) students in ART testing. METHOD: This study used a paper survey distributed by mail to a random sample of audiologists. Participants were 102 audiologists, representing diversity across age, clinical experience, and work setting. The survey asked participants to provide (a) demographics, (b) ART protocols, (c) rationale for ART testing, and (d) perspectives on mentoring of ART testing. RESULTS: When ART testing is conducted, 100% of respondents conduct ipsilateral ART testing, compared to 75% for contralateral testing. Most use 500-, 1000-, and 2000-Hz stimulus frequencies, and 56% report 4000 Hz. Patient-related factors are the primary reason participants cite for conducting, or not conducting, ART tests. Most supervisor-participants encourage AuD students to conduct ART tests, based on patient-centered and student learning-centered reasons, and use a variety of strategies to guide students when ART findings are unusual. CONCLUSIONS: Fewer than half (43%) of participants conduct ART testing for all new patients, suggesting it is ancillary to the standard test battery for most participants. When ART testing is conducted, ipsilateral testing only or a combination of ipsilateral and contralateral testing is used. Ongoing trends in ART testing include continued popularity of 500-2000 Hz and ipsilateral-only or ipsilateral plus contralateral testing. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.21513987.

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.

No Reduction in the 226-Hz Probe Tone Acoustic Reflex Amplitude Following Severe Inner Hair Cell Loss in Chinchillas.

The relationship between the middle ear acoustic reflex (AR) and inner hair cell (IHC) loss is currently unknown. Given that IHC are believed to convey nearly all acoustic information to the central auditory nervous system, it has been assumed that loss of IHC would significantly impact the AR. To evaluate this relationship, we assessed the presence and amplitude of the AR in chinchillas before and after treatment with carboplatin, an anticancer drug that reliably and selectively destroys IHC in this species. Baseline measures of hearing sensitivity, including auditory brainstem response (ABR) thresholds and distortion product otoacoustic emissions (DPOAE), were assessed and then re-evaluated following carboplatin treatment. Post-carboplatin ABR thresholds and DPOAE were found to be unchanged or slightly elevated; results were consistent with published reports. Our main hypothesis was that loss of IHC would abolish the reflex or significantly reduce its amplitude. Contrary to our hypothesis, the ipsilateral 226-Hz AR continued to be reliably elicited following carboplatin treatment. Post-mortem histological analysis confirmed significant IHC loss (65-85 %), but no measurable loss of outer hair cells (OHCs). Given that loss of IHC alone does not significantly reduce the 226-Hz AR, our results suggest that few IHC are needed to maintain the 226-Hz AR response. These results suggest additional studies are needed to better understand the role of IHC in the reflex arc, present opportunities to further study the reflex pathway, and could change how we use the clinical AR as a potential diagnostic tool for IHC dysfunction, including those related to IHC synaptopathy.

A BK channel-targeted peptide induces age-dependent improvement in behavioral and neural sound representation.

Recent evidence suggests that modulation of the large-conductance, calcium-activated potassium (BK) channel regulates auditory processing in the brain. Because ion channel expression often changes during aging, this could be a factor in age-related hearing loss. The current study explored how the novel BK channel modulator LS3 shapes central auditory processing in young and old adult mice. In vivo extracellular recordings in the auditory midbrain demonstrated that LS3 differentially modulates neural processing along the tonotopic axis. Though sound-evoked activity was reduced in the mid and ventral tonotopic regions, LS3 enhanced excitatory drive and sound-evoked responses for some neurons in the dorsal, low-frequency region. Behavioral assessment using acoustic reflex modification audiometry indicated improved tone salience following systemic LS3 administration. Moderation of these responses with aging correlated with an age-related decline in BK channel expression. These findings suggest that targeting the BK channel enhances responsivity to tonal sounds, providing the potential to improve hearing acuity and treat hearing loss.

Evaluation of Acoustic Reflex Thresholds in COVID-19 Patients With Taste Disorders.

OBJECTIVE: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, can result in persistent loss of taste and smell. This study was performed to assess acoustic reflex threshold (ART) in patients with taste disorders caused by SARS-CoV-2. MATERIAL AND METHODS: This retrospective study enrolled 11 patients (9 men, 2 women; average age = 22.3 years) with a history of COVID-19 and had complaints of taste disorder and sensitivity to loud sounds. The control group consisted of 13 healthy participants (10 men, 3 women; average age = 23.4 years). Anamnesis, neuro-otological, ear, nose and throat, and eye examinations, as well as a taste test, pure tone audiometry, speech discrimination test, and impedance audiometry were performed in all participants. RESULTS: All participants in the study group had a negative taste test result. In addition, ART values were significantly higher in the study group than the control group at all frequencies. CONCLUSIONS: SARS-CoV-2 could be a neurotropic virus that can cause facial nerve neuropathy.

