Stimulation Of Ear Research Articles

MEASUREMENT OF BASIC HEMODYNAMICS DURING MULTIPOST TRANSCUTANEOUS EXTERNAL EAR STIMULATION: A TWO-CASE STUDY

The objectives of the investigation were to assess the short-term responses of the cardio-vascular system on the multipost transcutaneous stimulation (tANS) of the external ear (EE). The scope was to measure the forefinger photopleths (FPPG), toe photopleths (TPPG), aortic phonocardiogram (APCG), mitral phonocardiogram (MPCG) and brachial arterial blood pressure (BABP), assuming that they could be altered with the tANS. For the tANS, stimulator, two silicone ear plugs with four platinum electrodes each, and a large common electrode (CE), were used. Trials were carried out with two female volunteers, aged 25 years and 28 years. To capture the heart sounds, two customized electronic stethoscopes (transducers) were used. BABP was measured using a pressure transducer and blood-pressure appliance. To measure the FPPGs, a pulse oximeter and SpO2 finger clip were used. To measure the TPPGs, another pulse oximeter and customized SpO2 foot clip was used. Signals were gathered using a high-performance data-acquisition system. An offline analysis was made just before and just after the start of the tANS. To record the pulsations in the right brachial artery, the 2D ultrasound mode (B) of the ultrasound device was used before and during the tANS. Then, diagrams showing the vein cross-sectional area over time were constructed. The results show that vascular time intervals between heart sounds S1 and S2, captured as APCG and systolic peaks of the FPPG in the second volunteer, were slightly larger during the separate tANS of the left white (LW) and (RW) EE post than before the tANS. Furthermore, vascular time intervals between the heart sounds S1 and S2, captured as MPCG and systolic peaks of the TPPG in the second volunteer, were slightly smaller during the separate tANS of LW and RW EE post than before the tANS. Finally, tANS of the LW post elicited a slightly lower heart rate than the one measured when LW was not stimulated. In contrast, the tANS of the RW post elicited a slightly higher heart rate than the one measured when RW was not stimulated. It was also shown that the pattern of the vein cross-sectional area over time with tANS was different compared to both the FPPG and TPPG.

Electrical safety assessment of a prototype device for electromagnetic stimulation of the ear in patients with tinnitus.

<b><br>Aim:</b> The aim of the study was to evaluate the results of electrical safety results of a prototype electromagnetic ear stimulation device in patients with tinnitus.</br> <b><br>Material and methods:</b> The electrical safety tests of the prototype device for electro- and magnetostimulation of the hearing organ were carried out at the Center for Attestation and Certification Tests in Gliwice. The tests concerned selected parameters including the PN-EN standard.</br> <b><br>Results:</b> Safety studies of the prototype electrical stimulation device for the ear in patients with tinnitus were necessary to perform the planned further preclinical studies. Obtained results regarding: identification and labeling of the device; protection against electric shock; checking protective earthing, functional earthing and potential equalization; checking the leakage current and auxiliary currents of the patient; checking the distances through the solid insulation and the use of thin insulating spacers; checking the electrical strength of the device insulation; checking protection against mechanical hazards of the device; checking the risk associated with surfaces, corners and edges, and checking the protection against excessive temperatures and other threats comply with the standard PN-EN.</br> <b><br>Conclusions:</b> No risk to the patient and medical staff. Tests of protection against mechanical hazards of the device have shown that the only movable part whose contact with the patient could cause an unacceptable risk is the fan installed inside the housing.</br&gt.

Active TriCROS: A Simultaneous Stimulation With a (Bi)CROS System and a Hearing Aid in the Worst Ear for Severely Asymmetrical Hearing Loss.

Severely asymmetrical hearing loss (SAHL) is characterized by a moderately severe or severe hearing loss in one side and normal or mildly impaired controlateral hearing in the other. The Active tri-CROS combines the Contralateral Routing-of-Signal System (CROS, or BiCROS if the best ear is stimulated) and the stimulation of the worst ear by an in-the-canal hearing aid. This study aims to evaluate the benefit of the Active tri-CROS for SAHL patients. This retrospective study was conducted from September 2019 to December 2020. Ambulatory, tertiary care. Patients were retrospectively included if they had received the Active tri-CROS system after having used a CROS or BiCROS system for SAHL for at least 3 years. Audiometric gain, signal-to-noise ratio, spatial localization, and the Abbreviated Profile of Hearing Aid Benefit and Tinnitus Handicap Inventory questionnaires were performed before equipment and after a month with the system. Twenty patients (mean, 62 yr old) with a mean of 74.3 ± 8.7 dB HL on the worst ear were included. The mean tonal hearing gain on the worst ear was 20 ± 6 dB. Signal-to-noise ratio significantly rose from 1.43 ± 3.9 to 0.16 ± 3.4 dB ( p = 0.0001). Spatial localization was not significantly improved. The mean Tinnitus Handicap Inventory test score of the eight patients suffering from tinnitus rose from 45.5 ± 18.5 to 31 ± 25.2 ( p = 0.016). The Active tri-CROS system is a promising new therapeutically solution for SAHL.

