Sensorineural Hearing Loss

Millions of Americans experience some degree of hearing loss. The Social Security Administration (SSA) operates programs that provide cash disability benefits to people with permanent impairments like hearing loss, if they can show that their impairments meet stringent SSA criteria and their earnings are below an SSA threshold. The National Research Council convened an expert committee at the request of the SSA to study the issues related to disability determination for people with hearing loss. This volume is the product of that study. Hearing Loss: Determining Eligibility for Social Security Benefits reviews current knowledge about hearing loss and its measurement and treatment, and provides an evaluation of the strengths and weaknesses of the current processes and criteria. It recommends changes to strengthen the disability determination process and ensure its reliability and fairness. The book addresses criteria for selection of pure tone and speech tests, guidelines for test administration, testing of hearing in noise, special issues related to testing children, and the difficulty of predicting work capacity from clinical hearing test results. It should be useful to audiologists, otolaryngologists, disability advocates, and others who are concerned with people who have hearing loss.

The brain is the most complex organ in our body. Indeed, it is perhaps the most complex structure we have ever encountered in nature. Both structurally and functionally, there are many peculiarities that differentiate the brain from all other organs. The brain is our connection to the world around us and by governing nervous system and higher function, any disturbance induces severe neurological and psychiatric disorders that can have a devastating effect on quality of life. Our understanding of the physiology and biochemistry of the brain has improved dramatically in the last two decades. In particular, the critical role of cations, including magnesium, has become evident, even if incompletely understood at a mechanistic level. The exact role and regulation of magnesium, in particular, remains elusive, largely because intracellular levels are so difficult to routinely quantify. Nonetheless, the importance of magnesium to normal central nervous system activity is self-evident given the complicated homeostatic mechanisms that maintain the concentration of this cation within strict limits essential for normal physiology and metabolism. There is also considerable accumulating evidence to suggest alterations to some brain functions in both normal and pathological conditions may be linked to alterations in local magnesium concentration. This book, containing chapters written by some of the foremost experts in the field of magnesium research, brings together the latest in experimental and clinical magnesium research as it relates to the central nervous system. It offers a complete and updated view of magnesiums involvement in central nervous system function and in so doing, brings together two main pillars of contemporary neuroscience research, namely providing an explanation for the molecular mechanisms involved in brain function, and emphasizing the connections between the molecular changes and behavior. It is the untiring efforts of those magnesium researchers who have dedicated their lives to unraveling the mysteries of magnesiums role in biological systems that has inspired the collation of this volume of work.

A recent study indicates that 20 million people in the United States have significant sensorineural hearing loss. Approximately 95% of those people have partial losses, with varying degrees of residual hearing. These percentages are similar in other developed countries. What changes in the function of the cochlea or inner ear cause such losses? What does the world sound like to the 19 million people with residual hearing? How should we transform sounds to correct for the hearing loss and maximize restoration of normal hearing? Answers to such questions require detailed models of the way that sounds are processed by the nervous system, both for listeners with normal hearing and for those with sensorineural hearing loss. This book contains chapters describing the work of 25 different research groups. A great deal of research in recent years has been aimed at obtaining a better physiological description of the altered processes that cause sensorineural hearing loss and a better understanding of transformations that occur in the perception of those sounds that are sufficiently intense that they can still be heard. Efforts to understand these changes in function have lead to a better understanding of normal function as well. This research has been based on rigorous mathematical models, computer simulations of mechanical and physiological processes, and signal processing simulations of the altered perceptual experience of listeners with sensorineural hearing loss. This book provides examples of all these approaches to modeling sensorineural hearing loss and a summary of the latest research in the field.

Hearing loss in the pediatric population is often a source of anxiety both for families and health professionals, with current rehabilitation options mainly consisting of hearing aids and cochlear implants. As such, the authors of Sensorineural Hearing Loss: Prevalence, Risk Factors and Treatment present an overview of the causes of progressive hearing loss (both congenital and acquired) and explore the management of this condition. Sensorineural hearing loss, if not properly treated, may likely compromise speech and, consequently, the psychosocial development of the affected child. Therefore, early diagnosis and treatment has a significant impact on the likelihood of hearing rehabilitation and on social development. The authors provide an analysis of the prevalence, stratification of risk factors, and the most appropriate treatment for sensorineural hearing loss. The authors go on to review the role of the gender medicine in the field of audiology. Currently, there is growing interest on the effects of gender differences on the pathophysiology and pharmacology of several disorders; however, there are still few data about the relation between gender-related factors and hearing loss. This compilation also proposes hyperbaric oxygenation as an adjunct therapy in the treatment of sudden sensorineural hearing loss. The authors take into consideration the physiologic, biochemical and cellular effect of oxygenation on the human brain and body. The authors discuss congenital cytomegalovirus infection, the most common cause of nonhereditary sensorineural hearing loss during childhood worldwide. It affects 0.2% to 2.5% of all live-born neonates and the highest incidence occurs in developing countries, where 1% to 5% of all live births can be infected. An overview of hearing loss caused by the Zika virus infection (both congenital and adult) is provided and recent discussion on the management of this condition is explored. First isolated in 1947, Zika virus rose to prominence after its outbreak in Latin America in 2015. Due to a high incidence of microcephaly in the Brazilian northeast, the correlation between Zika virus infection during pregnancy and this congenital malformation was recognized. With 30-35% of people suffering from presbycusis, also known as age-related hearing loss, it is the leading cause of hearing impairment among the elderly. Even though it is a multifactorial disease, its prevalence increases with aging and is higher among men. The authors propose that once age-related hearing loss has been diagnosed, the possibility of benefitting from conventional hearing aids should be taken into account according to hearing test results.