Presence of ipsilateral acoustic reflex artifact may result in clinical misidentification.

OBJECTIVE: Upon calibration of a specific commercially available immittance device, an artifact was consistently measured in a calibration cavity when in ipsilateral acoustic reflex mode. These results were replicated in a controlled fashion, raising concerns about how clinical results might potentially be misinterpreted. DESIGN: Responses were measured from an Interacoustics Titan and Grason-Stadler Tympstar Pro immittance device coupled to a 0.2 cc and, separately, to a 1.0 cc calibration cavity when in ipsilateral acoustic reflex mode. The procedure was repeated with the same outcomes. RESULTS: Clinically significant responses ordinarily associated with presence of an ipsilateral acoustic reflex were obtained in a 0.2 cc and 1 cc coupler with stimuli presented at 0.5 kHz, 1 kHz, and 2 kHz with one of the Interacoustics Titan, but were not obtained in the same conditions with the Grason-Stadler Tympstar Pro. CONCLUSIONS: A commercially available immittance device yielded clinically-significant responses to ipsilateral acoustic reflex stimuli within calibration cavities of various sizes. Results suggest that false-positive responses may be obtained when certain immittance devices are used clinically, producing possible misleading or incorrect clinical impressions and assessment.

Automated Adaptive Wideband Acoustic Reflex Threshold Estimation in Normal-hearing Adults.

OBJECTIVES: Acoustic stapedius reflex threshold (ART) tests are included in a standard clinical acoustic immittance test battery as an objective cross-check with behavioral results and to help identify site of lesion. In traditional clinical test batteries, middle-ear admittance of a 226 Hz probe is estimated using ear-canal measurements in the presence of a reflex-activating stimulus. In the wideband (WB) acoustic immittance ART test used in this study, the pure-tone probe is replaced by a WB probe stimulus and changes in absorbed power are estimated using ear-canal measurements in the presence of the activator. The ART is defined as the lowest level at which a criterion change in admittance (clinical) or absorbed power (WB) is observed in the presence of the activator. In the present study, ARTs were obtained in adults with normal hearing using the clinical, manual method and with a new WB automated adaptive threshold detection method. It was hypothesized that the WB test would result in lower ARTs than the clinical test because reflex-related changes in power absorbance could be observed across multiple frequency bands in the WB test compared with a single frequency in the traditional test. DESIGN: Data were collected in a prospective research design. ARTs were obtained in ipsilateral and contralateral conditions using 500, 1000, 2000 Hz, and broadband noise (BBN) activators on a clinical system and on an experimental WB system. The bandwidth of the BBN activator was 125 to 4000 Hz on the clinical system and 200 to 8000 Hz on the wideband system. ARTs were estimated at both tympanometric peak pressure (TPP) and ambient pressure on the WB system. Data were collected in both ears of 39 adults (21 males) of mean age 47.7 years (range 23-72 years). Differences in ARTs among the three threshold estimation methods (clinical, WB at TPP, WB at ambient) were examined using the general linear model repeated measures test in SPSS. Post-hoc pairwise comparisons were completed with Bonferroni correction for multiple comparisons. Statistical significance was defined as p < 0.05 for all analyses. RESULTS: ARTs obtained on the WB system at TPP and ambient pressure were significantly lower than obtained on the clinical system. ARTs obtained on the WB system at TPP were significantly higher than at ambient pressure in the 500 and 2000 Hz ipsilateral conditions. CONCLUSIONS: WB automated adaptive ARTs in normal-hearing adults were lower than for clinical methods when measured at TPP and ambient pressure. Lower presentation levels required to estimate ART in the WB test may be more tolerable to patients. Patients with ARTs that are not present at the maximum level of a traditional reflex test may have present ARTs with a WB ART test, which may reduce the need to refer for additional testing for possible retrocochlear involvement. Automation of the test may allow clinicians more time to attend to the other requisite tasks of a hearing evaluation and make the system useful for telehealth applications.

The optimal probe tone frequency for eSRT measurements at individual electrodes in children with cochlear implants.

