-
Otolaryngology--head and Neck Surgery :... May 2024Cochlear implant (CI) electrode design has changed over time. Changes in intracochlear electrode design might influence the spread of neural activation along the...
OBJECTIVE
Cochlear implant (CI) electrode design has changed over time. Changes in intracochlear electrode design might influence the spread of neural activation along the auditory nerve and the number of independent channels. This study aimed to investigate the impact of intracochlear electrode design on the electrode-neuron interface using electrophysiological measures.
STUDY DESIGN
Prospective cohort study.
SETTING
A single tertiary hospital.
METHODS
Fifty-two ears who were implanted with CI divided into 3 groups based on the design of intracochlear electrode arrays. Twenty-three ears were implanted with lateral wall straight electrodes. Eighteen ears were implanted with the slim perimodiolar electrode, and 11 ears were implanted with the old perimodiolar electrode. Various electrically-evoked compound action potential (ECAP) metrics were measured to quantify spread of excitation and channel interaction.
RESULTS
ECAP threshold and slope were not significantly different among groups. ECAP spread of excitation (SOE) half-width and channel interaction index (CII) were significantly larger in subjects implanted with the lateral wall straight electrodes, indicating a wider spread of excitation compared to those with perimodiolar electrodes. Electrode impedance was significantly lower in subjects implanted with perimodiolar electrodes than those with lateral wall electrodes.
CONCLUSION
Perimodiolar electrode groups yielded significantly narrower SOE half-widths and smaller CII than the lateral wall straight electrode group. This may indicate that the electrode array that hugged the modiolus had less overlap in neural excitation between adjacent electrodes, resulting in reduced channel interaction and potentially better spectral resolution than the electrode array positioned more laterally.
PubMed: 38774957
DOI: 10.1002/ohn.799 -
Scientific Reports May 2024Organophosphorus nerve agents are toxic compounds that disrupt neuromuscular transmission by inhibiting the neurotransmitter enzyme, acetylcholinesterase, leading to...
Organophosphorus nerve agents are toxic compounds that disrupt neuromuscular transmission by inhibiting the neurotransmitter enzyme, acetylcholinesterase, leading to rapid death. A hybrid composite was synthesized using a hydrothermal process for the early detection of dimethyl methyl phosphonate (DMMP), a simulant of the G-series nerve agent, sarin. Quartz crystal microbalance (QCM) and surface acoustic wave (SAW) sensors were used as detectors. Nitrogen-doped multiwalled carbon nanotubes (N-MWCNTs), cobalt oxide (CoO), and N-MWCNT@CoO were compared to detect DMMP concentrations of 25-150 ppm. At 25 ppm, the differential frequencies (Δf) of the N-MWCNT, CoO, and N-MWCNT@CoO sensors were 5.8, 2.3, and 99.5 Hz, respectively. The selectivity results revealed a preference for the DMMP rather than potential interference. The coefficients of determination (R) of the N-MWCNT, CoO, and N-MWCNT@CoO sensors for detecting 25-150 ppm DMMP were 0.983, 0.986, and 0.999, respectively. The response times of the N-MWCNT, CoO, and N-MWCNT@CoO sensors for detecting 100 ppm DMMP were 25, 27, and 34 s, respectively, while the corresponding recovery times were 85, 105, and 181 s. The repeatability results revealed the reversible adsorption and desorption phenomena for the fixed DMMP concentration of 100 ppm. These unique findings show that synthesized materials can be used to detect organophosphorus nerve agents.
PubMed: 38773127
DOI: 10.1038/s41598-024-56354-1 -
Journal of Voice : Official Journal of... May 2024The objective of this study was to assess voice changes in patients with nasopharyngeal carcinoma (NPC) using subjective and objective assessment tools and to make...
OBJECTIVES
The objective of this study was to assess voice changes in patients with nasopharyngeal carcinoma (NPC) using subjective and objective assessment tools and to make inferences regarding the underlying pathological causes for different phases of radiotherapy (RT).
