Key Terms


Aicardi Syndrome – A rare genetic disorder that is characterized by the absence of the corpus callosum, (a part of the brain that sits between the right and left sides of the brain and allows the right side to communicate with the left). There can be infantile spasms, mental retardation, lesions of the retina of the eye, (very specific to this disorder), microcephaly or proencephalic cysts can accompany this disorder. Affects females only, (X-linked). Children usually identified with this syndrome between the ages of three and five months.

Alport Syndrome – It is characterized by hereditary nephritis,(kidney disease, also known as Bright’s disease) and sensorineural hearing loss. The mode of inheritance may be X-linked or autosomal dominant. Symptoms may include a defect of the lens of the eye called anterior lenticonus and a defect of blood platelets that can cause bleeding complications. Males are affected more severely than females, (even though the inheritance is X-linked). It is usually diagnosed by a test for blood and protien in the urine, hearing tests, and an extended family history.

Cockayne Syndrome – This syndrome is a rare autosomal recessive disorder characterized by growth retardation, photosensitive dermatitis, microcephaly, deafness, pigmentary degeneration of the retina, disproportionately long limbs, skeletal malformations with knee contractures, and neurological abnormalities.

Down Syndrome – A syndrome caused by chromosomal abnormalities that develop during egg and sperm cell formation. Approximately one out of every 800 babies born in the United States has Downs Syndrome,(Petrakis, 1990). 94% of individuals with Down Syndrome have it as a result of Trisomy 21. Which means there are three number 21 chromosomes, which makes a total of 47 chromosomes instead of the normal 46. Characteristics of individuals with Down Syndrome vary considerably. Characteristics can include: Mild to profound mental retardation, delayed physical development, reduced muscle strength and tone, congenital heart defects, poorly developed digestive tracts and immune systems, significant vision and hearing impairments, stocky build, and low set ears.

Goldenhar Syndrome – This inherited condition has an incidence rate of one in every 5,600 births. It is characterized by irregular facial structure and features (usually only one side of the face is affected), eye and ear abnormalities, congenital spinal column irregularities, cleft lip, cleft palate, congenital heart and kidney disease, mild mental retardation possible if any retardation exists, a skin fold located on the lower corner of the eyeball, irregular curving of the cornea and/or lens, coloboma, reduced size of the bony structure which holds the eye (orbit), nystagmus, strabismus, and possible retinal detachment. Approximately 55% of individuals with Goldenhar Syndrome have a hearing loss, most likely conductive, but in rare cases, can be sensorineural.

Stickler Syndrome/Marshall Syndrome – These are genetic disorders of the connective tissue, ( a substance that holds other tissues together) which can cause hearing loss. The three most common areas affected are the eyes, joints, and orofacial structures. These two syndromes closely resemble each other: in fact they are so similar, some say they are the same.

The characteristics may include; myopia, cataracts, detached retina, hyperextensibility and arthritis, cleft palate, flat midface, unusually large eyes, sensorineural hearing loss, and conductive losses due to otitis media.

These syndromes have an autosomal dominant pattern of inheritance, (there is a 50% chance of passing on the gene with each pregnancy).

Trisomy 13 – A genetic disorder where there is an extra chromosome 13 present. This occurs in approximately one in every 8,000 live births, (Batshaw & Peret, 1992). The characteristics are; small at birth and experience apnea (interrupted breathing), incomplete development of the brain and central nervous system, microcephaly, congenital heart defects, extra fingers and/or toes, small eyes, cleft lip or palate, the ears are irregularly shaped and low set which may cause a hearing loss, there may be degeneration of the cochlea, (the organ of Corti may be absent), structural irregularities of the eyes may cause vision loss; small underdeveloped eyes, coloboma( key shaped opening of the iris), abnormally developed retina, cataracts, corneal opacities (clouding), and defective development of the optic nerve.

Trisomy 18 – A genetic disorder in which there is a third chromosome 18. This occurs in approximately one in every 6,600 births, (Batshaw & Perret, 1992).The most common characteristics include; mental retardation, growth deficiencies, craniofacial abnormalities, congenital heart defects, deafness (may be due to abnormally narrow ear canals, low set ears, malformed outer ears), cataracts, abnormally small eyes, nystagmus, glaucoma, degeneration of the retina, deterioration of the optic nerve, strabismus, hernias, clenched hands, excessive hair growth, short sternums, underdeveloped skeletal muscles, and a failure to thrive.

Usher Syndrome – An inherited condition characterized by congenital hearing loss and progressive visual impairment due to retinitis pigmentosa, (a disorder which gradually damages the cells in the retina and results in the gradual loss of peripheral vision). There are several types of Usher Syndrome, (Types I-IV). However, 99% of all individuals with Usher Syndrome have either Type I or Type II. Individuals with Type I Usher Syndrome typically have profound congenital deafness, retinitis pigmentosa, and absent vestibular responses (balance). Individuals with Type II Usher Syndrome typically have a moderate to severe hearing loss, retinitis pigmentosa, and normal vestibular responses. This is a recessive inheritant. Both parents must carry the gene in order for the syndrome to be passed on to their children. There is a one in four chance a child will develop Usher Syndrome and a one in two chance the child will be a carrier of the gene.

