Congenital Causes

The term congenital hearing loss implies that the hearing loss is present at birth. It can include hereditary hearing loss or hearing loss due to other factors present either in utero (prenatal) or at the time of birth.

Genetic factors are thought to cause more than 50% of all incidents of congenital hearing loss in children (4). Genetic hearing loss may be autosomal dominant, autosomal recessive, or X-linked (related to the sex chromosome).

In autosomal dominant hearing loss , one parent who carries the dominant gene for hearing loss and typically has a hearing loss passes it on to the child. In this case there is at least a 50% probability that the child will also have a hearing loss. The probability is higher if both parents have the dominant gene (and typically both have a hearing loss) or if both grandparents on one side of the family have hearing loss due to genetic causes. Because at least one parent usually has a hearing loss, there is prior expectation that the child may have a hearing loss.

In autosomal recessive hearing loss , both parents who typically have normal hearing, carry a recessive gene. In this case the probability of the child having a hearing loss is 25%. Because both parents usually have normal hearing, and because no other family members have hearing loss, there is no prior expectation that the child may have a hearing loss.

In X-linked hearing loss, the mother carries the recessive trait for hearing loss on the sex chromosome and passes it on to males, but not to females.

There are some genetic syndromes,in which, hearing loss is one of the known characteristics. Some examples are Down syndrome (abnormality on a gene), Usher syndrome (autosomal recessive), Treacher Collins syndrome (autosomal dominant), Crouzon syndrome (autosomal dominant), and Alport syndrome (X-linked).

Other causes of congenital hearing loss that are not hereditary in nature include prenatal infections, illnesses, toxins consumed by the mother during pregnancy or other conditions occurring at the time of birth or shortly thereafter. These conditions typically cause sensorineural hearing loss ranging from mild to profound in degree. Examples include:

Intrauterine infections including rubella (German measles), cytomegalovirus, and herpes simplex virus Complications associated with the Rh factor in the blood Prematurity Maternal diabetes Toxemia during pregnancy Lack of oxygen (anoxia)

Acquired Causes

Acquired hearing loss is a hearing loss which appears after birth, at any time in one's life, perhaps as a result of a disease, a condition, or an injury. The following are examples

Ear infections (otitis media) Ototoxic (damaging to the auditory system) drugs Meningitis Measles Encephalitis

Chicken pox Influenza Mumps Head injury Noise exposure

In some cases, hearing loss or deafness is due to hereditary factors. Genetics is considered to play a major role in the occurrence of sensorineural hearing loss. Congenital deafness can happen due to heredity or birth defects.

Human deafness causes also include continuous exposure to loud noises. This is commonly observed in people working in construction sites, airports, nightclubs, etc. This is also experienced by people working with firearms and heavy equipment, and those who use music headphones frequently. The longer the exposure, the greater is the chance of getting affected by hearing loss and deafness.

Some diseases and disorders can also be a contributory factor for deafness in humans. This includes, measles, meningitis, some autoimmune diseases like Wegener's granulomatosis, mumps, presbycusis, AIDS, chlamydia, etc. Fetal alcoholic syndrome, developed in babies born to alcoholic mothers, can cause hearing loss in infants. Growing adenoids can also cause hearing loss by obstructing the Eustachian tube. Otosclerosis, which is a disorder of the middle ear bone, is another cause of hearing loss and deafness. Likewise, there are many other medical conditions which can cause deafness in humans.

Some medications are also considered to be the cause of permanent hearing loss in humans, while others can lead to deafness which can be reversed. The former category includes medicines like gentamicin and the latter includes NSAIDS, diuretics, aspirin and macrolide antibiotics. Narcotic pain killer addiction and heavy hydrocodone abuse can also cause deafness.

Human deafness causes include exposure to some industrial chemicals as well. These ototoxic chemicals can contribute to hearing loss if combined with continuous exposure to loud noise. These chemicals can damage the cochlea and some parts of the auditory system.

Sometimes, loud explosions can cause deafness in humans. Head injury is another of the causes of deafness in humans.

o A: Diseases are a common cause of sensorineural deafness. The diseases include arteriosclerosis, chicken pox, influenza, Meniere's disease, meningitis, mononucleosis, mumps, Rh disease, and syphilis.

o Many children born with sensorineural deafness have mothers who contracted rubella (German measles) during the first three months of pregnancy.

o Other causes of sensorineural deafness include tumors of the brain or the middle ear, concussion, blows to the ear, and repeated loud sounds. The toxic effects of certain drugs can also cause sensorineural deafness in some persons.

Hereditary disorders - some types of deafness are hereditary, which means parents pass on flawed genes to their children. In most cases, hereditary deafness is caused by malformations of the inner ear.

Genetic disorders - genetic mutations may happen: for example, at the moment of conception when the father’s sperm joins with the mother’s egg. Some of the many genetic disorders that can cause deafness include osteogenesis imperfecta, Trisomy 13 S and multiple lentigines syndrome.

Prenatal exposure to disease - a baby will be born deaf or with hearing problems if they are exposed to certain diseases in utero, including rubella (German measles), influenza and mumps. Other factors that are thought to cause congenital deafness include exposure to methyl mercury and drugs such as quinine.

Noise - loud noises (such as gun shots, firecrackers, explosions and rock concerts) can damage the delicate mechanisms inside the ear. If you are standing next to someone, yet have to shout to be heard, you can be sure that the noise is loud enough to be damaging your ears.

Trauma - such as perforation of the eardrum, fractured skull or changes in air pressure (barotrauma). Disease - certain diseases can cause deafness including meningitis, mumps, cytomegalovirus and chicken

pox. A severe case of jaundice is also known to cause deafness. Other causes - other causes of deafness include Meniere’s disease and exposure to certain chemicals.

Age-related hearing lossOur hearing gradually becomes less acute as we age. This is normal, and rarely leads to deafness.

Tinnitus is often associated with deafnessTinnitus means a sensation of ringing in the ears. Some of the causes of tinnitus include middle ear infections and damage to the ear from loud noises. Tinnitus may occur on its own, or in conjunction with hearing loss.

Pregnancy-Related: Cytomegalovirus

Cytomegalovirus, another pregnancy-related cause, was cited as being responsible for 1.8% of the pregnancy-related cases nationally. CMV is very similar to rubella in how it can affect a fetus. Like rubella, it is a dangerous virus that can result in a baby being born with a progressive hearing loss, mental retardation, blindness, or cerebral palsy. Information on CMV is available from the National Congenital CMV Registry.

Pregnancy-Related: Other Pregnancy Complications

"Other pregnancy complications" was the next most cited specific pregnancy-related cause in the survey, at 3.8% of pregnancy-related cases nationally. A pregnancy complication is anything that can harm the baby, mother, or both of them, and it can be mild or serious. According to the American Speech-Language-Hearing Association, this is a category that includes things such as prenatal infection, Rh factor, and lack of oxygen.

My own deafness is the result of a pregnancy complication called rubella. Rubella used to be a common pregnancy complication until a vaccine was developed in the 1960s. It can still occur today if a mother has not been vaccinated.

Post-Natal: Otitis MediaOtitis media was the most common post-natal cause cited, at 4.8% of post-natal cases nationally. Ear infections associated with otitis media are frustrating for both parents and doctors, who must decide whether or not to prescribe antibiotics. An occasional bout of otitis media may cause temporary hearing loss due to the fluid build-up in the middle ear, but repeated bouts of otitis media can cause permanent hearing loss.

Post-Natal: Meningitis

Meningitis, at 3.6 percent of post-natal cases nationally, was the next most common post-natal cause of deafness cited. The antibiotics needed to treat bacterial meningitis can cause hearing loss, but this risk can be reduced with the use of steroids.

Genetic or Syndromic: Down Syndrome

Genetic or syndromic factors were cited in the 2004-2005 report as being responsible for 22.7% of the genetic or syndromic cases. The 2006-2007 report actually showed a slight increase in genetic causes to 23%. Down syndrome was the most common syndromic cause, at 8.7% of the cases of genetic or syndromic hearing loss.

Genetic or Syndromic: CHARGE Syndrome

CHARGE syndrome, at 5.6% of the genetic or syndromic cases, was the next most common genetic or syndromic cause after Down syndrome. CHARGE is a craniofacial disorder.

Genetic or Syndromic: Waardenburg Syndrome

Waardenburg syndrome can create unique physical features as well as cause hearing loss; it was responsible for 4.8% of the cases of genetic or syndromic causes nationally.

Genetic or Syndromic: Treacher Collins Syndrome

Treacher Collins syndrome was the next most frequently cited genetic or syndromic cause. Like CHARGE, Treacher Collins is a craniofacial disorder that can cause deafness.

Unknown Causes

Finally, in the 2004-2005 report, the remainder of the cases were due to unknown causes (approximately 54% of cases). The 2006-2007 report saw an increase in unknown causes, to 57% of the cases of deafness.

Accidents, see Trauma

Achondroplasia

Also called chondro-dystrophy. An inherited condition (autosomal dominant), but can also arise as a new mutation; incidence is roughly 1 per 25,000 births, and affects both sexes. Characterized by short stature (dwarfism). Frequent middle ear infections are common, which can lead to conductive deafness later in life due to the repeated ear infections. Sensorineural deafness can also occur. DSID p.9-13, EGDBD p.5-6.