METHODS
A total of 187 (123 males and 64 females) patients with post-RT NPC with no recurrence of malignancy or other voice diseases and 17 (11 males and 6 females) healthy individuals were included in this study. The patients were equally divided into 11 groups according to the number of years after RT. The acoustic analyses, GRBAS (grade, roughness, breathiness, asthenia, and strain) scales, and Voice Handicap Index (VHI)-10 scores were collected and analyzed.
RESULTS
The fundamental frequency (F0) parameters in years 1 and 2 and year 11 were significantly lower in patients with NPC than in healthy individuals. The maximum phonation times in years 1 and 11 were significantly shorter than those in healthy individuals. The jitter parameters were significantly different between year 1 and from years 8 to 11 and the healthy individuals. The shimmer parameters were significantly different between years 1, from years 9 to 11, and healthy individuals. Hoarseness was the most prominent problem compared to other items of the GRBAS. The VHI-10 scores were significantly different between years 1 and 2 and year 11 after RT in patients with NPC.
CONCLUSIONS
Voice quality was worse in the first 2 years and from years 8 to 11 but remained relatively normal from years 3 to 7 after RT. Patient-reported voice handicaps began during year 3 after RT. The most prominent problem was perceived hoarseness, which was evident in the first 2 years and from years 9 to 11 after RT. The radiation-induced mucous edema, laryngeal intrinsic muscle fibrosis, nerve injuries, upper respiratory tract changes, and decreased lung capacity might be the pathological reasons for voice changes in post-RT patients with NPC.
PubMed: 38772832
DOI: 10.1016/j.jvoice.2024.04.017 -
Otolaryngology--head and Neck Surgery :... May 2024To identify associations between cochleovestibular anatomy findings and hearing outcomes found in children with imaging evidence of an absent or hypoplastic cochlear...
OBJECTIVE
To identify associations between cochleovestibular anatomy findings and hearing outcomes found in children with imaging evidence of an absent or hypoplastic cochlear nerve treated with cochlear implantation (CI).
STUDY DESIGN
retrospective review.
SETTING
Cochlear implant program at tertiary care center.
METHODS
A retrospective review was performed to identify children with imaging evidence of cochlear nerve absence or deficiency who underwent CI evaluation. High-resolution 3-dimensional T2-weighted magnetic resonance imaging in the oblique sagittal and axial planes were reviewed by a neuroradiologist to identify cochleovestibular anatomy. Hearing was assessed pre and postoperatively with Speech Perception Category scores.
RESULTS
Seven CI recipients were identified (n = 10 ears) who had bilateral severe to profound sensorineural hearing loss with lack of auditory development with binaural hearing aid trial and imaging evidence of cochlear nerve aplasia/hypoplasia. All ears had 2 nerves in the cerebellopontine angle (100%, n = 10), half of the ears had evidence of 2 or less nerves in the internal auditory canal (IAC). All children showed large improvement in speech perception after CI.
CONCLUSION
Our experience with CIs for children with absent or hypoplastic cochlear nerves demonstrates that CI can be a viable option in select patients who satisfy preoperative audiological criteria. Radiological identification of a hypoplastic or aplastic cochlear nerve does not preclude auditory innervation of the cochlea. CI recipients in this subgroup must be counseled on difficulty in predicting postimplantation language and speech outcomes, and cautioned about facial nerve stimulation.
PubMed: 38769854
DOI: 10.1002/ohn.827 -
Otology & Neurotology : Official... Jul 2024To evaluate quality-of-life outcomes for patients with vestibular schwannomas (VS) undergoing a middle cranial fossa (MCF) approach.
OBJECTIVE
To evaluate quality-of-life outcomes for patients with vestibular schwannomas (VS) undergoing a middle cranial fossa (MCF) approach.
STUDY DESIGN
Prospective study from 2018 to 2023.
SETTING
Tertiary academic institution.
PATIENTS
Adults with sporadic VS.
INTERVENTIONS
MCF.
MAIN OUTCOME MEASURES
The primary outcome measure was the change in preoperative and 1-year postoperative Penn Acoustic Neuroma Quality-of-life (PANQOL) scores. Secondary outcome measures included hearing preservation and facial nerve function.