Measurements of bone-conducted sound in the chinchilla external ear

We measure bone-conduction (BC) induced skull velocity, sound pressure at the tympanic membrane (TM) and inner-ear compound-action potentials (CAP) before and after manipulating the ear canal, ossicles, and the jaw to investigate the generation of BC induced ear-canal sound pressures and their contribution to inner-ear BC response in the ears of chinchillas. These measurements suggest that in chinchilla: i.) Vibrations of the bony ear canal walls contribute significantly to BC-induced ear canal sound pressures, as occluding the ear canal at the bone-cartilaginous border causes a 10 dB increase in sound pressure at the TM (PTM) at frequencies below 2 kHz. ii.) The contributions to PTM of ossicular and TM motions when driven in reverse by BC-induced inner-ear sound pressures are small. iii.) The contribution of relative motions of the jaw and ear canal to PTM is small. iv.) Comparison of the effect of canal occlusion on PTM and CAP thresholds point out that BC-induced ear canal sound pressures contribute significantly to bone-conduction stimulation of the inner ear when the ear canal is occluded.

Effectiveness of Auricular Acupucture (Akar) on Interleukin-6 Levels and Duration of Labor in The Primigravidal Active Phase

Background: Auricular acupuncture (AKAR) is a diagnostic and treatment system based on normalizing bodily dysfunctions through stimulation of specific points on the ear. Ear stimulation involves neurological reflexes, neurotransmitters, cytokines, the immune system, and inflammation. Subjects and Method: This study is a true experimental design with a pretest-posttest control group. The study population was all 43 primigravida mothers who were expected to give birth between May and July 2023. The research sample was part of the first stage of labor during the primigravida active phase. The selection of research subjects was carried out by consecutive sampling. Subjects who met the inclusion criteria were divided into two groups, namely the AKAR intervention group and the deep breathing relaxation control group. The dependent variable was auricular acupuncture, and the independent variable was a duration of labor and interleukin-6. The instrument uses laboratory tests that are carried out, the research site only has a simple laboratory room and does not have a deep freezer - 800C, so the biomarker test is carried out in the laboratory. Assessment of the length of labor using a partograph. Data analysis used the Mann-Whitney test, the Wilcoxon Signed Rank test and the Independent Sample test Results: The results of post-treatment serum IL-6 levels in the AKAR group were higher (Mean= 187.24; SD= 41.65) pg/mL before the pre-treatment (Mean= 157.67; SD= 51.85) pg/mL, and this difference was significant (p <0.001). Post-treatment serum IL-6 levels in the RND group were higher (Mean= 181.30; SD= 56.86) pg/mL before the pre-treatment (155.65; SD= 50.07) pg/mL. The results of the pre-treatment serum IL-6 levels in the AKAR group were slightly higher (Mean= 157.67; SD= 51.85) pg/mL compared to the RND group (Mean= 155.65; SD= 50.07) pg/mL. Post-treatment, the IL-6 serum level in the AKAR group were higher (Mean= 187.24; SD= 41.65) pg/mL compared the RND group (Mean= 181.30; SD=56.86) pg/mL. The AKAR group had 12 (57%) active phase I stages of labor that lasted less than 360 minutes and 9 (33%) more than 360 minutes. In the RND group, 9 (45%) delivered less than 360 minutes, and 11 (55%) more than 360 minutes. The mean length of labor for the AKAR group was shorther (Mean= 365.40; SD= 65.60) minutes than the RND group (Mean= 407.55; SD = 77.27). Conclusion: There was a difference between IL-6 levels before and after treatment, so it was concluded that AKAR and RND affected serum IL-6 levels in the first stage of labor in the active primigravida phase. There was no significant difference in the length of labor in the active phase of the first stage of labor in primigravidas between AKAR and RND. Keywords: acupuncture, auricular, interleukin-6, length of labor. Correspondence: Setiana Andarwulan. Program Study Midwife Professional Education, Faculty of Science and Health, PGRI Adi Buana University, Surabaya Jl Dukuh Menanggal XII No. 4, East Java, Indonesia. Email: setianaandarwulan@unipasby.ac.id. Mobile: 085806227033.