Acoustic neuroma, see Auditory nerve tumors

Acoustic trauma

Sensorineural hearing loss caused by exposure to excessive noise or abnormally loud sound. It may be cumulative (building up from repeated exposure, as from daily working in noisy environments) or abrupt, as from a single exposure to an extremely loud sound such as an explosion. The eardrum may be ruptured, and the middle ear bones can be disrupted. Often, significant damage to the hair cells inside the cochlea results in permanent hearing loss, as hair cells, like most other nerve tissue, do not regenerate themselves. GEDPD v.2 p.17-20, 151-152; EDHD2 p.4; EDHD p.2.

Adair-Dighton syndrome, see Van der Hoeve syndrome

Adenoids

Normally shrinking after about age 5 and disappearing by adolescence, on occasion the adenoids (lymph glands at the back of the nose) continue to grow instead and may obstruct the Eustachian tube, causing conductive hearing impairment and nasal infections that can spread to the middle ear. This condition is corrected by surgical removal of the adenoids. EDHD2 p.5; EDHD p.3.

Adhesive otitis media, see Otitis media

Adult myxedema, see Thyroid disorders

Aero-otitis media, see Barotrauma

Aging, see Presbycusis

AIDS (Acquired Immunodeficiency Syndrome)

Infection by the human immunodeficiency virus (HIV) can result in AIDS or in AIDS-related complex (ARC). Both are associated with neurological complications that often include hearing loss. "Auditory system anomalies" afflict an estimated 75% of adult AIDS patients and 50% of all ARC patients. Hearing disorders may be caused directly by HIV infection of the cochlea or of the central auditory system, but are often caused by opportunistic infections rather than HIV itself-i.e., the body's loss of its normal resistance to infection allows

other non-related infections to take hold. The most common of these opportunistic infections is cytomegalovirus inclusion disease (CMV) (q.v.), which is found in over 90% of AIDS patients. EDHD2 p.7.

AIDS-related complex (ARC), see AIDS

Air bags

These crash safety devices, installed in nearly all passenger cars today, can be as loud as 150-170 dB for about 0.1 seconds when triggered, possibly causing tinnitus or acoustic trauma (q.v.). EDHD2 p.7.

Alcohol, see Fetal alcohol syndrome

Almaric syndrome

Partial deafness; minor vision problems with normal visual fields, dark vision and color vision.

Alport syndrome or Alport disease

Also called hereditary nephritis, familial nephritis, or Fetchner syndrome. Genetic (genes COL4A5, COL4A3, and COL4A4). It may be inherited in two ways: in an X-linked manner, in which twice as many females as males are affected, but the males tend to be more severely affected; or as an autosomal dominant characteristic, in which case equal numbers of both sexes are affected (this latter variety is also called Fetchner syndrome). Can be passed on to successive generations. Characteristics, generally appearing in mid-childhood, include nephritis (blood and/or protein in the urine) in all cases and progressive degeneration of kidney function leading to renal failure. Kidney dialysis and/or kidney transplants are eventually required. About half of all Alport syndrome cases, males more commonly than females, have progressive sensorineural deafness from the toxic effects of unremoved body metabolic waste products on membranes in the cochlea. This deafness may appear as early as age 3 or 4. DSID p.25-28; EDHD2 p.9; EDHD p.7; GEDPD v.2 p.31; EGDBD p.128.

Andre syndrome, see Oto-palato-digital syndrome

Anoxia, see Asphyxia at birth

Apert syndrome

A rare condition characterized by premature fusion of the bones of the skull along the sutures (edges of the bone plates). Though it can be inherited (autosomal dominant), most cases seem to arise as new mutations. Among other facial, cranial and manual malformations, the ears tend to be low-set and a congenital hearing loss is frequently present. DSID p.35-37; EGDBD p.30.

Asphyxia at birth

Difficulties during delivery of the infant at birth can cause the infant to go without oxygen for a dangerously long period of time (anoxia--total loss of oxygen, or more usually hypoxia--reduced oxygen supply). The permanent neurological damage that can result includes sensorineural hearing impairment in about 3% of cases. GEDPD v.2 p.25; EDHD2 p.15-16.

Aspirin, see Ototoxic drugs

Atresia

Atresia of the ear is a birth defect in which the opening of the external ear is nearly closed or entirely absent, blocking sound from entering the middle ear. Post-birth, it can also result from burns, tumors, accidents, and infections. It can be corrected by surgically making the necessary opening. EDHD2 p.20, EGDBD p.33.

Auditory nerve tumors

Tumors may grow on the auditory nerve, causing hearing impairment on the affected side. Most common in women between 40 and 60 years of age. If it occurs on both sides, this is usually an inherited form indicating central neurofibromatosis (q.v.). EDHD2 p.26-27; EDHD p.26-27.

Auditory neuritis

An inflammation of the auditory nerve following infections such as scarlet fever, typhoid fever, or other infections having high fevers. Deafness may be immediate but is usually progressive over several days or weeks. EDHD2 p.27.

Autoimmune inner ear disease (AIED)

Several autoimmune diseases can cause or are associated with AIED, in which immune cells attack the inner ear, causing deafness and/or dizziness. Relatively rapid hearing loss plus tinnitus over a period of a few months, or attacks of hearing loss and tinnitus resembling Ménière disease. Half of all victims also have balance problems. Rare, accounting for less than 1% of all cases of hearing impairments or dizziness. EDHD2 p.29.

Bacterial labyrinthitis, see Labyrinthitis

Bacterial meningitis, see Meningitis

Bardet-Biedl syndrome

Also called Laurence-Moon-Bardet-Biedl syndrome. A familial syndrome comprising retinitis pigmentosa, polydactyly, intellectual retardation, obesity of the Frohlich type and genital hypoplasia. Sometimes accompanied by deafness. Autosomal recessive inheritance. EGDBD p.39.

Barotitis, see Barotrauma

Barotrauma

Also known as aero-otitis media or barotitis. A temporary but painful condition where external air pressure and pressure in the middle ear are significantly different, causing great pressure on the eardrum. It can be experienced by rapid descent in a poorly-pressurized airplane, diving in water to more than a few feet deep, or other quick changes of surrounding pressure. In extreme cases, the eardrum may rupture, causing some reduced hearing even after it heals, due to scarring. EDHD2 p.5; EDHD p.3.

Bilateral acoustic neurofibromatosis, see Neurofibromatosis

Birth defects

Deafness often results from one or more birth defects. There are hundreds of different birth defects associated with deafness, mostly from genetic causes but many from factors affecting the development of the fetus during pregnancy, such as ototoxic drugs and substances, trauma to the mother also affecting the fetus, syphilis, and many others. Most of these are included throughout this document.

Brachio-Oto-Renal syndrome

Genetic (gene EYA1 and one other unidentified).

Brailsford syndrome, see Morquio syndrome

Brittle bone disease, see Osteogenesis imperfecta

Cancer of the outer ear

Usually appears in areas of the external ear exposed to the sun for years, and therefore is a variety of skin cancer. If caught and treated early, recovery rate is very high. The main risk is from cancer that may begin inside the ear canal, spreading to the surrounding bone before being discovered and far more serious to treat. Survival of such cancer nearly always includes deafness in the affected ear. EDHD2 p.42.

Cardio-cutaneous syndrome, see LEOPARD syndrome

Catarrhal deafness

Caused by inflammation of the mucous membrane lining the head's and throat's air passages, combined with a blocked Eustachian tube. Results from an ear infection; antibiotics and decongestants are the usual treatment. EDHD2 p.43.

Cerebral palsy

Any of several non-progressive disorders of movement, posture or speech caused by brain damage during pregnancy, birth or early childhood. 0.2% to 0.6% of infants develop cerebral palsy before or during birth; postnatal causes can be from head injury, encephalitis (q.v.) or meningitis (q.v.). Hearing impairment occurs in about 25% to 30% of cerebral palsy victims. EDHD2 p.44; EGDBD p.57-58.

Cerebro-spinal meningitis, see Meningitis

Cerumen buildup

An excess buildup of cerumen (earwax) in the ear canal can cause temporary conductive deafness either by stopping up the ear canal or by pressing against the eardrum and restricting its vibration. The solution is simply removal of the excess earwax, either by a doctor or under a doctor's direction. EDHD2 p.72.

Cervical fusion syndrome, see Klippel-Feil syndrome

Charcot-Marie-Tooth disease (CMT)

Also known as peroneal muscular atrophy. A familial disease characterized by muscle weakness, mainly in the lower limbs, from degeneration of the nerves supplying the muscles. Usually inherited as autosomal dominant, but can also be inherited as autosomal recessive. Research suggests that a duplication of part of chromosome 17 seems to be responsible for CMT. Severity of symptoms vary in individual cases, but include the following symptoms that do not arise until age 10 or later: awkward gait with progressive wasting of the lower leg muscles and foot drop, a similar but usually milder effect on the upper limbs, nephritis in a few cases, and in many cases a sensorineural hearing loss manifesting itself as early as the teenage years, often becoming severe by early middle age. DSID p.56-58; EGDBD p.59-60.

