Chapter 13: Special Senses: Ears

stapedectomy

the removal (-ectomy) of the third ossicle, the stapes (staped/o). This procedure is performed to correct otosclerosis

incus

"anvil" anvil; middle of the three auditory ossicles of the middle ear

malleus

"hammer" Auditory ossicle attached to tympanic membrane

stapes

"stirrup" Auditory ossicle attached to oval window.

perilymph

(peri = surrounding; lymph/o = lymph) and filled with endolymph (endo- = within). The bony labyrinth consists of three parts: the vestibule (vestibul/o), semicircular canals, and the cochlea (cochle/o). The first two contribute to the body's sense of equilibrium, or balance. The cochlea houses the organ of Corti, a sensitive receptor with hair cells that relay sound waves to the eighth cranial nerve, or vestibulocochlear nerve. This nerve then conveys impulses to the temporal lobe of the brain. Before long, we'll see that Sara's hearing difficulty may very well be caused by age-related changes of these inner ear structures

cochle/o

cochlea

anacusis

complete deafness

microtia

condition of abnormaly small auricles

semicircular canals

contribute to the body's sense of equilibrium, or balance

vestibule

contribute to the body's sense of equilibrium, or balance

ceruminoma

derived from the glands that produce earwax, which can obstruct the ear canal and detract from a patient's ability to hear

otorrhea

discharge from the ear

ot/o aur/o auricul/o

ear

otalgia

ear pain

tympan/o myring/o

eardrum

cerumen

lubricates the ear and prevents the entry of foreign particles into the internal portions of the ear

macrotia

macrotia (macro- = large; ot/o = ear; -ia = condition), while a condition of abnormally small (micro-) auricles is called microtia

macul/o

macula

tympanoplasty

surgical repair of the tympanum

cochlear implant

surgically implanted to electrically stimulate the cochlea

infectious myringitis

the inflammation occurs in the eardrum (myring/o) and vesicles due to a bacterial or viral infection, it is called infectious myringitis

tympanometry

the process of measuring (-metry) the condition and mobility function of the tympanic membrane or eardrum (tympan/o). A tympanogram is the graph seen as a result of this test

presbycusis

Age-related hearing loss.

auditory brainstem response (ABR)

An electrophysiologic response to sound, consisting of five peaks that represent neural function of auditory pathways. We are most concerned about the timing between 1 and 5. Absence and/or delay in response could represent a problem. (276)

otoscope

An instrument for examining the external canal and tympanic membrane of the ear.

vestibulocochlear nerve

CN VIII Cranial nerve VIII, which runs from the cochlea to the brainstem auditory nuclei

secretory otitis media (OM)

Caused by a myriad of bacteria, acute otitis media is characterized by a sense of fullness in the ear, diminished hearing, pain, and fever. If the inflammation is accompanied by a pus-filled fluid, it is called suppurative OM. If it is characterized, instead, by a clear fluid discharge, it is secretory OM

supporative otitis media (OM)

Caused by a myriad of bacteria, acute otitis media is characterized by a sense of fullness in the ear, diminished hearing, pain, and fever. If the inflammation is accompanied by a pus-filled fluid, it is called suppurative OM. If it is characterized, instead, by a clear fluid discharge, it is secretory OM

organ of Corti

Center part of the cochlea, containing hair cells, canals, and membranes

endolymph

Fluid within the labyrinth of the inner ear

sensorineural hearing loss

Hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called nerve deafness

conductive hearing loss

Hearing loss or impairment resulting from interference with the transmission of sound waves to the cochlea

oval window

Membrane that covers the opening between the middle ear and inner ear

cerumin/o

cerumen

Meniere disease

The structures responsible for equilibrium and balance are housed in the labyrinth of the inner ear. Meniere disease affects the vestibular labyrinth and can lead to profound hearing loss. The cause of the disease is unknown, but it is marked by vertigo, a sensation that the body is spinning or that objects are spinning around the body. Tinnitus, a subjective noise such as ringing, buzzing, whistling, or clicking—heard in the absence of sound—is another symptom of Meniere disease. Various options exist to treat this disorder, including tranquilizers, antihistamines, diuretics, and surgery to reduce the pressure of the endolymph on cochlear hair cells. It can also spontaneously go away, as Sara's did after two years

eustachian tube

Within the middle ear is the opening for the auditory, or eustachian tube (salping/o). This structure is sometimes identified as the pharyngotympanic tube as well because it joins the nasopharynx (part of the throat) with the middle ear cavity, where the tympanic membrane is. The eustachian tube is lined with a mucous membrane and its job is to equalize air pressure between the middle ear and the external atmosphere

acoustic neuroma vestibular schwannoma

a benign tumor of the auditory nerve that can cause tinnitus and hearing loss

impacted cerumen

a blockage of the external auditory canal with earwax, or cerumen

cholesteatoma

a cystic mass composed of epithelial cells and cholesterol (chol/e = bile; steat/o = fat; -oma = tumor). This can not only occlude the middle ear but also destroy adjacent bones

otologist

a physician who studies and treats diseases of the ear. If nose and throat involvement were also suspected, Sara might have been referred to an ear, nose, and throat (ENT) specialist. But determining which part of the ear is affected is another part of the problem. Dr. Harris has in mind several possible disorders affecting the external, middle, and inner ear. Certain tests will help to narrow these down

tinnitus

a subjective noise such as ringing, buzzing, whistling, or clicking—heard in the absence of sound

