Chapter 47 Assessment of Auditory Function

The nurse implements which actions prior to the patient undergoing diagnostic studies of the ear? A. Verify the patient's understanding of the scheduled test B. Request that the nurse technician obtain consent for the test C. Reassure the patient that he should complete the ordered test D. Inform the patient that teaching for this procedure is a provider's responsibility

A

When the nurse assesses a patient regarding the auditory system, which is the most important question to ask? A. "Do you have any chronic illnesses that require you to take daily medication?" B. "Have you ever been told that you are tone deaf?" C. "Did you ever have a foreign body in your ear?" D. "Do you notice that you have wax in your ears?"

A

The nurse recognizes which function(s) as an essential aspect of the auditory system? (Select all that apply.) A. Transfer of sound waves through the auditory canal B. Vibration of the eardrum C. Warming air as it enters the outer ear D. Balance E. Secretion of cerumen

A B D E

Hearing loss is categorized in three ways:

Conductive hearing loss, Sensorineural hearing loss, Mixed conductive-sensorineural hearing loss

How can you effectively communicate with hearing impaired patients?

Face them directly when talking, speak slowly and clearly, lower the pitch of voice, don't shout

Watch test

This simple test is performed to assess high-frequency sounds. The test is performed with a ticking watch. The watch is held about 5 inches from each ear, and the practitioner verifies whether a patient is able to hear the ticking. The patient with normal high-frequency hearing will be able to hear the watch tones.

Weber Test

This test is used to distinguish between conductive (bone conduction) and sensorineural (air conductive) hearing loss. To perform this test, activate the tuning fork by holding the stem and striking the two tines with the back of the hand. Place the vibrating tuning fork in the midline of the patient's skull and ask whether the tone sounds the same in both ears or better in one.

Pure tone audiometry

generates tones with an audiometer that are presented to the patient at frequencies for hearing speech, music, and other common sounds. The testing is done by air conduction and bone conduction and determines whether hearing loss is present and, if loss is noted to be present, whether the loss is conductive, sensorineural, or mixed. An increase in air conduction threshold with a normal bone conduction threshold indicates a conductive hearing loss. An elevated threshold for both air and bone conduction thresholds indicates a sensorineural hearing loss, and an increase of air conduction that is greater than an increase in the elevated threshold of bone indicates a mixed hearing loss.

The middle ear

includes the tympanic membrane (eardrum), the malleus, the incus, the stapes, and the eustachian tube. The middle ear has three functions that include conducting sound waves from the outer ear to the inner ear, protecting the inner ear from loud sounds, and equalizing pressure in the middle ear.

Organs of Corti

located in the cochlea and are the receptors and organs of hearing. They contain hair cells, and as the hairs bend, they change vibrations into electrical impulses that are then carried by cranial nerve VIII to the brain.

speech audiometry

the patient's ability to hear spoken words is measured through a microphone connected to an audiometer. The two components of speech audiometry are the speech reception threshold and speech discrimination. The speech reception threshold determines the softest level at which you begin to recognize speech. Speech discrimination determines how well speech is heard and understood when the volume is set at the patient's most comfortable level of hearing.

Bone conduction transmission

the skull bones (commonly tested using the mastoid bone located behind the ear) transport vibrations directly to the inner ear and then to the auditory nerve. The skull transmits high frequencies with less intensity than air, and that is why a person's voice sounds different to him or her when recorded and played back.

Vestibules

the small, oval-shaped bony chambers located between the semicircular canals and the cochlea. This area contains structures that are important for the sense of balance.

Stapes

the smallest bones in the human body; they are stirrup shaped and located in the middle ear and are important for transmission of sound to the inner ear.

Cochlea

the spiral-shaped, curled tubes located in the inner ear. As sound enters the cochlea, vibrations cause movement of the hairs within the structure, creating nerve signals from cranial nerve VIII that the brain then interprets as sound.

Semicircular canals

tubes composed of cartilage that contain both fluid and hair cells. The sense of equilibrium is maintained here.

