Impact of endolymphatic hydrops on the function of the horizontal canal during caloric stimulation in Ménière's disease.

PURPOSE: When a dizzy patient with episodic vertigo has an abnormal caloric and a normal video head impulse test (vHIT), this caloric-vHIT dissociation provides vital information for a diagnosis of Ménière's disease (MD). Endolymphatic hydrops (EH), a histological marker of MD, is hypothesized to be involved in the caloric-vHIT dissociation in MD through hydropic duct distension of the horizontal semicircular canal (SC). This study was designed to determine the impact of EH on the function of horizontal SC during caloric stimulation. METHODS: Caloric test and vHIT were used to evaluate the function of horizontal SC every six months, annual magnetic resonance imaging (MRI) was used to evaluate the degree of EH size in the vestibule, and monthly vertigo and hearing evaluation was done for 12 months. EH shrinkage was defined as the size change of vestibular EH from significant to none. RESULTS: Among 133 MD patients evaluated for eligibility, 67 patients with caloric-vHIT dissociation entered the study. Fifteen participants had EH shrinkage (G-I), while 52 participants had no remarkable EH change (G-II). Average values (IQR) of the maximum slow phase velocity in G-I and G-II were 29.6 (13.0-34.0) and 25.9 (17.3-31.3), respectively, at baseline, 26.1 (9.0-38.0) and 23.6 (18.0-28.3) at 12 months. Two-factor repeated-measures ANOVA showed no significant differences between the groups (P = 0.486). The values of vestibulo-ocular reflex gain of the horizontal SC in G-I and G-II remained above 0.8 during the study period. CONCLUSIONS: EH detected by MRI shows limited correlation with caloric stimulation results.

Cognitive neural responses in the semantic comprehension of sound symbolic words and pseudowords.

Introduction: Sound symbolism is the phenomenon of sounds having non-arbitrary meaning, and it has been demonstrated that pseudowords with sound symbolic elements have similar meaning to lexical words. It is unclear how the impression given by the sound symbolic elements is semantically processed, in contrast to lexical words with definite meanings. In event-related potential (ERP) studies, phonological mapping negativity (PMN) and N400 are often used as measures of phonological and semantic processing, respectively. Therefore, in this study, we analyze PMN and N400 to clarify the differences between existing sound symbolic words (onomatopoeia or ideophones) and pseudowords in terms of semantic and phonological processing. Methods: An existing sound symbolic word and pseudowords were presented as an auditory stimulus in combination with a picture of an event, and PMN and N400 were measured while the subjects determined whether the sound stimuli and pictures match or mismatch. Results: In both the existing word and pseudoword tasks, the amplitude of PMN and N400 increased when the picture of an event and the speech sound did not match. Additionally, compared to the existing words, the pseudowords elicited a greater amplitude for PMN and N400. In addition, PMN latency was delayed in the mismatch condition relative to the match condition for both existing sound symbolic words and pseudowords. Discussion: We concluded that established sound symbolic words and sound symbolic pseudowords undergo similar semantic processing. This finding suggests that sound symbolism pseudowords are not judged on a simple impression level (e.g., spiky/round) or activated by other words with similar spellings (phonological structures) in the lexicon, but are judged on a similar contextual basis as actual words.

80 Hz auditory steady state responses (ASSR) elicited by silent gaps embedded within a broadband noise.

Introduction: Although auditory temporal processing plays an important role in speech comprehension, it cannot be measured by pure tone audiometry. Auditory temporal resolution is often assessed by behavioral gaps-in-noise test. To evaluate whether auditory temporal resolution could be objectively assessed, we measured the auditory steady state response (ASSR) elicited by silent gaps embedded within broadband noises at 80 Hz. Methods: We prepared six sound types as test stimuli. One was a continuous broadband noise without a silent interval as a control stimulus and the others were broadband noises with 80 Hz silent intervals of 0.4, 0.8, 1.6, 3.1, and 6.3 ms. Results: Significant ASSRs were recorded only when the gap length was longer than the behavioral thresholds and the ASSR amplitude increased as the gap length increased. Conclusion: Eighty Hertz gap-evoked ASSR appears to reflect the neural activity related to the auditory gap processing and may be used as an objective measure of auditory temporal resolution in humans.

Assessment of inner ear morphology and function in response to local positive pressure for Ménière's disease: a nonrandomized controlled trial.