BACKGROUND: Higher probe tone frequencies have been shown to increase the elicitation rates in electrically evoked stapedius reflex threshold (eSRT) measurements. OBJECTIVES: To determine the optimal probe tone frequency for contralateral eSRT measurements at individual electrodes in children with unilateral cochlear implants and to assess the relationship between eSRTs for this frequency and most comfortable levels (M-levels). MATERIALS AND METHODS: Contralateral eSRT measurements with three probe tone frequencies (226, 678, and 1000 Hz) at individual electrodes were performed on 26 paediatric Advanced Bionics cochlear implant recipients. RESULTS: The elicitation rates of eSRTs for 226, 678, and 1000 Hz probe tones were 73.08% (57/78), 88.46% (69/78), and 88.46% (69/78), respectively. The average eSRT for the 1000 Hz probe tone was significantly lower than those for 226 and 678 Hz probe tones (p<.001 and p=.009, respectively). ESRTs for the 1000 Hz probe tone and M-levels were significantly correlated at all tested electrodes (all p<.001). CONCLUSIONS AND SIGNIFICANCE: The optimal probe tone frequency for contralateral eSRT measurement at individual electrodes in children with unilateral cochlear implants is 1000 Hz. ESRTs for the 1000 Hz probe tone are significantly correlated with M-levels and can be used to guide the M-levels setting in these children.

Taste and acoustic reflex after recovery from facial muscle paralysis in patients with facial nerve palsy.

BACKGROUND: There are few studies on taste or acoustic reflex (AR) in patients after recovery from facial muscle paralysis (FMP). OBJECTIVES: To investigate the recovery of AR and taste in patients who have recovered from peripheral facial nerve palsy (FNP). MATERIALS AND METHODS: The study included 25 patients whose FMP had resolved after treatment for FNP. A difference in taste threshold of ≤4 dB between the affected and unaffected sides in the electric taste test was defined as normal; an AR on the affected side was assessed to be ≥90% of the AR on the unaffected side was defined as normal. RESULTS: Six months after treatment, 8% of patients with FNP who had recovered from FMP still showed taste disorders, and 60% of patients showed abnormal AR. The number of subjects whose electric taste threshold was normal after treatment was significantly higher than the number of subjects whose AR assessment was normal (p < .01). CONCLUSION AND SIGNIFICANCE: This study demonstrates that even among subjects whose FMP is resolved after treatment for FNP, there are some whose taste and AR do not recover. Physicians should be aware of ear symptoms persisting after facial muscle recovery.

Acoustic reflex preshoot: A sign of contraction of the tensor tympani muscle?

Two tiny muscles are attached to the ossicles of the middle ear: the stapedius, whose role as a protector of the inner ear against loud noise has been widely accepted, and the tensor tympani, which remains a mystery since no valid method of detecting its contraction has yet been developed. However, tonic contraction of the tensor tympani has been associated with a number of otological conditions including fullness, tinnitus, slight hearing loss, and Menière-like findings. Our hypothesis is that an easily recognizable sign in the acoustic immittance testing that is part of almost every basic audiological evaluation indicates the contraction of the tensor tympani. During acoustic reflex assessment, a loud stimulus causes a bilateral contraction of the stapedial muscles and an increase in impedance which appears as a deflection in the tracing of the immittance test results. In the case of a contracted tensor tympani, when an intense sound is sent to provoke the acoustic reflex, the stapedius must overcome its resistance which would otherwise have the opposite effect on the footplate. This effort can be seen as a small peak or "preshoot" preceding the greater negative deflection of the impedance. We report the cases of ten patients with unilateral aural symptoms such as tinnitus, impaired noise tolerance, fullness, ear pressure and/or ear discomfort during chewing; the preshoot was present only in the symptomatic ear. If further studies confirm our hypothesis, this could give rise to new therapeutical strategies aimed at reducing contraction of the tensor tympani and balancing its function.

Intraoperative recordings of electromyogenic responses from the human stapedius muscle.

