audioanalgesia : reduction or abolition of the perception of pain
by listening through a head set to recorded music to which a background
of “white noise” has been added.
hyperacusis / hyperacousia / hyperacusia /
hyperakusis / acoustic or auditory hyperesthesia : exceptionally acute
hearing, the hearing threshold being unusually low. It may or may not be
accompanied by pain
Epidemiology : permanent childhood
hearing impairment (PCHI) is a congenital defect that affects 112 per
100,000 children worldwide.
Grading :
partial deafness : hypoacusis / hypacusia
/ hypacusis / acoustic or auditory hypoesthesia slightly diminished
auditory sensitivity, with hearing threshold levels above the normal limit
so that the impairment is measurable in dB
acoustic trauma deafness
: noise-induced hearing loss caused by a single loud noise such as blast
injury
boilermakers' deafness : noise-induced
hearing loss in boilermakers
rupture of round window
fracture of stapes
fracture of otic capsule
blow up of annular ligament of stapes followed by perilymphatic fistula
perceptive / sensorineural
/ transmission hearing loss
Epidemiology : approximately 1.2 children
per 1,000, or 40,000 children, will be diagnosed with moderate to profound
inner ear hearing loss each year in the USA. 80% of the patients with hearing
loss remain undiagnosed after their initial assessment based on standard
diagnostic tests
Aetiology : while there are as many as
150 genes suspected of being linked to inner ear hearing loss, at this
point, the gene chip targets 13 key genes.
sensory hearing loss (cochlear
deafness)
presbycusis / presbiacusia
: a progressive, bilaterally symmetric perceptive hearing loss occurring
with age.
Symptoms : unilateral hearing loss often associated
with transient vertigo and persistent tinnitus Treatment must be instituted within
48 hours to be most effective:
mandatory bed rest of 7-10 days.
donnatal or tincture Belladonna q.i.d.
nicotinic acid flushing q.i.d.
histamine vasodilation using 2.75 mg of histamine in 200 mL of 5% dextrose
in water I.V. at a rate to cause flushing, but not cause headache
or significant drop in blood pressure.
dextran, 500 cc per day (not with histamine)
systemic steroids, such as prednisone 60 mg daily x 7 days, tapered
to zero over another 7 days.
Laboratory examinations : hearing threshold
and speech testing are done at regular intervals, initially q.o.d., then
at longer intervals in the ensuing weeks and months.
Prognosis : most patients have some residual
hearing loss.
mixed hearing loss is simply a combination of conductive and sensorineural
components.
Laboratory examinations : Bilateral permanent
childhood hearing impairment that is moderate, severe, or profound affects
1 in 750 children and is present at birth in > 80% of affected childrenref1,
ref2,
ref3.
Such impairments are associated with impaired language acquisition, learning,
and speech developmentref1,
ref2,
ref3
(Allen TE. Patterns of academic achievement among hearing impaired students:
1974 and 1983. In: Schildroth AN, Karchmer AM, eds. Deaf children in America.
San Diego, Calif.: College-Hill Press, 1986:161-206). Currently, screening
for bilateral permanent childhood hearing impairment, with the use of transiently
evoked otoacoustic emissions and automated measurement of auditory brain-stem
responses, is recommended for all infants before the age of 3 months in
the USAref,
the UK (Quality standards in paediatric audiology. Vol. 1: guidelines for
the early identification of hearing impairment. London: National Deaf Children's
Society, 1994:1-10), and Europeref.
The value of these recommendations is supported by studies showing that
enrollment in an intervention program by nine months of age, as compared
with later intervention, is associated with improvements in the verbal
ability quotient by as much as 19 pointsref
(equivalent to 0.5 to 0.6 SD) and that birth during periods in which universal
hearing screening of newborns was in place is associated with a similar
benefitref.
The U.S. Preventive Services Task Force, however, has rated the quality
of evidence linking early treatment or birth during periods with universal
newborn hearing screening with improved language function as fair or poorref.
In a previous controlled trial in the Wessex region of southern England,
universal newborn screening increased the rate of early referral (i.e.,
before 6 months of age) for audiologic assessment of babies with bilateral
permanent childhood hearing impairment, defined as a hearing loss of at
least 40 dB hearing level (HL), on 2 assessments at least 12 months apartref1,
ref2.
Early detection of childhood hearing impairment was associated with higher
scores for language but not for speech in midchildhoodref
if air conduction and bone conduction overlap => perceptive deafness
if air conduction < bone conduction (air-bone gap) => transmissive
deafness
for simulated deafness
Gault test : the patient's good ear is closed and a sound is made
near the supposed bad ear; winking on the tested side indicates hearing.
Erhard's test : a test for detecting simulated deafness
Grading :
light deafness : 20 < HL < 40 dB
intermediate deafness : 40 < HL < 60 dB
severe deafness : 60 < HL < 80 dB
deep deafness : HL > 90 dB
The average HL or pure-tone average (PTA) should agree with the
SRT by + or -5 dB in the greatest proportion of hearing loss types. This
relationship is very often used as an internal reliability check between
pure-tone and speech test results. Someone attempting to feign a hearing
loss generally would have a much better SRT than would be predicted from
the pure-tone average. A hearing aid generally would not be considered
for a patient, unless the loss had reached the "moderate" classification
in the better ear.
Speech discrimination scores are more qualitative in their interpretation
than are SRTs. The general concept is that in sensorineural hearing loss,
the speech discrimination score will be directly proportional to the degree
of system damage (cochlear hair cells or neural fibers). There is no quantitative
way to predict speech discrimination ability from the pure-tone audiogram.
Most persons with sensorineural losses have greater difficulty with speech
discrimination in noise than in quiet. This is because the noise further
reduces their ability to hear high-frequency consonants which carry the
preponderance of speech information. Also, these patients may be very much
annoyed by loud sounds (because of the recruitment phenomenon) and make
less than ideal candidates for hearing aid use. Grading
:
> 80% on the W-1 lists are considered good
60-70% : fair
< 60% : poor
The Deaf (with a capital 'D') are a tight-knit community. They view deafness
not as a medical condition to be cured, but as a cultural identity to be
celebrated. It's a view that the hearing find difficult to understand.
But Kate Nelson, an actor with the Australian
Theatre of the Deaf (ATOD) in Sydney is ideally placed to try to explain
it. While some are born into the Deaf community, Nelson was born into a
hearing family and has only come to Deaf culture relatively late in life.
Nelson was born profoundly deaf, meaning that she could hear some sounds,
but not enough to understand speech. She was brought up completely in the
hearing world -- she wears hearing aids, can speak clearly and lip reads.