Ménière's disease (MD) is an inner ear disorder in which the main pathological feature is endolymphatic hydrops (EH). Positive pressure therapy (PPT) using a portable device is now a second-line therapy for intractable MD when initial medical treatment fails. However, it remains unknown whether PPT causes the morphological and functional changes of inner ear in patients with active MD in accordance with reduction of vertigo attacks. In this nonrandomized controlled trial of 52 patients with MD, the volume of EH significantly decreased with reduction of vertigo attacks during 8 months of PPT combined with medications while the volume of that significantly increased with medications alone. There was no difference between Control group (n = 26) and PPT group (n = 26) regarding the vertigo control, however, PPT group achieved a significant functional improvement of vertical semicircular canals. The effect of volume reduction by PPT has been firstly demonstrated and the functional changes of all semicircular canals during PPT have been firstly examined. Morphological and functional changes in the inner ear by administrating local positive pressure are quite different from those caused by medications alone.Clinical trial registration: UMIN-CTR UMIN000041164 (registered on July 20, 2020).

Auditory steady state responses elicited by silent gaps embedded within a broadband noise.

BACKGROUND: Auditory temporal processing plays an important role in speech comprehension. Usually, behavioral tests that require subjects to detect silent gaps embedded within a continuous sound are used to assess the ability of auditory temporal processing in humans. To evaluate auditory temporal processing objectively, the present study aimed to measure the auditory steady state responses (ASSRs) elicited by silent gaps of different lengths embedded within a broadband noise. We presented a broadband noise with 40-Hz silent gaps of 3.125, 6.25, and 12.5 ms. RESULTS: The 40-Hz silent gaps of 3.125, 6.25, and 12.5 ms elicited clear ASSRs. Longer silent gaps elicited larger ASSR amplitudes and ASSR phases significantly differed between conditions. CONCLUSION: The 40 Hz gap-evoked ASSR contributes to our understanding of the neural mechanisms underlying auditory temporal processing and may lead to the development of objective measures of auditory temporal acuity in humans.

Antivertiginous Effect of Caloric Stimulation for Acute Peripheral Vertigo.

OBJECTIVE: To clarify therapeutic effect of caloric stimulation for acute peripheral vertigo. PATIENTS: Two patients with acute peripheral vertigo accompanied by spontaneous nystagmus. INTERVENTIONS: Therapeutic. MAIN OUTCOMES AND MEASURES: Changes in the maximum slow phase velocity of spontaneous nystagmus and subjective vertigo. RESULTS: Reduction in the maximum slow phase velocity of spontaneous nystagmus and mitigation of subjective vertigo was observed in both patients. CONCLUSION: Caloric stimulation could be one potential option as a suppressant for acute peripheral vertigo.

Development of receptive vocabulary and verbal intelligence in Japanese children with unilateral hearing loss.

OBJECTIVE: In the past, it was believed that unilateral hearing loss has a minimal impact on the speech and language development in children. However, several studies have suggested that some school-age children with unilateral hearing loss have learning impairments in language. In the present study, we first examined whether preschool-age children with unilateral severe-to-profound hearing loss (UHL) have delays in the development of receptive vocabulary and verbal intelligence. In the follow-up study, we tested the children again after school admission. The objective of the present study was to reveal the development of receptive vocabulary and verbal intelligence from preschool to school years in children with UHL. METHODS: Fifteen Japanese preschool-age children with UHL and a control group of 20 age-matched Japanese children with bilateral normal hearing (NH), who were examined because articulation disorder was suspected, were enrolled in this study. The development of receptive vocabulary and verbal intelligence was evaluated using the Picture Vocabulary Test-Revised (PVT-R) and the Wechsler Intelligence Scale, respectively. The present retrospective study was approved by the Committee for Medical Ethics of Tokushima University Hospital (#3801). RESULTS: The scaled score (SS) of the PVT-R and verbal intelligence quotient (VIQ)/verbal comprehension index (VCI), but not performance intelligence quotient/perceptual reasoning index in children with UHL were significantly lower than those in the control children with NH at preschool-age. The SS of the PVT-R and VIQ/VCI in children with UHL significantly improved after school admission. In the subgroup analysis, the SS of the PVT-R in the lower receptive vocabulary group of children with UHL at preschool-age was significantly increased after school admission, but the SS in the normal and higher receptive vocabulary group of children with UHL at preschool-age were still around the standardized mean of SS after school admission. CONCLUSION: These findings suggest that the development of receptive vocabulary and verbal intelligence was delayed in preschool-age children with UHL and that most of them caught up to exhibit normal language ability after school admission.

Neurophysiological Evaluation of Right-Ear Advantage During Dichotic Listening.