Transcutaneous auricular vagus nerve stimulation on upper limb motor function with stroke: a functional near-infrared spectroscopy pilot study

BackgroundTranscutaneous auricular vagus nerve stimulation (taVNS) emerges as a promising neuromodulatory technique. However, taVNS uses left ear stimulation in stroke survivors with either left or right hemiparesis. Understanding its influence on the cortical responses is pivotal for optimizing post-stroke rehabilitation protocols.ObjectiveThe primary objective of this study was to elucidate the influence of taVNS on cortical responses in stroke patients presenting with either left or right hemiparesis and to discern its potential ramifications for upper limb rehabilitative processes.MethodsWe employed functional near-infrared spectroscopy (fNIRS) to ascertain patterns of cerebral activation in stroke patients as they engaged in a “block transfer” task. Additionally, the Lateralization Index (LI) was utilized to quantify the lateralization dynamics of cerebral functions.ResultsIn patients exhibiting left-side hemiplegia, there was a notable increase in activation within the pre-motor and supplementary motor cortex (PMC-SMC) of the unaffected hemisphere as well as in the left Broca area. Conversely, those with right-side hemiplegia displayed heightened activation in the affected primary somatosensory cortex (PSC) region following treatment.Significantly, taVNS markedly amplified cerebral activation, with a pronounced impact on the left motor cortical network across both cohorts. Intriguingly, the LI showcased consistency, suggesting a harmonized enhancement across both compromised and uncompromised cerebral regions.ConclusionTaVNS can significantly bolster the activation within compromised cerebral territories, particularly within the left motor cortical domain, without destabilizing cerebral lateralization. TaVNS could play a pivotal role in enhancing upper limb functional restoration post-stroke through precise neuromodulatory and neuroplastic interventions.

Evaluation the results of electromagnetic compatibility of a prototype device for ear stimulation in patients with tinnitus.

<b><br>Aim:</b> The aim of the study was to evaluate the results of electromagnetic compatibility of a prototype device for ear stimulation in patients with tinnitus.</br> <b><br>Material and methods:</b> The electromagnetic compatibility tests of the prototype device for electro- and magnetostimulation of the hearing organ were carried out at the Center for Attestation and Certification Tests OBAC Sp. z o. o. in Gliwice in 2020. The following product standards were used: PN-EN 60601-1-2:2015-11 - medical electrical equipment (general requirements for basic safety and essential functioning; PN-EN 55011:2012 - industrial, scientific and medical equipment [characteristics of radio frequency disturbances] ) PN-EN 61000-3-2:2014-10 - electromagnetic compatibility (EMC), permissible levels of harmonic current emissions (phase load current ≤ 16 A).</br> <b><br>Results:</b> The level of expanded uncertainty in the measurement of conducted disturbances in the range of 0.150-30MHz does not exceed the level specified in the PN-EN-55016-4-2:2011 standard. In the study of the emission of radiated disturbances up to 1GHz in the frequency range of 30-1000MHz (PN-EN 55011:2012 standard), it was found that the setting of the EUT during the tests was in accordance with the requirements of the standard. The level of expanded uncertainty in the measurement of radiated disturbances in the 30-1000MHz range does not exceed the level specified in the PN-EN 55016-4-2:2011 standard. The measured current harmonic levels (phase power supply current ≤16A) with a frequency range of 50Hz-2kHz do not exceed the permissible levels specified in the PN-EN 61000-3-2:2014-10 standard. The test of resistance to the magnetic field at the frequency of the power grid (PN-EN 61000-4-8: 2010 standard also showed that the setting of the EUT during the tests was in accordance with the requirements of the standard and the result was positive.</br> <b><br>Conclusions:</b> Testing of immunity to radiated radio frequency electromagnetic field (PN-EN 61000-4-3:2007 +A1:2008+A2:2011 standard) and testing of resistance to magnetic field at power frequency (PN-EN 61000-4-8 standard :2010) did not exceed the level specified in the standard and showed a positive result. The measured harmonic levels of the network current (phase supply current ≤16A) with the frequency range 50Hz-2kHz do not exceed the permissible levels specified in the PN-EN 61000- 3-2:2014-10 standard for a class A device.</br&gt.