She did not discover sign language until she was 21. Now in her 30s, Nelson's
hearing is deteriorating further, and she finds herself increasingly identifying
with the Deaf community. Sign language is much more than creating hand
shapes, she points out. It incorporates facial expressions, posture and
other body movements. When Nelson switches from speaking to signing, she
becomes more animated, with her whole face and body conveying meaning and
feeling. In the future, Nelson wants to explore more deaf issues, such
as the desire of some deaf people to have deaf childrenref Therapy :
aural rehabilitation comrises methods of amplification (provision of hearing
aids and instruction in their use), and the maximisation of communication
skills
amplification
provision of hearing aid
instruction and counselling in its use
maximisation of communication skills
lip reading
"learning to listen"
speech conservation
utilising visual clues
Patients must be counselled to understand that the aid does not allow them
to hear normally but will enable them to have less difficulty understanding
others. This will not happen overnight and patients need to be aware that
it will take some time for them to get used to certain patterns of sound
made louder. Where available, group orientation programmes have proved
useful in increasing the benefits obtained by new hearing aid users. In
addition to being supplied with hearing aids patients also need to be taught
how to improve their communication skills. This may involve speech reading,
learning to listen (listening is an active process unlike hearing), tuition
to maintain good quality speech, and instruction on how to utilise visual
clues such as facial and body gestures. Speech and language therapists
have a significant role in the teaching of speech conservation and lip
reading classes are taught by audiologists or at adult education centres.
environmental aids :
sound enhancement
telecommunications
television enhancement
signal alerting
To distinguish words and sounds hearing aid users need the primary signal
to be significantly louder than the background noise. This is feasible
if the speaker is close and background noise is at a minimum. At home older
people can ask visitors to come closer and switch off the television. However
in restaurants, theatres, and noisy wards where the doctor may stand at
the foot of the bed the listening environment can be very taxing. It is
important for patients and doctors to realise that turning up the volume
may make matters worse. Assistive listening devices or environmental aids
are invaluable in such circumstances. These fall into 4 categories. An
example of sound enhancement technology, a voice amplifier, was used in
the study of Fook et al.. With sound enhancement technology the signal
(such as speech from an individual or sound from a television) is transmitted
directly to the ear of the individual via hardwire, radiotransmission,
or infrared. The problems of environmental noise and distance are thus
avoided. The voice amplifier or communicator is a an example of a hardwired
system. These are relatively inexpensive and are ideal for use when being
interviewed by professionals in a ward environment. Radiosystems may be
used when speaker and listener are in different rooms, and the receiver
may be incorporated into a behind-the-ear aid. Infrared systems are most
suited for transmission from media such as televisions and stereo systems
(as in concert halls). Built in amplifiers can be used to help those with
hearing impairment use the telephone. Even despite these measures some
elderly people still have difficulty discriminating speech over the telephone.
The boom in home computers and email (not the sole province of the young!)
has been a blessing in such circumstances. Telecaptioning, where dialogue
is displayed across the bottom of the television screen, is another helpful
visual adaptation, while a vibrating pillow, which notifies someone it
is time to get up, or flashing doorbells are examples of a signal alerting
devices. Audiologists who specialise in environmental aids can provide
advice to individuals and institutions about all such devices, and they
can be supplied to individuals through social services departments.
diplacusia / diplacusis / double disharmonic
hearing : the perception of a single auditory stimulus as 2 sounds,
as a result of cochlear pathology
binaural diplacusis : different perception of a single auditory
stimulus by the 2 ears
disharmonic diplacusis : a form of diplacusis in which a given pure
tone is heard differently in the two ears.
echo diplacusis : a form in which a sound of brief duration is heard
in the one ear a fraction of a second later than in the other ear.
monaural diplacusis / diplacusis monauralis : a form in which a
pure tone is heard in the same ear as a split tone of 2 frequencies
pseudotinnitus : sensation of pulsation
or murmur sensed when lying at bed and/or lying the ear over the cushion.
It may cause alarm in patients with panic
disorder
tinnitus (aurium) / acuphen : a noise in
the ears, such as ringing, buzzing, roaring, or clicking
tinnitus cerebri : tinnitus experienced as being inside the head
rather than in an ear.
objective tinnitus : a rare type of tinnitus that is audible to
others, such as to an examiner with a stethoscope
clicking tinnitus : a form of objective tinnitus in which the patient
hears a clicking sound; it occurs with serous
otitis media.
Leudet's tinnitus : a form of objective tinnitus in which the patient
hears a crackling sound, produced by involuntary contraction of an internal
muscle, coinciding with a tic of fibers of the mandibular division of the
trigeminal nerve.
subjective tinnitus : the usual type of tinnitus, in which the sound
cannot be heard by an examiner or measured by objective instruments
nonvibratory tinnitus : produced by biochemical changes in the nerve
mechanism of hearing.
vibratory tinnitus : caused by transmission to the cochlea of vibrations
from adjacent tissues or organs, most often from blood in vascular malformations.
Occasionally the vibrations are loud enough to be heard by an examiner.
pulsatile tinnitus : sound is rhythmic and synchronous with the
heartbeat
objective vertigo : the objects seen by the patient seem to be moving
around him
subjective, rotar, rotatory or systematic vertigo : the patient
has a sensation of turning round and round
encephalic vertigo : a sensation of movement of tissues within the
skull, as of the brain turning over and over.
Lermoyez's syndrome : tinnitus and hearing loss preceding an attack
of vertigo and then subsiding after the vertigo has become established
It is rotatory (differential diagnosis from lipothymia
and obnubilation), has acute-onset and may
last hours. The difference between objective and subjective has no prognostic
meaning
Aetiology :
central vertigo : vertigo due to disease
of the CNS
cerebral or organic vertigo : vertigo resulting from a brain lesion,
such as a cerebellar infarct
angiopathic or
arteriosclerotic vertigo : vertigo due to arteriosclerosis
of cerebral vessels, particularly the vertebral or basilar arteries (vertebrobasilar
insufficiency)
Aetiology : associated with either an
URT infection (in the autumn) or gastroenteritis (in mid-January)
Symptoms & signs : acute onset of
severe dizziness,
nausea
and vomiting,
a slight fever,
headache,
and asthenia, with a duration of several weeks to months.
Laboratory examinations : caloric and
audiological tests usually are normal, but spinal fluid may show some lymphocytic
cells.
Treatment : antivertiginous and antinausea
drugs such as Dramamine, Vontrol, Torecan, and Tigan.
Prognosis : recovery is usual
epileptic vertigo : vertigo that accompanies vertiginous epilepsy,
usually as part of an aura
primary, peripheral
or vestibular vertigo : vertigo due to disturbances of the vestibular
system
alternobaric or pressure
vertigo : a transient vertigo sometimes affecting those such as caisson
workers and members of airplane crews who are subjected to large, rapid
variations in barometric pressure
ocular vertigo : a form due to eye
disease,
especially to paralysis of or lack of balance in the eye muscles, uncorrected
myopia, diplopia
pilot's vertigo
/ spatial disorientation : a condition in which a pilot or other air
crew member is unable to determine accurately his spatial attitude in relation
to the surface of the earth; it occurs only in conditions of poor visibility
or when vision is otherwise restricted and results from vestibular illusions
Tullio's phenomenon : vertigo induced by high-intensity sounds.
mechanical vertigo : vertigo due to long-continued turning or vibration
of the body
kinetosis : any disorder caused by unaccustomed
motion, characterized by nausea
and vomiting,
anorexia, headache, malaise, salivation, drowsiness, lethargy, and cold
sweats
riders' vertigo / motion sickness
:
sickness caused by motion experienced in any kind of travel, such as ...
mal de mer / sea sickness :
caused by the motion of a ship
train sickness : produced by the motion
of trains
car sickness : produced by the motion
of automobiles or other vehicles
aerial, air or aviation
sickness : due to change in air pressure and to the movements experienced
in an airplane
space adaptation
syndrome / space sickness : a form of motion sickness occurring in
a weightless environment during space flight. It is probably caused by
conflicting signals concerning motion from the otolith (whose proper function
depends on the presence of gravity) and the visual system (which affects
the autonomic nervous system)
somatosensorial vertigo : due to peripheral neuropathies associated to
diseases of the vestibular apparatus
posttraumatic vertigo : vertigo following some injury, such as fracture
of the temporal bone, whiplash (cervical vertigo), or lesions of
the cerebral cortex or cerebellum.
residual vertigo : 1. vertigo in the aftermath of some disease process.