CHARGE association

Also known as CHARGE syndrome or choanal atresia. The acronym CHARGE comes from the list of the main features seen in this rare condition, which was first identified only in 1979. Cause is not yet clear, but both autosomal dominant and recessive modes of inheritance have been identified. Symptoms include Colomba of the eye, Heart disease, coanal Atresia, Retarded growth, Genital hypoplasia, and Ear abnormalities. The latter are not always present, but ears may be very small or have a characteristic triangular shape; deafness may also occur, ranging from mild to profound and can be either conductive or sensorineural. DSID p.59-62; EGDBD p.60.

Chicken pox, see Varicella zoster

Chlamydia

This venereal disease affecting women has been documented as causing hearing loss in newborns to whom the disease has been passed at birth.

Choanal atresia, see CHARGE association

Cholesteatoma

A rare and serious chronic condition in which skin cells and debris collect within the middle ear, usually as a result of a middle ear infection that has caused the eardrum to burst. May be present at birth or later in life; there is also a very rare congenital variety. Left untreated, the cholesteatoma may grow and damage the middle ear bones and surrounding bony structure, causing a conductive or mixed conductive-sensorineural hearing loss. Serious additional complications can include secondary infections, labyrinthitis (q.v.), meningitis (q.v.) or a brain abscess. EDHD2 p.47.

Chondro-dystrophy, see Achondrophasia

Choristoma

A middle ear tumor usually accompanying a middle ear malformation. Although itself benign, this tumor can cause conductive deafness by physically filling the middle ear, destroying the ossicles and restricting eardrum movement. EDHD2 p.48.

Chromosome 45/X syndrome, see Turner syndrome

Cleft palate

Some children with cleft palate also have mild to moderate hearing impairments due to the cleft condition also deforming the middle ear. This is usually treatable through surgery. EDHD2 p.48; EGDBD p.72-73.

Cockayne syndrome or Cockayne disease

A very rare genetic syndrome (inherited as autosomal recessive); its effects are thought to be from an enzyme defect. Onset of symptoms as early as the second year of life, usually after a normal infancy. Great photosensitivity of the skin, with pigmentation and scars; progressive decrease of vision, mental deficiency, unsteady gait, progressive sensorineural deafness, dwarfism, and precociously senile appearance. Death usually in early childhood, but some survive into the late teens. DSID p.66-67; EGDBD p.75.

Coffin-Lowry syndrome

Also known as Coffin syndrome. An X-linked recessive hereditary disease, with some additional cases believed to arise frequently through new mutations. Mental retardation, short stature from spinal defects, and puffy-appearing fingers are usual; deafness sometimes occurs also. Males tend to be afflicted to a greater extent than females. DSID p.68-69; EGDBD p.75-76.

Cogan syndrome

Affects mostly young adults, occasionally old persons. Sudden onset of unilateral or bilateral blurring of vision, inflammation of the cornea and pain in the eye, lacrimation, blepharospasm, nausea, vomiting, tinnitus, vertigo, and rapid development of deafness. About 50% of patients have an associated systemic disease, most commonly polyarteritis nodosa. EDHD2 p.55; EDHD p.49; GEDPD v.2 p.31.

Congenital brevicollis, see Klippel-Feil syndrome

Congenital central hypoventilation syndrome

Also sometimes called Ondine's curse. A rare condition that may be congenital or may follow an acquired viral encephalitis (q.v.), affecting both sexes. Cause has not been definitively established, but is almost certainly a genetic fault. Characterized by breathing difficulties and apnea, especially during sleep; cyanosis (blue skin) soon after birth is often the first noticeable symptom. Problems with body temperature control, seizures, and urine production; hearing problems have also been reported in some cases. DSID p.73-75; EGDBD p.246.

Congenital cytomegalic inclusion disease (CID)

A systemic disease due to infection of the fetus by cytomegalovirus. Significant damage to the central nervous system occurs in about 10% of affected infants. Intellectual retardation; in 50% of cases, microcephaly and occasionally hydrocephalus. Accompanying sensorineural deafness. Postnatal CID infection is usually benign.

Craniofacial dystosis, see Crouzon syndrome

Crouzon syndrome

Also known as craniofacial dystosis. A rare condition; half of the cases are inherited (autosomal dominant) and the other half appears as a fresh mutation. Characterized by a premature fusion of the cranial sutures (the edge of the bony plates making up the skull); small head, sometimes cleft palate, a beaked nose, and protruding eyes. Learning disabilities are common, and underdevelopment of the external meatus (pinna) of the ear can cause hearing impairment. DSID p.82-84; EGDBD p.89-90.

Cytomegalovirus inclusion disease (CMV)

Affects developing fetuses if the mother becomes infected with CMV during pregnancy; roughly 11% of infected infants have some degree of hearing loss, usually profound but sometimes milder. Different reports blame CMV for between 2 and 40 percent of all congenital deafness, rivaling rubella as the most common viral cause of prenatal deafness. It is also found in over 90% of AIDS patients as an opportunistic infection. EDHD2 p.7, 60; GEDPD v.2 p.23.

D1 Trisomy syndrome, see Trisomy 13 syndrome

Diabetes mellitus type II and sensorineural hearing loss

A genetic (mitochondrial) condition caused by mutations. Diabetes can cause blood vessels and peripheral nerves to degenerate, disrupting blood supply to, among other places, the ear and the internal auditory canal. This in turn can cause a degeneration of cochlear and vestibular nerves, causing a sensorineural hearing loss. EDHD2 p.65; EGDBD p.99-101.

Distopia canthorum, see Waardenburg syndrome

Diuretics, see Ototoxic drugs and other substances

Down syndrome

Also known as mongolism (obsolete) or trisomy 21. Caused by a chromosomal abnormality which can express itself in two different ways: Most commonly, an extra chromosome is added in the 21 position, leading to a chromosome count of 47 instead of the normal 46. Much less often, the extra chromosome attaches to another chromosome, leading to a normal count of 46, but one of these is a "compound" chromosome. Overall incidence in Caucasian, Japanese, and African American populations ranges between 1 in 660 births and 1 in 800 births, and is also sensitive to the age of the mother, with risk rising sharply when she is over 35. Both sexes can be affected. Very characteristic facial features including an upward slant to the eyes; the head may be smaller and flatter at the back and with a short neck. Eye abnormalities may be present, limbs are relatively short, fingers are short and stubby, and muscle tone is poor. Delay and slowness in mental development (not mental deficiency). Conductive deafness often occurs from frequent middle ear infections, and in some cases Down patients are born with irregularities in the middle and inner ears that can also cause conductive hearing impairment. DSID p.90-94; EDHD2 p.66; EGDBD p.104-106.

Drugs, see Ototoxic drugs and other substances

Dwarfism

Dwarfism (very short stature) is not in itself a cause of deafness. However, many of the causes of dwarfism also cause deafness. Achondroplasia (q.v.) accounts for approximately half of all cases of dwarfism and commonly also involves deafness. Other causes of dwarfism with deafness may include chromosome abnormalities such as Turner syndrome (q.v.), spondyloepiphyseal dysplasia (q.v.) and some ototoxic drugs and other substances (q.v.) and other teratogens. However, other etiologies of dwarfism, such as pituitary dwarfism, primary or secondary growth failures, hormone failures, or poor nutrition are not usually linked with deafness. EGDBD p.107-108.

Dysostosis mandibulofacial, see Treacher Collins syndrome

Ear infection, see Otitis media

Eardrum, see Perforated eardrum

Earwax, see Cerumen buildup

Ectodermal dysplasia-pancreatic insufficiency, see Johanson-Blizzard syndrome

Edema

This is retention of excess water in the body, especially during pregnancy. It can cause a conductive deafness through water in the middle ear, muffling the action of the middle ear bones. Diuretic medications can help, though with caution since, ironically, diuretics are ototoxic drugs.

Encephalitis

An inflammation of the brain itself, distinguished from cerebral meningitis which is an inflammation of the membrane surrounding the brain. Usually caused by infective viruses (like rabies or herpes), bacteria, protozoa, worms, or even some chemicals. It is also possible for humans to be infected with equine (horse) encephalitis carried by mosquitoes. Damage is caused either directly to the nerve cells of the brain or to the sheath (myelin) around the nerve cell. If the damage involves those areas of the brain responsible for hearing, a hearing impairment may result. Common symptoms include fever, headache, drowsiness, lethargy, tremors and coma; convulsions sometimes occur, mainly in infants. Lesser symptoms may include uncoordinated movements, weakness, and unusual sensitivity of the skin. EDHD2 p.77.