Signs of Hearing Loss

• Frequently asking for instructions to be repeated • Turning the head or leaning forward to gain clarity of the question being asked • Loud conversation initiated by the patient • Failing to respond when spoken to (especially when not looking in the direction of the sound) • Answering questions incorrectly on a consistent basis • Raising the volume of the television/radio on a consistent basis •Avoiding large groups • Withdrawing from social functions or interactions • Symptoms of depression

External auditory canals

. The canals are lined with glands that secrete cerumen (a yellow waxy material). The cerumen lubricates and protects the ear by forming a sticky barrier that helps prevent foreign bodies from reaching the tympanic membrane.

How can you help prevent hearing loss?

Certain measures should be taken to prevent hearing loss. These include yearly hearing evaluation with an annual physical examination; use of earplugs, earmuffs, or other protective equipment in the presence of loud or excessive noise to protect sensitive structures of the ear; limiting use of earbuds for listening to music at levels well beyond recommended sound levels; and use of waterproof earplugs for patients with recurrent ear infections or those with specific pathology requiring earplugs around water conditions. Additionally, cotton swabs should not be used to "clean out" ear canals due to the risk of eardrum rupture or impaction of cerumen

What cranial nerve is responsible for transmitting sound and equilibrium information from the inner ear to the brain?

Cranial nerve VIII (vestibulocochlear nerve)

Why are cotton swabs considered dangerous?

can cause tissue injury to the sides of the canal and can also cause cerumen to be moved. Movement of the cerumen by a foreign object places the patient at risk for cerumen impaction, causing changes in hearing, as well as rupture of the eardrum

The inner ear

consists of the bony labyrinth, which holds the vestibule and semicircular canal. The cochlea is also housed here and contains the main hearing apparatus. Cranial nerve VIII contains the sensory cells (hair cells) of the inner ear and consists of the cochlear nerve, which carries information about hearing, and the vestibular nerve, which carries information about balance directly to the brain.

Sensorineural hearing loss

deficit present in the cochlea, cranial nerve VIII, or the brain

Bony labyrinth

structure that holds the sensory organs for equilibrium and hearing.

What are the three parts of the ear that work together to allow hearing and processing sound?

the external (outer) ear, the middle ear, and the inner ear

Incudes

the tiny bones that pass vibrations from the hammer to the cochlea.

Assessment of Hearing Function. Example questions?

1. Does anyone in your family have hearing problems? If so, at what age did the hearing difficulties start? Did it affect both ears? 2. Do people seem to mumble or speak in a softer voice than they used to? 3. Do you frequently need to ask people to repeat themselves during conversations? 4. Do you have difficulty understanding conversations in a crowded room? 5. Do you often need to increase the volume on electronic items such as televisions or radios? 6. Do you have difficulty hearing conversations on the telephone? 7. Do you sometimes miss the telephone ringing or doorbell ringing? 8. Do family/friends complain about your hearing?

Patient Teaching Prior to Computed Tomography Scan

1. Explain to the patient that he will be placed on a table and systematically moved through a shallow tunnel. An IV may be started if the patient is going to receive contrast. 2. Verify that the patient does not have allergies to iodine or other IV dyes. 3. IV contrast, if used, may cause a very warm sensation to the body, which is temporary and disappears shortly after injection. 4. Drink plenty of fluids after the CT scan if IV dye is used to assist in helping the body excrete the IV dye. Instruct the patient that increased urination is to be expected secondary to an increase in fluid volume and the dye's diuretic effect on the kidneys. 5. Certain medications such as metformin may need to be "held" prior to and after the CT scan to prevent an increased serum level of the medication and, therefore, a decrease in blood glucose.

Patient Teaching Prior to the Magnetic Resonance Imaging Scan

1. Instruct the patient on the type of machine being used. (MRI machines can be "open" or "closed." Sedation is often needed by patients undergoing "closed" MRIs because many patients become claustrophobic when placed in the MRI machine for a period of time.) 2. Patients with vascular surgical metal clips will not be eligible for MRI because of the presence of the large magnet of this machine. Newer surgical clips that are made from titanium are acceptable for this test. 3. Patients with pacemakers or implantable defibrillators should check with their practitioner before having any MRI procedure.

