Effects of endoscopic sinus surgery on nasal spray deposition using dye-based methods for humans and a human silicone sinonasal cavity model.

OBJECTIVE: We have evaluated that the deposition patterns of corticosteroid nasal spray in the sinonasal cavity of both post-operated human cases, which were further compared with a computed tomography-based sinonasal airway model. METHODS: Fifty-one patients with chronic rhinosinusitis following an endoscopic sinus surgery were enrolled in this study. Nasal spray mometasone furoate hydrate (Nasonex®) containing 0.1% indigocarmine was applied to the patients' nasal cavities and the sinonasal cavity was observed by endoscopy and video documentation. A single plaster sinonasal model was used to quantify the sinonasal deposition of nasal sprays containing 10% red ink solution using 12 round paper strips. RESULTS: The predominant areas of the spray deposition of the operated sinonasal cavities were recognized in the ethmoid sinus and the olfactory cleft in the human study. The droplets were mainly deposited in the inferior turbinate followed by the posterior part of the ethmoid sinus, the olfactory cleft, and anterior part of the ethmoid sinus in a sinonasal model. CONCLUSION: The corticosteroid nasal spray efficiently reached the olfactory cleft and the ethmoid sinus in post-operative conditions, which was demonstrated by post-operated human cases and a computed tomography-based sinonasal airway model.

Stochastic electrical stimulation of the thoracic or cervical regions with surface electrodes facilitates swallow in rats.

Introduction: Aspiration pneumonia, a leading cause of mortality, poses an urgent challenge in contemporary society. Neuromuscular electrical stimulation (NMES) has been commonly used in dysphagia rehabilitation. However, given that NMES at motor threshold targets only specific muscles, it carries a potential risk of further compromising functions related to swallowing, respiration, and airway protection. Considering that the swallow motor pattern is orchestrated by the entire swallow pattern generator (the neural mechanism governing a sequence of swallow actions), a rehabilitation approach that centrally facilitates the entire circuit through sensory nerve stimulation is desirable. In this context, we propose a novel stimulation method using surface electrodes placed on the back to promote swallowing. Methods: The efficacy of the proposed method in promoting swallowing was evaluated by electrically stimulating sensory nerves in the back or neck. Probabilistic stimulus was applied to either the back or neck of male and female rats. Swallows were evoked by an oral water stimulus, and electromyographic (EMG) activity of the mylohyoid, thyroarytenoid, and thyropharyngeus muscles served as the primary outcome measure. Results: Gaussian frequency stimulation applied to the skin surface of the thoracic back elicited significant increases in EMG amplitude of all three swallow-related muscles. Neck stimulation elicited a significant increase in EMG amplitude of the thyroarytenoid during swallow, but not the mylohyoid or thyropharyngeus muscles. Discussion: While the targeted thoracic spinal segments T9-T10 have been investigated for enhancing respiration, the promotion of swallowing through back stimulation has not been previously studied. Furthermore, this study introduces a new probabilistic stimulus based on Gaussian distribution. Probabilistic stimuli have been reported to excel in nerve stimulation in previous research. The results demonstrate that back stimulation effectively facilitated swallow more than neck stimulation and suggest potential applications for swallowing rehabilitation.

A Systematic Review of the Audiological Efficacy of Cartilage Conduction Hearing Aids and the Factors Influencing Their Clinical Application.

This systematic review evaluates the efficacy and benefit of cartilage conduction hearing aids (CC-HAs) and that factors that influence purchasing decisions. The hearing thresholds and functional gain following CC-HA wear were synthesised. A one-way analysis of variance compared the differences in the hearing thresholds and functional gain at individual frequencies and in patients with a variety of pathological changes. The synchronised aided hearing threshold and functional gain at 2.0 kHz were significantly better than at 0.5, 1.0, and 4.0 kHz. There was no significant difference in the synchronised unaided hearing thresholds across individual frequencies between 0.5 and 4.0 kHz. The synchronised functional gain in patients with atresia was significantly greater than in patients with aural atresia or stenosis and middle ear pathologies with normal ear canals. The acceptability of CC-HAs in terms of purchase decision is influenced by the condition of the external auditory meatus and severity of hearing loss, with the highest purchase rate seen in patients with aural atresia or stenosis. CC-HAs' fitting procedure advantages and cosmetic considerations make these devices a viable and preferred choice for individuals with microtia and aural atresia. Additional research to evaluate the benefits towards emotional well-being is crucial to gain insights into the psychological impact of CC-HA use.