Left or right ear? A neuroimaging study using combined taVNS/fMRI to understand the interaction between ear stimulation target and lesion location in chronic stroke

BackgroundImplanted vagus nerve stimulation (VNS) and transcutaneous auricular VNS (taVNS) have been primarily administered clinically to the unilateral-left vagus nerve. This left-only convention has proved clinically beneficial in brain disorders. However, in stroke survivors, the presence of a lesion in the brain may complicate VNS-mediated signaling, and it is important to understand the laterality effects of VNS in stroke survivors to optimize the intervention. ObjectiveTo understand whether taVNS delivered to different ear targets relative to the lesion (ipsilesional vs contralesional vs bilateral vs sham) impacts blood oxygenation level dependent (BOLD) signal propagation in stroke survivors. MethodsWe enrolled 20 adults with a prior history of stroke. Each participant underwent a single visit, during which taVNS was delivered concurrently during functional magnetic resonance imaging (fMRI) acquisition. Each participant received three discrete active stimulation conditions (ipsilesional, contralesional, bilateral) and one sham condition in a randomized order. Stimulation-related BOLD signal changes in the active conditions were compared to sham conditions to understand the interaction taVNS and laterality effects. ResultsAll active taVNS conditions deactivated the contralesional default mode network related regions compared to sham, however only ipsilesional taVNS enhanced the activations in the ipsilesional visuomotor and secondary visual cortex. Furthermore, we reveal an interaction in task activations between taVNS and cortical visuomotor areas, where ipsilesional taVNS significantly increased ipsilesional visuomotor activity and decreased contralesional visuomotor activity compared to sham. ConclusionLaterality of taVNS relative to the lesion is a critical factor in optimizing taVNS in a stroke population, with ipsilesional stimulation providing largest direct brain activation and should be explored further when designing taVNS studies in neurorehabilitation.

A clinical case of a patient with an anomaly in the development of the inner ear and refractory stimulation of the facial nerve after a coronavirus infection and meningitis

Background. Thanks to the development of technology and new surgical approaches, it has become possible to perform cochlear implantation (CI) in patients with malformations of the inner ear. The experience of this type of rehabilitation has more than 15 years in Russian practice and more than 20 years in the world. Unfortunately, the COVID-19 pandemic has added not only one more cause of deafness, but also etiological factor of the complications. The purpose of this paper is to describe a clinical case of facial nerve stimulation (FNS) in a CI user with an inner ear malformation and a coronavirus infection complicated by meningitis. A clinical case demonstrating a combination of all these etiological factors of FNS has not been previously described in the scientific literature.
 Aim. To describe a clinical case of FNS in a CI user with an inner ear malformation and a coronavirus infection complicated by meningitis.
 Materials and methods. In 2017 4 years old patient underwent cochlear implantation on her right ear in Saint Petersburg Research Institute of Ear, Throat, Nose and Speech. In May 2022 the patient was admitted to the infectious diseases department of the medical institution with the diagnosis: coronavirus infection (confirmed), severe course; complication: purulent meningoencephalitis. After recovery, the patient complained of facial muscles twitching when using the speech processor of the cochlear implant. In order to correct the non-hearing sensation, the patient was sent to the Saint Petersburg Research Institute of Ear, Throat, Nose and Speech for rehabilitation in June 2022. During repeated fitting, it was possible to improve the reactions to sounds. Phoneme discrimination has improved. Positive dynamics was registered against the background of the changed settings. The average hearing thresholds using 3-phase stimulation were 42.5 dB. However, it was not possible to completely eliminate the FNS, and the compulsory settings of the speech processor did not allow the patient to achieve sufficient speech intelligibility.
 Conclusion. Meningitis after CI can cause an increase in the transmittance of the inner ear tissues to electric current and, as a consequence, the development of the FNS. Modern technologies make it possible to rehabilitate such patients, including those with abnormalities of the inner ear. To increase the effecacy of rehabilitation, special coding strategies are used including the 3-phase stimulation.

Evaluation of Difference in Performance of Young Adults in Dichotic Digit Test in Tamil and Dichotic Consonant Vowel Test

Background and Aim: Dichotic listening has been defined as the simultaneous stimulation of both ears and has been used to evaluate a listener’s binaural integration/separation ability. Dichotic tests are available in various languages and use varied stimuli. The study aimed to evaluate the differential performance of Tamil-speaking young adults in two tests of dichotic perception namely Dichotic Consonant Vowel (DCV) test and Dichotic Digit Test in Tamil (DDT T). Methods: Sixty adults with normal hearing aged 18 to 35 years were the participants of the study. All the young adults were native speakers of the Tamil language without significant auditory history. DCV and DDT-T were administered in randomized order at 50 dB SL (re: SRT) in free recall condition. The participants were instructed to respond orally and the responses were noted. Results: Better performance was observed in dichotic digit compared to DCV test for all participants. This was attributed to the higher number of cues available in DDT-T. Further, error analyses of participants’ responses revealed that voicing errors were higher with the highest errors in the identification of unvoiced consonant /ta/ in both ears. The reason for this could be the lack of contextual cues in DCV test for Tamil-speaking individuals to interpret the voicing feature of a consonant. Conclusion: It can be concluded that DDT-T was more useful in assessing binaural integration ability of native Tamil speakers compared to DCV. It is recommended to be used in the behavioral test battery for evaluating auditory processing disorder in native Tamil speakers. Keywords: Dichotic digit; dichotic consonant vowel; free recall