Endemic cretinism, see Thyroid disorders

Erythroblastosis fetalis, see Rh incompatibility disease

Exanthema infantum or exanthema subitum, see Roseola infantum

Facio-scapulo-humeral dystrophy, see Muscular dystrophy

Falls, see Trauma

Familial nephritis, see Alport syndrome

Fechtner syndrome, see Alport syndrome

Fetal alcohol syndrome (FAS)

Reported to cause hearing loss in up to 64% of infants born to alcoholic mothers, from the ototoxic effect on the developing fetus plus malnutrition during pregnancy from the excess alcohol intake. Common characteristics include small size, narrow foreheads with a "sleepy" facial appearance, and a long, smooth upper lip; mental retardation often occurs, as does hyperactivity and speech delay. DSID p.115-117; EDHD2 p.82; EDHD p.156; EGDBD p.129-130.

Fevers

A variety of illnesses and diseases are known to be able to damage the delicate hair cells in the cochlea, and sometimes other hearing-related nerve cells, from prolonged exposure to high fever temperatures. One example of this is roseola infantum (q.v.) Such sensorineural nerve damage is permanent, as most nerve cells do not regenerate themselves.

First and second branchial arch syndrome, see Goldenhar syndrome

Flynn-Aird syndrome

Ocular changes, including severe myopia, cataracts and retinitus pigmentosa, nerve deafness, cutaneous atrophy, joint stiffness, muscle wasting and neurological changes including peripheral neuropathology, ataxia, epilepsy and dementia.

Forney syndrome

Familial mitral insufficiency, conductive hearing loss, short stature, and bony fusion of cervical vertebrae and carpal and tarsal bones.

Franceschetti syndrome, see Manibulofacial dystosis

Franceschetti-Klein syndrome, see Treacher Collins syndrome

Friedrich ataxia

Also called Friedrich disease, hereditary spinal ataxia, or recessive spinocerebellar degeneration. Inherited as an autosomal recessive characteristic, the affected gene being on chromosome 9. The basic cause is not yet established, but it may be a metabolic disease. Atrophy of specific parts of the spinal chord. Ataxia (an inability to coordinate the voluntary muscular movements) is the most obvious symptom, though they do not begin to show until around age 3, and in some cases not until puberty. Unsteadiness begins in the legs and progresses up the body, accompanied by weakness and loss of reflexes. Disturbances of eye movement and hypertrophia of the heart follow, plus diabetes in about 20% of cases. Deafness is less often seen but can accompany the other symptoms. Victims are almost always forced into a wheelchair by their early twenties, and death from heart or respiratory problems usually occurs by age 40. DSID p.121-123; EGDBD p.134-135.

Functional hearing loss

Also known as psychogenic hearing loss or hysterical hearing loss. Deafness that results from psychological or emotional factors, rather than from physical causes. Hearing is actually present, but the brain's recognition of it is psychologically blocked. Often caused by anxiety over emotional conflicts, and is involuntary; can be either partial or total. Diagnosis is sometimes complicated by the presence of a real physical hearing loss, either "overlaid" by the functional loss or in one ear while the other ear has the functional loss (unilateral functional deafness). EDHD2 p.85.

Genetic mutations

Many medical syndromes that include deafness result from mutations in one or more genes that are linked to deafness. The gene called Connexin 26 may be responsible for up to 40% of cases of inherited hearing impairment. Another gene called GJB2 can have many different deafness-causing mutations, the one called 35delG being the most common one. In 2001, researchers reported that gene DFNA15 had been linked to early deafness within a family. Many deafness-causing syndromes result from genetic mutations, and can be found throughout this paper. EDHD2 p.93.

Geniculate syndrome, see Hunt syndrome

German measles, see Rubella

Goldenhar syndrome

Also known as Goldenhar-Gorlin syndrome, ocularauriculovertebral dysplasia, or first and second branchial arch syndrome. At birth, facial asymmetry, both external and internal ear malformations, epibulbar dermoids, preauricular appendages, vertebral anomalies, hearing defect of various degrees from near-normal to severe hearing loss (conductive type) and vision defects, including diplopia of various degrees. Inheritance is sporadic in most cases; about a 1% risk of occurrence in siblings. DSID p.130-133; EGDBD p.150.

Gregg syndrome, see Rubella

Hallgren syndrome, see Usher syndrome

Heavy metals, see Ototoxic drugs and other substances

Hereditary factors causing deafness.

There is a good short discussion of the many factors causing deafness from various hereditary causes in EGDBD p.96-98.

Hereditary nephritis, see Alport syndrome

Hereditary progressive arthro-ophthalmopathy, see Stickler syndrome

Hereditary spinal ataxia, see Friedrich ataxia

Heredopathia atactica polyneuritoformis, see Refsum syndrome

Herpes simplex virus, type II

Acquired by the infant during birth if the mother is infected. Fatal in most cases, but survivors may have hearing loss. EDHD2 p.106.

Herpes zoster auricularis, see Hunt syndrome

HIV (Human Immunodeficiency Virus), see AIDS

Hunt syndrome

Also known as geniculate syndrome. Herpes zoster auricularis ("shingles") with associated facial paralysis; a viral infection of the nerves supplying certain areas of the skin. In some cases, intense pain in the region of the ear and mastoid process, paralysis of the facial nerve, hearing loss, vertigo and hyperacusia. Herpetic lesions over the mastoid process and around the external auditory canal and eardrum. EDHD p.168.

Hunter syndrome

Also called mucopolysaccharidosis 2 and MPS II. A genetic defect in the metabolism of the complex sugars; the enzyme iduronate sulphatase is lacking (see also Hurler syndrome, Morquio syndrome, and Sanfilippo syndrome). X-linked recessive, so affects males only. Two types of Hunter syndrome, one milder and less progressively downhill than the other. Signs and symptoms of this syndrome include normal appearance at birth except for possible noisy breathing and umbilical hernias, both common normal childhood syndromes and so not usually alarming. At around age 2, facial features become more coarse, erupting teeth are widely spaced, the boy's growth rate slows down, and joints become stiff. The liver and spleen become enlarged. Other complications can include meningitis (q.v.), which in turn frequently leads to deafness. Death usually occurs in the late teens or early twenties from cardiac or respiratory problems. DSID p.152-155; EGDBD p.225-226.

Hurler syndrome

Also called mucopolysaccharidosis 1-H, MPS I, or gargoylism. A genetic defect in the metabolism of the complex sugars; the enzyme alpha-L-iduronidase is lacking (see also Hunter syndrome, Morquio syndrome, and Sanfilippo syndrome). Affects both sexes equally and has been found in all races. Caused by a genetic defect inherited as an autosomal recessive. Appearance at birth is normal, though sometimes very large. From the early months of life, other symptoms begin to appear: coarsening of the facial features, noisy breathing

accompanied by a persistently blocked and runny nose, enlargement of the liver and spleen, stiffening of the joints, progressive blindness from clouding of the corneas, acquired mental retardation, and cardiac defects. Deafness also commonly occurs from the progressive accumulation of mucopolysaccharides. DSID p.156-159; EGDBD p.225.

Hyperbilirubinemia

A condition present at birth in which high levels of bilirubin damage the cochlear nuclei in the brainstem by deposition of pigment in the gray matter (kerniciterus). The pigment apparently impairs the functioning of the cochlear nerves, causing central nerve deafness. May result from various previous diseases, including Rh incompatibility disease (q.v.). GEDPD v.2 p.25; EDHD2 p.122.

Hypoxia, see Asphyxia at birth

Hysterical hearing loss, see Functional hearing loss

Immotile cilia syndrome, see Kartagener syndrome

Infantile Refsum disease

Not to be confused with "classical" Refsum disease (q.v.), which is actually a different condition. Like Refsum disease, it is a rare genetic disorder characterized by the body's inability to metabolize and rid itself of phytanic acid, which then accumulates to ototoxic levels. It differs in being a member of a group of genetic diseases called leukodystrophies. Symptoms may include eye problems such as retinitis pigmentosis and nystagmus, decrease in muscle tone, failure to thrive, developmental delays, poor muscle coordination, enlarged liver, low cholesterol level and facial abnormalities. EDHD2 p.178.

Jervell and Lange-Nielson syndrome

Congenital sensorineural deafness with ventricular fibrillation, causing fainting and sometimes death. Affects children of either sex with bilateral conduction type deafness, presenting in infancy or early childhood repeated attacks of syncope. Seizures may begin with a piercing scream followed by pallor and then cyanosis and loss of consciousness of short duration, followed by deep sleep. Attack may result in sudden death. An autosomal recessive inheritance (genes KVLT1 and KCNE1). GEDPD v.2 p.21; EGDBD p.187-188.

Johanson-Blizzard syndrome

Also known as ectodermal dysplasia-pancreatic insufficiency. A rare genetic condition probably inherited in an autosomal recessive way. Symptoms include unusually small and short nose, small upper jaw, and, sometimes, microcephaly. Teeth are small and widely spaced, and some may be absent altogether. Failure to thrive due to malabsorption of food from the pancreatic enzyme deficiency. Learning difficulties are also often present. Sensorineural deafness in some cases. DSID p.166-168.

Kartagener syndrome

Also known as Kartagener's triad (dextrocardia, bronchiectasis, and sinusitis) or immotile cilia syndrome. Onset in early infancy. Characterized by dyspnea, productive cough, recurrent respiratory infection, palpitation, otitis media, nasal speech and conductive hearing loss. No exact figures for numbers of victims, but possibly as many as 1 in 4000 births may be affected. Both sexes can be affected. DSID p.169-172; EGDBD p.190-191.