2. vertigo associated with motion, resulting from hypofunction or absence
of vestibular sensory or neural elements
essential vertigo : vertigo whose cause is unknown.
positional vertigo / postural vertigo
: vertigo associated with a specific position of the head in space or changes
in the position of the head in space
cupulolithiasis that causes exaggerated movement of the endolymph
mal de debarquement syndrome
is
an uncommon illness affeting travelers after debarkation. It is characterized
by an unsteadiness and lurching., without dizziness, which may not resolve
for months or years. It is a diagnosis of exclusion, based on a characteristic
history, and paucity of findings on neurologic and ENT clinical examination,
although in some cases positional nystagmus has been detected during electronystagmography.
There are references in the literature as well to a similar and more common
entity, which typically lasts a matter of hours after debarkation. Some
have suggested the use of the term persistent mal de debarquement syndrome
to differentiate the two. The great majority of sufferes are women, and
the age range is primarily from the fourth decade into the eighth, with
a few younger patients. The duration of the unsteadiness varies from 4
weeks to 5 years
Therapy : medications used to treat dizziness
or seasickness are typically of no help. Benzodiazepines
have been reported to afford a degree of relief in some patients. Vestibular
rehabilitation has been suggested as a useful treatment. Further cruises
should be avoided once the illness has first manifested itself, even if
that first experience is of short duration.
Symptoms & signs : onset of nystagmus
and vertigo occur when the head moves to a certain position such as with
one ear down, and relieved by returning to an upright position. There usually
is a latent period of several seconds, and the nystagmus fatigues with
repeated testing. Most cases have normal calorics and audiological examinations.
Symptoms abate in about 8 weeks, but they may recur or even last for years.
Laboratory examinations : Hallpike's
maneuver (the examiner turns the head of the seated patient to one
side and pulls the patient backwards into a supine position with the head
hanging over the edge of the examining table; the patient then looks straight
ahead and the examiner observes for positional nystagmus, which is indicative
of benign positional vertigo.
Therapy :
avoidance of the position that creates the nystagmus and vertigo
liberatory maneuvers
Lempert or Baloh "barbecue" maneuver in BPPV of the horizontal semicircular
canal
Vannucchi "forced position" maneuver in elderly or overweight patients
and in those with reduced mobility
Semont maneuver, moving the patient from a seated position to a
position on the right or left side, depending the pathology and type of
vertigo (geotropic/apogeotropic)
disabling positional vertigo : constant positional vertigo or dysequilibrium
and nausea and vomiting
in the upright position, without hearing disturbance or loss of vestibular
function.
horizontal vertigo : positional vertigo experienced when a person
lies down.
vertical vertigo : positional vertigo experienced when a person
is in an upright position.
lateral vertigo : vertigo caused by rapidly passing a row of similar
objects, such as a fence or a series of pillars.
Symptoms & signs : it is associated
with a sense of lateral pull (due to connections to vestibulospinal nuclei),
consciousness of movements and head position (due to connections to thalamocerebral
nuclei), associated to nystagmus
(due to connections to nuclei of III, IV, ad VI cranial nerves), nausea
and vomiting,
pallor, salivation, and sweating (due to connections to dorsal vagal nucleus
tractus solitarii), eventually deagness, tinnitus or neurological deficiencies
paralyzing vertigo : vertigo so severe that the patient is afraid
to move
nocturnal vertigo : a sensation of falling occurring as the subject
is going to sleep.
paroxysmal vertigo : vertigo occurring in sudden, brief attacks
benign paroxysmal
vertigo of childhood : a form of paroxysmal vertigo occurring in young
children otherwise in good health; sudden attacks are accompanied by pallor,
sweating, and immobility and less often by nausea
and vomiting
and nystagmus.
Timing : status vertiginosus : prolonged
vertigo
single episode :
current
in the past : labyrinthitis (in absence of neurological signs or deafness
with tinnitus)
recurrent :
benign (Meniere's
disease,
neuronitis, BPPV) :
mixed nystagmus not inhibited by fixation of sight, more intense; strong
and latent (40 seconds) response to Hallpike maneuver, with mixed and not
repeatable nystagmus
malignant (vestibular epilepsy) : pure nystagmus, mild and repeatable response
to Hallpike maneuvers, with immediate and pure nystagmus
central injury (pons and cerebellum) : vascular injury, demyelination,
neoplasms, trauma, other neurological lesions
Differential diagnosis with other lightheadedness
: orthostatic
systemic arterial hypotension,
walking disorders (peripheral neuropathies, myelopathies, cerebellar ataxia,
Parkinson's disease combined with visual deficiencies); Krishaber's
disease / cerebrocardiac syndrome : a syndrome characterized by tachycardia,
insomnia, lightheadedness or vertigo, hyperesthesia, and a feeling of emptiness
in the head
Differential diagnosis between central and peripheral nystagmus is
made on the basis of : kind of nystagmus, intensity (more severe in peripheral
nystagmus, auditory disturbances (deafness, tinnitus : if it is not Meniere
disease, it is probably acoustic
neurinoma),
occurrence of other neurological symptoms (e.g. lack of abdominal reflexes
=> CNS, motor disorders => vestibular nuclei)
Therapy : antivertiginous
drugs
and antiemetic
drugs
cerebrospinal fluid otorrhea
/ otoliquorrhea : escape of CSF through the external auditory meatus
due to fracture or other pathology of the temporal bone leading to CSF
fistula.
otohematoma due to fracture of rocca petrosa
without perforation of tympanic membrane
sensation of fullness or pressure in the ears
Laboratory examinations :
acoumetry
vocal acoumetry
aphonous voice
conversation voice
high tones
low tones
diapason acoumetry (pure tones)
Rinne test : a hearing test performed, with the opposite ear masked,
with tuning forks of 256, 512, and 1024 Hz by alternately placing the stem
of the vibrating fork on the mastoid process and 1/2 inch from the external
auditory meatus until it is no longer heard at one of these positions.
When air conduction is greater than bone conduction (positive Rinne test),
it indicates normal hearing or sensorineural hearing loss. When bone conduction
is greater than air conduction (negative Rinne test), it indicates conductive
hearing loss
Weber acoumetry : placed on forehead, symmetric or asymmetric hearing
Schwabach's test : a hearing test performed, with the opposite ear
masked, with tuning forks of 256, 512, 1024, and 2048 Hz, alternately placing
the stem of the vibrating fork on the mastoid process of the patient and
that of the examiner (whose hearing should be normal) until it is no longer
heard by one of them. The result is expressed as “Schwabach prolonged”
if heard longer by the patient (indicative of conduction deafness), as
“Schwabach shortened or diminished” if heard longer by the examiner (indicative
of sensorineural deafness), and as “Schwabach normal” if heard for the
same time by both.