Deficiency of Autophagy-Related Gene 5 in Keratinocytes Leads to Aggravation of Epidermal Damage in 2,4-dinitrochlorobenzene-induced Allergic Contact Dermatitis

Objective: To determine whether keratinocyte-specific autophagy-related gene 5 (ATG5) deficiency can regulate apoptosis to inhibit skin damage in mice with 2,4-dinitrochlorobenzene (DNCB)-induced allergic contact dermatitis (ACD). Methods: This study involved keratinocyte-specific Atg5 conditional knockout (cKO) mice (Krt14cre/+-Atg5 flox/flox) and control mice (Krt14+/+-Atg5 flox/flox). We painted DNCB on the right ear of each mouse to induce ACD. Dermatitis scoring and measurements of ear weight and thickness were performed to evaluate inflammation levels. An immunohistochemical assay was performed to analyze immune cell infiltration. Histological study and TUNEL staining were performed to compare the differences in skin lesions between Atg5 cKO mice and control mice. Immunofluorescence and western blotting were used to examine the levels of ATG5 and apoptosis-related protein. The results were statistically analyzed by t test. Results: After DNCB stimulation of mice ears, we observed a more severe phenotype in Atg5 cKO mice than in control mice (dermatitis score: 7.5 ± 2.5884 vs. 3.25 ± 0.8216, P = 0.0033). Further analysis of ATG5 protein confirmed keratinocyte-specific ablation of Atg5 in cKO mice and showed that DNCB did not influence ATG5 expression. Immunohistochemistry assay revealed that the infiltrated immune cells were not involved in aggravation of the phenotype of DNCB-stimulated Atg5 cKO mice. However, the histological study (P = 0.0238), TUNEL staining (P = 0.0238), immunofluorescence (P = 0.0357), and western blotting showed that the increase in keratinocyte death, especially apoptosis, contributed to aggravation of the phenotype of DNCB-stimulated Atg5 cKO mice. Conclusion: Deficiency of Atg5 in keratinocytes increases apoptosis, aggravating skin damage in DNCB-induced ACD mice. This has no relationship with the involvement of immune cells.

Study of aged central auditory function using the auditory middle latency response

ObjectiveInvestigate the auditory function of the elderly using the middle latency potentials. MethodologyGroup 1 (G1): 20 healthy individuals of both genders, older than 60 years, without hearing loss. Group 2 (G2): 20 healthy individuals of both sexes, older than 60 years, with hearing loss in frequencies from 4 to 8 kHz. Potential recording was performed with unilateral and bilateral stimulation and the Binaural Interaction Component was calculated. ResultsNa latency in C3A1 was greater in the stimulation of the right ear in G2 and the amplitude of Na-Pa was greater in the stimulation of the right ear and recording in C3A1 in G1. The latency of the Pa component was higher in the stimulation of the right ear recorded in C4A2. The Pb component in G2 by bilateral stimulation and recorded in C4A2 had higher latency. The first and second negative and positive peaks presented greater amplitude in G1. In C3A1, the 1st negative peak was more negative in G1 and the 2nd positive peak showed greater amplitude in C4A2 in both groups. ConclusionThe transmission of auditory information to the primary auditory cortex is impaired with aging, especially in unilateral stimulation, reinforced by losses in elderly people with peripheral hearing loss, such as in the binaural interaction at the cortical and subcortical levels. Thus, the AMLR has shown to be a sensitive examination to investigate neuroauditory disorders in the elderly, especially related to high-frequency hearing loss and primary auditory cortex dysfunctions caused by the aging process.