Right-ear advantage refers to the observation that when two different speech stimuli are simultaneously presented to both ears, listeners report stimuli more correctly from the right ear than the left. It is assumed to result from prominent projection along the auditory pathways to the contralateral hemisphere and the dominance of the left auditory cortex for the perception of speech elements. Our study aimed to investigate the role of attention in the right-ear advantage. We recorded magnetoencephalography data while participants listened to pairs of Japanese two-syllable words (namely, "/ta/ /ko/" or "/i/ /ka/"). The amplitudes of the stimuli were modulated at 35 Hz in one ear and 45 Hz in the other. Such frequency-tagging allowed the selective quantification of left and right auditory cortex responses to left and right ear stimuli. Behavioral tests confirmed the right-ear advantage, with higher accuracy for stimuli presented to the right ear than to the left. The amplitude of the auditory steady-state response was larger when attending to the stimuli compared to passive listening. We detected a correlation between the attention-related increase in the amplitude of the auditory steady-state response and the laterality index of behavioral accuracy. The right-ear advantage in the free-response dichotic listening was also found in neural activities in the left auditory cortex, suggesting that it was related to the allocation of attention to both ears.

Rupture-Like Shrinkage and Regrowth of Endolymphatic Hydrops in Ménière's Disease During Remission.

OBJECTIVE: To clarify pathophysiological characteristics of Ménière's disease during the remission phase. PATIENTS: Two Ménière's disease patients with different disease durations, whose endolymphatic hydrops was longitudinally observed using 3-T magnetic resonance imaging. INTERVENTIONS: Diagnostic. MAIN OUTCOMES AND MEASURES: Morphological changes of endolymphatic hydrops visualized using 3-T magnetic resonance imaging. RESULTS: Rupture-like shrinkage and regrowth of endolymphatic hydrops during the remission phase was observed in both patients. CONCLUSION: The remission phase with hearing improvement could be as important as vertigo attacks in Ménière's disease.

A new combined index of SUVmax of lymph node in PET / CT by a weighting coefficient plus its maximum minor axis in CECT to evaluate occult lymph node metastasis in clinical N0 patients with tongue cancer.

To predict occult nodal metastasis in clinical N0 patients with tongue cancer, we developed combined index (CI) : SUVmax of the largest lymph node in PET / CT by weighting coefficient plus its maximum minor axis (< 10 mm) in contrast-enhanced CT (CECT). In this retrospective study, 57 clinical N0 patients with tongue cancer, who underwent elective supraomohyoid neck dissection at cervical levels of I-III were enrolled. The cutoff value of SUVmax of 2.0 obtained using receiver operating characteristic (ROC) analysis predicted the postoperative positive cervical levels containing metastatic lymph nodes from clinical N0 cervical levels in tongue cancer patients with a sensitivity of 54.5% and a specificity of 78.2%. The cutoff value of CI with weighting coefficient of 1.5 obtained using ROC analysis was 9.8 at the maximum area under the curve of 0.750. The cutoff value of 9.8 predicted the postoperative positive cervical levels containing metastatic lymph nodes from clinical N0 cervical levels in tongue cancer patients with a sensitivity of 68.2% and a specificity of 81.5%. These findings suggest that CI of functional PET / CT and morphological CECT components might improve the diagnostic performance of occult nodal metastasis to select clinical N0 patients with tongue cancer preferable for elective neck dissection. J. Med. Invest. 68 : 154-158, February, 2021.

Effects of FM system fitted into the normal hearing ear orcartilage conduction hearing aid fitted into the affected ear on speech-in-noise recognition in Japanese children with unilateral congenital aural atresia.

The effects of FM system fitted into the normal hearing ear (NHE) or a cartilage conduction hearing aid (CCHA) fitted into the affected ear (AE) on the speech recognition ability in noise were examined in children with unilateral congenital aural atresia (UCAA). In children with bilateral normal hearing (BNH), speech recognition score (SRS) was significantly decreased in the noisy environment of -5 dB signal-to-noise ratio (SNR), compared with those in quiet. In children with UCAA, SRS was significantly decreased in noisy environments of 0 and -5 dB SNR, compared with those in quiet. In noisy environments of 0 and -5 dB SNR, SRS in children with UCAA was significantly decreased, compared those in children with BNH. In the noisy environment of -5 dB SNR, SRS in UCAA children aided by FM system fitted into NHE was significantly better than those in unaided children in the same group. In the noisy environment of 0 dB SNR, SRS in UCAA children aided by CCHA into AE tended to be higher than those in unaided children in the same group. FM system and CCHA can be recommended as an audiological management for the improvement of speech recognition in children with UCHL in classrooms. J. Med. Invest. 67 : 134-138, February, 2020.