Following surgical implantation of a cochlear implant, the external processor must be programmed individually, which is typically achieved by behavioral measurements, with the user indicating the perceived loudness between the threshold and the maximum comfort levels (MCLs). However, the stapedius reflex measurement could be used instead, as the basis for programming the fitting maps. The electrically evoked stapedius reflex threshold is known to have a high correlation with the MCLs and thus is used as an objective tool to determine the MCL, especially in children and non-cooperative patients. Previous studies demonstrated that the electromyogenic (EMG) activity of the stapedius muscle could be measured to determine stapedius reflex responses. The objective of this study was to demonstrate that intraoperative EMG recordings from the stapedius muscle could be performed with an EMG recording electrode designed for chronical implantation. Ten adult subjects with single sided deafness (SSD) participated in this study. The study was split up into a pre-, intra- and postoperative phase. In the preoperative phase the subjects were screened for the presence of the acoustic stapedius reflex by using a standard tympanometer in the ear to be implanted, while the contralateral ear was stimulated acoustically. During the intraoperative phase an EMG recording electrode was placed in the stapedius muscle and EMG responses were recorded during acoustical and electrical stimulation. The surgical procedure consisted of two interconnected procedures: A classical surgical approach for cochlear implantation with two additional surgical steps, and the temporary placement of an EMG recording electrode in the stapedius muscle made through an opening in the pyramidal eminence, allowing EMG recordings. The postoperative phase was used to evaluate the preservation of the stapedius reflex postoperatively at 1- and 6-months with contralateral acoustic and ipsilateral electrical stimulation. The EMG recording electrode could successfully be placed in the stapedius muscle in all subjects and was able to reliably record EMG signals from the stapedius muscle elicited by acoustic and electrical stimulation. Overall, EMG recordings were obtained intraoperatively in all subjects tested (8 out of 8 subjects). Contralateral acoustic stapedius reflexes were obtained in 6 out of 8 subjects and ipsilateral electrical stapedius reflex in 7 out of 8 subjects. In the postoperative phase, the preservation of the postoperative reflex was observed in 6 out of 10 subjects 1-month after surgery and in 8 out of 10 subjects 6-months after surgery. The study showed that intraoperative EMG recordings from the stapedius muscle can be performed with an EMG recording electrode designed for chronical implantation. The minimally invasive procedure is promising; in particular with regard to the future perspective of measurements in the long-term with an integrated closed-loop self-fitting system.

Auditory hypersensitivity in Williams syndrome.

OBJECTIVES: The objective of this study was to investigate auditory hypersensitivity in WS and to evaluate hyperacusis through standardized protocols, checking if it can be associated with the absence of acoustic reflexes in people with WS. METHOD: The study was performed in 17 individuals with WS, aged between seven and 17 years old (10 males and seven females), and 17 individuals with typical development age- and gender-matched to individuals with WS. Statistical tests were used to analyze the responses collected with the Loudness Discomfort Level (LDL) test as well as ipsilateral and contralateral reflex responses. RESULTS: Auditory hypersensitivity was commonly found. Individuals with WS had phonophobia and were less tolerant to high sound intensity, presenting a reduced discomfort threshold compared to those with typical development. However, hyperacusis was found in 35.29% of individuals with WS and was mild in 50% of cases. There was an association between hyperacusis and acoustic reflex responses, and individuals with absence of the contralateral acoustic reflex were more likely to have hyperacusis. CONCLUSIONS: Individuals with WS have a high prevalence of auditory hypersensitivity, with the presence of phonophobia; however, hyperacusis was not as prevalent and may be associated with the absence of contralateral acoustic reflexes.

Stapedial Reflex: A Possible Novel Biomarker of Early Bulbar Involvement in Amyotrophic Lateral Sclerosis Patients.

BACKGROUND AND AIM: Amyotrophic lateral sclerosis (ALS) is a neuromuscular progressive disorder, characterized by limb and bulbar muscle wasting and weakness. 30% of patients present a bulbar onset, while 70% a spinal outbreak, although most of them develop bulbar impairment later on. Due to the lack of an early biomarker of bulbar involvement, we chose to evaluate the role of stapedial reflex (SR) in order to predict preclinical bulbar impairment in ALS. MATERIALS AND METHODS: We enrolled 36 ALS patients. We assessed revised-ALS functional-rating-scale and SR for a total of 4 visits. We established the presence of SR, acoustic reflex latency test (ARLT), and SRs Decay. Patients who had not develop bulbar signs at fourth visit continued follow-up up to 15 months. Data were analyzed by using Mann-Whitney U test, Friedman test, and Cox regression analysis. RESULTS: We observed that SRs Decay at 500 and 1,000 Hz is the first parameter of SR to get altered in all ALS patients before the development of bulbar impairment. Twenty-eight patients developed bulbar impairment during the study. We highlighted a correlation between the progression rate of disease and both time of SRs Decay alteration and time of bulbar impairment from disease onset. Four patients who did not develop bulbar impairment had a progression rate lower than the other ones (p < 0.05). DISCUSSION AND CONCLUSIONS: This study shows that SR Decay test could be a sensitive measure for detecting pre-symptomatic bulbar involvement in ALS and could represent a simple, noninvasive, and useful biomarker of disease progression.