The ear is a sensitive organ with many fragile parts. Several categories of medications can prove dangerous to the proper functioning of the ear (ototoxic). What drugs are included in this?

Antibiotics, diuretics, nsaids, chemotherapeutic agents, and miscellaneous It should be noted that this is only a guideline and that not all medications in each category pose this risk; medications should be assessed on an individual basis.

How do you complete a physical inspection of the ear?

Assessment of the ear includes inspection, otoscopic examination, and evaluation of the vestibulocochlear nerve (cranial nerve VIII).

In addition to the detailed history and physical examination needed for a thorough evaluation of auditory function, there are also diagnostic studies used to assess hearing and determine underlying pathology. What are these test called?

Audiometry, Tympanometry, Electronystagmography, Computed Tomography and Magnetic Resonance Imaging

Which findings are expected age-related changes in the auditory system? (Select all that apply.) A. Increase in frequency of ear infections B. Hearing acuity may decrease. C. The ability to hear high frequencies is lost first. D. The tympanic membrane loses elasticity. E. Increased flexibility of the stapes

B C D

The nurse correlates which anatomical structure as the location of the sensory organs for hearing and equilibrium? A. Eustachian tube B. Ossicles C. Bony labyrinth D. Tympanic membrane

C

The nurse recognizes which medication as ototoxic? A. Non-salicylate pain medications B. Calcium channel blockers C. Antibiotics such as gentamicin D. Beta blockers

C

Which is the most common examination used to assess a patient's auditory function? A. Examination using the tuning fork B. Examination and assessment of all the cranial nerves C. Examination using the otoscope D. Evaluation of a written questionnaire

C

What age related changes occur to the outer ear?

Cilia lining the ear canal become coarse and stiff, which may decrease hearing as it impedes sound waves from traveling toward the middle ear. Cerumen can also accumulate and oxidize secondary to the coarse, stiff cilia. Atrophy of the apocrine glands (glands that produce cerumen) causes the cerumen to become drier.

The nurse should instruct the patient to prevent possible ear trauma by which action? A. Whisper when possible to prevent ear strain B. Select earbuds for electronic devices over external earphones C. Be cautious when taking oral medications D. Never use a cotton swab or other similar instrument in an attempt to remove wax

D

What age related changes occur in the middle ear?

Membrane changes that include stiffening of the tympanic membrane and stiffness or calcification of the ossicles occur with advancing age.

How do you prepare your patient for an electronystagmography?

Preparation for this test includes a detailed explanation of the purpose and procedure to the patient. The following teaching points should be made clear to the patient prior to the test being performed: • The patient should refrain from ingestion of caffeine for at least 24 hours prior to the test. Caffeine can cause stimulation of the central nervous system and therefore possibly influence testing results. • The patient should be NPO for at least 3 hours prior to the test. Patients may experience nausea and vomiting with this test; NPO status may help to decrease this sensation. • Patients with pacemakers should not have this test done. Pacemaker signals interfere with the sensitivity of this test. • Patients who normally wear eyeglasses should bring them to the test with them. Eyeglasses assist the patient in vision during the testing. • Patients should be informed that reintroduction of fluids after this test will be gradual to prevent the occurrence of nausea and vomiting. • Patients might want to consider having a family member drive them home from the test because sometimes nausea, vomiting, or vertigo can continue after testing.

What age related changes occur in the inner ear?

Presbycusis is a type of hearing loss that occurs with older adults. This loss is gradual and sensorineural (perceptive) in nature and is caused by nerve degeneration in the inner ear or auditory nerve. The onset for this type of hearing usually begins around age 50, and then it slowly progresses.

You should also address problems such as vertigo, tinnitus, hyperacusis. What are these?

