Guidelines for Hearing Screening in the School Setting

Appendix A - Ear Anatomy

The ear receives sound waves that are processed and transmitted to the hearing center in the brain for interpretation. The ear is divided into three parts: 1) outer, 2) middle, and 3) inner. See Appendix G.

The outside ear consists of the auricle, or pinna, and external auditory canal. The auricle, or visible part of the ear, directs and concentrates the sound waves along the external ear canal to the tympanic membrane. The ear canal contains hairs and wax producing glands that serve to protect the eardrum from dirt, inserts, or foreign matter. The tympanic membrane is a thin diaphragm that completely closes the end of the ear canal and separates the outer ear from the middle ear.

The middle ear is a tiny, air-filled cavity between the eardrum and the bony wall of the inner ear, and contains the three smallest bones, called Ossicles. The first bone in the ossicular chain is the hammer (malleolus) which is attached to the eardrum. The anvil (incus) fits between the hammer and the third bone, known as the stirrup (stapes). The footplate of the stapes is set in the window of the inner ear. A passage between the middle ear and the back of the nose (Eustachian tube) serves as a means for equalizing air pressure and ventilating the middle ear cavity.

The inner ear contains the sensory organ for balance (including the semi-circular canals), as well as, the organ for hearing known as the cochlea. The cochlea resembles a snail shell in appearance and is filled with fluid. Sound vibrations from the eardrum are transmitted through the ossicular chain to the oval window to the fluid in the cochlea. The sound sets in motion thousands of hairlike sensory cells in the cochlea called the organ of Corti. These sensory cells transform fluid movements into electrical impulses and, by a series of complicated processes, transmit them to the auditory nerve to the brain, where they are perceived as sound.

The school nurse must know and understand the anatomy and physiology of the ear if she/he is to understand the results of hearing tests. Interpretation of the findings of the hearing test is often based on the structure and functioning of the ear and its many parts.

Normal Hearing Defined

Normal hearing occurs between -10 decibels and 20 decibels (loudness of sound). The ability to hear is more developed at birth than the ability to see. There is a normal developmental progression in the ability of an infant to respond to sound.

Description and Types of Hearing Loss

1. Conductive Impairments: Any dysfunction of the outer or middle ear is termed a conductive impairment of hearing. In other words, the difficulty is not with the perception of sound, but with the conduction of sound to the analyzing system. Conductive hearing loss results from injury to the outer ear, the eardrum, the hearing bones, or the middle ear space. Medicine or surgery usually correct this type of hearing loss. Hearing aids are often helpful with this type of loss if not otherwise corrected.
   
   Causes of conductive hearing impairments:
   • Wax buildup;
   • Objects lodged in the ear drum (plastic toys, seeds, insects, etc.);
   • Damage to the Ossicles behind the ear drum;
   • Infections of outer or middle ear; and
   • Fluid buildup in the middle ear.
2. Sensorineural Hearing Impairment: When the loss of hearing function is due to pathology in the inner ear, or along the nerve pathway from the inner ear to the brain stem, the loss is referred to as a sensorineural impairment. In other words, sound is conducted properly to the fluid of the inner ear, but it cannot be analyzed or perceived normally. This loss can be discovered at any age. This type of hearing loss may be a sign of a serious illness and should not be neglected. Hearing aids are usually helpful with this type of hearing loss. Medication and/or surgery are usually effective treatment options for sensorineural hearing impairment. High frequency sounds tend to be more affected, although some congenital losses affect all tones equally. Cochlear implants have been helpful for some individuals, especially if implanted early in childhood.
   
   Causes of Sensorineural Hearing Impairment:
   • Damage during fetal development or at birth;
   • Familial-hereditary factors;
   • Infections;
   • Certain medications;
   • Certain diseases;
   • Prolonged exposure to excessive noise;
   • Head injuries; and
   • Aging.
3. Mixed Hearing Impairment: In some instances, an individual may exhibit symptoms of both conductive and sensorineural hearing loss. For example, a child with a congenital sensorineural hearing loss may also have some degree of conductive hearing loss due to otitis media. A patient with a mixed impairment shows some loss by bone conduction, but a greater loss by air conduction.
4. Unilateral Hearing Impairment: An individual may have normal hearing in one ear and a hearing loss in the other ear that could impact learning. These children may benefit from hearing aids or a sound field system.

Educational Implications

Many factors affect the speech/language abilities and academic success of each child. Some children have severe loss, very intelligible speech and make good grades. Other children with very mild loss and little family support exhibit considerable academic failure. Labels such as mild, moderate, severe, or profound, based on the pure tone thresholds, do not predict handicap or academic success. The possibility of hearing loss, however mild, needs to be evaluated to assure attention to a learning barrier. Being able to hear all sounds is important when learning to read. Any loss, no matter how mild, needs to be evaluated in order to assure attention to any barrier of learning.

