hearing loss and deafness
ear, nose, and throat disorders
Hearing Loss
Hearing loss has many causes (see table). Different parts of the hearing pathway can be affected, and loss is classified as conductive, sensorineural, or mixed, depending on the part of the pathway that is affected. Conductive hearing lossoccurs when something blocks sound from reaching the sensory structures in the inner ear. The problem may involve the external ear canal, the eardrum (tympanic membrane—TM), or the middle ear. Sensorineural hearing lossoccurs when sound reaches the inner ear, but either sound cannot be translated into nerve impulses (sensory loss) or nerve impulses are not carried to the brain (neural loss). The distinction between sensory and neural loss is important because sensory hearing loss is sometimes reversible and is seldom life threatening. A neural hearing loss rarely goes away and may be due to a potentially life-threatening brain tumor—commonly a cerebellopontine angle tumor. An additional type of sensorineural loss is termed auditory neuropathy spectrum disorder, when sound can be detected but the signal is not sent correctly to the brain. Mixed lossinvolves both conductive and sensorineural loss. It may be caused by severe head injury, chronic infection, or one of many rare genetic disorders. Themost common causesoverall are Ear Blockages None Noise Aging Overview of Middle Ear Infections in Young Children (particularly among children and young adults) Earwax accumulationis the most common cause of treatable hearing loss, especially among older people. can cause sudden or gradual sensorineural hearing loss. Exposure to a single, extreme noise (such as a nearby gunshot or explosion) can cause a sudden hearing loss referred to as acoustic trauma. Some people with acoustic trauma also develop ringing or buzzing in the ears ( Ear Ringing or Buzzing ). Hearing loss from acoustic trauma usually goes away within a day (unless there is also blast damage to the eardrum or middle ear), though there may be subtle damage to the inner ear that might accelerate age-related hearing loss years later. However, long-term exposure to noise causes most noise-induced hearing loss. Noise louder than about 85 decibels (dB) can cause hearing loss if exposure continues long enough. Although people vary somewhat in susceptibility to noise-induced hearing loss, nearly everyone loses some hearing if they are exposed to sufficiently intense noise for a long enough time. , together with noise exposure and genetic factors, is a common risk factor for hearing loss. Age-related hearing loss ( Presbycusis ) limits a person’s ability to hear higher frequencies more than lower frequencies. Ear infectionsare a common cause of temporary mild to moderate hearing loss (mainly in children). Most children regain normal hearing in 3 to 4 weeks after an ear infection resolves, but a few have persistent hearing loss. Persistent hearing loss is more likely in children who have recurring ear infections. Less common causes include the following: Autoimmune disorders Congenital disorders Drugs that damage the ear ( Ear Disorders Caused by Drugs ) Injuries Ear Tumors None 