Deafness is one of the most common communication disorders in humans. Approximately one out of every thousand infants is born with a significant hearing deficit. The prevalence of hearing loss increases dramatically with age. By age 65 years, one out of three of us will suffer from hearing impairment sufficient to interfere with the understanding of speech. Hearing impairment is a very heterogeneous disorder with a wide range of causes. Worldwide, estimates from the World Health Organization are that hearing loss affects 538 million people. Hearing loss may be classified into three types: sensorineural, involving the inner ear, cochlea, or the auditory nerve; conductive, when the outer or middle ear structures fail to optimally capture, collect, or transmit sound to the cochlea; and mixed loss, which is a combination of conductive and sensorineural hearing loss. In this chapter, we propose to briefly define each cause of hearing loss as follows: (1) outer ear causes (congenital, infection, trauma, tumor, dermatologic, and cerumen), (2) middle ear causes (congenital, eustachian tube dysfunction, infection, tumors, otosclerosis, tympanic membrane perforation, middle ear barotrauma, and vascular), and (3) inner ear causes (congenital or hereditary, presbycusis, infection, Ménière disease, noise exposure, inner ear barotrauma, trauma, tumors, endocrine/systemic/metabolic, autoimmune hearing loss, Iatrogenic, ototoxic, and neurogenic).
Part of the book: Update On Hearing Loss