Kearns-Sayre syndrome (KSS)

A genetic (mitochondrial) condition that appears before the age of 20. Cardiac and neural abnormalities, ophthalmoplegia and retinal disease, often accompanied by short stature, mental retardation, ataxia, and sensorineural hearing loss. EGDBD p.221.

Kernicterus, see Hyperbilurbinemia

Klein-Waardenburg syndrome, see Waardenburg syndrome

Klippel-Feil syndrome

Also known as Klippel-Feil anomaly (or ...sequence or ...disorder), congenital brevicollis, or cervical fusion syndrome. Incidence rate is around 1 in 40,000 live births; approximately 60% of the victims are girls. Congenital ear dysplasia, combined with cleft palate, short neck, fusion of the cervical vertebrae, and abnormalities of the brain stem and cerebrellum. Either conductive or sensorineural deafness in a small proportion of cases. DSID p.176-178; EGDBD p.192.

Labyrinthine syndrome, see Ménière disease

Labyrinthitis

An inflammation of the labyrinth within the inner ear; also called otitis interna. Symptoms include nausea, vomiting, tinnitus, vertigo and deafness. Usually caused by either a bacterial or viral infection entering the inner ear from the middle ear. Infection can come from a cholesteatoma (q.v.), head trauma (q.v.), or contamination from a stapes operation or mastoidectomy. A possible complication is spread of the infection to the meninges, causing meningitis (q.v.). A form in infants caused by syphilis in the mother is called syphilitic labyrinthitis (see syphilis). EDHD2 p.123.

Laurence-Moon-Bardet-Biedl syndrome (LMBBS), see Bardet-Biedl syndrome

LEOPARD syndrome

Also known as multiple lentigines syndrome, multiple lentiginosis, or cardio-cutaneous syndrome. A very rare syndrome in which the prominent features are LEntigines (small dark-brown skin spots), Ocular defects, Pulmonary infundibular stenosis, Abnormal genitalia, growth Retardation, and Deafness. The name also reflects the small brown spots all over the face and skin, reminiscent of the markings of a leopard. Affects both sexes; about 1/4 to 1/3 of the cases also include congenital sensorineural deafness. Autosomal dominant inheritance. Lentigines may be present at birth or appear gradually over the first three or four years of life. DSID p.190-192; EGDBD p.229-230.

Lermoyez syndrome

A rare syndrome resembling Ménière disease. Increasing deafness and tinnitus, interrupted by sudden vertigo during which hearing improves.

Lobstein syndrome, see Osteogenesis imperfecta

Macular dystrophy, see Almaric syndrome

Mandibulofacial dystosis

Genetic condition caused by a mutation on gene TCOF1; incidence rate unknown, though recurrence in families throughout several generations has been recorded and studied. Characterized by coloboma or notch of the lower

eyelid, malformation of facial bones, low-set malformed external ears, atypical hair growth, occasional pits or clefts between the mouth and ear. Called Franceschetti syndrome if complete or near-complete, Treacher Collins syndrome if limited to orbit and malar areas. About half of Treacher Collins cases also have conductive hearing impairment from small and malformed external ears and auditory canal and/or an abnormally developed middle ear. DSID p.308-310; EGDBD p.313.

Mastoidectomy

This is surgical removal of an infected or damaged mastoid portion of the temporal bone, located behind the external ear. Most mastoidectomies do not in themselves result in hearing loss, but a form called a radical mastoidectomy removes the eardrum and most of the contents of a seriously infected middle ear, necessarily causing a permanent conductive hearing loss of up to 50 dB. EDHD2 p.131-132.

May-White syndrome

Progressive cerebellar ataxia, myoclonic seizures and sensorineural hearing loss.

Measles, see Roseola; Rubella

Ménière disease or Ménière syndrome

Inner ear disorder of unknown origin, affecting over 1 million Americans. Initial stages include unilateral hearing loss of the fluctuating inner ear type, affecting first only low tones, then both low and high. Tinnitus first low pitched, then high pitched tones. Sudden appearance of violent and often incapacitating vertigo. Cochlear Ménière disease is an atypical form in which the hearing impairment, dizziness and trinities are present, but not the vertigo. Vestibular Ménière disease causes the vertigo without the hearing loss. EDHD2 p.55, 133-135; EDHD p.121-122; GEDPD v.1 p.112, 344-345, v.2 p.30.

Meningitis

An inflammation of the outer membranes surrounding the brain and/or the spinal cord, usually from a bacterial infection and almost always a complication from another bacterial infection. Less commonly, meningitis can also be caused by a viral infection, though the viral form is normally mild and without permanent consequences. If bacterial meningitis is caught and treated early, the prognosis is good and complications rare; however, delayed treatment or no treatment can be very severe (70%-100% death rate if untreated). Prolonged inflammation may spread and suddenly destroy some nerve cells, including those associated with hearing (about 6% or more of child cases). About 15% of children deafened by meningitis also suffer mental retardation. EDHD2 p.135; EDHD p.122-123.

Mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS)

A genetic (mitochondrial) condition caused by a mutation and often characterized by short stature; approximately 30% of affected persons also have hearing loss. EGDBD p.221.

Mitochondrial syndromes-see

Kearns-Sayre syndrome Myoclonic epilepsy and ragged red fibers Mitochondrial encephalopathy Diabetes mellitius type II

Möbius syndrome or Möbius sequence

Also spelled Moebius.... Congenital facial diplegia (paralysis), usually associated with other neurological disorders, sometimes including deafness. EGDBD p.222.

Mohr syndrome, see Oral-facial-digital syndrome, type II

Mondini dysplasia

A developmental abnormality of the inner ear. Characterized by bony and membranous anomalies of the inner ear exhibiting a wide range of morphological and functional abnormalities. Severe forms show no hearing or vestibular response. EDHD2 p.140.

Mongolism, see Down syndrome

Mononucleosis

A viral infection that can cause sudden deafness in one ear.

Morquio syndrome

Also known as Morquio-Ullrich syndrome, Brailsford syndrome, or mucopolysaccharidosis 4. Autosomal recessive inheritance. Caused by a genetic defect in the metabolism of the complex sugars; the enzyme for metabolizing keratin sulfate is lacking (see also Hurler syndrome, Hunter syndrome, and Sanfilippo syndrome). Affects both sexes in about 1 out of 100,000 births. Normal appearance at birth, but onset begins in early childhood. Skeletal deformities accompanied by weak extremities and waddling gait. Absence of corneal capacity and typical "gargoyle" face and hepatosplenomegaly. Short stature, short neck, kyphosis, large swelling at the knee, clouding of the corneas, protruding abdomen. Deafness is common, resulting directly from the accumulation of the unmetabolized complex sugar involved. More severe cases usually die in their twenties, though those with the milder type of the syndrome have a longer life expectancy. DSID p.203-206; EGDBD p.226.

Mucopolysaccharidosis 1-H, see Hurler syndrome

Mucopolysaccharidosis 2, see Hunter sydrome

Mucopolysaccharidosis 3, see Sanfilippo syndrome

Mucopolysaccharidosis 4, see Morquio syndrome

Multiple lentigines syndrome, see LEOPARD syndrome

Multiple sclerosis (MS)

A chronic autoimmune disorder of unknown causes that destroys the myelin insulation covering the nerve fibers (neurons) in the brain and spinal chord. MS can cause permanent deafness if it affects the part of the brain that performs hearing. Most victims are female, and onset is usually between 20 and 40 years of age. Estimates of the population go as high as 1 in 1000 individuals in the U.S., as many as 250,000. How many of these are also deaf is not known. EGDBD p.230-231.

Mumps

A viral illness that is a common cause of severe one-sided deafness, usually sudden in onset but often not noticed for many days or even years before being identified. Usually occurring in childhood; destroys the inner ear, though without affecting the balance mechanism. EDHD2 p.141-142; EDHD p.129.

Muscular dystrophy

A group of hereditary disorders characterized by progressive muscle weakness and wasting. Most MD does not affect the ears or hearing, but one form, facio-scapulo-humeral dystrophy (the third most common form of MD) begins during the teens in the muscles of the face, shoulders and upper arms before spreading to the trunk and leg muscles. Hearing loss is one frequent consequence of this variation. EGDBD p.231-232.

Myoclonic epilepsy and ragged red fibers (MERRF)

A genetic (mitochondrial) condition characterized by myoclonus, epilepsy, and ataxia. Sensorineural deafness, blindness, and/or mental impairment often, though not always, occur. Arises as a result of mutations. EGDBD p.221.

Neurofibromatosis (NF)

Also called von Recklinghausen disease. An inherited developmental disorder of the nervous system, muscles, bones and skin, in which soft tumors (neurofibromas) and café-au-lait spots (flat, darkened skin areas) grow. NF type 2 (bilateral acoustic neurofibromatosis) is the more severe form. Its neurofibromas may cause various neurological, skeletal, endocrinal, and skin problems, and gradual deafness occurs in many NF type 2 victims by growing nodes on the hearing nerve. NF type 2 occurs in about 1 of 50,000 births. Present at birth, but symptoms generally appear during adolescence or in the 20s. 50% risk of passing NF on to a child. Autosomal dominant inheritance; the defective gene has been mapped to gene 22q. DSID p.211-215; EGDBD p.238-239.