Problems such as vertigo (spinning sensation) tinnitus (ringing in ears), hyperacusis (intolerance for sound levels not normally experienced by others),

Voice test

Simple hearing acuity test performed on both ears at the same time. To perform, the practitioner stands 1-2 feet away from the patient and asks the patient to cover one ear. The practitioner whispers a short statement of four words or fewer into the patient's uncovered ear and asks the patient to repeat the words. If the patient is unable to respond or responds incorrectly, repeat the statement choosing new words and in a slightly louder whisper.

How is sound transmitted by air?

Sound is gathered by the pinna, and the waves enter the ear traveling through the auditory canal until they reach the tympanic membrane (eardrum). The sound waves set up vibrations in the eardrum. The vibrations of the eardrum cause the auditory ossicles (the malleus, incus, and stapes) in the middle ear to move back and forth. The cochlea receives the sound vibrations next. Finally, the sound stimulus travels to the vestibulocochlear nerve (acoustic or auditory nerve), cranial nerve VIII, and terminates in the cerebral cortex. Cranial nerve VIII is the cranial nerve that is concerned with hearing, balance, and head position. The eighth cranial nerve branches into two parts, a cochlear part that is integral to hearing and a vestibular part that mediates the sense of balance and head position. The cerebral cortex is a most highly developed part of the brain that is divided into right and left hemispheres. The temporal lobe of the cerebral cortex is involved with hearing and language.

What should the ear drum look like?

The eardrum is flat, slightly pulled in the center, and flutters when the patient swallows or holds his nose. The eardrum should be inspected around its entire circumference to ensure that the tympanic membrane is intact (Figure 47.4). White dense patches may be present on the drum and indicate scarring from repeated ear infections or past ruptures.

The inner ear, with innervation from cranial nerve VIII, also controls equilibrium and balance. How?

The labyrinth in this portion of the ear constantly provides information to the cerebral cortex of the brain about the body's position in space. It works like an imaginary line to determine verticality or depth. The ears register the angle of the head in relation to gravity. Inflammation of the labyrinth causes the wrong information to be sent to the brain, thus resulting in a staggering gait and a spinning, whirling sensation known as vertigo

Rinne test

This test compares air conduction and bone conduction. The tuning fork is activated as above. When activated, place the stem of the vibrating tuning fork on the patient's mastoid process, and the patient is asked to indicate when the sound goes away. The tuning fork is then quickly inverted, with the tines located about 2 inches from the patient's ear; the patient should still be able to hear the vibrating sound if hearing is normal.

Audiometry

This test measures frequency (the highness or lowness of tones expressed in hertz; hertz is the international unit of frequency defined as the number of cycles per second of a sound). Low pitch is determined by fewer vibrations, and high pitch is determined by a greater number of vibrations. Sound intensity is noted in decibels (dB), and threshold is noted as the lowest level of intensity at which pure tones and speech are heard by a patient about 50% of the time. Normal conversation is heard at about 60 dB; whispers are 20 dB; and very loud, dangerous sounds are considered at about 110 dB. Documented injury can occur from sounds greater than 85 dB. There are two types of audiometry, pure tone and speech audiometry

Audioscopy

This tests hearing ability with a handheld device to assess general tones. The test measures at 40-decibel intensity and at frequencies of 500; 1,000; 2,000; and 4,000 cycles per second, or hertz. This test is done in a quiet setting with headphones in place and is most often seen as a screening device in schools or clinics.

Tympanometry

Tympanometry is performed to assess the mobility of the eardrum and structures of the middle ear because these changes are consistent with presence of fluid in the middle ear. Changes in air pressure are systematically introduced into the external auditory canal at a predictable rate. This test is helpful in distinguishing middle ear pathologic conditions such as otosclerosis, ossicular disarticulation, otitis media, and perforation of the eardrum. Earpieces are placed in the patient's ear prior to the start of the test, and the machine is able to determine the degree of progression or resolution of serous otitis media.

What test are used to assess hearing function?

Voice test, watch test, audioscopy, Weber test, Rinne test

What common genetic disorders are linked to hearing loss?

