SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Ear

240

Recent neuroscience research suggests that tinnitus may reflect synaptic loss in the cochlea that does not express in the audiogram but leads to neural changes in auditory pathways that reduce sound level tolerance (SLT). Adolescents (N = 170) completed a questionnaire addressing their prior experience with tinnitus, potentially risky listening habits, and sensitivity to ordinary sounds, followed by psychoacoustic measurements in a sound booth. Among all adolescents 54.7% reported by questionnaire that they had previously experienced tinnitus, while 28.8% heard tinnitus in the booth. Psychoacoustic properties of tinnitus measured in the sound booth corresponded with those of chronic adult tinnitus sufferers. Neither hearing thresholds (≤15 dB HL to 16 kHz) nor otoacoustic emissions discriminated between adolescents reporting or not reporting tinnitus in the sound booth, but loudness discomfort levels (a psychoacoustic measure of SLT) did so, averaging 11.3 dB lower in adolescents experiencing tinnitus in the acoustic chamber. Although risky listening habits were near universal, the teenagers experiencing tinnitus and reduced SLT tended to be more protective of their hearing. Tinnitus and reduced SLT could be early indications of a vulnerability to hidden synaptic injury that is prevalent among adolescents and expressed following exposure to high level environmental sounds.

Concepts: Auditory system, Acoustics, Ultrasound, Ear, Sound, Audiogram, Hearing

182

Candida auris, an emerging fungus that can cause invasive infections, is associated with high mortality and is often resistant to multiple antifungal drugs. C. auris was first described in 2009 after being isolated from external ear canal discharge of a patient in Japan (1). Since then, reports of C. auris infections, including bloodstream infections, have been published from several countries, including Colombia, India, Israel, Kenya, Kuwait, Pakistan, South Africa, South Korea, Venezuela, and the United Kingdom (2-7). To determine whether C. auris is present in the United States and to prepare for the possibility of transmission, CDC issued a clinical alert in June 2016 informing clinicians, laboratorians, infection control practitioners, and public health authorities about C. auris and requesting that C. auris cases be reported to state and local health departments and CDC (8). This report describes the first seven U.S. cases of C. auris infection reported to CDC as of August 31, 2016. Data from these cases suggest that transmission of C. auris might have occurred in U.S. health care facilities and demonstrate the need for attention to infection control measures to control the spread of this pathogen.

Concepts: United States, Developed country, United Kingdom, Olympic Games, Ear, Pakistan, Liberal democracies, G20 nations

168

Spontaneous nystagmus, which has been considered a typical sign of acute vestibulopathy, has recently been reported in benign paroxysmal positional vertigo involving the lateral semicircular canals (LC-BPPV) without unilateral vestibulopathy (pseudo-spontaneous nystagmus, PSN), but research about its clinical application is still limited. Here we investigate the frequency and characteristics of PSN in LC-BPPV patients, and estimate its prognostic value.

Concepts: Medical terms, Semicircular canal, Prognosis, Ear, Canal, Pathologic nystagmus, Benign paroxysmal positional vertigo, Horizontal semicircular canal

168

The development of minimally invasive procedures such as the balloon dilation Eustachian tuboplasty (BET) is an alternative to the grommet tympanum membrane. BET is applied in the cases where, after elimination of all factors influencing the ET and middle ear functioning, no sufficient improvement is observed. The aim of this study was to present the therapeutic benefits of the BET method in the treatment of ETD caused by disorders in the middle ear ventilation. The BET procedure was offered to four patients (3 men and 1 woman) after subjective, physical, otorhinolaryngological and audiometric examinations including pure tone audiometry, tympanometry and pressure-swallow test. As the method was novel, preinterventional CT angiography of the carotid arteries was performed in all patients. Any complications were noticed during and after the procedure (bleeding or damage of regional mucosa) in any patients. Our clinical studies assessed the feasibility and safety of the BET during a short-term period-only a 6-week observation. Although patients revealed a significant improvement of ET score, longer long-term studies are necessary to determine whether this method will demonstrate lasting benefits and safety in the treatment of chronic Eustachian tube dysfunction. In other investigations, improvement was found to be time dependent.

Concepts: Scientific method, Auditory system, Common carotid artery, Middle ear, Eustachian tube, Otitis media, Ear, Patulous Eustachian tube

167

To evaluate the onset of vertigo, hearing loss and tinnitus in Ménière’s disease and the associated endolymphatic hydrops (EH) of the inner ear.