Bing test : a vibrating tuning fork is held to the mastoid process
and the auditory meatus is alternately occluded and left open: changes
in loudness (positive Bing) are perceived by the normal ear and in sensorineural
deafness, but in conduction deafness no difference is perceived (negative
Bing).
audiometry
basic hearing tests
the ability to hear a vibrating tuning fork (Weber test)
may help the doctor to determine if hearing loss is transmissive (due to
a middle ear problem) or neurosensorial (due to nerve damage) in origin
audiometers => audiogram
manual, self-recording
microprocessor controlled
pure-tone audiometry / liminar tonal audiometry : the patient is
asked to respond whenever he hears a pure tone, increasing or decreasing
intensity of the signal. The lowest intensity at which the patient responds
at a particular frequency is called the hearing level (HL). HLs
are determined at
octave frequencies 250, 500, 1000, 2000, 4000 and 8000 Hz
half-octave frequencies of 3000 and 6000 Hz.
Each continuous tone is presented for a period not exceeding 1". Intermittent
(pulse) tones are also frequently used, especially in patients where tinnitus
is present. There will be several tone presentations at a particular frequency
before the HL is recorded on the audiogram. Masking noise generated
within the audiometer is used when one ear needs to be isolated from the
other in order to get a correct threshold measurement for the test ear
broad-frequency band noise is most efficient for masking pure-tones
narrow-frequency band noise
In a situation where one ear of the patient is "dead", incorrect information
would be obtained for the nonfunctional ear if masking were not used for
the good ear. By air conduction measurement, the nonfunctional ear would
yield HL's around 50 to 60 dB. This is due to a phenomenon called "crossover."
Even
though the signal is presented at the nonfunctional ear, it is heard by
the good ear primarily by direct energy transmission through the head from
the vibrating earphone cushion. The head creates about a 50 to 60 dB
"barrier" between ears. If proper masking noise is applied to the good
ear in the case mentioned, then a correct determination of a profound hearing
loss would be made. Masking of the contralateral ear is done more frequently
in BC than in AC. This is because interaural attenuation, while
about 50-60 dB for AC, is practically nonexistent (0-5 dB) for BC. In the
previous example of the "dead" ear, a BC measurement without proper contralateral
masking would have shown normal BC hearing in the nonfunctional ear due
to the low (0-5 dB) crossover levels. In general, pure-tone HLs are determined
for both ...
air conduction (AC) (earphones)
left ear = x (if masked square)
right ear = o (if masked triangle
with upward apex)
bone conduction (BC) (electromechanical vibrator). HLs are determined
at 250, 500, 1000 and 2000 Hz (Weber), Gellé, Bing and occlusion
index. Since it requires more energy to drive a mechanical vibrator than
an earphone, the maximum hearing loss that can be measured for BC is less
than for AC, (e.g., 70 dB for BC and 110 for AC). Care should be taken
to place the vibrator on the mastoid without contacting the pinna. This
is to ensure that responses at low frequencies are auditory and not tactile
in nature.
left ear = < (if masked triangle
with leftward apex)
right ear = > (if masked triangle
with rightward apex)
speech audiometry
speech reception threshold (SRT) : the amplitude at which the patient
can repeat back approximately 50% of the 2-syllable words presented to
him. There are 6 word lists, each list being a different scrambling of
the same 36 words. The most widely used form is CID Auditory Test W-1
phonetically-balanced (PB) score / PB Max : the percentage of 50
single-syllable words the patient can correctly repeat back is determined.
When these word lists (24 lists with 50 words each, and 200 words in the
corpus) were developed in the late 1940's, it was believed that the phonemes
in each 50-word list had to have the same proportionate frequency of occurrence
as that in everyday English, in order for the test to be valid. This was
later shown to be unnecessary, but the terminology "PB" still remains today.
The relationship between word discrimination and amplitude (SPL) is called
articulation
curve or performance intensity (PI) function. The PB words,
the most widely used form being CID Auditory Test W-22, are
presented
at a level of 40 dB above the SRT in routine use. Since this represents
a supra-threshold presentation, masking noise is almost always used in
the contralateral ear. It is at this amplitude or sensation level
(SL) that most patients would achieve maximum performance. However,
there are instances where this is not the case. So, ideally, a performance
intensity function would be generated by presenting the monosyllabic word
lists at a variety of sensation levels. A phenomenon called roll-over
is is characterized by a wornsening of discrimination as loudness
is increased. This finding is characteristic of retrocochlear disorders
(e.g., acoustic neuroma) and to a lesser extent Meniere's syndrome.
Often speech discrimination testing is done in a noise background. A variety
of word lists and test formats are used for this purpose. The basic concept
behind this is to provide a more realistic environment in the measurement
of speech discrimination. The signal to noise ratio (S/N) is expressed
in dB, and represents the number of dB the average signal (speech in this
case) is above or below the level of the noise.
threshold tone decay test (TDT) is a pure-tone, supra-threshold
test usually done at 4,000 Hz first, and, if positive, the test frequency
is dropped by octaves until 500 Hz is tested. The tone is presented at
5 dB sensation level (SL) for 1 minute. If the patient can hear
the tone for the entire period at the same level, the test is negative.
If the level of the tone has to be raised by 20 or more dB above the starting
level, the test is positive. The TDT is a measure of auditory adaptation
and is considered a screening test for retrocochlear pathology. If the
test is positive, other, more detailed, tests would be done in order to
help establish the reason for the abnormal adaptation and the site of the
lesion. The suprathreshold adaptation test (STAT) is also frequently
used. The test is positive if a high level (e.g., 100 dB) tone cannot be
heard over a 60" period.
advanced hearing tests
short increment
sensitivity index (SISI) : tones of 1- to 5-decibel increments in intensity
and lasting 0.5 second are superimposed on a continuous (carrier) tone
of the same frequency at random intervals, the carrier tone being 20 decibels
above the speech reception threshold. Pure-tones (250, 500, 1000, 2000,
4000 or 6000 Hz) are presented at 25 dB SL. The result is expressed in
terms of % correct identification out of 20, 1-dB increments, added to
a reference pure-tone level. A high % correct response is indicative of
a cochlear pathology as only patients with cochlear damage can detect these
increments
alternate binaural
loudness balance (ABLB) test is 1 of 2 direct tests of a phenomenon
called recruitment. Recruitment is an abnormal growth of loudness in which
soft sounds are not heard while loud sounds are perceived to be as loud
as in a normal ear. The presence of recruitment narrows the dynamic range
of hearing significantly and is characteristic of a cochlear (sensory)
pathology. In order to do this test, it is necessary for hearing to be
within normal limits in the contralateral ear at the same frequency at
which the test is being done in the poorer ear.
