Publications by authors named "Tadao Okayasu"
Prognosis of asymptomatic endolymphatic hydrops in healthy volunteers: A five-year cohort study.
Laryngoscope Investig Otolaryngol
December 2024
Background: This study aimed to clarify the prognosis of asymptomatic endolymphatic hydrops (EH) in healthy volunteers via five-year follow-ups with inner ear magnetic resonance imaging (MRI).
Methods: Inner ear MRI was performed on 115 participants recruited as controls in a previous study on Meniere's disease. The endolymphatic space was visualized using Naganawa's method of contrast-enhanced MRI with intravenous gadolinium injection and evaluated using Nakashima's method of 2D imaging analysis.
Article Synopsis
- - The study focuses on how aging affects the vestibular system, particularly the otolith organs in mice, which are critical for balance and can increase fall risk in older adults.
- - Researchers used young and old mice to analyze the morphology and function of the otoliths, finding significant differences in otolith density and structural changes that correlated with age.
- - The results suggest that aging leads to a decline in otolith function, evidenced by reduced responsiveness in eye movement during tests, which may contribute to increased falls in the elderly.
Reviewing Kampo medicine (Traditional Japanese Herbal Medicine) for otology/neurotology diseases.
Auris Nasus Larynx
February 2024
Article Synopsis
- Kampo medicine, a traditional Japanese herbal remedy, is specifically used for treating ear and nervous system diseases in Japan and some Asian nations.
- In Japan, only licensed medical doctors can prescribe both Kampo and conventional Western medicine, which may improve the quality of clinical research on these treatments.
- This article aims to present existing evidence from previous studies on the effectiveness of Kampo treatment for otologic and neurotologic conditions, as there is currently no English review available on this topic.
Introduction: Dizziness is a common disease. However, approximately 10-40% of patients were diagnosed unknown dizziness even though general, neurological, and otological examinations were performed. The aim of this otopathological study was to investigate the histopathology of the peripheral vestibular system of patients who suffered from undiagnosed dizziness.
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- The study investigated prognostic factors for idiopathic sudden sensorineural hearing loss (SSNHL) in 115 patients, particularly focusing on the effects of vertigo/dizziness and age on hearing loss outcomes.
- Results showed that patients with vertigo/dizziness experienced more severe hearing loss and poorer recovery, especially at certain frequency ranges, while older patients (65+) had higher post-treatment hearing thresholds.
- The findings emphasize the importance of comparing affected and nonaffected ear thresholds to better understand the impact of pre-existing hearing loss on SSNHL outcomes.
Many people are affected by tinnitus, a sensation of ringing in the ear despite the absence of external sound. Goshajinkigan (GJG) is one of the formulations of Japanese traditional herbal medicine and is prescribed for the palliative treatment of patients with tinnitus. Although GJG is clinically effective in these patients, its behavioral effects and the underlying neuroanatomical substrate have not been modeled in animals.
View Article and Find Full Text PDFEffect of transducer placements on thresholds in ears with an abnormal ear canal and severe conductive hearing loss.
Laryngoscope Investig Otolaryngol
December 2021
Article Synopsis
- A study examined the effectiveness of cartilage conduction (CC) hearing aids for patients with aural atresia, focusing on whether placing the transducer on the aural cartilage or mastoid provides better sound transmission.
- The research involved 35 patients with severe conductive hearing loss, comparing hearing thresholds for different transducer placements.
- Results showed that for patients with bony atresia, the aural cartilage placement significantly improved hearing thresholds at lower frequencies, while no benefits were found for non-atretic ears, indicating placement is crucial for effective hearing compensation.
Meniere's disease is a common inner ear disorder accompanied by vertigo attacks and fluctuating hearing loss that some believe is due to a stressful lifestyle. To elucidate the scientific relationship in neuro-endocrinology between Meniere's disease and stress, we examined the surgical results of endolymphatic sac drainage surgery and changes in stress-induced plasma arginine-vasopressin levels. We enrolled 100 intractable Meniere's patients and examined surgical results and plasma vasopressin levels.
View Article and Find Full Text PDFObjective: Congenital aural atresia causes severe conductive hearing loss disturbing auditory development. The differences in speech recognition were investigated between bilateral and unilateral aural atresia.
Design: The maximum speech recognition scores (SRSs) were compared between patients with bilateral and unilateral aural atresia.
Article Synopsis
- The study investigates whether cochlear implantation leads to an increase in monocyte-derived macrophages within cochlear vessels, finding that macrophages are more prevalent in implanted ears compared to unimplanted ones.* -
- Using light microscopy and anti-Iba1 immunostaining, researchers analyzed human cochlear samples, revealing that Iba1-positive macrophages were significantly more common in vessels near the round window of implanted ears.* -
- Results indicate that the density of these macrophages correlates with the duration since implantation, suggesting that the immune response may play a key role in changes observed in the cochlea post-surgery.*
Article Synopsis
- The study investigates how speech-modulated bone-conducted ultrasound (SM-BCU) can convey information about vowel duration, a crucial aspect of spoken language, particularly in distinguishing between words with different vowel lengths.
- Eight Japanese-speaking participants performed a task to differentiate between "hato" (pigeon) and "haato" (heart) based on varying vowel durations presented through SM-BCU and traditional air-conducted sound.
- Results showed that while the SM-BCU method required slightly longer vowel durations for accurate recognition compared to traditional sound (274.6 ms vs. 269.6 ms), both methods had a similar ability to convey vowel duration differences. *
Article Synopsis
- Ultrasound is typically considered inaudible, but bone-conducted ultrasound (BCU) can be heard, especially by individuals with profound deafness.