Nicotine, see Smoking

Noise-induced hearing loss, see Acoustic trauma

Noonan syndrome

Low-set ears, antimongoloid slant to eyes, mental retardation, and stunted growth. In males, differentiation of male genitalia or complete absence or disappearance; in females, from normal sexual development to absent development and primary amenorrhea; occasionally, mild deafness. Symptoms are similar to that of Turner syndrome, though deafness, if present, is less severe in Noonan syndrome. DSID p.220-223.

Norrie disease

A rare X-linked genetic condition occurring only in males. Classic symptoms include various specific pathologies of the eye, including blindness; most affected patients also have mental retardation and many also have severe progressive sensorineural hearing loss that appears as they grow older. EGDBD p.243.

Oculoauriculoverteral dysplasia, see Goldenhar syndrome

Oculovestibuloauditory syndrome, see Cogan syndrome

Ondine's curse, see Congenital central hypoventilation syndrome

Oral-facial-digital syndrome, type II (OFD II)

OFD is a group of genetic disorders with varying origins and unknown basic cause; nine variants are recognized. They have in common deformities and anomalies of the mouth, face, fingers and toes. Of the nine variants, OFD II, an autosomal recessive trait also called Mohr syndrome, frequently includes deafness due to a defect in the incus (one of the middle ear bones). EGDBD p.246-247.

Ossicular interruption

A blow to the head, or an infection of the middle ear, can cause separation of two or all three ossicles (inner ear bones) that carry sound vibrations from the eardrum to the inner ear, causing a conductive deafness. The degree of separation determines the amount of hearing loss. This condition is readily correctible by surgery. EDHD2 p.160; EDHD p.146.

Osteitis deformans, see Paget disease

Osteogenesis imperfecta

Also called brittle bone disease or Lobstein syndrome. A rare genetic disease (3 to 4 cases per 100,000 live births), afflicting boys and girls equally; hereditary (autosomal dominant) plus some new mutations; four distinct types. A defect in the production of one of the precursors of collagen, a substance closely involved in skeletal makeup, causes the bones to be brittle and fragile. Hearing is sometimes impaired due to deformity in the middle ear bones. DSID p.227-230; EGDBD p.248-249.

Otitis externa

An infection of the outer ear canal, often occurring after swimming in dirty or heavily chlorinated water (hence the common name swimmer's ear). About 5 out of 10,000 people contract it; it is more common among diabetics and in individuals with immune systems weakened by diseases or medication. In more extreme cases, pus can block the ear, causing temporary conductive deafness. A much less-common extreme form is called malignant oititis externa, in which infection from the outer ear can spread, causing inflammation and eventual permanent damage to the bones and cartilage at the base of the skull and to the cranial nerves, the brain, or other parts of the body. EDHD2 p.129; EDHD p.180.

Otitis media

An infection of the middle ear, in which a buildup of fluid or pus can cause a conductive hearing impairment by muffling or immobilizing the middle ear bones and/or the eardrum. Deafness is usually not permanent unless chronic severe cases cause middle ear damage, resulting in the collapse of the eardrum and its adherence to the ossicles; this is known as adhesive otitis media. Serous otitis media, also called secretory otitis media or glue ear, is a form in which the middle ear fills with a thin and watery fluid which causes a conductive hearing loss. Although of unclear and possible multiple causes, serous otitis media is the most common current cause of hearing problems in childhood. It may arise from allergy or viral infection of the middle ear, barotrauma (q.v.), blockage of the eustachian tube, or use of antibiotics without adequate drainage to treat other forms of otitis media. A form characterized by thick fluid in the middle ear, damping the motions of the ossicles and eardrum, is called mucous otitis media. EDHD2 p.5, 141,160-161, 187.

Oto-palato-digital syndrome

A genetic disorder affecting only males (female carriers with both copies of the gene may show mild expression of the disorder, but never full OPD). Cleft palate and hearing loss combined with abnormalities of the thumbs and toes, frequently with mental impairment. Two forms, OPD-I (Taybi syndrome) and OPD-II (Andre syndrome) are distinguished from each other by their severity and mode of inheritance. OPD-1 is generally the milder form and is X-linked recessive. OPD-II is also X-linked and generally includes microcephaly, wide-set eyes and a small mouth, significant development delays, deformations of the fingers and bowing of the long leg

and forearm bones. Most OPD-II victims are stillborn or die before 5 months of age from respiratory problems. EGDBD p.249.

Otosclerosis

Also called otospongiosis. A disease in which spongy bone overgrows the stapes in the middle ear, immobilizing it and causing a conductive hearing loss. Usually bilateral, more common among women than men, and begins in early adulthood (between 20 and 30 years of age). A tendency to otosclerosis seems to be inherited as autosomal dominant (gene 15q, affecting 25 to 50% of those who inherit the gene), though apparently it is not genetic in all cases. Prevalence is 0.2 to 1% in whites (making it the single most common cause of hearing impairment), about one in 3,300 for blacks, and about one in 33,000 for Asians. The usual treatment is a stapedectomy. EDHD2 p.162-163; EDHD p.148-149; EGDBD p.249-250.

Otospongiosis, see Otosclerosis

Ototoxic drugs and other substances

Some drugs, chemicals and other substances can affect the function of the inner ear by poisoning the delicate hair cells and other nerve cells in that area, or by interfering with the proper development of the ear or hearing system. Damage may occur during fetal development or at any time after birth. A wide variety of drugs are known or believed to be damaging, either alone or in combination with others; the drug families involved include antibiotics, loop diuretics, excess use of salicylates (aspirins), and quinine derivatives. Most of these have permanent effects, though aspirin's and quinine's effects usually disappear within days after discontinuation of use. Aminoglycosides (kanaycin, neomycin, gentamicin, tobramycin and amikacin), streptomycin, and thalidomide have all also been implicated as casing ear malformation or deafness in fetuses. High levels of alcohol (see fetal alcohol syndrome), nicotine, and caffeine sometimes also produce deafness in fetuses and may cause temporary deafness in children and adults. The overuse of certain pain-relieving narcotics (hyocodone and acetaminophen) in combination is also known to cause a rapid and permanent total deafness. Ground contamination by heavy metals and related byproducts, in the vicinity of some mines, has also been blamed for hearing loss in children growing up in those areas. EDHD2 p.17-18, 127-128, 143, 163-165, 172, 175; EDHD p.155-156.

Paget disease

Also called osteitis deformans. A common genetic disease usually appearing in middle age. It weakens the bones of the skull, pelvis, collarbone, and long bones of the leg. Changes in the skull can cause distortion and damage to the inner ear, resulting in tinnitus, vertigo, and sensorineural hearing loss. EDHD2 p.167; EDHD p.151.

Patau syndrome, see Trisomy 13 syndrome

Pendred syndrome

A genetic condition (on the PDS gene), characterized by congenital sensorineural deafness with familial goiter (enlarged thyroid gland). Affects both sexes equally. Various degrees of bilateral deafness from birth (perceptive in type, in some cases associated with defective vestibular function), more complete loss for high than low tones. Autosomal recessive inheritance. Prevalence estimated at between 1 in 12,500 and 1 in 100,000 live births. EDHD2 p.167-168; EDHD p.152; GEDPD v.2 p.21; EGDBD p.255.

Perforated eardrum

A hole, tear or rupture of the eardrum causes a conductive hearing loss. The perforation can be from a variety of causes, including rupture from otitis media (q.v.), barotrauma (q.v.), skull fracture (see temporal bone

fracture) or other physical traumas (q.v.), the insertion of sharp or narrow objects into the ear canal, growth of a tumor, etc. EDHD2 p.69.

Peroneal muscular atrophy, see Charcot-Marie-Tooth disease

"Poisoned blood", see Toxemia

Premature birth

Approximately 5% of prematurely born infants have sensorineural hearing loss due to an abnormally short gestational period. GEDPD v.2 p.25.

Presbycusis

A type of sensorineural hearing loss usually found among older people, starting usually after age 50; it affects over 10 million Americans. The cochlea begins to lose nerve cells, especially those that respond to high-frequency sounds and then progressing to middle and eventually lower frequencies. It is not clear how much of this loss is from physiological aging, and how much from cumulative exposure to noise throughout the person's life. Approximately one in three persons over age 65 have presbycusis, rising to nearly one in two persons over age 75. EDHD2 p.6-7, 173; EDHD p.4-5, 156-157.