Bekesy audiometry is an advanced site-of-lesion test and is a special
form of the more routine, self-recording audiometry procedure. The patient
is asked to track his pure-tone threshold by means of a response button,
first for a pulsing tone and then for a continuous tone. Either a discrete
frequency or continuous frequency tracing can be generated. The audiograms
are traced on the same graph. The audiogram is then categorized according
to the relationship between the pulsed and continuous tracings. There are
5 recognized types of Bekesy audiograms
type I Bekesy tracing
type II Bekesy tracing
type III Bekesy tracing
type IV Bekesy tracing
type V Bekesy tracing in patients attempting to feign a hearing
loss. It has essentially a type IV configuration, except that the continuous
and pulsed tracings are reversed (i.e., hearing for the continuous tone
is shown as being better than hearing for the pulsed tone). Perceptually,
the loudness of a supra-threshold tone is greater for a continuous signal
than for a pulsed signal. What the patient is actually doing is tracing
an equal loudness contour for each type of signal. It should be noted that
this test can be done with some of the self-recording screening audiometers
in the fleet. All that is necessary is to be able to select either a pulsed
or continuous tone on the instrument. In a clinical setting, the LOT test,
mentioned previously, would be done and would in most cases accentuate
the dB separation between the 2 tracings.
Bekesy testing is much more effective in identifying sensory problems than
it is in identifying retrocochlear problems.
Bekesy comfortable loudness technique (BCL)
reverse Bekesy tracings
lengthened off time (LOT) test is also used where malingering is
suspected. This is basically a Bekesy test with the period between pulses
lengthened and unequal to the duration of the pulse itself, (e.g., 800
ms off and 200 ms on). This temporal pattern magnifies the difference between
the pulsed and continuous tracings, making the identification of possible
malingering easier.
electrophysiological noninvasive measures of auditory function that
involve computer averaging of the auditory system's electrical response
to clicks or tone pips used in cases of functional (nonorganic) hearing
loss or psychogenic problems (noncollaborative babies)
sensitized speech tests are tests in which the auditory stimulus
is speech that has been altered, either in the amplitude, temporal, or
frequency domain. They are used when a central auditory disorder is suspected.
"Central" is defined as a site of lesion somewhere in the brainstem or
cortical auditory areas. Pure-tone tests are not sufficiently complex in
nature to identify these lesions. In general, as the site of lesion proceeds
centrally in the auditory system, the tests to identify it need to become
more and more complex in structure. The flight surgeon's contact with this
type of test information would be quite rare in the active duty population.
It would more likely occur in the retired or dependent groups.
binaural distorted speech tests : tests of the capacity of the CNS
to coordinate 2 incoming speech patterns, each of which is incomplete.
monaural loudness balance (MLB) test : a test to determine recruitment
in bilateral sensorineural deafness; the loudness sensation at impaired
frequencies is compared with that at normal frequencies
impedance audiometry / impedancemetry measures various mechanical
aspects of the middle ear. A probe tip is inserted into the test ear and
an airtight seal is obtained before testing begins. A standard earphone
is placed over the contralateral ear. There are 3 holes in the probe tip
:
to introduce a pure tone with n = 220 Hz into
the space created between the tip of the probe and the tympanic membrane
to a microphone which measures the SPL in the space
to introduce air into the space (either negative or positive pressure relative
to normal atmospheric pressure can be achieved)
4 general measurements are obtained using the impedance audiometer
Metz test / acoustic reflex test
: measurement of the acoustic reflex threshold by testing for contraction
of the stapedial muscle in response to sound; used to differentiate between
conductive and sensorineural deafness and to diagnose acoustic neuroma.
Stapedial
reflex thresholds - ipsilateral and contralateral - are determined
by introducing an acoustic stimulus at various amplitudes through the earphone.
When the amplitude is high enough (75 dB above the threshold for that frequence
for pure tones (usually 500, 1000 or 4,000 Hz) : maybe the device cannot
produce such SPL), the stapedius will contract. Since this is a consensual
reflex that stiffens both tympanic membranes, it can be monitored on the
opposite side as a change on the compliance meter indicating lowered compliance
(i.e., higher impedance). It lacks in otosclerosis,
tympanosclerosis,
and facial nerve palsy before stapedial
ramus.
static compliance is calculated from the difference in volume between
the resting compliance measurement and the measure taken with 200 MMW (equivalent)
pressure - the inverse of impedance and expressed in cc or mL
tympanogram : a dynamic plot of compliance (inversely related to
acoustic impedance) as a function of externally applied pressure (from
-400 to +200 mmH2O to avoid mechanical damage) automatically
generated by the machine and recorded on an associated plotter. This indirectly
measures pressure in middle ear as compliance is maximal when Pmiddle
ear = Papplied (expressed in MMW or daPa)
type A (normal) tympanogram : bell-shaped with peak = 0.7 mL at
P = Patm.
type D tympanogram : enlarged and flattened curve with peak = 0.2
mL at P = - 200 mmH2O
type E tympanogram : curve with peak = 0.5 mL at P = - 300 mmH2O
type F tympanogram : curve with peak = 0.7 mL at P = + 100 mmH2O
type G tympanogram :curve with first peak = 0.7 mL at P = -75 mmH2O,
incisure = 0.3 mL at P = Patm, and second peak = 0.9 mL at P
= + 50 mmH2O
type H tympanogram : bell-shaped with peak = 0.95 mL at P = Patm
(seen in interruption of ossicle chain)
Exam may be painful if patient has otitis externa and makes no sense if
he has perforation of tympanic membrane
Andersson test / reflex decay test :
alternate binaural loudness balance (ABLB) test : comparison of
the intensity levels at which a given pure tone sounds equally loud to
the normal ear and the ear with hearing loss; done to determine recruitment
with unilateral sensorineural loss.
alternate loudness balance test : a hearing test done with pure
tones that compares the loudness perceived in one ear with that perceived
in the other, with the frequency kept constant.
In addition to defining middle ear problems, impedance audiometry can yield
useful information in helping to identify the following conditions :
latent nystagmus : nystagmus which occurs only when one eye is covered.
positional nystagmus : that which
occurs, or is altered in form or intensity, on slow assumption of certain
positions of the head without practicing head rotations
Signs : Cawthorne, Dix, and Hallpike
method : with the patient's eyes in the straight ahead position, the
patient is rapidly placed supine with the head hanging over the edge of
the table, and the eyes are observed for 60". The patient is then raised
up and then returned to the hyperextended position with the head in one
direction, again for 60". The procedure is repeated in the opposite direction.
The position should be held until the nystagmus subsides
permanent positional nystagmus : it persists for > 60" and has central
origin
PAN I begins about 30' after ingestion, as the blood alcohol peaks,
and lasts approximately 3 and a half hours. The nystagmus is always in
the direction of the gaze or toward the position of the head, for examble,
a right-beating nystagmus appears with right gaze, head turned to the right
side or if the right of the patient's head is down in the lateral position.
There is a gradual diminution after the peak and an intermediate period
of about 1.7 hr in which there is no nystagmus.