Multiple Congenital Anomalies

CHARGE Association – CHARGE is an acronym in which each letter stands for an associated condition:

C- Coloboma (a lack of normal fusion in the structures of the eye,

usually seen as a notch or keyhole opening in the iris)

H- Heart defects ( defects may vary from a murmur to serious

structural abnormalities)

A - Atresia choanae (a blockage of the nasal passages from the back of

the nose to the throat)

R- Retarded growth ( mental retardation is common, but some

individuals can have normal cognition)

G- Genital anomalies (genitals may be incomplete or underdeveloped,

usually hormone deficiencies exist)

E- Ear anomalies or deafness (losses range from mild to profound and

can be conductive, sensorineural, or mixed)

This cluster of associated conditions was first noted as one of 25 most common multiple congenital anomalies in 1981 (Hall, 1981). The exact cause of CHARGE is unknown. Possibly an agent crosses the placenta, such as alcohol, thalidomide, or the rubella virus. These substances affect the embryo during the third to seventh week of gestation; the period during which all organs develop that are affected by CHARGE.

Fetal Alcohol Syndrome – The alcohol consumed by the mother passes through the placenta. The fetus is unable to metabolize the alcohol resulting in impaired cellular growth and development. The impaired growth in the developing fetal central nervous system is responsible for the defects. Characteristics of Fetal Alcohol Syndrome include retarded growth, mental retardation, central nervous system defects, skeletal abnormalities, heart problems, low birth weight, tremors in the hands and feet, strabismus, myopia, ptosis (droopy eyelids), structural deformities which may contribute to a conductive hearing loss, cleft palate and/or lip, misshapen outer ears, and eustachian tube dysfunction.

Hydrocephaly - Individuals with hydrocephaly have an enlarged head and a small face, mouth, and chin. It affects the circulation of the cerebral spinal fluid in the cavaties of the brain. A block in the circulation results in increased intraventricular pressure. The extent of the blockage as well as the success of the treatment will determine the amount of damage to the brain. Hydrocephaly may be inherited or the result of maternal intoxications or infections. Other characteristics may be seizures, cleft lip and palate, heart and kidney problems. vision and hearing impairments, strabismus, and optic nerve atrophy. If left untreated, it may result in mental retardation.

Microcephaly – Microcephaly is a symptom usually found in association with other disorders. It is characterized by poor growth of the entire brain and an abnormally small head (more than 2 deviations from the normal circumference). It can be caused by something genetic, congenital, birth trauma, brain disorders, or environmental factors, such as exposure to radiation or severe malnutrition. There may be a seizure disorder, motor difficulties, severe mental retardation, visual conditions such as retinitis (inflammation of the retina), nystagmus (rapid eye movement), and strabismus (crossing eyes). Hearing impairments may be the result of disorders associated with microcephaly, such as Trisomy 13 and Trisomy 18.


Retinopathy of Prematurity – This is a common complication of prematurity. Retinopathy of Prematurity (ROP) is an eye disorder in which the blood vessels in the retina stop growing normally and begin to branch excessively. This causes the development of scar tissue which may eventually pull the retina off the inner wall of the eye. In the most serious stages, there may be partial or complete retinal detachment. ROP affects both eyes, though one might be more damaged than the other. It occurs frequently in premature infants whose blood vessels have not had time to fully develop. Other factors that can contribute to ROP include excessive oxygen therapy, blood transfusions, apnea, infections, prenatal complications, and genetic factors. The survival rate for premature babies has improved greatly, which has resulted in more infants with ROP. Often, these premature babies also have auditory losses at birth. Other problems associated with ROP include strabismus, macular distortions, glaucoma, and nearsightedness.

Congenital Prenatal Dysfunction

AIDS – Acquired Immune Deficiency Syndrome (AIDS) is a disease which is caused by the virus, Human Immunodeficiency Virus (HIV), which attacks the body’s immune system leaving a person vulnerable to infections. If a pregnant woman is infected with the HIV virus, it can be transmitted across the placenta to the fetus during the birth process, and in rare cases, breast milk. Although there is no conclusive evidence that AIDS virus has a direct affect on vision and hearing, there is a risk the virus can cross the placenta and act as a teratogen on the developing fetus. If this occurs during the critical period of development for eyes and ears (4 to 9 weeks gestation), vision and hearing impairments can occur. Because of the susceptibility to infections, these infections can occur; toxoplasmosis, meningitis, encephalitis, and cytomegalovirus.