Federal programs exist in all states to assist families and children with early-identified hearing concerns. In Missouri, the First Steps program is designed for children, birth to age 3, who have delayed development or diagnosed conditions that are associated with developmental disabilities. Deafness and hearing impairments are one of the eligibility criteria that qualify young children to receive free services through this program.

Appendix B - Assessment Schedule

Hearing screening begins at birth and continues throughout life. The majority of states (including Missouri) currently conduct newborn hearing screenings. The following schedule lists the methods of screening appropriate for individuals at different ages. As the age of the person being screened changes, so should the screening protocol.

Specific program guidelines may differ from the following recommendations:

Appendix C - History Related to Hearing

A variety of conditions may put a child “at risk” for developing hearing problems after birth. Some children with significant hearing loss are identified after 1 year of age when behaviors may indicate inability to hear. Health care providers should observe children with a health history that includes the following conditions for development of hearing loss.

1) High Risk Register (for early childhood screening)

Some babies may be identified at birth as being “at risk” for hearing impairments. The following is a list of criteria to indicate infants who might be considered at risk:

• Family history of any blood relative with childhood hearing impairment;
• Rubella or other nonbacterial transplacental infection (e.g.,cytomegalovirus infection, herpes infection, syphilis);
• Defects of the ear, nose, or throat, such as malformed, low-set or absent pinnae, cleft lip or palate (including sub mucous cleft), or any residual abnormality of the otorhinolaryngol system;
• Birthweight less than 1,500 grams;
• Bilirubin level greater than 15 mg/100 ml serum or exchange transfusions;
• Significant asphyxia associated with acidosis, as determined by attending physician, and proven meningitis;
• Low Apgar Scores (zero to three at five minutes, zero to six at ten minutes);
• Respiratory distress;
• Physical features associated with syndromes that include progressive hearing loss; and
• NICU stay greater than five days.

If one or more of the criterion are present, refer the infant to the appropriate health care professional.

2) Supplemental Questions

• Did the child receive a newborn hearing screening?
• Does the child presently have a continuous or recurrent ear infection?
• Has the child suffered from any of the following: meningitis, encephalitis, cerebral palsy, mumps, head injury, chemotherapy, or birth defects?
• Was the child in an intensive care nursery after birth?

3) Parental Screening Questions

• Have you had any worry about your child’s hearing?
• When he is sleeping in a quiet room, does he move and begin to wake up when there is a loud noise?
• Does he turn his head directly toward an interesting sound or when his name is called?
• Is he beginning to repeat some of the sounds that you make?
• By 15 months, can he use three or four words correctly, other than “mama and dada?”
• Can he identify familiar pictures when you name them?
• Does he name things when he wants them, like candy or juice?

Appendix D - Observational Screening for Hearing Problems

Techniques for screening are indicated below and are intended for use in a well-baby clinic, physician’s office, parent’s home, or for children who cannot be conditioned to an audiometer. The screener should be trained to do the observational screening, and have the appropriate materials.

• Select a quiet room for screening with little distraction from the outside.
• Have several noisemakers available–squeeze toys, bells, rattles, etc. Select these carefully to provide a variety of pitch and intensity levels.
• Seat the mother on a chair with the child on her lap. A colorful toy should be available as a distraction, but it should not be too attractive or it will engage the entire attention of the child.
• The screener kneels at a 45-degree angle to the side of the child, with the distracting toy in one hand and the noisemaker well hidden in the other. When the toy held in front of him engages the baby’s attention, the screener makes a sound with the noisemaker in the hand held close to the floor, out of the peripheral vision of the child. If an orientation response is seen after one or two presentations of the sound, the screener moves to the other side. The screener will learn by experience that for the 0 to 4 month age level, the noisemaker must be presented loudly; by 6 to 9 months, it can be presented more softly; and by 10 to 12 months, it should be made as soft as possible.

The expected response is some sort of head turn toward the sound. An exact description of the head turn and accompanying eye movement should be noted. A normal-hearing child’s orientation to sound will progress as follows:

• Newborn—arousal from sleep, or eye widening, eye blinking;
• 3 to 4 months—rudimentary head turn, a wobble of the head even slightly toward the sound;
• 4 to 7 months—localization to side only;
• 7 to 9 months—localization to side and indirectly below;
• 9 to 13 months—localized to side and below;
• 13 to 16 months—localized directly to all signals to side, below, and above; and
• 21 to 24 months—locates directly to a sound at any angle.

Interpretation of Observational Screening

When there appears to be no response, the screener should repeat the use of a particular stimulus at his discretion until the observer is satisfied that the failure to respond is genuine. Two repetitions should be adequate to establish this fact.

It must be kept in mind that the failure of the child to locate the sound does not always indicate that the child did not hear it. The simple fact that the child may not be interested in that particular sound can account for the lack of response. For this reason, more than one stimulus in a particular pitch range should be available for use at the discretion of the screener. In addition, it is important to conduct the screening when the infant or child is otherwise alert and calm.