PAN II begins approximately 5 hours after the initial ingestion,
and the nystagmus is in the opposite direction of the gaze or lateral head
position and persists for several hours after the blood alcohol level has
disappeared. PAN II is greatest when the "hangover" symptoms are greatest.
rotatory nystagmus : even in presence of disease, the 2 labyrynths
are symmetric and answers are overlapped up to a
= 15°/s2
head- shaking test (20 passive head oscillations in 10") under Frenzel
eyeglasses => uncompensated system with unknown aetiology
rotating seat have upper limit for a
= 18°/s2, only 1 or 2 measures are meaningful
caloric nystagmus : rotatory nystagmus induced by irrigating the
ears with 250-300 mL of warm or cold water for 40" (Hallpike-Fitzgerald
technique) or air when patient has head inclined downward by 30°
to place the lateral semicircular canals (the most used in vivo)
on horizontal plane (Brunig position)
caloric test / Búrúny's test, sign, or symptom / nystagmus
test (for ocular and vestibular functioning) : irrigation of the normal
ear with warm water produces rotatory nystagmus (caloric nystagmus) toward
the irrigated side; irrigation with cold water produces similar nystagmus
away from that side
cold water (30°C) => ampullifugal current => inhibitory current for
120"
warm water (44°C) => ampullipetal current => excitatory current for
100"
The fast component of nystagmus is directed toward the prevalent labyrinth.
total system reflectivity (TR) = warm waterright ear
+ cold waterright ear + warm waterleft ear + cold
waterleft ear
Normal values are within 1s from average (i.e.
±15% for LP and ±18% for DP)
galvanic or electrical nystagmus : a vestibular nystagmus caused
by electrical stimulation of the labyrinth of the inner ear
optokinetic nystagmus
pendular nystagmus
pneumatic nystagmus
harmonic acceleration test (for vestibulo-ocular reflex): rotation
of a patient seated in a chair in complete darkness, with monitoring of
eye movements; with normal vestibulo-ocular reflexes the eyes will undergo
rotatory nystagmus to the same degree in both eyes in the direction opposite
to that of the rotation.
Hitzig test (for vestibular apparatus): the positive electrode of
a galvanic current is applied just in front of the ear being examined while
the negative electrode is held in the patient's hand, the patient standing
with feet together and eyes closed. A current of 5 mA causes a leaning
toward the positive pole in normal persons
stabilometry
static stabilometry
dynamic stabilometry
Diseases :
panotitis : an inflammation of all the parts
or structures of the ear
diseases of outer ear
congenital malformations
of the outer ear
coloboma :
fistula auris congenita /
congenital preauricular fistula : an epidermis-lined tract communicating
with an ear pit on the skin; it results from imperfect fusion of the first
and second branchial arches in formation of the auricle
atresia auris / aural atresia : obstruction
of the external acoustic meatus; it may be either congenital or acquired
through trauma or disease
anotus / anotia : congenital absence of the
external ear(s)
microtia : gross hypoplasia or aplasia of
the auricle (pinna) of the ear, with a blind or absent external acoustic
meatus
polyotia : the condition of having more than
2 ears.
triotus : an individual with a supernumerary ear
melotia : a developmental anomaly characterized
by displacement of the ear onto the cheek
macrotia : abnormal enlargement of the pinna
of the ear.
otohematoma / auricular hematoma / hematoma
auris : hematoma of the perichondrium of the auricle, most often on
the superior lateral surface, resulting in a hematoma.
Aetiology : trauma
Therapy :
in the early stages, aspiration of the blood using sterile technique with
a large 14-gauge needle. A pressure dressing is then applied.
for large, chronic, or recurrent hematomas, incision and drainage are recommended.
The entire ear is disinfected and anesthetized, a large curving incision
is made through the skin of the scaphoid fossa following the curvature
of the helix. The hematoma is then evacuated using sterile technique. In
some chronic or recurrent cases, instead of blood there is only xanthochromic
fluid. Some surgeons advise curettement of the cyst walls. A thin rubber
drain is inserted the length of the hematoma sac and then withdrawn over
the next 2-3 days. Fine nylon or silk interrupted sutures about 1 cm apart
are used for closure of the incision, and a pressure dressing is applied.
Through and through monofilament sutures tied over soft sponges for direct
pressure are also effective.
Prognosis : left untreated, the slow absorption
of blood, loss of nourishment to the cartilage, and infection may lead
to a deformed auricle or "cauliflower ear".
lacerations
Therapy : avoid excessive debridement,
approximate the cartilage with perichondrial sutures on both sides, use
white silk or cotton for buried sutures on the thin lateral surface, and
use good splinting with a pressure dressing. Even though a portion of the
ear may look nonviable, it is usually best to clean, approximate, splint,
and then wait for demarkation before final debridement. Through and through
sutures tied lightly over cotton rolls, etc., may be used for splinting
as well as the pressure dressing. Exposed cartilage or subcutaneous tissue
should be covered with fine mesh gauze impregnated with an antibiotic ointment.
Adequate antibiotic coverage is strongly recommended.
foreign bodies in
the external canal. Anything that will fit has been found in the external
auditory canal. Some of the foreign bodies are inert and cause no problems
or symptoms, but most commonly they produce a canal blockage with a mild
decrease in hearing, itching, infection, and drainage or even a cough,
mediated through pressure on the twig of the tenth cranial nerve (Arnold's
nerve). Removal of round objects is most difficult, and it is best accomplished
with a fine, blunt, right angle hook that can be inserted past and behind
the object. Special cup or serrate jaw forceps can also be used. Hard,
sharp, and large objects should be softened, if possible, and removed with
care, protecting the canal from trauma and bleeding. Compressed strips
of Gelfoam® may be tried on sharp corners. Friable or adherent
material may require loosening or dissolution before removal. Debrox®
(carbamide peroxide) works well in most cases. A fine stream of water,
2% acetic acid in water, or alcohol is used for irrigation and directed
under direct vision and controlled pressure. Hydroscopic objects such as
corn or peas may swell if saturated with water, therefore, alcohol irrigation
or forcep/hook removal is recommended. Live insects should be killed rapidly
by flooding of the canal with ether, alcohol, or oil and then removed with
forceps. After the object has been removed, the canal should be suction-cleaned
or wiped dry and eardrops or ointments applied for treatment of any possible
tissue trauma or infection.
hypertrichosis pinnae auris
/ hairy ears : hypertrichosis involving the pinna of the ear; it may
be a Y-linked or an autosomal dominant trait
chondrodermatitis
nodularis chronica helicis / Winkler's disease : a small, painful,
scaly, nodular lesion on the helix of the ear, colored skin color, grayish,
or translucent; multiple lesions may occur along the rim of the ear. Seen
usually in middle-aged men and more often on the right ear
keratosis obturans : obstruction of the external auditory meatus
by a mass of desquamated epithelium and cerumen
otitis externa / external otitis
Aetiology : maceration of the skin from
water or other fluid drainage and trauma, often self-inflicted, when trying
to scratch or clean wax from the canal. Infection may take place in cartilage,
hairs and sebaceous and ceruminous glands
acute otitis externa (AOE)
/ swimmer's ear / tank ear
diffuse otitis externa : involving
a relatively wide area, without formation of a furuncle
malignant AOE / necrotizing AOE : Pseudomonas
aeruginosa
(38%) : progressive, necrotizing, frequently fatal infection of the external
auditory canal and base of the skull; it affects chiefly elderly diabetes
mellitus
and immunocompromised patients.
fungal AOE / otomycosis / Hong Kong, hot weather,
Singapore, or tropical ear (< 5% all AOEs)
Aetiology : commonly associated with long-term
use of antibiotic drops and wet debris in the canal.
when the canal is not inflamed and the infection is mostly a saprophytic
fungal growth, the cerumen, debris, and fungal growth are suctioned out
followed by flushing of the canal with alcohol and thorough drying
when the canal is inflamed, gentle, meticulous suction is the first step
in treatment.