Waardenburg syndrome Branchio-oto-renal (BOR) syndrome Neurofibromatosis type 2 Stickler syndrome Usher syndrome osteogenesis imperfecta Down syndrome

Conductive hearing loss

a physical obstruction of sound wave transmission.

What is the most common pathway of hearing?

air conduction

electronystagmography

done to detect both central and peripheral diseases of the vestibular system (the system in the inner ear that is responsible for maintaining balance and orientation in space) in the ear. The ENG detects and records nystagmus (involuntary eye movements), because the eyes and ears depend on each other for balance.

Malleus

the part of the middle ear that is in the shape of a hammer. The function of this structure is to transmit sound vibrations from the eardrum to the incus.

What are some risk factors for hearing loss?

• Advanced aging • Repeated infections of the ear • Medications with ototoxic side effects • Ear trauma • Occupations that place the patient in the presence of loud noises • Tumors of the ear • Continuous exposure to loud noises

Eustachian tubes

connect the middle ear with the nasopharynx, thereby allowing for passage of air. These tubes are usually in a closed position but open with swallowing or yawning. Their function is to stabilize the air pressure between the external atmosphere and the middle ear. In children, this tube is more flat in appearance and gradually evolves in the adult to have a more slanted appearance, thereby making drainage more efficient and lessening the chance of infection.

The external ear

consists of the pinna, mastoid process, and external auditory canal, and the major function of this portion of the ear is to funnel sound waves

Tympanic membranes

are structures that separate the external ear from the middle ear. They are translucent membranes with a pearly gray color and are oval in shape.

Pinnae

are the most visible part of the ear, and their primary function is to collect sounds. Composed of cartilage covered by skin, the pinnae are present on both sides of the face and are embedded in the temporal bone bilaterally at the level of the eye.

Inspection:

begins with palpation of the external ear. The practitioner notes the size and shape of the ears. They should be equal in size bilaterally without swelling or thickening. The color of the ears should be consistent with the facial skin tone of the patient. Inspection for lumps or lesions is done as well. The pinna should feel firm and should be freely moveable without causing any discomfort. Palpation of the mastoid process should also be done at this time, and there should be no swelling or complaint of pain present during the examination.

Examination With an Otoscope

otoscope is used to examine the internal structures of the ear and consists of a light, handle, magnifying lens, and pneumatic bulb (often used with children) to test the movement of the tympanic membrane the practitioner tilts the patient's head away from the examiner. The pinna is pulled up and back in the adult and older child, and the pinna is pulled down on an infant or child under 3 years of age. This important action helps straighten the ear canal and affords better visualization due to the flat anatomical position of the infant's eustachian tube. The pinna is held lightly but firmly, maintaining a steady grip until the examination is complete and the otoscope is removed from the ear canal. The practitioner holds the otoscope in an "upside-down" position and steadily places the speculum of the otoscope into the ear canal using his hand along the patient's cheek to steady the otoscope. The practitioner takes care to watch the insertion to ensure safe and easy introduction. On occasion, the practitioner is not able to see any structures, and a reattempt is made to reposition the otoscope. (If cerumen is present and creating an obstruction, it will need to be removed before a visual examination can take place.) Once the otoscope is in place, the practitioner rotates it slowly to visualize the eardrum. The otoscopic examination is usually completed before any hearing tests are conducted.

Mastoid processes

parts of the skull that contain spongy bone located just behind the ear. The middle ear and the cochlea portion of the inner ear are embedded in the mastoid bone.

Mixed conductive-sensorineural hearing loss

profound hearing loss that encompasses both conductive and sensorineural injuries

What questions are important when gathering a personal history?

questions regarding past ear infections, past ear trauma, past ear surgeries, exposure to loud noises and music, possible occupational hazards regarding loud noises, and itching of the ears history of current health, past illnesses (especially those requiring treatment with known ototoxic medications), smoking history (nicotine may cause damage to the sensory cells), allergies, and family history provide important information about the auditory system.