Herpes - This virus can be transmitted to the infant through contact with active genital herpes during the birth process. The greatest risk to the infant is when a mother has an active herpes infection shortly before delivery, but the infection can also be passed to infants whose mothers show no symptoms. The incidence of herpes in infants is approximately one in 7,500 births, (Batshaw & Perret, 1992). An infected infant may not show symptoms until 5 to 9 days after birth. Infants may develop both vision and hearing impairments. Vision impairments may include; underdeveloped or small eyes, cataracts, optic atrophy, and corneal scarring from retinal hemorrhages. Hearing impairments in infants infected with herpes are usually high frequency sensorineural losses.

Cytomegalovirus – (CMV) It is a viral infection, and may be transmitted through the placenta or passed to the infant through an infected birth canal. It is the most common congenital infection with an incidence of 20 per 1000 live births. Approximately 90% of newborns with CMV have no symptoms at birth. However, some of these infants will develop diseases of the retina, deafness, and developmental delays. The remaining 10% of infants will be born with symptoms such as low birth weight, jaundice, rash, anemia, an enlarged liver and spleen, and encephalitis. Infants with CMV may have vision loss as a result of inflammation of the choroid and retina. Infants with CMV may also develop sensorineural hearing losses due to chronic infections of the inner ear.

Toxoplasmosis – This is an infection transmitted through the ingestion of raw, poorly cooked, or infected meat, as well as direct or indirect contact with animal feces. The organism crosses the placenta causing the congenital infection. Depending on what trimester the maternal infection occurs, will depend on the severity of the damage from infection. The most severe damage to the infant occurs in the first trimester. Toxoplasmosis is the second most common congenital infection, occurring in one in every 1,000 live births. A severely infected fetus may have intruterine growth retardation, microcephaly, hydrocephaly, jaundice, and fever. Sometimes, the infant may appear normal at birth, but later develop conditions such as; mental retardation, seizures, choroidoretinitis, and sensorineural hearing loss. Vision loss occurs in 75% of severely infected infants. Cataracts, nystagmus, and strabismus have also been reported. Interestingly enough, sensorineural hearing losses related to Toxoplasmosis develop later in life, and typically high frequency losses.

Congenital Rubella – A viral infection that may be transmitted to the infant through the placenta. It is usually found in infants whose mothers were infected with the virus immediately before conception or during the first 17 weeks of gestation. In most cases of congenital rubella, symptoms appear at birth. The most common characteristics include; hearing loss, vision problems, heart disease, and mental retardation. Other problems that might occur; low birth weight, poor bone development, enlarged liver and spleen, microcephaly, behavior disorders, jaundice, and anemia. The most common vision problems are cataracts and glaucoma.

Syphilis – This is a sexually transmitted infection. If left untreated, the infection in the mother may be transmitted to the fetus, usually after the 16th week of gestation. Congenital syphilis causes death in as many as 50% of all cases left untreated. Approximately 25% of those surviving show early symptoms which include; anemia, pneumonia, fever, lesions, mucous membrane patches, loss of hair, nail exfoliation, and bone inflammations. The remaining 75% may show no symptoms at birth, but later may show abnormalities of the teeth, skeleton, central nervous system, blindness, mental retardation, and deafness.

Post-Natal Causes

Asphyxia – This occurs when the blood supply does not receive enough oxygen leading to a loss of consciousness, and possible death or brain damage. Asphyxia may be caused by anything that cuts off the oxygen supply such as a collapsed or twisted umbilical cord, an obstructed airway, or prolonged labor. It can occur before, during, and after birth. Over half of infants suffering from asphyxia do not survive. Of the survivors, there may be damage to the central nervous system and widespread injuries to the organs. The organ systems that may be affected include the brain, lungs, cardiovascular, renal, gastrointestinal, blood, and metabolic systems. Asphyxia also may cause cerebral palsy. Asphyxia appears to be a leading cause of hearing loss. The hearing impairment is a sensorineural loss resulting from damage to the cochlea.

Encephalitis – Is an infection that affects the brain. It is caused by a virus. The most common viruses responsible for encephalitis include mumps, rabies, and herpes simplex viruses, along with 60 other viruses which are carried by ticks and mosquitoes. Encephalitis may also occur following an infectious disease such as measles or after a vaccination. Individuals with encephalitis may have visual impairments due to permanent neurological damage. Vision loss may be attributed to optic atrophy caused by a lesion either in the nerve or the central nervous system. Encephalitis may also cause hearing loss. The loss is sensorineural and may be either in one or both ears.

Meningitis – Meningitis is a potentially fatal inflammation of the membranes covering the brain and spinal cord. Meningitis may result from infections caused by bacteria and viral agents. The meningitis caused by viral agents is not usually serious, but bacterial meningitis may be life threatening. Meningitis is the most common cause of hearing loss in children. The loss results from damage to the cochlea. It is considered a sensorineural loss and is usually severe to profound.


        Batshaw, M. & Perret, Y. (1992). Children with disabilities: A medical primer (3rd ed.). Baltimore, MD: Paul Brookes Pub. Co.

        Hall, B. (1981). The twenty-five most common multiple congenital anomaly syndromes. In M. Kaback (Ed.), Genetic issues in pediatric and obstetric practice. Chicago, IL: Yearbook Medical Pub.

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