Update on Hearing Loss encompasses both the theoretical background on the different forms of hearing loss and a detailed knowledge on state-of-the-art treatment for hearing loss, written for clinicians by specialists and researchers. Realizing the complexity of hearing loss has highlighted the importance of interdisciplinary research. Therefore, all the authors contributing to this book were chosen from many different specialties of medicine, including surgery, psychology, and neuroscience, and came from diverse areas of expertise, such as neurology, otolaryngology, psychiatry, and clinical and experimental audiology.

This book presents standard imaging techniques, basic anatomy and an approach to common pathology encountered in temporal bone imaging. Intended as a survival guide for residents and general radiologists, it covers all topics comprehensively, and provides intuitive point-by-point summaries, similar to those of popular radiology reference sites, for easy comprehension at a glance. The book also offers guidance on the pertinent points that need to be included in a report and how to answer basic questions that are likely to be asked by the referring clinician or supervising radiologist. This book will be a valuable resource for general radiologists, radiology residents, ENT residents, otology surgeons and anyone involved in the occasional temporal bone study.

This book systematically discusses the pathogenesis, prevention, and the current and potential clinical treatment of hearing loss, as well as the latest advances in hearing research. Hearing loss is a prevalent sensory disorder, which according to a 2015 World Health Organization (WHO) report affected 9% of the global population in 2015. As populations continue to age, more and more people are suffering from the condition, with 60% of those aged between 65 and 75 affected. Hearing loss seriously affects patients’ ability to work ability and quality of life, and as such deafness has become an increasingly urgent social problem around the globe. Sensorineural hearing loss is mainly caused by damage to the hair cells (HCs), and the subsequent loss of spiral ganglion neurons (SGNs). Damage to the HCs in the inner ear can result from exposure to loud noises and environmental and chemical toxins as well as genetic disorders, aging, and certain medications. This book provides ENT specialists and researchers, as well as individuals affected a comprehensive introduction to the field of hearing loss.

In the Occupational Safety and Health Act of 1970, Congress declared that its purpose was to assure, so far as possible, safe and healthful working conditions for every working man and woman and to preserve our human resources. In this Act, the National Institute for Occupational Safety and Health (NIOSH) is charged with recommending occupational safety and health standards and describing exposure concentrations that are safe for various periods of employment-including but not limited to concentrations at which no worker will suffer diminished health, functional capacity, or life expectancy as a result of his or her work experience. By means of criteria documents, NIOSH communicates these recommended standards to regulatory agencies (including the Occupational Safety and Health Administration [OSHA]) and to others in the occupational safety and health community. Criteria documents provide the scientific basis for new occupational safety and health standards. These documents generally contain a critical review of the scientific and technical information available on the prevalence of hazards, the existence of safety and health risks, and the adequacy of control methods. In addition to transmitting these documents to the Department of Labor, NIOSH also distributes them to health professionals in academic institutions, industry, organized labor, public interest groups, and other government agencies. In 1972, NIOSH published Criteria for a Recommended Standard: Occupational Exposure to Noise, which provided the basis for a recommended standard to reduce the risk of developing permanent hearing loss as a result of occupational noise exposure [NIOSH 1972]. NIOSH has now evaluated the latest scientific information and has revised some of its previous recommendations. The 1998 recommendations go beyond attempting to conserve hearing by focusing on preventing occupational noise-induced hearing loss (NIHL). This criteria document reevaluates and reaffirms the recommended exposure limit (REL) for occupational noise exposure established by the National Institute for Occupational Safety and Health (NIOSH) in 1972. The REL is 85 decibels, A-weighted, as an 8-hr time-weighted average (85 dBA as an 8-hr TWA). Exposures at or above this level are hazardous. By incorporating the 4000-Hz audiometric frequency into the definition of hearing impairment in the risk assessment, NIOSH has found an 8% excess risk of developing occupational noise-induced hearing loss (NIHL) during a 40-year lifetime exposure at the 85-dBA REL. NIOSH has also found that scientific evidence supports the use of a 3-dB exchange rate for the calculation of TWA exposures to noise. The recommendations in this document go beyond attempts to conserve hearing by focusing on prevention of occupational NIHL. For workers whose noise exposures equal or exceed 85 dBA, NIOSH recommends a hearing loss prevention program (HLPP) that includes exposure assessment, engineering and administrative controls, proper use of hearing protectors, audiometric evaluation, education and motivation, recordkeeping, and program audits and evaluations. Audiometric evaluation is an important component of an HLPP. To provide early identification of workers with increasing hearing loss, NIOSH has revised the criterion for significant threshold shift to an increase of 15 dB in the hearing threshold level (HTL) at 500, 1000, 2000, 3000, 4000, or 6000 Hz in either ear, as determined by two consecutive tests. To permit timely intervention and prevent further hearing losses in workers whose HTLs have increased because of occupational noise exposure, NIOSH no longer recommends age correction on individual audiograms.