Ipsilateral auditory cortex responses to the intact ear after unilateral noise trauma in juvenile rats

BackgroundWhile ear stimulation produces a robust response in the contralateral auditory cortex (AC), it produces only a weak response in the ipsilateral AC, known as interhemispheric asymmetry. Unilateral deafness can lead to AC plastic changes, resulting in reduced interhemispheric asymmetry and auditory perceptual consequences. However, the unilateral hearing loss-associated plastic changes are far from fully understood. The purpose of this study was to investigate AC responses to the ipsilateral unimpaired ear after noise injury to the contralateral ear in juvenile rats. MethodsRats (50 days) were monaurally exposed to an intense noise (10.0-12.5 kHz, 126 dB SPL) for 2 hours. The unexposed ear-induced ipsilateral AC responses were recorded 2 days and 4 months after exposure and compared between groups. ResultsThe noise exposure resulted in complete hearing loss in the exposed ear, but normal function in the other. Two days after exposure, the ipsilateral AC response induced by the intact ear was significantly enhanced and the threshold decreased (the early-onset effect). Four months after noise exposure, in addition to the increased response amplitude, the “slow-increasing” firing pattern of the neurons in the ipsilateral AC turned into the contralateral-AC-response-like “sharp-increasing” pattern (the late-onset effect) with shortened response latency. DiscussionThe early-onset effect can result from release of inhibition due to decreased contralateral input, while the late-onset effect may imply the formation of direct connections in the ipsilateral auditory pathway. The enhanced AC response may help maintain loudness perception and monaural sound localization after unilateral deafness.

Assessment of Subjective Tinnitus Treatment Results Using a Prototype Device for Electrical and Magnetic Stimulation of the Ear-Preliminary Study

Background: The aim of the study was to evaluate the effectiveness of subjective tinnitus treatment in patients with cochlear sensorineural hearing loss with magnetic ear stimulation using a prototype device. Since the 1970s, studies have been conducted on the use of electrical stimulation of the ear in the treatment of tinnitus. The available literature contains various hypotheses about the influence of electrical stimulation of the ear on tinnitus. Material and Methods: Preclinical studies were performed for 100 patients, 40 women and 60 men (124 ears in total), aged 38–72 years, treated for tinnitus. A subjective assessment of the loudness of tinnitus was performed, and the frequency and intensity as well as hearing threshold were determined using a prototype device for electro-magnetic stimulation of the ear. The treatment cycle consisted of 10 five-minute stimulations performed daily 5 times a week. Results: Before treatment, persistent tinnitus was found in 100 ears (80.6%) and periodic tinnitus in 24 ears (19.4%). Immediately after treatment, persistent tinnitus was present only in 50 ears (40.3%) and periodic tinnitus in 40 ears (32.3%). Complete resolution of tinnitus was noted in 34 ears (27.4%). On the other hand, the examination performed 3 months after the treatment showed persistent tinnitus in 40 ears (32.3%) and periodic tinnitus in 50 ears (40.3%), and complete resolution of tinnitus was recorded in 34 ears (27.4%). Based on the VAS analog scale, there was an improvement in tinnitus in 98 ears (79.0%) immediately after treatment and no improvement in 26 ears (20.0%). The mean VAS scale before treatment was 4.9 points, after treatment it was 2.1 points and 3 months after treatment it was 1.9 points. Conclusions: The preliminary research results show the high effectiveness of magnetic stimulation in the treatment of tinnitus with the use of a prototype device for electromagnetic stimulation of the ear. There was no negative effect of the stimulation on hearing or tinnitus.

Effect of cochlear implant side on early speech processing in adults with single-sided deafness

ObjectiveIn binaurally deaf subjects, speech processing particularly benefits from a cochlear implant (CI) in the right ear, which is contralateral to the commonly left speech-dominant hemisphere. However, it is unclear whether such effects of implantation side also occur in speech processing in patients with single-sided deafness (SSD). MethodsLateralization of N1 responses was analyzed with a high-density electroencephalogram (EEG) in fourteen adults with postlingually acquired left or right SSD who received a CI in adulthood. During recording, patients performed a speech and a pure-tone discrimination task. Lateralization of N1 responses was assessed by side-specific global field power (GFP) and compared (a) between normal hearing and CI-implanted ears within subjects and (b) between implantation sides across subjects. ResultsN1 responses were stronger in the contralateral than in the ipsilateral hemisphere during stimulation of the normal hearing ear (except for left speech stimulation), and was bilateral symmetric with CI stimulation on either side. A significant correlation between speech discrimination performance and left lateralization was found across subjects for the left CI ear. ConclusionsCI stimulation altered auditory processing across hemispheres. Speech discrimination in left CI-implanted SSD patients improved with left lateralization of the N1 response. SignificanceSide-specific rehabilitation in SSD patients might improve speech processing across hemispheres.

Cortical imbalance following delayed restoration of bilateral hearing in deaf adolescents.