Daily auricular stimulation with capsaicin ointment improved cough reflex sensitivity in elderly patients with dysphagia: a pilot study.

Background: In our previous study, a single auricular application of capsaicin ointment, but not placebo improved cough reflex in elderly patients with dysphagia.Aims/Objectives: In the present study, we examined whether daily auricular application of capsaicin ointment continued to improve cough reflex in similar patients.Material and methods: With a cotton swab, 0.025% capsaicin ointment was applied in each external auditory canal alternately once a day for 2 weeks. The cough reflex sensitivity was evaluated on videoendoscopy using a numerical score and inhalation cough challenge test using citric acid in elderly dysphagic inpatients.Results: After daily auricular application of capsaicin ointment for 2 weeks, the endoscopic score of glottal closure and cough reflexes significantly improved, and the citric acid cough threshold significantly decreased. There was a significant correlation between the endoscopic score and the citric acid cough threshold before and after daily capsaicin application in the patients.Conclusions: Daily auricular stimulation with capsaicin ointment for 2 weeks continued to improve the cough reflex sensitivity in elderly patients with dysphagia.Significance: Daily auricular stimulation with capsaicin ointment would be a safe and effective intervention to prevent pneumonia in elderly with a risk of aspiration.

Aural stimulation with capsaicin prevented pneumonia in dementia patients.

OBJECTIVE: In the present study, we examined the effects of daily application of capsaicin ointment to the external auditory canal for 6 months on the development of pneumonia in elderly dementia patients at high risk of aspiration. METHODS: Twenty-nine oldest-old bedridden dementia inpatients at high risk of aspiration were enrolled in the present study. Ointment containing 0.025% capsaicin was applied to each external auditory canal with a cotton swab alternatively once a day for 6 months. RESULTS: The incidence of pneumonia during the 6 months before the intervention was 1.80±0.37 in these patients. However, this incidence significantly decreased to 0.40±0.29 (p<0.01) during the 6 months of the alternative application of capsaicin ointment to each auditory canal. No adverse effect such as otalgia was observed. CONCLUSION: These findings suggest that daily long-term aural stimulation with capsaicin ointment enhanced the cough reflex via Arnold's ear-cough reflex as a glottis protective measure, resulting in the reduction of incidence of pneumonia in elderly dementia patients at high risk of aspiration. The daily aural stimulation with capsaicin ointment may be a safe and promising intervention to prevent aspiration pneumonia in elderly people, especially those who cannot undergo swallowing exercise.

Effects of FM system fitted into normal hearing ear on speech-in-noise recognition in Japanese school-aged children with unilateral severe-to-profound hearing loss.

OBJECTIVES: We examined speech recognition ability of elementary school-aged Japanese children with unilateral hearing loss under noisy environments and then examined the effects of the FM system fitted into their normal hearing ear on their speech recognition ability. METHODS: Twelve children with severe-to-profound sensorineural hearing loss and ten age-matched children with bilateral normal hearing received speech recognition test in quiet and noisy environments. Other nine children with severe-to-profound sensorineural hearing loss received speech recognition test with or without the FM receiver fitted to the normal hearing ear in quiet and noisy environments. RESULTS: Signal-to-noise ratio (SNR) in Japanese elementary school classrooms was estimated to be -6.9 dB at a preferential seat. In noisy environment of -5 dB SNR similar to working classrooms, the correct rates of speech recognition test in children with unilateral hearing loss were significantly lower, compared with those in children with bilateral normal hearing. In the noisy environment, the correct rates in children aided by the FM system with unilateral hearing loss were significantly better, compared with unaided ones. CONCLUSION: The results suggested that the FM system is recommended as an audiological management for improvement of speech recognition of children with unilateral hearing loss in noisy classrooms. J. Med. Invest. 65:216-220, August, 2018.

Manipulation of Auditory Inputs as Rehabilitation Therapy for Maladaptive Auditory Cortical Reorganization.

Neurophysiological and neuroimaging data suggest that the brains of not only children but also adults are reorganized based on sensory inputs and behaviors. Plastic changes in the brain are generally beneficial; however, maladaptive cortical reorganization in the auditory cortex may lead to hearing disorders such as tinnitus and hyperacusis. Recent studies attempted to noninvasively visualize pathological neural activity in the living human brain and reverse maladaptive cortical reorganization by the suitable manipulation of auditory inputs in order to alleviate detrimental auditory symptoms. The effects of the manipulation of auditory inputs on maladaptively reorganized brain were reviewed herein. The findings obtained indicate that rehabilitation therapy based on the manipulation of auditory inputs is an effective and safe approach for hearing disorders. The appropriate manipulation of sensory inputs guided by the visualization of pathological brain activities using recent neuroimaging techniques may contribute to the establishment of new clinical applications for affected individuals.