RESULTS
Of the 164 patients who underwent MCF for sporadic VS, 78 patients elected to voluntarily complete preoperative PANQOL assessments prior to surgery. Seventy-one (91%) of those 78 patients completed postoperative PANQOL surveys. Fifty (70%) of the respondents were female and the median age was 48 years (range, 27-71 years). Overall, at 1-year postsurgery, a minimal clinically important difference (MCID) was obtained in the hearing (mean difference, 10.5; 95% confidence interval [CI], 4.3-16.7) and anxiety (mean difference, 18.8; 95% CI, 11.7-25.9) domains. For patients with hearing preservation (n = 48, 68%), MCIDs were reached in the hearing (mean difference, 13.4; 95% CI, 6.3-20.6), anxiety (mean difference, 20.8; 95% CI, 11.8-29.9), energy (mean difference, 13.7; 95% CI, 3.6-23.8), pain (mean difference, 13.7; 95% CI, 3.6-23.8) domains, and overall PANQOL scores (mean difference, 12.7; 95% CI, 7.1-18.3). Postoperatively, 64 (90%) patients maintained a House-Brackmann I.
CONCLUSIONS
To our knowledge, this is the largest study examining disease-specific QOL for VS patients undergoing MCF. Based on our institution's experience, MCF approach for small VS is associated with clinically meaningful improvements in QOL, hearing preservation, and excellent facial nerve outcomes.
Topics: Humans; Quality of Life; Neuroma, Acoustic; Female; Middle Aged; Male; Adult; Cranial Fossa, Middle; Aged; Prospective Studies; Craniotomy; Treatment Outcome
PubMed: 38769097
DOI: 10.1097/MAO.0000000000004202 -
Audiology & Neuro-otology May 2024Otosclerosis is a bone disorder affecting the labyrinthine capsule that leads to conductive and occasionally sensorineural hearing loss. The etiology of otosclerosis...
INTRODUCTION
Otosclerosis is a bone disorder affecting the labyrinthine capsule that leads to conductive and occasionally sensorineural hearing loss. The etiology of otosclerosis remains unknown; factors such as infection, hormones, inflammation, genetics, and autoimmunity have been discussed. Treatment consists primarily of surgical stapes replacement and cochlear implantation. High-resolution computed tomography is routinely used to visualize bone pathology. In the present study, we used synchrotron radiation phase-contrast imaging (SR-PCI) to examine otosclerosis plaques in a temporal bone for the first time. The primary aim was to study their three-dimensional (3D) outline, vascular interrelationships, and connections to the middle ear.
METHODS
A donated ear from a patient with otosclerosis who had undergone partial stapedectomy with the insertion of a stapes wire prosthesis was investigated using SR-PCI and compared with a control ear. Otosclerotic lesions were 3D rendered using the composite with shading technique. Scalar opacity and color mapping were adjusted to display volume properties with the removal of bones to enhance surfaces. Vascular bone channels were segmented, and the communications between lesions and the middle ear were established.
RESULTS
Fenestral, cochlear, meatal, and vestibular lesions were outlined three-dimensionally. Vascular bone channels were found to be frequently connected to the middle ear mucosa, perilabyrinthine air spaces, and facial nerve vessels. Round window lesions partly embedded the cochlear aqueduct which was pathologically narrowed, while the inferior cochlear vein was significantly dilated in its proximal part.
CONCLUSION
Otosclerotic/otospongiotic lesions were imaged for the first time using SR-PCI and 3D rendering. The presence of shunts and abnormal vascular connections to the labyrinth appeared to result in hyper-vascularization, overloading the venous system, and leading to sensorineural hearing loss. We speculate about possible local treatments to alleviate the impact of such critical lesions on the labyrinthine microcirculation.