Diagnosing Middle Ear Malformation by Pure-Tone Audiometry Using a Three-Dimensional Finite Element Model: A Case-Control Study.

BACKGROUND: Hearing loss caused by middle ear malformations is treated by tympanoplasty to reconstruct the acoustic conduction system. The mobility of the ossicles plays a crucial role in postoperative success. However, identifying the location of ossicular malformation based solely on preoperative audiograms is challenging due to the complex relationship between fixation location, deformity levels, and ossicular mobility. METHODS: Middle ear finite element models for simulating ossicular malformations were created, and the results were compared with the actual preoperative audiograms. RESULTS: This approach objectively diagnosed ossicular fixation and disarticulation, bypassing traditional criteria reliant on physician examination or imaging. CONCLUSION: This study suggests that future research should focus on developing a diagnostic framework utilizing large-scale data.

Effects of an Active Noise Control Technology Applied to Earphones on Preferred Listening Levels in Noisy Environments.

BACKGROUND AND OBJECTIVES: The harmful effects of frequent exposure to loud sounds through portable music players (PMPs) in combination with earphones have been suggested to result in a high prevalence of recreational noise-induced hearing loss among children, adolescents, and young adults. The present study aimed to evaluate the effects of an active noise control technology applied to earphones on the preferred listening levels (PLLs) while listening to music in the presence of background noise. SUBJECTS AND METHODS: Twenty-three adults between 20 and 40 years with normal hearing were recruited for this study. PLLs for listening to pop-rock and classical music were measured in the participants' ear canal with a commercially available PMP for four earphone/headphone configurations in quiet and noisy conditions. Ear canal insertion loss was measured in open ear conditions as well as earphone/headphone conditions. RESULTS: The average PLL while using earphones and headphones exceeded 85 dBA corresponding to the sound level to induce hearing damage, but in the case of canal earphones with noise cancelling (NC), it was below 75 dBA, corresponding to potentially harmful levels. The background subway noise significantly increased the PLL measured in quiet conditions using any four earphone/headphone types except canal earphones with NC. Canal earphones with NC showed the lowest PLLs compared with participants' average PLLs using the other three earphone/headphone types. CONCLUSIONS: To minimize recreational noise exposure at the risk of PMP use, the use of earphones with NC is recommended in noisy environments.

Exploring Mechanisms Underlying Unexplained Air-Bone Gaps Post-Myringoplasty: Temporal Bone Model and Finite Element Analysis.

PURPOSE: Air-bone gap (ABG) is an essential indicator of middle ear transfer function after myringoplasty. However, there is still uncertainty about the mechanisms behind unexplained ABGs in patients post-myringoplasty. The present study investigated these mechanisms using cadaveric temporal bone (TB) measurement and finite element (FE) modeling. METHODS: Three conditions of tympanic membrane (TM) perforation were modeled with a perforated area of 6%, 24%, and 50% of the total TM area to simulate a small, medium, or large TM perforation of TB model. A piece of paper was used to patch the TM perforation to simulate the situation post-myringoplasty. In the FE model for post-operation, the material properties at the perforation area were changed. Measurement of TM vibration at the umbo was undertaken with a laser Doppler vibrometer (LDV). RESULTS: As the perforated area increased vibration of the TM at the umbo decreased in both the TB and FE models. But the reduction of TM vibration is more minor in the FE model than in the TB model. After the perforation was repaired, the displacement of TM at the umbo could not be recovered totally in the TB and FE models. In the FE model, the displacement of TM at the umbo decreased markedly when the cone shape of TM flattened, and the reduction was almost the same as that in the TB model in the condition of large perforation. CONCLUSION: The material properties and the anatomical shape of the repaired TM could influence the TM's modal motion and wave motion. Except for appearance and shape current clinical instruments are unable to resolve factors that affect TM motion. Consequently the ABG seen post-myringoplasty remains unexplained.

Moths produce extremely quiet ultrasonic courtship songs by rubbing specialized scales.