Unilateral auditory deprivation in early childhood can lead to cortical strengthening of inputs from the stimulated side, yet the impact of this on bilateral processing when inputs are later restored beyond an early sensitive period is unknown. To address this, we conducted a longitudinal study with 13 bilaterally profoundly deaf adolescents who received unilateral access to sound via a cochlear implant (CI) in their right ear in early childhood before receiving bilateral access to sound a decade later via a second CI in their left ear. Auditory‐evoked cortical responses to unilateral and bilateral stimulation were measured repeatedly using electroencephalogram from 1 week to 14 months after activation of their second CI. Early cortical responses from the newly implanted ear and bilateral stimulation were atypically lateralized to the left ipsilateral auditory cortex. Duration of unilateral deafness predicted an unexpectedly stronger representation of inputs from the newly implanted, compared to the first implanted ear, in left auditory cortex. Significant initial reductions in responses were observed, yet a left‐hemisphere bias and unequal weighting of inputs favoring the long‐term deaf ear did not converge to a balanced state observed in the binaurally developed system. Bilateral response enhancement was significantly reduced in left auditory cortex suggesting deficits in ipsilateral response inhibition of new, dominant, inputs during bilateral processing. These findings paradoxically demonstrate the adaptive capacity of the adolescent auditory system beyond an early sensitive period for bilateral input, as well as restrictions on its potential to fully reverse cortical imbalances driven by long‐term unilateral deafness.

Effect of the Temporal Window of Integration of Speech Sound on Mismatch Negativity.

Speech-sound stimuli have a complex structure, and it is unclear how the brain processes them. An event-related potential (ERP), known as mismatch negativity (MMN), is elicited when an individual's brain detects a rare sound. In this study, MMNs were measured in response to an omitted segment of a complex sound consisting of a Japanese vowel. The results indicated that the latency from onset in the right hemisphere was significantly shorter than that in the frontal midline and left hemispheres during left ear stimulation. Additionally, the results of latency from omission showed that the latency of stimuli omitted in the latter part of the temporal window of integration (TWI) was longer than that of stimuli omitted in the first part of the TWI. The mean peak amplitude was found to be higher in the right hemisphere than in the frontal midline and left hemispheres in response to left ear stimulation. In conclusion, the results of this study suggest that would be incorrect to believe that the stimuli have strictly the characteristics of speech-sound. However. the results of the interaction effect in the latencies from omission were insignificant. These results suggest that the detection time for deviance may not be related to the stimulus ear. However, the type of deviant stimuli on latencies was found to be significant. This is because the detection of the deviants was delayed when a deviation occurred in the latter part of the TWI, regardless of the stimulation of the ear.

Cortical Auditory Evoked Potentials Recorded Directly Through the Cochlear Implant in Cochlear Implant Recipients: a Feasibility Study.

The use of objective measures in cochlear implant (CI) mapping, has greatly contributed to the refinement of the setting of audible and comfortable stimulation levels, which serve as the basis of the mapping process, especially in cases of infants and young children. In addition, objective measures can also confirm the integrity of the CI system. Current CI objective measures mainly reflect neural activity from the auditory nerve and brainstem site. An objective cortical CI measure that reflects directly central auditory activity is greatly needed, especially since it is closely related to CI outcomes in both children and adults. Recording the brain activity currently requires an external evoked potential (EP) system including scalp electrodes, rendering it impractical for widespread clinical use. This study aimed to assess the feasibility of recording cortical auditory evoked potentials (CAEPs) directly and solely through the cochlear implant in response to external acoustic stimulation in the non-implanted ear. A total of nine CI users (four females and five males) participated, including seven post-lingual adults (23 to 72 years), and two pediatric cases, one teenager (15 years), and one child (8 years)-both pre-lingual. All participants had a residual hearing in the ear contralateral to the ear with CI. CAEPs were recorded in the implanted ear in response to acoustic stimulation of the non-implanted ear, consisting of a brief tonal stimulus at comfortable listening levels. Recordings used an intracranial montage consisting of an intracochlear apical electrode (active) and one of the two ( case and ring ) extra-cochlear implanted electrodes serving as reference electrodes. The CI CAEPs were compared with a single-channel conventional CAEP recording obtained simultaneously via scalp electrodes (Fz-mastoid) using a standard EP system and an external trigger from the CI system. Statistical comparisons were made between the CI and the scalp recorded CAEPs and for differences between the CI CAEP measures acquired using the ring and the case as the reference electrode. CAEPs recorded directly and solely through the CI were equivalent to the standard scalp recorded CAEP responses. CAEP responses acquired using the case electrode as the reference were highly correlated in terms of morphology, latencies, and amplitudes of the CAEP components. The CI CAEP latencies of the two pediatric cases were consistent with their normal developed age group and delayed relative to adult CAEP latencies, as expected. This study demonstrated the feasibility of recording long latency CAEPs directly and solely through CI in adults with residual hearing, in response to acoustic stimulation of the non-implanted ear. The CI CAEPs closely resembled the CAEPs recorded simultaneously by an external EP system and via scalp electrodes. The ability to record directly from the implant, without the need of an external recording system, presents an innovative method with many clinical and research implications.

