12/13/2023 0 Comments Weber test sensorineural hearing lossPatients who present with presbycusis will give a history of progressive decline in hearing. Previous ear surgery, history of noise exposure, previous head trauma, barotrauma, or ototoxic exposure to aminoglycosides are asked. Establishing the premorbid hearing level is crucial to direct rehabilitation and to assess if the hearing loss is new or deterioration of an existing picture. Essential points to obtain include age of onset, laterality of symptoms, rapidity of decline, fluctuating symptoms, and associated symptoms such as tinnitus, aural fullness, disequilibrium, and vertigo. It is important to take a thorough history when assessing a patient with SNHL. There are several pathophysiological mechanisms by which damage to the inner ear results in SNHL. The inner hair cells (IHCs) in the cochlea transduce the energy of the traveling wave to an electric action potential and synapse at the spiral ganglion to form the auditory nerve. The base of the basilar membrane responds to higher-frequency sounds, while the apex responds to lo frequencies. The basilar membrane of the cochlea is highly frequency-specific and tonotopically organized. The cochlea receives an acoustic signal, and a traveling wave is generated, which traverses the basilar membrane of the cochlea stimulating outer hair cells (OHCs), which act as a biological amplifier/compressor and modifies the signal. Sound which reaches the cochlea undergoes first amplification by the outer hair cells and then electrochemical transduction by the inner hair cells. The interface between the stapes and the oval window delivers sound transmission to the cochlea. Inner ear – cochlea and part of the auditory nerveĮach of the above components is important for the conduction of sound waves, but in SNHL, we are concerned with pathology in the inner ear that leads to hearing loss. There are many genetic syndromes with hearing loss as a component, and SNHL developing in childhood warrants a thorough workup. In patients with robust prenatal care, congenital infectious causes such as cytomegalovirus are rare and the most common causes are genetic. This remains a common occupational disease despite legislation in place in most developed countries to prevent NIHL.Ĭongenital hearing loss is nearly always sensorineural in nature, and can have various etiologies. It has been estimated that 16% of adults worldwide disabling hearing loss is occupational noise related. Another important cause of hearing loss in the adult population is noise-induced hearing loss (NIHL). In presbycusis, hearing loss prevalence doubles every decade of life from the second through to the seventh decade, and is nearly universal past the eighth decade of life. Due to different studies using varying thresholds when classifying hearing loss, there is little consensus in the literature regarding the epidemiology of age-related hearing known as presbycusis. In the United States, sudden SNHL affects between 5-27 per 100,000 people each year, with approximately 66,000 new annual cases. The incidence of sensorineural hearing loss varies in different countries.
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