Insects have evolved a marked diversity of mechanisms to produce loud conspicuous sounds for efficient communication. However, the risk of eavesdropping by competitors and predators is high. Here, we describe a mechanism for producing extremely low-intensity ultrasonic songs (46 dB sound pressure level at 1 cm) adapted for private sexual communication in the Asian corn borer moth, Ostrinia furnacalis. During courtship, the male rubs specialized scales on the wing against those on the thorax to produce the songs, with the wing membrane underlying the scales possibly acting as a sound resonator. The male's song suppresses the escape behavior of the female, thereby increasing his mating success. Our discovery of extremely low-intensity ultrasonic communication may point to a whole undiscovered world of private communication, using "quiet" ultrasound.

Excited-state hydrogen detachment from a tris-(o-phenylenediamine) iron(ii) complex in THF at room temperature.

We previously reported that a tris-(o-phenylenediamine) iron(ii) complex promotes photochemical H2 generation and C-H carboxylation of o-phenylenediamine without any additives under N2 and CO2 atmospheres, respectively, in tetrahydrofuran at room temperature. Herein, the key mechanistic process, namely, excited-state hydrogen detachment from the o-phenylendiamine moiety, is demonstrated under an N2 atmosphere.

Use of sound-elicited fetal heart rate accelerations to assess fetal hearing in the second and third trimester.

OBJECTIVES: We previously reported that fetal heart rate (FHR) accelerations could be obtained after fetal sound stimulation. We examined FHR accelerations during 20-37 weeks gestational age (GA) in order to assess the optimal time for the test. METHODS: The fetus was stimulated from the maternal abdomen with pure tone 2000 Hz, 90 dB, 5 s. Changes in the FHR before and after the sound stimulation were measured by a cardiotocometer. RESULTS: Compared with the positive rate of FHR accelerations at 20-21 weeks GA, significant increases were recognized in 26-27, 28 to 29, 30 to 31, and 34-35 weeks GA. Comparing the positive rate of FHR accelerations between the minimal and moderate variability of FHR baseline, no significant differences were observed at 20-27 weeks GA. On the other hand, at 28-37 weeks GA, the positive rate to detect FHR accelerations due to sound stimulation was 100% in moderate FHR baseline variability. CONCLUSION: Considering development of human fetal hearing, the method should be performed between 28 and 37 weeks GA and during moderate FHR variability corresponding to active sleep conditions. The method developed in the present study may provide a promising tool for evaluating the fetal hearing.

Development of distortion product otoacoustic emissions in C57BL/6J mice.

Distortion product otoacoustic emissions (DPOAEs) have been used to examine the development of hearing in the rat and gerbil. However, no reports of DPOAE measurement from the onset of hearing in mice are available. Commercially-available components were assembled and adapted to provide a suitable probe microphone and sound delivery system for measuring DPOAE in developing C57BL/6J mice. Furthermore, DPOAE data were compared with the findings of the auditory brainstem response (ABR). DPOAEs were obtained at 8 kHz from 11 days after birth, 20 kHz from 12 days, and 30 kHz from 13 days. Adult-like patterns of DPOAE were obtained 21 days at 8 and 20 kHz, and 28 days at 30 kHz. On the other hand, the ABR thresholds at 12 to 36 kHz appeared between 11 and 12 days and were saturated at 14 days. Based on these data, the onset of measureable DPOAEs in the mouse were earlier than in the rat and gerbil. The maturation of DPOAE in the mouse begins at a lower frequency in the high frequency range. In addition, the ABR threshold reached maturation earlier than DPOAE.

Estimation of Muscle Activity Change under Different Bolus Conditions using Musculoskeletal Model of Swallowing.

Swallowing, deglutition, is realized by highly coordinated activities of many nerves and muscles, but it is hard to observe directly due to intracorporal movement, and there is a limitation to the number of muscles that can be percutaneously measured. In addition, since there are few studies on the mechanical analysis of the swallowing movement, the detailed muscle activity pattern during swallowing has not yet been clarified. To tackle this problem from the viewpoint of biomechanics, we have been developing the musculoskeletal model of swallowing which can estimate the activities of swallowing-related muscles based on the movements of hyoid bone and thyroid cartilage. In this paper, we analyzed the activities of swallowing-related muscles under two different bolus conditions: bolus of water and nectar thickened liquid to investigate the effect of physical property of bolus in the activities of swallowing-related muscles.

Development of intra-operative assessment system for ossicular mobility and middle ear transfer function.