Mycostatin or Fungizone cream is applied for Candida infections
Aspergillus species may require treatment with 2% gentian violet
in 55% alcohol, or 1% thymol solution in ethyl alcohol, or perhaps best
of all, a 25% m-cresyl acetate (Cresatin) solution.
In chronic otorrhea, the underlying pathology must be controlled,
or the fungus will return.
Symptoms & signs :
no hypoderma => undistendable skin => otalgia
spontaneous (=> dysphagia)
or evoked by pressure over tragus, traction of lobus or movement of TMJ
Symptoms : painful, hot cellulitis of the
pinna with brawny edema
Therapy : systemic antibiotic therapy
and warm, wet compresses, repeated cleaning of the wound. If chondritis
develops, the infected area must be opened and drained with excision of
infected cartilage.
otitis desquamativa : otitis externa in which there are overdevelopment
and desquamation of the cutaneous epithelium.
The fissures of Santorini in the floor of the external meatus cartilage
may allow for spread of infection into the soft tissues of the periauricular
region.
Therapy :
application of dry heat to the external ear
topical or systemic (in diffuse swelling or cellulitis) antibiotics
of the furuncle points, the top should be removed by suction or needle
to allow for drainage. the entire canal should be gently suctioned
and cleared of visible debris, and the inflamed tissue should be wiped
with antibiotic drops or 2% acetic acid solution. Carbamide peroxide (Debrox®)
may be needed if there is hard or thick debris. Blind suction and wiping
of diffusely swollen canals should be very gentle with attention to the
direction of the canal and distance to the tympanic membrane (2.5 cm).
A wet cotton canal wick about 3/4 to 1 inch long or the commercial wicks
(i.e., Pope Oto-wick®) are recommended for use in all cases
with diffuse swelling of the canal. Burrow's solution (1:10) is an excellent
astringent-type medication, but any of the antibiotic-cortisone aqueous
otic preparations can be used on the wick. The cotton wick should be large
enough to be snug and in contact with the inflamed tissues. It is kept
wet and removed after 24 hours. Antibiotic drops themselves create debris,
so the canal should be cleaned and a new wick inserted daily until the
swelling has markedly resolved. Patients with adenopathy and cellulitis
should be treated with systemic antibiotics, and the pain can be controlled
with a strong anodyne
ear dressingto splint, protect, and absorb drainage from
the ear with maximum comfort to the patient. It must also resist movement
or displacement. The bandage material most commonly used is a supportive
pad behind the ear, a fluff dressing of loose gauze or mechanic's waste,
and a support covering of the dressing with material like Kling®
or Kerlix® elastic or stretch gauze. First, 2-3 4 x 4-inch
pads are folded together in half, and then a "C" shape is cut out of the
center that will fit behind and around the ear. Next, the entire ear is
covered with 2-3 inches of fluff dressing or mechanic's waste. If splinting
of the pinna contours is important, as in lacerations, this can be accomplished
by careful insertion of ointment-impregnated cotton in the grooves of the
scaphoid fossa, canal meatus, and concha. The external bandage of an elastic
or stretch gauze usually begins on the forehead and is always wrapped from
the front to the back of the ear. To keep the dressing out of the patient's
eyes, 2 pieces of umbilical tape or thin gauze are laid vertically on both
sides of the forehead. The stretch gauze is wrapped first across the center
of the fluff, across the lower occiput, above the opposite ear, and then
repeated below and above the first wrap, resulting in a football helmet
like appearance. The forehead tapes are now tied and tape strips applied
to hold the gauze in position, using intermittent applications about 6
inches in length.
tympanocervical abscess : one arising in the tympanum and extending
to the neck
tympanomastoiditis : inflammation
of the tympanic cavity and the pneumatic cells of the mastoid process
tympanomastoid abscess : an abscess of the tympanum and mastoid
ear lobe crease : a diagonal crease
in the ear lobe associated with aging;
when present in younger persons it may be a sign of coronary
artery disease (CAD).
Pathogenesis : mucosa of cassa tympani and
mastoid absorb O2 => pressure negativization => retraction of
tympanic membrane => transmissive
hypoacusia and trasudate => muciparous metaplasia => mucus => blood
Symptoms & signs : fullness in the
ear, mild intermittent discomfort or pain, and hypoacusia (not referred
by babies; evident as attention deficit, dyslalia, unless neurosensorial
problems are associated), autophonia, acuphens, loud tonality, relapsing
otalgia, vertigo. tubotympanic disease :
inflammatory disease of the middle ear resulting from eustachian tube dysfunction
and decreased pressure in the tympanic cavity.
Laboratory examinations :
otoscopy shows some with either a normal appearance or slight hyperemia
of the vascular strip. The short process of the malleus is prominent or
foreshortened, and the malleus may angle more posteriorly than usual (horizontal).
In chronic cases, there is a "dimple" or retraction of the pars flaccida.
ventilation tube (temporaneous prosthesis) and tympanocentesis
patulous eustachian tube
: abnormal patency of the tuberef
Aetiology : associated with pregnancy,
rapid weight loss, mucosal atrophy (e.g., that due to atrophic rhinitis
or occurring after radiotherapy), or muscular dysfunction. In many instances,
however, a satisfactory explanation cannot be found
Pathogenesis : this anomaly permits the
movement of air into and out of the middle ear by means of the eustachian
tube during nasal breathing. The tympanic membrane moves outward when the
patient exhaled, owing to the transmission of positive nasopharyngeal air
pressure (relative to the atmospheric pressure) to the middle ear.
Symptoms & signs : when the patient
inhales, the tympanic membrane moves inward because of the opposite mechanism.
Adopting a recumbent position relieved the symptoms because of increased
venous stasis and passive compression of the eustachian tube.
Therapy : insertion of a grommet into
the right tympanic membrane, which led to the resolution of his symptoms.
direct trauma to middle ear
Aetiology : the increase in air or fluid
pressure in the ear canal caused by a slap to the side of the head, falling
off water skis, improper water entry during a dive, ear blocks while flying,
ear squeeze during SCUBA, or improper irrigation of the ear canal.
Pathogenesis : rupture of the tympanic
membrane, laceration of the canal, and occasionally, ossicular disarticulation
or subluxation of the stapes.
Symptoms : bleeding, often marked tinnitus,
and occasional vertigo and hearing loss, depending
on the degree and location of the injury. Infection could result when foreign
material, especially water, is forced into the middle ear through a ruptured
tympanic membrane.