Psychogenic hearing loss, see Functional hearing loss

Ramsay Hunt syndrome, see Hunt syndrome

Recessive spinocerebellar degeneration, see Friedrich ataxia

Refsum syndrome or Refsum disease

Also known as heredopathia atactica polyneuritoformis. This rare genetic condition develops between ages 4 to 7. It is caused by a defect in catabolism of phytanic acid in the diet. Phytanic acid is normally excreted harmlessly, but if it builds up in the body, it becomes ototoxic. Children develop this rare genetic condition between ages 4 and 7. Progressive sensorineural deafness, concentric constriction of visual fields, night blindness, chronic polyneuropathy involving motor and sensory nerves, cerebellar ataxia, loss of sense of smell. Autosomal recessive inheritance, on chromosome 10. Infantile Refsum disease (q.v.) is actually a different condition. EDHD2 p.177-178; EGDBD p.277-278.

Retinitis pigmentosa, see Usher Syndrome

Retracted eardrum

During head colds, allergy attacks, or infections in the back of the nose and throat, the eustachian tube is forced closed so that no air can enter the middle ear. When the air pressure inside the middle ear then drops relative to the pressure in the external ear canal, the eardrum gets pressed into the inner ear. In extreme cases, the flexed eardrum can push aside the ossicles or even touch the cochlea, causing varying degrees of conductive hearing loss. EDHD2 p.179-180.

Retrocochlear lesion

A lesion located on the auditory nerve itself can cause a sensorineural hearing impairment. EDHD2 p.180.

Rh incompatibility disease

Also called Rh factor incompatibility and erythroblastosis fetalis. If a pregnant mother has an Rh negative blood type, and the fetus has an Rh positive blood type, and if any fetal blood cells cross the placental wall into the mother's blood stream, her body will react by manufacturing antibodies against the fetus' blood. This is not a problem for first pregnancies, but later pregnancies may be affected by the antibodies remaining in the mother's blood from the first one. If those antibodies cross the placental wall in the other direction, they may attack the fetus' blood, causing fetal anemia. Rh incompatibility disease does not directly cause deafness, but afflicted babies who survive pregnancy may develop kernicterus (see hyperbilurbinemia), which in turn can lead to cerebral palsy, mental retardation, speech problems, and/or deafness. EDHD2 p.180; EGDBD p.161.

Roseola infantum

Also called sixth disease (obsolete), exanthema infantum or exanthema subitum. This type of measles often causes permanent sensorineural deafness due to persistent high fever temperatures that damage the hair cells in the cochlea. As its name implies, it usually strikes infants. Its immediate cause is human herpesvirus 6. EDHD2 p.132-133.

Rubella

Also known as Gregg syndrome and popularly called German measles. Affects primarily newborns from mothers exposed to the rubella virus during the first trimester of pregnancy, but can occur in either of the other two trimesters, and indeed after birth at any age. Not the measles itself but rather complications from it, including ear infections and encephalitis (q.v.), are responsible for causing deafness in many victims. Symptoms in infants and young children include hepatosplenomegaly, instetitial pneumonia, congenital heart defects, low birth weight, congenital cataracts, purpura, hearing loss (in the cochlea), inguinal hernias, mental retardation, and failure to thrive. Hearing loss affects up to 50 percent of exposed infants. Rubella used to run in minor epidemic cycles 6-9 years apart and major cycles approximately every 20-30 years. The last major epidemic was in 1964-1965, causing nearly 12,000 infants to be born deaf. The 1969 development of an effective rubella vaccine has stopped all major epidemics, though limited outbreaks still occur in settings where large groups of unvaccinated individuals are in close contact with each other, such as schools. EDHD2 p.132-133, 181; GEDPD v.2 p.23; EGDBD p.311.

Saethre-Chotzen syndrome

A form of craniosynostosis, a group of disorders caused by premature closing of the sutures separating the cranial bones, causing an abnormal shape of the skull. Typical characteristics evident at birth include lopsided face, wide-set eyes, beaked nose, low hairline, digital abnormalities, ears low-set and rotated somewhat backward, and sometimes mild to moderate mental retardation. Vision problems and mild hearing loss may also be present. Autosomal dominant inheritance from a gene located on 7p. New mutations may also occur, attributed to increased paternal age. EGDBD p.286.

Sanfilippo syndrome

Also known as mucopolysaccharidosis 3. A genetic defect in the metabolism of the complex sugars; an enzyme is lacking (see also Hurler syndrome, Morquio syndrome, and Hunter syndrome). About 1 in 25,000 live births are affected, both sexes equally. An autosomal recessive genetic defect with four identified subtypes, Sanfilippo A being most common. Symptoms are normal at birth, but at age 2 or 3, or even later, a rapid mental and physical decline become apparent, plus stiffening of the joints, coarsening of facial features and enlargement of the head. Conductive deafness may show up later in childhood, probably caused by the repeated upper respiratory tract infections that are also characteristic of this syndrome. Life expectancy is low, usually ending before age 20. DSID p.259-261; EGDBD p.226.

Scarlet fever

Also called scarletina. An acute infectious disease caused by streptococcus bacteria. Deafness may arise from complications that include sinus infections, followed by abscesses of the ear and then mastoiditis. Symptoms arise 2-7 days after exposure, and include fever, sore throat, headache, and (in children) vomiting. 2-3 days later, a rash appears in the neck, armpit, groin and chest, plus red spots on the tongue. Once common, scarlet fever is not often seen any more in the U.S. EDHD2 p.183.

Schinzel-Gideon syndrome

A collection of birth anomalies involving the kidneys, heart, brain and skeleton, accompanied by a characteristic flat face. Short lower limbs, nose is short and low, eyes wide-set, and ears low-set, frequently with hearing, vision and mental difficulties. EGDBD p.287.

Shingles, see Hunt syndrome

Sinusitis

An inflammation of the lining of the sinuses (air chambers in the facial bones around the nose). It can cause a temporary conductive hearing loss if it causes swelling of the eustachian tube, the blockage of which then interferes with the functioning of the middle ear. EDHD2 p.192.

Sixth disease, see Roseola infantum

Smoking

Nicotine is known to constrict blood vessels in smokers, which in the long term can cause degeneration of some delicate tissues, including those in and around the ear. In addition to tinnitus and hearing loss, studies indicate that nicotine is connected with a higher failure rate following myringoplasty (a surgical reconstruction of the eardrum made necessary by other causes). Other research shows an increased risk of ear infections in the children of women who smoked while pregnant, up to three times the rate of children whose mothers did not smoke. The chances of the children having to undergo ear surgery before age 5 are also tripled. EDHD2 p.151, 193.

Spinal meningitis, see Meningitis

Spondyloepiphyseal dysplasia

A form of short-trunk dwarfism that has three forms. In all forms, the cartilage of the vertebrae is gradually replaced by bone as the infant develops and grows, stopping the growth of the spine. Mutations in the gene for type II collagen, COL2A on 12q. S.d. congenita is present at birth, inherited as an autosomal dominant trait. Lack of muscle tone, flat face, "floppy infant" appearance, possibly cleft palate, clubfoot, vision impairment and/or a moderate hearing loss. S.d. tarda is a delayed form appearing only in males, and appears in autosomal recessive and a rare autosomal dominant form, both X-linked. Hunched shoulders, enlarged chest, osteoarthritis of the spine and hip bones, but usually no deafness. EGDBD p.296-297.

Stickler syndrome

Also known as hereditary progressive arthro-ophthalmopathy. An autosomal dominant genetic disease caused by mutations on genes COL2A1, COL11A2, or COL11A1 (chromosome 12). Symptoms include progressive myopia, vitreoretinal degeneration, premature joint degeneration, cleft palate deformity, and sometimes variable sensorineural hearing loss. DSID p.289-291; EGDBD p.298-299.

Strokes

May cause permanent deafness by damaging the part of the brain that performs hearing.

Surdocardiac syndrome, see Jervell and Lange-Nielson syndrome

Swimmer's ear, see Otitis externa

Syphilis

Many pregnant women having this disease transmit it to their fetuses, and about a third of the infected children will eventually become deaf. The disease affects the neural portion of the auditory system, but the hearing loss usually does not manifest itself until well into childhood or even in adulthood. If syphilis is contracted in adulthood, deafness from untreated syphilis appears gradually, either as a hearing loss or as a fluctuation in hearing intensity. Rarely, congenital syphilis can also cause syphilitic labyrinthitis, which often results in a sudden, flat sensorineural deafness, or a sudden, increasingly fluctuating sensorineural deafness. EDHD2 p.199; GEDPD v.2 p.23; EDHD p.181; EGDBD p.302.

Systemic infections

Many infections, such as measles, scarlet fever, tuberculosis, and typhoid fever can cause a bilateral sensorineural deafness.

Taybi syndrome, see Oto-palato-digital syndrome

Temporal bone fracture

A type of head trauma with skull fracture involving the two temporal bones, often damaging the middle ear and causing a conductive hearing loss. If the fracture is traverse, it can also injure the inner ear or internal auditory meatus, causing a sensorineural hearing loss, vertigo, tinnitus, and facial nerve paralysis. See also Trauma. EDHD2 p.204; EDHD p.184.

Temporomandibular joint syndrome (TMJ)

Believed to be caused by improper function of the jaw joints and their muscles and ligaments. Symptoms include severe pain in the jaw, face, and head, especially around the ears; clicking or popping in the jaw and ears; "locking" of the jaws, and pain in opening the mouth. Hearing loss often also occurs, apparently from muscle spasms including the muscles of the middle ear. Hearing usually returns after treatment of the TMJ.