Objective measurements of the ossicular mobility have not been commonly performed during the surgery, and the assessment of ossicular mobility is made by palpation in most cases. Palpation is inherently subjective and may not always be reliable, especially in milder degrees of ossicular fixation and in the case of multiple fixation. Although several devices have been developed to quantitatively measure the ossicular mobility during surgery, they have not been widely used. In this study, a new system with a hand-held probe which enables intraoperative quantitative measurements of ossicular mobility has been developed. This system not only measures the ossicular mobility, but also investigates "local" transmission characteristics of the middle ear by directly applying vibration to the ossicles and measuring cochlear microphonic. The basic performance of this system was confirmed by measuring the mobility of artificial ossicles and cochlear microphonics in an animal experiment. Our system may contribute to selection of a better surgical method and reducing the risks of revision surgery.

Simultaneous Measurement of Swallowing Sound and Mechanomyogram of Submental Muscle with PVDF Film.

The difficulty of swallowing, called dysphagia, causes aspiration pneumonia which is particularly a big health concern in aging society. Therefore, prevention and treatment of dysphagia would contribute to extending healthy-life and QOL of elderly people and decreasing healthcare cost. Conventional reliable methods for evaluating swallowing function require special equipment and are not suitable for long-term monitoring at home or welfare facilities. Therefore, various kinds of quantitative assessment method using biological signals such as swallowing sound, electromyography, and so forth have been proposed as a non-invasive and accessible method. The goal of this study is to realize comprehensive quantitative assessment of swallowing function using multiple biological signals simultaneously measured by a single sensor device. In this study, we propose the use of PolyVinylidene DiFluoride (PVDF) film to measure both mechanomyogram (MMG) signal for evaluating muscle activity and swallowing sound for detecting swallowing sequence. In our previous study, we confirmed PVDF film can detect MMG signal of swallowing-related muscles. We conducted experiments to confirm that PVDF film can detect swallowing sound in this study. The experimental results indicated that swallowing sound can be measured in parallel with MMG signal at the same position by changing frequency band of the signal of PVDF film.

Direct Photochemical C-H Carboxylation of Aromatic Diamines with CO2 under Electron-Donor- and Base-free Conditions.

We report the photochemical carboxylation of o-phenylenedimamine in the absence of a base and an electron donor under an atmosphere of CO2, which afforded 2,3-diaminobenzoic acid (DBA) in 28% synthetic yield and 0.22% quantum yield (Φ(%)). The synthetic yield of DBA in this reaction increased to 58% (Φ(%) = 0.47) in the presence of Fe(II). The photochemical reaction described in this work provides an effective strategy to use light as the driving force for the direct carboxylation of organic molecules by CO2.

Piezoelectric vibrator-stimulated potential and heart rate accelerations detected from the fetus.

OBJECTIVES: The fetus is well known to have a substantial capacity for sound recognition in the uterine environment. The aim of this study was to develop a sound stimulus system equipped with a piezoelectric vibrator (PV), record the PV-stimulated potential (PVSP) of the fetus and monitor changes of the fetal heart rate (FHR) under PV stimulation. METHODS: The relationship between the input voltage applied to a piezoelectric vibrator and the sound pressure generated in the uterus was calibrated based on a model of the maternal abdomen. Fourteen fetuses for the measurement of the PVSP and 22 fetuses for the measurement of the heart rate changes from low-risk pregnant women were recruited. RESULTS: The PVSP responses were obtained in 9 out of 14 fetuses. All the tested fetuses accelerated the FHR after the 2 kHz tone stimulation at 70 dB intensity generated by PV from 32 to 37 weeks gestational age. CONCLUSIONS: Using a newly developed sound stimulus system equipped with PV, the electric responses of a fetus recorded from electrodes placed on the mother's abdomen may be closely related to the auditory evoked response. Significant accelerations of FHR were objectively, accurately and readily obtained after the sound stimulation.

Autophony in patients with patulous eustachian tube: experimental investigation using an artificial middle ear.

OBJECTIVE: To investigate the contribution of anatomical factors, such as the caliber of the patent eustachian tube (ET) and the volume of the middle ear cavity, on vocalized sound transmission to the inner ear. METHODS: Model experiment using artificial middle ear. RESULTS: In the present model experiment, sound transmission from the pharynx to the inner ear under patulous conditions was affected by the caliber of the ET and by the mastoid volume, especially in the low-frequency region, that is, a larger caliber of the ET and smaller mastoid volume resulted in greater sound transmission from the pharyngeal space to the inner ear. CONCLUSION: Patulous symptoms may be more distressful in patients with poorly developed mastoid cavity than in those with well-aerated mastoid under similar conditions of patulous ET.