Referral Criteria for Observational Screening

In making the observations previously described, a hearing loss should be suspected if the child does not respond appropriately on either side, or if he orients to the wrong side. The child who deviates markedly in these behaviors should be referred for further testing.

Tympanometry, or pneumatic otoscopy, and rescreening of failures may significantly reduce false positives and over-referrals. An infant who fails these additional tests should be referred to an appropriate health care professional.

Appendix E - Screening Students for Dual Sensory Loss

Students who are born deaf, or have a profound hearing loss should be screened for the possibility of the genetic disorder, Usher syndrome. This condition is of very low incidence (three to six percent of the deaf population have Usher’s) but the condition, if present, will progress to total blindness. Individuals usually develop retinitis pigmentosa (RP) in adolescence. It is important to identify these students as early as possible in order to prepare them for the future. Deaf students may function well using sign language or lip reading, but when they lose their vision, they must develop other means of communication. Students identified with Usher syndrome are often referred to special centers where they learn communication skills and mobility before they become totally blind.

If there are students in the population who are congenitally or profoundly deaf, it is helpful to complete the Usher Syndrome Screening Checklist. This checklist can rule out more than 99 percent of the students who might need further screening. The Vision Screening Guidelines contain the checklist and directions to test for balance (vestibular dysfunction), dark adaptation, and loss of peripheral vision that occurs with RP.

There are three types of Usher syndrome:

1. Type I congenitally deaf (up to 90 percent of Usher syndrome)
   • Impaired balance
   • Retinitis pigmentosa
2. Type II moderate to severe hearing loss (up to 10 percent of Usher syndrome)
   • Normal balance
   • Retinitis pigmentosa
3. Type III progressive hearing loss, normal at birth
   • Fifty percent have balance problems
   • Retinitis pigmentosa
   • Possible mental retardation

Not all students with a hearing loss and RP have Usher syndrome. Type II and III will be mainstreamed in schools, so it is important to remember this possibility when reviewing your hearing screening results. There is no cure for Usher syndrome and no way to prevent it, but you can screen high-risk students. If the screener finds reason for concern after doing the additional screening by history and expanded vision and balance testing, they should contact the family for a referral for diagnostic testing.

Appendix F - Missouri History Related to Hearing Screening

Each year, nearly 80,000 newborns are added to Missouri’s population. Children born in Missouri receive a newborn hearing screening, as required by law (effective January 1, 2002), to detect hearing loss present at birth. All hospitals delivering babies must now assure babies are screened prior to discharge. Parents who object to the screening based on religious reasons must document their refusal in writing. Informational materials must be provided to the parents prior to the screening describing the procedures and following the screening for those infants who fail. The Department of Health and Senior Services (DHSS) shall establish standards for screening, records maintenance, and the development of follow-up procedures for newborns with reported hearing loss. Information maintained in this system shall be kept confidential. A newborn hearing screening advisory committee assists DHSS in developing rules, reporting forms and procedures, educational materials, and program evaluation forms. For a variety of reasons, e.g., equipment failure, home births, etc., newborn screenings may not occur; however, the vast majority (greater than 90 percent) will have been screened.

The purpose of the Missouri Newborn Hearing Screening Program (MNHSP) is to assure all babies born in Missouri receive a hearing screen and appropriate follow-up, including audiological evaluation, enrollment into early intervention, and medical intervention, when indicated. Statistics show that three newborns per 1,000 have some degree of permanent hearing loss. Congenital hearing loss is more common than cleft lip or Down syndrome. Early identification of hearing loss and enrollment in appropriate intervention services during the first 6 months of life allows children who are deaf or hard of hearing to take advantage of the critical first few years of life, when language (spoken or signed), is acquired and allows children to develop language at a level equal to that of their hearing peers.

Currently, the MNHSP employs two Regional Representatives (RRs) who follow-up each newborn who missed or failed the hearing screen. The RRs contact the parents of newborns who need to return for an initial screen, a rescreen, or obtain an audiological evaluation. Additionally, they contact birth hospitals and primary care physicians to obtain screening results that were not submitted to DHSS. Their goal is to ensure infants are screened no later than one month after birth, diagnosed by 3 months of age, and enrolled into early intervention no later than 6 months of age.

The MNHSP successfully collaborates with numerous entities. The MNHSP works with the Department of Elementary and Secondary Education (DESE) in order to acquire data about the intervention services children with hearing loss receive through First Steps, Missouri’s Part C program. Additionally, Missouri State University provides a contract audiologist consultant who advises the MNHSP in audiological matters and who is available to provide assistance to newborn hearing screening programs throughout the state. All Missouri birth facilities and audiologists report hearing screening and evaluation results to MNHSP, as required by state statute.

Appendix G - Diagrams and Forms

Diagrams

Audiogram of Familiar Sounds

Diagram of the Ear

Forms