[Diagnosis of Subjective Tinnitus].

Subjective tinnitus is one of the most common diseases in industrialized countries; however, the mechanisms of tinnitus generation and maintenance remain elusive. Currently, there are no objective parameters in the diagnosis of tinnitus. In order to meet the overwhelming demand for evidence-based tinnitus therapy, an objective measurement of subjective tinnitus is necessary. Here, we discuss the possible objective diagnosis of tinnitus from different perspectives.

Aural stimulation with capsaicin ointment improved swallowing function in elderly patients with dysphagia: a randomized, placebo-controlled, double-blind, comparative study.

OBJECTIVE: The aim of this study was to assess whether aural stimulation with ointment containing capsaicin improves swallowing function in elderly patients with dysphagia. STUDY DESIGN: A randomized, placebo-controlled, double-blind, comparative study. SETTINGS: Secondary hospital. PATIENTS AND METHODS: Twenty elderly dysphagic patients with a history of cerebrovascular disorder or Parkinson's disease were randomly divided into two groups: 10 receiving aural stimulation with 0.025% capsaicin ointment and 10 stimulated with placebo. The ointments were applied to the external auditory canal with a cotton swab. Then, swallowing of a bolus of blue-dyed water was recorded using transnasal videoendoscopy, and the swallowing function was evaluated according to both endoscopic swallowing scoring and Sensory-Motor-Reflex-Clearance (SMRC) scale. RESULTS: The sum of endoscopic swallowing scores was significantly decreased 30 and 60 min after a single administration in patients treated with capsaicin, but not with placebo. Reflex score, but not Sensory, Motion and Clearance scores, of the SMRC scale was significantly increased 5, 30 and 60 min after single administration in patients treated with capsaicin, but not with placebo. No patient showed signs of adverse effects. CONCLUSION: As capsaicin is an agonist of the transient receptor potential vanilloid 1 (TRPV1), these findings suggest that improvement of the swallowing function, especially glottal closure and cough reflexes, in elderly dysphagic patients was due to TRPV1-mediated aural stimulation of vagal Arnold's nerve with capsaicin, but not with a nonspecific mechanical stimulation with a cotton swab.

Modulation of Auditory Evoked Magnetic Fields Elicited by Successive Frequency-Modulated (FM) Sweeps.

In our daily life, we are successively exposed to frequency-modulated (FM) sounds that play an important role in speech and species-specific communication. Previous studies demonstrated that repetitive exposure to identical pure tones resulted in decreased neural activity. However, the effects of repetitively presented FM sounds on neural activity in the human auditory cortex remain unclear. In the present study, we used magnetoencephalography to investigate auditory evoked N1m responses elicited by four successive temporally repeated and superimposed FM sweeps in three sequences: (1) four FM sweeps were identical, (2) four FM sweeps had the same FM direction and rate, but different carrier frequencies, (3) four FM sweeps differed with respect to the FM rate and/or direction and their carrier frequencies. In contrast to our expectations, the results obtained demonstrated that N1m responses were maximal when the four FM sweeps were identical and minimal when they were distinct. These results suggest that the neural processing of repetitive FM sweeps in the human auditory cortex may differ from that of repetitive pure tones.

Broadened population-level frequency tuning in the auditory cortex of tinnitus patients.

Tinnitus is a phantom auditory perception without an external sound source and is one of the most common public health concerns that impair the quality of life of many individuals. However, its neural mechanisms remain unclear. We herein examined population-level frequency tuning in the auditory cortex of unilateral tinnitus patients with similar hearing levels in both ears using magnetoencephalography. We compared auditory-evoked neural activities elicited by a stimulation to the tinnitus and nontinnitus ears. Objective magnetoencephalographic data suggested that population-level frequency tuning corresponding to the tinnitus ear was significantly broader than that corresponding to the nontinnitus ear in the human auditory cortex. The results obtained support the hypothesis that pathological alterations in inhibitory neural networks play an important role in the perception of subjective tinnitus.NEW & NOTEWORTHY Although subjective tinnitus is one of the most common public health concerns that impair the quality of life of many individuals, no standard treatment or objective diagnostic method currently exists. We herein revealed that population-level frequency tuning was significantly broader in the tinnitus ear than in the nontinnitus ear. The results of the present study provide an insight into the development of an objective diagnostic method for subjective tinnitus.