Fixation of the anterior mallear ligament: diagnosis and consequences for hearing results in stapes surgery.

In the search for possible causes of unfavorable results after stapes surgery, the study reported here focused on the anterior mallear ligament, since it has been previously reported that partial mallear fixation (PMF) leads to functional failure in 38% of cases of stapes revision surgery. The aims of the study were to identify effective methods for the diagnosis of PMF and experimentally assess the conductive hearing loss that results from PMF. The study included vibration amplitude measurements of the ossicles by laser Doppler interferometry (LDI) in 19 patients and 5 fresh human temporal bone (TB) specimens. Analysis of their dynamic behavior was performed by finite element modeling (FEM). Similar, significant changes of manubrium vibration patterns for PMF were found by FEM calculations, in TB experiments, and in patients. We could identify PMF either before operation, using LDI, or during operation, by manual palpation. In the TB experiments and FEM calculations, the attenuation of the stapes displacement due to an isolated PMF was approximately 10 dB and frequency-dependent. Untreated anterior mallear ligament fixation produced a persistent air-bone gap of approximately 10 dB after stapedioplasty.

Safety of ultrasonic bone curette in ear surgery by measuring skull bone vibrations.

HYPOTHESIS: Mastoidectomy using an ultrasonic bone curette (UBC) is as safe for the inner ear as a mastoidectomy using a high-speed drill. BACKGROUND: Transcanal endoscopic ear surgery (TEES) is a minimally invasive, secure, and functional technique, which has been performed using high-speed drills. We have started to use a UBC instead of the high-speed drill because a UBC allows for simultaneous bone cutting, irrigation, and aspiration. These features of the UBC make it an excellent candidate for use in one-handed TEES, but the safety of the UBC still needs to be confirmed. We thus measured skull vibrations caused by the UBC to estimate the effects of UBC on the inner ear. METHODS: Eight patients with cholesteatoma underwent mastoidectomy using a Sonopet UST-2001 UBC (Stryker, MI, USA) and 2 high-speed drills (drills A and B). Skull vibrations were measured using polyvinylidene difluoride film taped to the forehead as a piezoelectric vibration sensor. The recorded data were transformed to the power spectrum in the frequency domain by fast Fourier transform. The mean and peak values of vibrations were analyzed in four frequency bands: 200 to 500 Hz, 500 to 2,000 Hz, 2,000 to 8,000 Hz, and 8,000 Hz to 20 kHz. RESULTS: Both the mean values and the peak values of skull vibrations caused by the UBC were significantly smaller than those values obtained for drill B between 500 and 8,000 Hz, (p < 0.05). No significant differences were found among the 3 instruments below 500 Hz or above 8,000 Hz. CONCLUSION: Skull vibration levels generated by the UBC were found to be comparable or even lower than those levels associated with conventional high-speed drills. These findings indicated that the UBC can be safely applied to TEES without the risk of harmful effects on the inner ear.

Effects of a perilymphatic fistula on the passive vibration response of the basilar membrane.

In this study, a three-dimensional finite-element model of the passive human cochlea was created. Dynamic behavior of the basilar membrane caused by the vibration of the stapes footplate was analyzed considering a fluid-structure interaction with the cochlear fluid. Next, the effects of a perilymphatic fistula (PLF) on the vibration of the cochlea were examined by making a small hole on the wall of the cochlea model. Even if a PLF existed in the scala vestibuli, a traveling wave was generated on the basilar membrane. When a PLF existed at the basal end of the cochlea, the shape of the traveling wave envelope showed no remarkable change, but the maximum amplitude became smaller at the entire frequency range from 0.5 to 5kHz and decreased with decreasing frequency. In contrast, when a PLF existed at the second turn of the cochlea, the traveling wave envelope showed a notch at the position of the PLF and the maximum amplitude also became smaller. This model assists in elucidating the mechanisms of hearing loss due to a PLF from the view of dynamics.

Finite element analysis of the middle ear transfer functions and related pathologies.

With developments in software and micro-measurement technology, a three-dimensional middle ear finite element (FE) model can now be more easily constructed to study sound transfer function. Many FE models of the middle ear have been constructed to date, and each has its own particular advantages and disadvantages. In this article, we review the latest developments and technologies in the field of the FE models of the middle ear, and the use of FE in the study of middle ear pathology. Proposals are made for future developments in the field of finite element analysis of middle ear transfer function.