Thyroid disorders

Deafness is associated with three types of thyroid disorders: Pendred syndrome (q.v.), adult myxedema and endemic cretinism. However, the causal link between the hearing deficit and the thyroid disorder has not been established. EGDBD p.255.

Tinnitus-Deafness-Vertigo syndrome, see Lermoyez syndrome

Toxemia

In mainstream medicine, toxemia is the presence of excess toxic bacterial products in the bloodstream. In "alternate medicine" and in much quackery, toxemia is equated to "poisoned blood" and blamed for a very wide

variety of ailments, including deafness. However, mainstream medicine rarely, if ever, accepts toxemia as a cause of deafness.

Toxoplasmosis

A parasitic infection that hits about 0.2% of pregnant women; a third of these pass it on to their infants, and a small percentage of infected infants have hearing loss. Infection commonly occurs from pregnant women eating or handling raw meat, or from coming in contact with the feces of infected cats. Outdoor cats that hunt are more likely to have the infection; the risk from cats kept strictly indoors and fed regular cat food is low. EDHD2 p.208; GEDPD v.2 p.23; EDHD p.188; EGDBD p.310-311.

Townes-Brock syndrome

Autosomal dominant trait, first described in 1972, caused by a mutation in the SALL1 gene on 16q. Over 50 cases reported; symptoms include an imperforate anus, malformed ears, and mental retardation; most cases also have malformation of the thumb and other digits, and mild to moderate deafness. EGDBD p.312-313.

Trauma

Trauma is any physical damage caused by a physical blow or impact, as from a serious fall, automobile accident, gunshot wound, etc. Deafness may result from damage to the eardrum, inner ear mechanism, and/or nerves. Its permanence or temporariness depends on the extent of injury, what is damaged, the medical attention given, age, and a variety of other factors. For example, a ruptured eardrum will usually heal, but damage to the inner ear bones is usually irreversible. See also Acoustic trauma and Temporal bone fracture. EDHD2 p.97-98, 138.

Treacher Collins syndrome¸ see Mandibulofacial dystosis

Trigeminal nerve abnormality

A developmental abnormality of the fifth cranial nerve, which divides into three branches, responsible for supplying sensation from the face, scalp, nose, teeth, mouth lining, upper eyelid, sinuses, and the front part of the tongue. Abnormalities of this nerve are often associated with malformation of the ear, and up to 60% of that population has a sensorineural hearing loss. EDHD p.188.

Trisomy 13 syndrome

Also called Patau syndrome. Caused by the presence of an extra chromosome 13. Severe mental retardation, microcephaly, polydactyly, cleft lip or palate; over 30 signs in all. Infants are blind and deaf. Usually fatal within weeks or months; in rare cases they may survive past 3 years. EGDBD p.252-253; EGDBD p.252-253.

Trisomy 21 syndrome, see Down syndrome

Trisomy D1 syndrome, see Trisomy 13 syndrome

Tumors

Middle ear tumors, which are rare and can be either malignant or benign, cause conductive hearing loss by blocking the middle ear and auditory canal, destroying the ossicles, and/or interfering with the eardrum. Malignant tumors may also protrude into the inner ear and cause an sensorineural hearing impairment. The most common types of malignant tumors found are squamous cell carcinoma (especially in middle age) and globus

tumor. Symptoms, especially in women, may include tinnitus, vertigo, and facial paralysis. Also see Choristoma. For tumors that form on hearing-related nerves, see Neurofibramatosis. EDHD2 p.139, 208-209; EDHD p.189.

Turner syndrome

Also known as chromosome 45/X syndrome or Ullrich-Turner syndrome. A sex-linked genetic disorder that affects only females. In Turner syndrome, about 1 out of every 2500 live female births have a missing X chromosome, leaving only 45 chromosomes instead of the usual 46. Characteristic symptoms include short stature, infertility, heart and eye problems, and others; girls with this syndrome often have frequent otitis media (q.v.), which can lead to a conductive hearing loss. DSID p.314-318; EGDBD p.316-317.

Tympanosclerosis

A chronic middle ear infection can cause the growth of new bony tissue along the lining of the middle ear. If this calcification occurs on the tympanum (eardrum), it can cause conductive deafness. EDHD2 p.210.

Typhoid fever

An infectious disease spread through food or water contaminated by contact with food handled by an infected person, flies, or feces from infected persons. This carries the bacterium Salmonella typhosis, which passes from the victim's intestines into the blood, then the spleen and liver, eventually accumulating in the gall bladder until re-released into the intestine. Symptoms include a mild headache, fever, loss of appetite and malaise, sometimes accompanied by delirium. Constipation develops, then changes to diarrhea; during the second week of illness, a rash appears on the chest and abdomen. Complications sometimes include a sensorineural hearing loss. EDHD2 p.210.

Ullrich-Turner syndrome, see Turner syndrome

Usher syndrome

A genetic condition consisting of congenital hearing impairment plus progressive retinitis pigmentosa. Prevalences vary; the worldwide average seems to be about 5 in every 100,000, but much higher incidences are known in Finland, Norway, and parts of the U.S. In the U.S., the average is between one in 15,000 and one in 30,000 live births, accounting for 3% to 6% of all American deaf children and possibly an equivalent percentage of hard of hearing children. Males and females are affected in equal numbers. Genes involved are MYO7A, USH2A, and several others still unidentified. Inheritance is autosomal recessive. 90% of Usher syndrome victims are born with sensorineural deafness. Classified into three types: Type I has congenital profound hearing loss, no vestibular response, and onset in the first decade. Type II exhibits a sloping audiogram for congenital hearing loss plus normal vestibular response and onset in first or second decade. Type III has progressive hearing loss, variable vestibular response, and onset is variable. General characteristics of all type include family history of poor night vision, blue-green color blindness, or total blindness. During childhood, progressive hearing loss (evident at age 4-6) and secondary lack of speech development. Usually a few years later (average age 9), progressive poor night vision, degeneration of peripheral visual fields, tunnel vision, blindness. Profound degrees of deafness and blindness develop by early adulthood. A few cases of Usher syndrome occur with mental instability and/or mental retardation and are termed Hallgren syndrome. DSID p.319-322; EDHD p.192; GEDPD v.1 p.237-238; EGDBD p.321-322.

Van der Hoeve syndrome

Also called Adair-Dighton syndrome. About half of patients with osteogeneis imperfecta, a bone disorder causing the entire skeleton to have brittle bones that may fracture before or during birth and postnatally following minor trauma, plus short stature, also have van der Hoeve syndrome. This adds blue sclera (a blue

tinge to the whites of the eyes) and conductive hearing loss to the symptoms. Bilateral deafness starts at about age 20 due to otosclerosis. Onset of manifestations apparent at birth or early childhood. EDHD2 p.160.

Varicella zoster

A common and mild childhood infectious viral disease; its outward symptoms are commonly called chicken pox. After recovery, the victim has lifelong immunity to a reoccurrence, but the virus remains dormant and may erupt in later life as herpes zoster (see Hunt syndrome). Children with varicella zoster usually have only a slight fever and are generally left unharmed, but adults may become very ill, with complications including encephalitis (q.v.) which can lead to deafness, usually just in one ear. Women in late pregnancy are particularly vulnerable and may pass on the disease to their infants, who may have severe cases. EDHD2 p.45; EDHD p.43; EGDBD p.323-324.

Venereal disease, see

Chlamydia Syphilis

Von Recklinghausen disease, see Neurofibromatosis

Waardenburg syndrome

Genetic (known genes involved are PAX3, MITF, EDNRB, EDN3, and SOX10); no sex preference and reported in all ethnological groups. Autosomal dominant inheritance, though in a few families having a specific variant of the syndrome, inheritance appears to be recessive. Occurs in between 1 in every 20,000 and 1 in every 40,000 live births. No sex preference and reported in all ethnological groups. Among children who are deaf from birth, 3 in every 100 have Waardenburg syndrome. Sensorineural deafness is present from birth in 20%, 25%, or up to 50% of cases (sources differ). Divided into two types (I and II) based on the presence (Type I) or absence (Type II) of dystopia canthorum. Type I combined with upper limb abnormalities is called WS Type III or Klein-Waardenburg syndrome, and Type II plus Hirschsprung disease is called WS Type IV or Waardenburg-Shah syndrome. Visible characteristics of WS include a white forelock in most cases, and smaller number of cases may show different color in each eye, a small nose, and/or confluent eyebrows. DSID p.328-331; EDHD2 p.219; EDHD p.195; GEDPD v.2 p.22; EGDBD p.328-329.

Wildervanck syndrome

Consists of the Klippel-Feil deformity of the spine with eyeball retraction, lateral gaze, weakness, and hearing loss. Short neck and paralysis of external ocular muscles. Conductive hearing loss, as well as the more frequently occurring sensorineural hearing loss, is caused by dysplasia of the inner ear. Occurs mostly in females. GEDPD v.2 p.23.

Wolfram syndrome 1

Identified in 2001 as a genetic cause of hereditary low-frequency hearing loss.

Wounds, see Trauma