The Influence of Motoric Maneuvers on Cervical Vestibular Evoked Myogenic Potentials (cVEMPs).

The cervical vestibular evoked myogenic potential (cVEMP) is a vestibular response that is produced by the saccule in response to intense, often low-frequency, short-duration auditory stimuli, and is typically recorded from a contracted sternocleidomastoid (SCM) muscle. Previous research has shown that the amplitude of the cVEMP is related to the amount of SCM electromyographic (EMG) activity. The aim of this study was to determine the influence of various remote motoric maneuvers on the amplitude of the cVEMP, as well as whether they influence the level of SCM EMG activity. The cVEMP was recorded from the left SCM muscle to left ear stimulation, in response to the SCM condition, as well as three different motoric maneuvers (jaw clench, eye closure, and the Jendrassik maneuver). EMG activity was also varied between 50, 75, and 100% of maximal EMG activity. Data from 14 healthy subjects, with a mean age of 25.57 years (standard deviation = 5.93 years), was included in the present study. Mean latency and amplitude of the cVEMP were compared across the four conditions and varying magnitudes of EMG contraction. SPSS 26 was used to statistically analyze the results. cVEMP latency did not vary across condition. cVEMP amplitude decreased with decreasing EMG magnitude. SCM contraction with jaw clench produced the largest increase in cVEMP amplitude; however, this condition was not significantly different from the SCM condition alone. SCM contraction with the Jendrassik maneuver produced a cVEMP amplitude that was similar and not statistically different from SCM contraction alone, and the addition of the eye closure maneuver to SCM contraction resulted in the lowest cVEMP amplitude, which was found to be statistically different from the standard SCM condition at 100 and 75% EMG activity. The amplitude relationship across the conditions was not found to vary with changes in EMG activity; however, a significant increase in EMG amplitude was found during the 50% muscle contraction condition when subjects performed the Jendrassik maneuver in addition to the standard SCM contraction. The addition of the eye closure maneuver to SCM contraction resulted in a significant decrease in cVEMP amplitude, while the addition of the Jendrassik maneuver resulted in a significant increase in EMG activity at the lowest level of SCM activation (i.e., 50%). Additional research is necessary to determine how motoric maneuvers influence the cVEMP amplitude, and whether the results are also dependent on how SCM contraction is being produced (e.g., while supine vs. sitting).

Electric hearing and tinnitus suppression by noninvasive ear stimulation

While noninvasive brain stimulation is convenient and cost effective, its utility is limited by the substantial distance between scalp electrodes and their intended neural targets in the head. The tympanic membrane, or eardrum, is a thin flap of skin deep in an orifice of the head that may serve as a port for improved efficiency of noninvasive stimulation. Here we chose the cochlea as a target because it resides in the densest bone of the skull and is adjacent to many deep-brain-stimulation structures. We also tested the hypothesis that noninvasive electric stimulation of the cochlea may restore neural activities that are missing in acoustic stimulation. We placed an electrode in the ear canal or on the tympanic membrane in 25 human adults (10 females) and compared their stimulation efficiency by characterizing the electrically-evoked auditory sensation. Relative to ear canal stimulation, tympanic membrane stimulation was four times more likely to produce an auditory percept, required eight times lower electric current to reach the threshold and produced two-to-four times more linear suprathreshold responses. We further measured tinnitus suppression in 14 of the 25 subjects who had chronic tinnitus. Compared with ear canal stimulation, tympanic membrane stimulation doubled both the probability (22% vs. 55%) and the amount (−15% vs. −34%) of tinnitus suppression. These findings extended previous work comparing evoked perception and tinnitus suppression between electrodes placed in the ear canal and on the scalp. Together, the previous and present results suggest that the efficiency of conventional scalp-based noninvasive electric stimulation can be improved by at least one order of magnitude via tympanic membrane stimulation. This increased efficiency is most likely due to the shortened distance between the electrode placed on the tympanic membrane and the targeted cochlea. The present findings have implications for the management of tinnitus by offering a potential alternative to interventions using invasive electrical stimulation such as cochlear implantation, or other non-invasive transcranial electrical stimulation methods.