Estimated cochlear neural degeneration is associated with loudness hypersensitivity in individuals with normal audiograms

Audiometric Profiles Across a Clinical Population of Children With Hyperacusis

PURPOSE

Hyperacusis (sound sensitivity) is well documented among adults, but little is known about hyperacusis in children. Here, we assess relationships among the presence of hyperacusis, audiometric profiles, and nonauditory factors in a pediatric clinical population.

METHOD

A retrospective review of clinical records from 329 children, ages 2-17 years, was performed to assess the prevalence of hyperacusis and correlations among hearing status, behavioral or communication concerns, and the presence of hyperacusis.

RESULTS

In 329 study participants, 18% reported hyperacusis (58% male and 42% female). No significant sex or age differences were found. Hyperacusis was more likely to occur alongside normal hearing or with unilateral hearing loss relative to bilateral hearing loss. Among children with hyperacusis, there was a high prevalence of audiovestibular problems, mental health concerns, speech and language delays, difficulty in school, and behavioral problems. Tinnitus was also found to be comorbid with hyperacusis, but the comorbidity was less than that reported in adults.

CONCLUSIONS

This study identified common hearing profiles and critical comorbidities in a large clinical cohort of children with hyperacusis. These results demonstrate the urgent need for standardized multidisciplinary assessment and treatment protocols for pediatric hyperacusis.

Perceptual Consequences of Cochlear Deafferentation in Humans

Cochlear synaptopathy, a form of cochlear deafferentation, has been demonstrated in a number of animal species, including non-human primates. Both age and noise exposure contribute to synaptopathy in animal models, indicating that it may be a common type of auditory dysfunction in humans. Temporal bone and auditory physiological data suggest that age and occupational/military noise exposure also lead to synaptopathy in humans. The predicted perceptual consequences of synaptopathy include tinnitus, hyperacusis, and difficulty with speech-in-noise perception. However, confirming the perceptual impacts of this form of cochlear deafferentation presents a particular challenge because synaptopathy can only be confirmed through post-mortem temporal bone analysis and auditory perception is difficult to evaluate in animals. Animal data suggest that deafferentation leads to increased central gain, signs of tinnitus and abnormal loudness perception, and deficits in temporal processing and signal-in-noise detection. If equivalent changes occur in humans following deafferentation, this would be expected to increase the likelihood of developing tinnitus, hyperacusis, and difficulty with speech-in-noise perception. Physiological data from humans is consistent with the hypothesis that deafferentation is associated with increased central gain and a greater likelihood of tinnitus perception, while human data on the relationship between deafferentation and hyperacusis is extremely limited. Many human studies have investigated the relationship between physiological correlates of deafferentation and difficulty with speech-in-noise perception, with mixed findings. A non-linear relationship between deafferentation and speech perception may have contributed to the mixed results. When differences in sample characteristics and study measurements are considered, the findings may be more consistent.

Hyperacusis Diagnosis and Management in the United States: Clinical Audiology Practice Patterns

PURPOSE

Hyperacusis often leads to debilitating psychosocial consequences, but there is no standard protocol for its diagnosis and management in the United States. In this study, we surveyed U.S. clinical audiologists to understand their education and clinical practices surrounding the evaluation and treatment of hyperacusis.

METHOD

An online survey was distributed to clinical audiologists across the United States. Survey responses were quantified using descriptive statistics and inductive content analysis.

RESULTS

Hyperacusis definitions and clinical practice patterns varied widely across the 102 respondents. Respondents cited a lack of education and training as the primary barrier to effective audiological diagnosis and management of hyperacusis, with most respondents reporting ≤ 5 hr of hyperacusis education. Other primary barriers to effective audiological management of hyperacusis included time constraints, reimbursement, poor sensitivity and specificity of available diagnostic tools, and poor efficacy of available treatments and management strategies. Most respondents (82.5%) agreed that audiologists are the primary professionals who are responsible for implementing hyperacusis interventions. However, 63.3% of respondents reported that their clinic does not have a hyperacusis management protocol, and 80.0% routinely recommend treatment that is outside their scope of practice to implement (cognitive behavioral therapy).