tympanotomy myringotomy

a surgical incision (-tomy) of the tympanum to relieve the pressure and build-up of fluid. This procedure may be required for those who don't respond to antibiotic treatment

ruptured tympanic membrane

any type of tear or injury to the eardrum/possibly resulting from pressure, force, or insult from the exterior aspect

tympanic membrane

eardrum (tympan/o, myring/o), marks the division between the external and middle ear. This thick membrane in the middle ear transmits sound vibrations from the external auditory canal through the middle ear and on to the inner ear

hearing aid

electronic devices that amplify sound

salping/o

eustachian tube

audiometric testing

evaluates hearing acuity and helps to establish the degree and severity of hearing loss (audi/o = hearing; -metric = pertaining to measurement). An audiometer is an electric device used to measure the sensitivity of hearing by delivering a series of acoustic tones that range from very low to very high frequencies. The listener signals when the tone is perceived and the results are plotted on a graph called an audiogram. In a variation on this test, pure tone audiometry—measurement of perception of pure tones—is made with all extraneous noises screened out. Still another variation is speech audiometry, measurement of the ability to hear and understand speech

auricle pinna

gathers sound waves and funnels them into the external auditory canal, or meatus. The auricle, a skin-covered cartilaginous flap, projects from the side of the head

otosclerosis

hardening of the innr ear Abnormal bone formation in the osseous labyrinth of the temporal bone causing the footplate of the stapes to become fixed or immobile in the oval window. The result is a conductive hearing loss.

audi/o acous/o

hearing

cochlea

houses the organ of Corti, a sensitive receptor with hair cells that relay sound waves to the eighth cranial nerve, or vestibulocochlear nerve. This nerve then conveys impulses to the temporal lobe of the brain. Before long, we'll see that Sara's hearing difficulty may very well be caused by age-related changes of these inner ear structures

ossicles ossicular chain

include the malleus, incus, and stapes (staped/o), named because they resemble a hammer, anvil, and stirrup, respectively. They are attached to, or articulate with, one another. The "handle" of the malleus is connected to the tympanic membrane. When the eardrum conducts sound to these three ossicles, the ossicles transmit the sound to the oval window through vibration of the stapes. The footplate of the stapes, when it moves, touches this oval window, which leads to the inner ear. Within the middle ear is the opening for the auditory, or eustachian tube (salping/o). This structure is sometimes identified as the pharyngotympanic tube as well because it joins the nasopharynx (part of the throat) with the middle ear cavity, where the tympanic membrane is. The eustachian tube is lined with a mucous membrane and its job is to equalize air pressure between the middle ear and the external atmosphere

labyrinthitis

inflammation of the inner ear (labyrinth/o), may be due to either infection or trauma. Symptoms usually include vertigo, nausea, and nystagmus. Another disorder that can be caused either by trauma or disease is ruptured tympanic membrane, shown in the illustration. This is just what it sounds like—a tear, or perforation, of the eardrum

mastoiditis

inflammation of the mastoid process (mastoid/o) of the temporal bone

otitis media (OM)

inflammation of the middle ear

otitis externa

inflammation of the outer ear

labyrinth/o

inner ear

tympanometer

instrument used to measure middle ear (function)

speech audiometry

measurement of ability to hear and understand speech

auditory canal

meatus

ossicul/o

ossicles

paracusis

partial loss of or impaired hearing

otoplasty

refers to the surgical or plastic repair (-plasty) and/or reconstruction of the external ear

otoacoustic emissions (OAEs)

sounds made by the vibration of the outer hair cells in the organ of Corti; can be measured and used to verify a normal functioning cochlea

staped/o

stapes

macula

structures of the ear involved in maintaining equilibrium are the macula (macul/o) and the semicircular canals, both of which are found in the vestibule. Sensitive hair cells and fluid within these structures can detect changes in the position of the head. Movement of the hair cells generates nerve impulses, which communicate through the brain to the body's muscles and provide for the recovery of balance

tympanostomy myringostomy

the surgical creation of an opening (-stomy) through the eardrum to promote drainage. This procedure also allows the insertion of artificial tubes to maintain this new opening, something often useful in preventing those recurrent ear infections mentioned earlier. In the accompanying photograph, we see the tympanostomy tube in place

mastoidectomy

the surgical removal of the mastoid process

Rinne tuning fork test

the tuning fork is placed alternately near the auditory canal and behind the ear on the mastoid bone to compare how the patient hears sounds transmitted through air (near the auditory canal) with how the patient hears sounds transmitted through bone. This test helps the examiner distinguish between conductive and sensorineural hearing loss. Not being able to hear the tuning fork longer when the sound waves are conducted through the air is a sign of conductive hearing loss. The Weber test is done in conjunction with the Rinne test

Weber tuning fork test

the tuning fork is placed on the midline of the skull to assess bone conduction of sound for evaluation of auditory acuity. It can detect unilateral conductive hearing loss and unilateral sensorineural hearing loss. With normal hearing, the sound the patient hears is the same loudness on each side

pure tone audiometry

used to determine threshold at each test frequency for both ears

Universal Newborn Hearing Screening Test (UNHS)

uses otoacoustic emissions (OAEs) measured by insertion of a probe into the infant's ear canal. Four electrodes are then placed on the baby's head and auditory brainstem response (ABR) is measured while the baby sleeps

vestibul/o

vestibule