PubMed: 38763131
DOI: 10.1159/000539422 -
Frontiers in Molecular Neuroscience 2024Hearing loss constitutes a major global health concern impacting approximately 1.5 billion people worldwide. Its incidence is undergoing a substantial surge with some... (Review)
Review
Hearing loss constitutes a major global health concern impacting approximately 1.5 billion people worldwide. Its incidence is undergoing a substantial surge with some projecting that by 2050, a quarter of the global population will experience varying degrees of hearing deficiency. Environmental factors such as aging, exposure to loud noise, and the intake of ototoxic medications are implicated in the onset of acquired hearing loss. Ototoxicity resulting in inner ear damage is a leading cause of acquired hearing loss worldwide. This could be minimized or avoided by early testing of hearing functions in the preclinical phase of drug development. While the assessment of ototoxicity is well defined for drug candidates in the hearing field - required for drugs that are administered by the otic route and expected to reach the middle or inner ear during clinical use - ototoxicity testing is not required for all other therapeutic areas. Unfortunately, this has resulted in more than 200 ototoxic marketed medications. The aim of this publication is to raise awareness of drug-induced ototoxicity and to formulate some recommendations based on available guidelines and own experience. Ototoxicity testing programs should be adapted to the type of therapy, its indication (targeting the ear or part of other medications classes being potentially ototoxic), and the number of assets to test. For multiple molecules and/or multiple doses, screening options are available: (otic cell assays), (cochlear explant), and (in zebrafish). In assessing the ototoxicity of a candidate drug, it is good practice to compare its ototoxicity to that of a well-known control drug of a similar class. Screening assays provide a streamlined and rapid method to know whether a drug is generally safe for inner ear structures. Mammalian animal models provide a more detailed characterization of drug ototoxicity, with a possibility to localize and quantify the damage using functional, behavioral, and morphological read-outs. Complementary histological measures are routinely conducted notably to quantify hair cells loss with cochleogram. Ototoxicity studies can be performed in rodents (mice, rats), guinea pigs and large species. However, in undertaking, or at the very least attempting, all preclinical investigations within the same species, is crucial. This encompasses starting with pharmacokinetics and pharmacology efficacy studies and extending through to toxicity studies. In life read-outs include Auditory Brainstem Response (ABR) and Distortion Product OtoAcoustic Emissions (DPOAE) measurements that assess the activity and integrity of sensory cells and the auditory nerve, reflecting sensorineural hearing loss. Accurate, reproducible, and high throughput ABR measures are fundamental to the quality and success of these preclinical trials. As in humans, otoscopic evaluations are routinely carried out to observe the tympanic membrane and auditory canal. This is often done to detect signs of inflammation. The cochlea is a tonotopic structure. Hair cell responsiveness is position and frequency dependent, with hair cells located close to the cochlea apex transducing low frequencies and those at the base transducing high frequencies. The cochleogram aims to quantify hair cells all along the cochlea and consequently determine hair cell loss related to specific frequencies. This measure is then correlated with the ABR & DPOAE results. Ototoxicity assessments evaluate the impact of drug candidates on the auditory and vestibular systems, de-risk hearing loss and balance disorders, define a safe dose, and optimize therapeutic benefits. These types of studies can be initiated during early development of a therapeutic solution, with ABR and otoscopic evaluations. Depending on the mechanism of action of the compound, studies can include DPOAE and cochleogram. Later in the development, a GLP (Good Laboratory Practice) ototoxicity study may be required based on otic related route of administration, target, or known potential otic toxicity.
PubMed: 38756707
DOI: 10.3389/fnmol.2024.1379743 -
Audiology & Neuro-otology May 2024Noise-induced hearing loss is one of the most frequent recognized occupational diseases. The time course of the involved pathologies is still under investigation....
INTRODUCTION
Noise-induced hearing loss is one of the most frequent recognized occupational diseases. The time course of the involved pathologies is still under investigation. Several studies have demonstrated an acute damage of the sensory tissue, but only few experiments investigated the degeneration of (type I) spiral ganglion neurons (SGNs), representing the primary neurons in the auditory system. The aim of the present study was to investigate the time course of SGN degeneration within a 7-day period after traumatic noise exposure starting immediately after trauma.
METHODS
Young adult normal hearing mice were noise exposed for 3 h with a broadband noise (5-20 kHz) at 115 dB SPL. Auditory threshold shift was measured by auditory brainstem recordings, and SGN densities were analyzed at different time points during the first week after acoustic trauma.
RESULTS
Significant reduction of SGN densities was detected and is accompanied by a significant hearing loss. Degeneration starts within hours after the applied trauma, further progressing within days post-exposure.
DISCUSSION
Early neurodegeneration in the auditory periphery seems to be induced by direct overstimulation of the auditory nerve fibers. SGN loss is supposed to be a result of inflammatory responses and neural deprivation, leading to permanent hearing loss and auditory processing deficits.