Concepts: Auditory system, Cochlea, Hearing impairment, Ear, Tinnitus, Ménière's disease, Inner ear, Endolymph

136

Interactions between sensory pathways such as the visual and auditory systems are known to occur in the brain, but where they first occur is uncertain. Here, we show a multimodal interaction evident at the eardrum. Ear canal microphone measurements in humans (n = 19 ears in 16 subjects) and monkeys (n = 5 ears in three subjects) performing a saccadic eye movement task to visual targets indicated that the eardrum moves in conjunction with the eye movement. The eardrum motion was oscillatory and began as early as 10 ms before saccade onset in humans or with saccade onset in monkeys. These eardrum movements, which we dub eye movement-related eardrum oscillations (EMREOs), occurred in the absence of a sound stimulus. The amplitude and phase of the EMREOs depended on the direction and horizontal amplitude of the saccade. They lasted throughout the saccade and well into subsequent periods of steady fixation. We discuss the possibility that the mechanisms underlying EMREOs create eye movement-related binaural cues that may aid the brain in evaluating the relationship between visual and auditory stimulus locations as the eyes move.

Concepts: Brain, Auditory system, Eye, Saccade, Eye movement, Ear, Sound, Hearing

70

Otitis media is the most common reason U.S. children receive antibiotics. The requisite 7- to 10-day course of oral antibiotics can be challenging to deliver in children, entails potential systemic toxicity, and encourages selection of antimicrobial-resistant bacteria. We developed a drug delivery system that, when applied once to the tympanic membrane through the external auditory canal, delivers an entire course of antimicrobial therapy to the middle ear. A pentablock copolymer poloxamer 407-polybutylphosphoester (P407-PBP) was designed to flow easily during application and then to form a mechanically strong hydrogel on the tympanic membrane. U.S. Food and Drug Administration-approved chemical permeation enhancers within the hydrogel assisted flux of the antibiotic ciprofloxacin across the membrane. This drug delivery system completely eradicated otitis media from nontypable Haemophilus influenzae (NTHi) in 10 of 10 chinchillas, whereas only 62.5% of animals receiving 1% ciprofloxacin alone had cleared the infection by day 7. The hydrogel system was biocompatible in the ear, and ciprofloxacin was undetectable systemically (in blood), confirming local drug delivery and activity. This fast-gelling hydrogel could improve compliance, minimize side effects, and prevent systemic distribution of antibiotics in one of the most common pediatric illnesses, possibly minimizing the development of antibiotic resistance.

Concepts: Medicine, Bacteria, Auditory system, Otitis media, Ear, Penicillin, Clostridium difficile, Haemophilus influenzae

61

The emergence and maintenance of animal communication systems requires the co-evolution of signal and receiver. Frogs and toads rely heavily on acoustic communication for coordinating reproduction and typically have ears tuned to the dominant frequency of their vocalizations, allowing discrimination from background noise and heterospecific calls. However, we present here evidence that two anurans, Brachycephalus ephippium and B. pitanga, are insensitive to the sound of their own calls. Both species produce advertisement calls outside their hearing sensitivity range and their inner ears are partly undeveloped, which accounts for their lack of high-frequency sensitivity. If unheard by the intended receivers, calls are not beneficial to the emitter and should be selected against because of the costs associated with signal production. We suggest that protection against predators conferred by their high toxicity might help to explain why calling has not yet disappeared, and that visual communication may have replaced auditory in these colourful, diurnal frogs.

Concepts: Auditory system, Acoustics, Ear, Sound, Communication, Radio, Amphibian, Frog

52

The rapid growth of aquaculture raises questions about the welfare status of mass-produced species. Sagittal otoliths are primary hearing structures in the inner ear of all teleost (bony) fishes and are normally composed of aragonite, though abnormal vaterite replacement is sometimes seen in the wild. We provide the first widespread evaluation of the prevalence of vaterite in otoliths, showing that farmed fish have levels of vaterite replacement over 10 times higher than wild fish, regardless of species. We confirm this observation with extensive sampling of wild and farmed Atlantic salmon in Norway, the world’s largest producer, and verify that vateritic otoliths are common in farmed salmon worldwide. Using a mechanistic model of otolith oscillation in response to sound, we demonstrate that average levels of vaterite replacement result in a 28-50% loss of otolith functionality across most of a salmonid’s known hearing range and throughout its life cycle. The underlying cause(s) of vaterite formation remain unknown, but the prevalence of hearing impairment in farmed fish has important implications for animal welfare, the survival of escapees and their effects on wild populations, and the efficacy of restocking programs based on captive-bred fish.

Concepts: Fish, Auditory system, Salmon, Ear, Inner ear, Audiogram, Aquaculture, Otolith

52

Autologous techniques for the reconstruction of pediatric microtia often result in suboptimal aesthetic outcomes and morbidity at the costal cartilage donor site. We therefore sought to combine digital photogrammetry with CAD/CAM techniques to develop collagen type I hydrogel scaffolds and their respective molds that would precisely mimic the normal anatomy of the patient-specific external ear as well as recapitulate the complex biomechanical properties of native auricular elastic cartilage while avoiding the morbidity of traditional autologous reconstructions.

Concepts: Collagen, Extracellular matrix, Skeletal system, Tissues, Ear, Reconstruction era of the United States, Reconstruction, Type-I collagen