ear disease
- Related Topics:
- tinnitus
- Ménière disease
- deafness
- otitis
- presbycusis
ear disease, any of the diseases or disorders that affect the human ear and hearing.
Impaired hearing is, with rare exception, the result of disease or abnormality of the outer, middle, or inner ear. Serious impairment of hearing at birth almost always results from a dysfunction of the auditory nerve and cannot be improved by medical or surgical treatment. In early and late childhood the most frequent cause for impaired hearing is poor functioning of the eustachian tubes with the accumulation of a clear, pale yellowish fluid in the middle-ear cavity, a disorder called serous, or secretory, otitis media. In early and middle adult life the usual cause for progressive impairment of hearing is otosclerosis. The usual cause of hearing loss after the age of 60 is presbycusis, a disorder that results from the aging process.
In most cases when loss of hearing is due to a problem with sound conduction, surgical restoration can correct the defect and restore hearing. When loss of hearing is the result of nerve damage, however, surgery is not of use. Medical treatment of auditory nerve damage is helpful only in rare cases—e.g., when the loss is due to syphilis or an early case of Ménière disease or in some instances when zinc deficiency is the underlying cause.
More important than a cure for auditory nerve damage is prevention. Cases of deafness in the newborn due to rubella (German measles) in the mother can be averted with the rubella vaccine. Nerve damage caused by exposure to excessive and prolonged noise is preventable by early detection. One approach is to give routine hearing tests to individuals who work in environments where excessive noise is unavoidable.
The incidence of impaired hearing in the general population depends on the degree of hearing loss defined as impaired (see ear: The physiology of hearing: Hearing tests: Audiometry). According to U.S. statistics, by age 6, 0.2 percent of all children have impaired hearing in one or both ears that is sufficient to warrant consultation of an ear specialist. By age 18 the number of children with hearing loss sufficient to require diagnostic examination reaches 2.5 to 3 percent. By age 65 the number of adults with a recognizable hearing impairment reaches 5 percent. After age 65 the incidence of impaired hearing rises rapidly. About 30 to 35 percent of individuals between the ages of 65 and 75 and 40 percent of those older than 75 are affected by hearing loss.
Comparable figures from Great Britain show that 1 in 6 persons is estimated to have some hearing difficulty, but only one-fourth of these have any real handicap, with one-third of this latter group needing hearing aids and 1 in 20 being deaf to all speech and beyond help with a hearing aid. Of British children, 1 in 1,000 is severely deaf, and as many as 7 per 1,000 are estimated to have a level of impairment that requires some form of help.
The structure and function of the human auditory and vestibular systems are treated in the following sections from the ear article: Anatomy of the human ear, The physiology of hearing, and The physiology of balance. This article deals with the more important diseases and disorders of the outer, middle, and inner ear.
Outer ear
Diseases of the outer ear are those that afflict skin, cartilage, and the glands and hair follicles in the outer-ear canal. The sound-transmitting function of the outer ear is impaired when the ear canal becomes filled with tumour, infected material, or earwax (cerumen), so that sound cannot reach the tympanic membrane, or eardrum. The most common diseases of the outer ear are briefly described in the following paragraphs.
Infections and injuries
Frostbite
The exposed position of the outer ear makes it the part of the body most frequently affected by freezing, or frostbite. Humidity, duration of exposure, and, most of all, wind, in addition to degrees of temperature below freezing, predispose to the occurrence of frostbite. The frozen area begins along the upper and outer edge of the ear, which becomes yellow-white and waxy in appearance, cold and hard to the touch, and numb with loss of skin sensation.
In treatment of frostbite the victim is placed as soon as possible in a warm room, but the frozen ear is kept cool by applying ice wrapped in a towel until the returning blood circulation gradually thaws the frozen part from within. Massage of the frozen ear is avoided, for it is likely to injure the skin. Heat applied to the frozen area before circulation is established can result in clotting of the blood in the blood vessels. This in turn can result in death of that part of the ear, which turns black and eventually falls off, a process called dry gangrene.
Hematoma
Injury to the outer ear can cause bleeding between the cartilage and the skin, producing a smooth, rounded, nontender purplish swelling called hematoma. The accumulation of clotted blood is removed by a surgeon because, if it is left, it will become transformed into scar tissue and cause a permanent, irregular thickening of the outer ear commonly called cauliflower ear and seen in boxers and wrestlers whose ears receive much abuse.
Perichondritis
Infection of the cartilage of the outer ear, called perichondritis, is unusual but may occur from injury or from swimming in polluted water. It is due to a particular microorganism, Pseudomonas aeruginosa. There is a greenish or brownish, musty or foul-smelling discharge from the outer-ear canal, while the affected outer ear becomes tender, dusky red, and two to three times its normal thickness. Prompt antibiotic treatment is necessary to prevent permanent deformity of the outer ear.
External otitis
Infection of the outer-ear canal by molds or various microorganisms occurs especially in warm, humid climates and among swimmers. The ear canal itches and becomes tender; a small amount of thin, often foul-smelling material drains from it. If the canal becomes clogged by the swelling and drainage, hearing will be impaired. Careful and thorough cleaning of the outer-ear canal by a physician, application of antiseptic or antibiotic eardrops, and avoidance of swimming are indicated to clear up the infection.
Boil in the ear (furuncle)
Infection of a hair follicle anywhere on the body is known as a boil, or furuncle. This can occur in a hair follicle in the outer-ear canal, especially when there is infection of the skin of the canal. It always occurs because of a particular type of germ known as staphylococcus. Because the skin of the ear canal is closely attached to the underlying cartilage, a boil in the ear canal is especially painful, with swelling, redness, and tenderness but generally without fever. Heat applied to the outer ear by a hot-water bottle or electric pad helps the infection to come to a head and begin to drain. Treatment with a systemic and local antibiotic is required to prevent other hair follicles from becoming infected.
Erysipelas of the outer ear
Erysipelas is an infection in the skin caused by a particular type of streptococcus and characterized by a slowly advancing red, slightly tender thickening of the skin. It may begin at the ear and spread to the face and neck. Centuries ago erysipelas epidemics caused severe and often fatal infections. In ad 1089 one of the most severe erysipelas epidemics occurred. The disease was referred to as St. Anthony’s fire because those who prayed to St. Anthony were said to recover; others, who did not, died. Today erysipelas is usually a mild and comparatively rare infection that clears up rapidly when treated with an antibiotic.
Leprosy
Leprosy, seen rarely outside the tropics today, was another scourge of ancient times that sometimes affected the outer ear. It is caused by the leprosy bacillus, Mycobacterium leprae, which causes a painless, slowly progressing thickening and distortion of the affected tissues. The diagnosis is made by examining a bit of the infected tissue under a microscope and finding the leprosy bacilli, which in appearance are not unlike the bacilli that cause tuberculosis. Fortunately, the antibiotics effective against tuberculosis are effective today in arresting the progression of the disease.
Osteoma of the bony ear canal
Osteoma of the bony ear canal is a bony knob that grows close to the tympanic membrane, especially in those who swim a great deal in cold water. It is not dangerous and does not need to be removed unless the bony overgrowth becomes large enough to block the ear canal.