PubMed: 38749408
DOI: 10.1159/000539359 -
BMC Surgery May 2024Hemifacial spasm (HFS) is most effectively treated with microvascular decompression (MVD). However, there are certain challenges in performing MVD for HFS when the...
BACKGROUND
Hemifacial spasm (HFS) is most effectively treated with microvascular decompression (MVD). However, there are certain challenges in performing MVD for HFS when the vertebral artery (VA) is involved in compressing the facial nerve (VA-involved). This study aimed to introduce a "bridge-layered" decompression technique for treating patients with VA-involved HFS and to evaluate its efficacy and safety to treat patients with HFS.
METHODS
A single-center retrospective analysis was conducted on the clinical data of 62 patients with VA-involved HFS. The tortuous trunk of VA was lifted by a multi-point "bridge" decompression technique to avoid excessive traction of the cerebellum and reduce the risk of damage to the facial-acoustic nerve complex. To fully decompress all the responsible vessels, the branch vessels of VA were then isolated using the "layered" decompression technique.
RESULTS
Among the 62 patients, 59 patients were cured immediately after the surgery, two patients were delayed cured after two months, and one had occasional facial muscle twitching after the surgery. Patients were followed up for an average of 19.5 months. The long-term follow-up results showed that all patients had no recurrence of HFS during the follow-up period, and no patients developed hearing loss, facial paralysis, or other permanent neurological damage complications. Only two patients developed tinnitus after the surgery.
CONCLUSION
The "bridge-layered" decompression technique could effectively treat VA-involved HFS with satisfactory safety and a low risk of hearing loss. The technique could be used as a reference for decompression surgery for VA-involved HFS.
Topics: Humans; Hemifacial Spasm; Female; Male; Middle Aged; Retrospective Studies; Vertebral Artery; Adult; Microvascular Decompression Surgery; Treatment Outcome; Aged; Decompression, Surgical; Follow-Up Studies
PubMed: 38745320
DOI: 10.1186/s12893-024-02415-1 -
Hearing Research Jun 2024Auditory nerve (AN) function has been hypothesized to deteriorate with age and noise exposure. Here, we perform a systematic review of published studies and find that... (Meta-Analysis)
Meta-Analysis Review
Auditory nerve (AN) function has been hypothesized to deteriorate with age and noise exposure. Here, we perform a systematic review of published studies and find that the evidence for age-related deficits in AN function is largely consistent across the literature, but there are inconsistent findings among studies of noise exposure history. Further, evidence from animal studies suggests that the greatest deficits in AN response amplitudes are found in noise-exposed aged mice, but a test of the interaction between effects of age and noise exposure on AN function has not been conducted in humans. We report a study of our own examining differences in the response amplitude of the compound action potential N1 (CAP N1) between younger and older adults with and without a self-reported history of noise exposure in a large sample of human participants (63 younger adults 18-30 years of age, 103 older adults 50-86 years of age). CAP N1 response amplitudes were smaller in older than younger adults. Noise exposure history did not appear to predict CAP N1 response amplitudes, nor did the effect of noise exposure history interact with age. We then incorporated our results into two meta-analyses of published studies of age and noise exposure history effects on AN response amplitudes in neurotypical human samples. The meta-analyses found that age effects across studies are robust (r = -0.407), but noise exposure effects are weak (r = -0.152). We conclude that noise exposure effects may be highly variable depending on sample characteristics, study design, and statistical approach, and researchers should be cautious when interpreting results. The underlying pathology of age-related and noise-induced changes in AN function are difficult to determine in living humans, creating a need for longitudinal studies of changes in AN function across the lifespan and histological examination of the AN from temporal bones collected post-mortem.
Topics: Humans; Noise; Aged; Cochlear Nerve; Middle Aged; Adult; Aged, 80 and over; Age Factors; Young Adult; Acoustic Stimulation; Adolescent; Aging; Evoked Potentials, Auditory; Hearing Loss, Noise-Induced; Female; Male; Animals; Action Potentials
PubMed: 38744019
DOI: 10.1016/j.heares.2024.109010