CONCLUSIONS

Clinical audiologists in the United States do not receive uniform education on hyperacusis, and they report multiple barriers to its evidence-based diagnosis and management. Effective hyperacusis management necessitates a multidisciplinary approach. The information obtained via this survey will pave the way toward the refinement of interprofessional education programs and the development of systematic, evidence-based clinical protocols for hyperacusis.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24431188.

Asymmetric hearing thresholds are associated with hyperacusis in a large clinical population

Hyperacusis is a debilitating auditory condition whose characterization is largely qualitative and is typically based on small participant cohorts. Here, we characterize the hearing and demographic profiles of adults who reported hyperacusis upon audiological evaluation at a large medical center. Audiometric data from 626 adults (age 18-80 years) with documented hyperacusis were retrospectively extracted from medical records and compared to an age- and sex-matched reference group of patients from the same clinic who did not report hyperacusis. Patients with hyperacusis had lower (i.e., better) high-frequency hearing thresholds (2000-8000 Hz), but significantly larger interaural threshold asymmetries (250-8000 Hz) relative to the reference group. The probability of reporting hyperacusis was highest for normal, asymmetric, and notched audiometric configurations. Many patients reported unilateral hyperacusis symptoms, a history of noise exposure, and co-morbid tinnitus. The high prevalence of both overt and subclinical hearing asymmetries in the hyperacusis population suggests a central compensatory mechanism that is dominated by input from an intact or minimally damaged ear, and which may lead to perceptual hypersensitivity by overshooting baseline neural activity levels.

Neural signatures of auditory hypersensitivity following acoustic trauma

Neurons in sensory cortex exhibit a remarkable capacity to maintain stable firing rates despite large fluctuations in afferent activity levels. However, sudden peripheral deafferentation in adulthood can trigger an excessive, non-homeostatic cortical compensatory response that may underlie perceptual disorders including sensory hypersensitivity, phantom limb pain, and tinnitus. Here, we show that mice with noise-induced damage of the high-frequency cochlear base were behaviorally hypersensitive to spared mid-frequency tones and to direct optogenetic stimulation of auditory thalamocortical neurons. Chronic two-photon calcium imaging from ACtx pyramidal neurons (PyrNs) revealed an initial stage of spatially diffuse hyperactivity, hyper-correlation, and auditory hyperresponsivity that consolidated around deafferented map regions three or more days after acoustic trauma. Deafferented PyrN ensembles also displayed hypersensitive decoding of spared mid-frequency tones that mirrored behavioral hypersensitivity, suggesting that non-homeostatic regulation of cortical sound intensity coding following sensorineural loss may be an underlying source of auditory hypersensitivity. Excess cortical response gain after acoustic trauma was expressed heterogeneously among individual PyrNs, yet 40% of this variability could be accounted for by each cell's baseline response properties prior to acoustic trauma. PyrNs with initially high spontaneous activity and gradual monotonic intensity growth functions were more likely to exhibit non-homeostatic excess gain after acoustic trauma. This suggests that while cortical gain changes are triggered by reduced bottom-up afferent input, their subsequent stabilization is also shaped by their local circuit milieu, where indicators of reduced inhibition can presage pathological hyperactivity following sensorineural hearing loss.

Clinical and investigational tools for monitoring noise-induced hyperacusis

Hyperacusis is a recognized perceptual consequence of acoustic overexposure that can lead to debilitating psychosocial effects. Despite the profound impact of hyperacusis on quality of life, clinicians and researchers lack objective biomarkers and standardized protocols for its assessment. Outcomes of conventional audiologic tests are highly variable in the hyperacusis population and do not adequately capture the multifaceted nature of the condition on an individual level. This presents challenges for the differential diagnosis of hyperacusis, its clinical surveillance, and evaluation of new treatment options. Multiple behavioral and objective assays are emerging as contenders for inclusion in hyperacusis assessment protocols but most still await rigorous validation. There remains a pressing need to develop tools to quantify common nonauditory symptoms, including annoyance, fear, and pain. This review describes the current literature on clinical and investigational tools that have been used to diagnose and monitor hyperacusis, as well as those that hold promise for inclusion in future trials.