- There are indications that BCU may serve as a potential hearing aid or therapy for tinnitus, as some patients can perceive and differentiate speech through this method.
- The review examines both the perception of BCU and its clinical applications, including the need to encode speech signals into BCU for effective hearing aids and its potential role in tinnitus treatment.
Autoimmune sensorineural hearing loss (ASHL) is a rare disease of uncertain etiology, with no established treatment strategy. The duration of morbidity is increased in refractory cases; and therefore, the preservation of hearing and the prevention of adverse effects with steroid therapy are serious long term issues to consider. Long-term follow up of patients treated for ASHL was performed retrospectively in order to elucidate the pathogenesis of ASHL, evaluate the consequences of steroid therapy, and determine a promising treatment course.
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- - The study hypothesizes that cochlear implantation increases macrophage presence in the cochlea, akin to previous observations in vestibular endorgans.
- - Researchers analyzed macrophage prevalence in the cochlea of 10 patients following unilateral cochlear implantation, comparing it to their unoperated ear.
- - Results indicated a significant rise in macrophage density in the cochlea of implanted ears, along with varying macrophage types, suggesting their role in both inflammation and homeostasis post-surgery.
Kleefstra syndrome is a rare neurogenetic disorder caused by a subtelomeric 9q34.3 deletion or by an intragenic mutation of the euchromatin histone methyl transferase 1 gene (EHMT1). Approximately 20% to 30% of individuals have hearing loss.
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- Cochlear implantation may lead to a higher density of macrophages in vestibular endorgans, which are areas in the inner ear responsible for balance.
- A study involving 10 human subjects showed that macrophage counts were significantly greater in implanted ears compared to unimplanted ones, except in specific zones of the utricle and posterior semicircular canal.
- The findings suggest a possible immune response, indicated by macrophages migrating from the subepithelial area into the neuroepithelium after the cochlear implantation procedure.
Introduction: Sensorineural hearing loss frequently has been described in patients with leukemia, and in fact, hearing loss may be the presenting symptom of this disease. However, the pathogenesis of sensorineural hearing loss in leukemia is not well understood.
Objective: To describe the temporal bone histopathology in 1 patient with leukemia and sensorineural hearing loss.
Article Synopsis
- Bone-conducted ultrasound (BCU) can be heard by both normal-hearing individuals and some profoundly deaf individuals, making it a potential technology for a bone-conducted hearing aid that transmits speech signals.
- Studies suggest that understanding speech through BCU relies more on temporal information rather than frequency, requiring further exploration of how this temporal processing works.
- Research using magnetoencephalography on normal-hearing participants indicated that BCU can integrate sounds effectively within a temporal window of approximately 150-200 milliseconds, similar to how we process air-conducted audible sounds (ACAS).
Background: We report a unique pattern of focal degeneration of the neuroepithelium of cristae ampullares, thick subepithelial extracellular deposits, and neural degeneration in three humans.
Objective: To characterize the pattern of vestibular degeneration and measure the thickness of subepithelial deposits in these three cases and controls.
Methods: The subepithelial deposits of vestibular end organs in three subject cases and controls were studied using hematoxylin and eosin, periotic acid-Schiff, Gomori trichrome staining, and immunostaining for antineurofilament, antimyosin VIIa, and anticollagen 4a1.
Objective: To examine the backgrounds of patients with audiovestibular disease regarding what influences their psychological state.
Methods: During a 12-year period, 375 successive patients with audiovestibular diseases were enrolled in this study. Diseases included unilateral (n=174) and bilateral (n=51) Menière's disease, sudden deafness with vertigo (n=70), and vestibular neuritis (n=80).
Objectives: Mental disorder is often one of the causes to make treatments for Ménière's disease more difficult. The aim in the present study is to examine ratios of the neurosis and depression in patients with intractable Ménière's disease and also relationships between the ratios and surgical results after endolymphatic sac drainage with large doses of steroids.
Methods: Between 1998 and 2009, we enrolled 263 intractable Ménière's patients and divided into two groups, 207 in surgical group and 56 in non-surgical group.
Article Synopsis
- Ultrasound can transmit speech information to the human ear through a method called bone-conduction, which some deaf individuals can also perceive.
- A study tested how well eight normal-hearing volunteers could understand speech-modulated bone-conducted ultrasound (BCU) when exposed to distracting background noise (masking), revealing different recognition patterns compared to regular speech.
- The findings indicated that both the demodulation of signals and direct ultrasonic stimulation are crucial for understanding speech-modulated BCU, particularly highlighting the direct stimulation's significance for profoundly deaf individuals.
When two tones are presented in a short interval of time, the presentation of the preceding tone (masker) suppresses the response evoked by the subsequent tone (signal). To address the processing in forward suppression, we applied 2- and 4-kHz maskers, followed by a 1-kHz signal at varying signal delays (0 to 320 ms) and measured the signal-evoked N1m. A two-way analysis of variance revealed a statistically significant effect for signal delay in both masker presentation conditions.
View Article and Find Full Text PDFSpeech-modulated bone-conducted ultrasound (BCU) can transmit speech sounds for some profoundly deaf individuals. Hearing aids using BCU are considered to be a novel hearing system for such individuals. In our previous study, the speech discrimination for speech-modulated BCU was objectively confirmed using a magnetoencephalography.
View Article and Find Full Text PDFWhen two tones are presented in a short time interval, the response to the second tone is suppressed. This phenomenon is referred to as forward suppression. To address the effect of the masker laterality on forward suppression, magnetoencephalographic responses were investigated for eight subjects with normal hearing when the preceding maskers were presented ipsilaterally, contralaterally, and binaurally.
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