Treatment : suction clearing, oral antibiotic
coverage for 5-7 days, and a base line audiogram. Clean, small traumatic
perforations usually heal within 3 weeks, but the patient must avoid any
significant barometric pressure changes as the perforation nears closure,
and at no time should water or other fluids be allowed in the ear. Never
use ear drops unless a true infection with purulent drainage develops and
then use only the suspension preparations.
perilymph or perilymphatic fistula : rupture of the round window
with leakage of perilymph into the middle ear, causing sensorineural deafness;
it usually results from trauma such as barotrauma or from an erosive disease
process.
barotitis media
/ baro-otitis media / otitic barotrauma / aerotitis media / aviation otitis
/ aviator's ear /middle ear barotrauma (90%)
Aetiology : as one ascends to altitude,
the outside pressure decreases, and the greater middle ear pressure forces
open the "flutter valve" pharyngeal end of the Eustachian tube every 400
to 500 feet to about 35,000 feet, and then every 100 feet thereafter. During
descent, the collapsed, closed, pharyngeal end of the Eustachian tube prevents
air from entering the tube. The increasing relative negative pressure in
the middle ear further holds the soft tissues together, and muscular
(active) opening of the Eustachian tube must be accomplished before the
differential pressure reaches 80-90 mmHg. Once this magnitude of differential
pressure is established, muscular action cannot overcome the suction effect
on the closed Eustachian tube, and the tube is said to be "locked" Symptoms & signs : nausea
and vomiting,
vertigo,
rupture of the tympanic membrane, shock or syncope,
retraction of the tympanic membrane with the classic backward displacement
of the malleus, a prominent short process, and anterior and posterior folds,
hyperemia or hemorrhages in the tympanic membrane, serous and bloody fluid
visible behind the membrane.
Treatment :
equalization of pressure
Valsalva maneuver : the nose and
mouth are closed and the vocal cords opened. Air pressure is then forced
into the nose and nasopharynx forcing open the Eustachian tube and increasing
the pressure in the middle ear space. This can be observed as a bulging
of the tympanic membrane, especially in the posterior superior quadrant.
One of the best methods to prevent vocal cord closure is to instruct the
patient or aircrewman to close his nose with his fingers and then attempt
to blow his fingers off his nose, causing the nose to bulge from the pressure.
The buildup of pressure should be < 1.5" to prevent the venous congestion
that reduces the efficiency of the Eustachian tube function.
Toynbee maneuver : close the nose and swallow => small, quick retraction
movement
Politzer method : politzerization is the mechanical inflation
of the middle ear with a source of pressure, either an air pump or rubber
bag, with a one-way valve. If no gauge is present, the starting pressure
should just be sufficient to blow off a lightly applied finger. When a
pressure gauge is available, initial attempts should be done with <
10 psi. To seal and deliver the pressure into the nose, an olive tip of
metal, hard rubber, or glass is the most efficient. This tip may be attached
to an atomizer if smoke or mist is desired for diagnostic or therapeutic
reasons.The first attempt at politzerization should be done by inserting
the olive tip into a nostril, getting a good seal but not striking the
vestibule or septal walls. The opposite naris is occluded, and the patient
is instructed to repeat K-K-K-K-K, loudly and sharply, as a one second
burst of air is delivered. A characteristic soft palate flutter sound is
heard if the procedure is performed correctly. If no results are obtained
with this technique, the patient is instructed to swallow, and as the thyroid
notch raises up, air pressure is again applied in the nose. For people
who have trouble with a dry swallow, a sip of water may be given. In the
low-pressure chamber, this method is most often used to get maximum opening
of the Eustachian tube. It must be remembered that with the water technique,
prolonged or high pressure might cause damage to the tympanic membrane
with even a remote possibility of damage to the round window membrane and
inner ear
persistent serous fluid may be removed by needle aspiration, but thick
mucoid or organized blood must be removed by myringotomy if it has not
cleared after 2-3 weeks of intensive therapy
relief of pain
prevention or treatment of infections in the ear, Eustachian tube, or nasopharynx
: antibiotics are used only when infection is present in the URT or develops
during treatment.
otitis media (10%)
acute otitis media
Aetiology :
purulent otitis media / suppurative
otitis media :
90% : direct extensions of infectious rhinitis
or nasopharyngitis,
frequently set up by improper blowing of the nose.
10% : direct extensions of outer ear infections when the tympanic membrane
is broken
Symptoms & signs : deep, sometimes throbbing
otalgia exacerbated by Valsalva maneuver or swallowing, fever,
and a mild to moderate hearing loss develop. Some people occasionally may
have dizziness, nausea and
vomiting Therapy :
penicillin for 7-10 days
antihistamine decongestant or plain decongestant medication by mouth
analgesics
catarrhal otitis media / secretory
otitis media / serous otitis media produces blockage of the Eustachian
tube and middle ear mucosa inflammation, without bacterial invasion.
mucoid otitis media : serous otitis media in which the secretion
is particularly viscous
Symptoms & signs : fullness or plugged
feeling in the ear and may feel as if fluid is present. There is hyperemia
of the vascular strip and annulus. There is usually little or no hearing
loss or tympanic membrane bulging
Therapy :
antihistamine decongestant or plain decongestant medication by mouth
analgesics
otitis desquamativa : overdevelopment and desquamation of the mucous
epithelium.
Laboratory examinations : tympanic membrane
hyperemia (malleus hand and epitympanic area) and slight bulging, especially
in the pars flaccida => bulging and inflammation distort or obscure the
normal landmarks on the tympanic membrane => blanching => perforation (pain
is usually decreased, but drainage may be inadequate)
Treatment : if perforation appears to
be imminent, it is wise to do a myringotomy to assure adequate drainage
and clear perforation that heals more rapidly. If the tympanic membrane
ruptures spontaneously, suction cleaning should be done, and if the drainage
area is inadequate, consideration should be given to enlarging it by myringotomy.
The draining ear should be cleaned frequently to prevent chronic complications.
Topical medication is only used in large perforations or when an external
otitis is present or develops from the drainage.
chronic otitis media
closed tympanic membrane
congenital cholesteatoma / dermoid cyst
secretory chronic otitis media
chronic catarrhal otitis media
otitis media with effusion
catarrhotubaric otitis media
catarrhal tubotympanitis
sero-mucous otitis media
‡
glue ear : a chronic condition marked by
a collection of fluid of high viscosity in the middle ear, due to obstruction
of the eustachian tube with or without tympanic membrane atelectasis
marginal (>> nonmarginal) perforation of tympanic membrane
simple chronic otitis media : exudate
granulomatous chronic otitis media : exudate, sometimes osteitis
cholesteatoma tympani : a type of cholesteatoma
usually associated with chronic infection of the middle ear, formed of
the outer desquamating layers of stratified squamous epithelium which has
extended inward and upward to line the tympanum, epitympanum, and antrum.
Pathogenesis :
immigration theory
retraction theory
papillary proliferation theory
metaplasia theory
Epithelial invasion fromexternal auditory canal => capsule of multilayered
squamous keratinized epithelium => desquamation => cholesteatoma => exudate
=> cell proliferation (positive feedback) ; osteitis
Symptoms & signs : loss of Politzer
light cone at otoscopy due to retraction of tympanic membrane
Therapy : surgery
chronic perforation
of the tympanic membrane
Symptoms & signs : small perforations
cause minimal hearing loss
Complications :
small, dry, central perforations may be closed by cauterizing the edge
of the perforation with trichloroacetic acid. It can be left open or one
may elect to place a small patch made from cigarette paper or other thin
paper over the perforation. Usually the patch is moistened in antibiotic
drops before application.
large perforations with a dry middle ear may be closed by a tissue graft
if the Eustachian tube is functioning. Testing of this function is fairly
accurate by tympanography. Poor or absent Eustachian tube function gives
surgery a decreased chance for success.
If the ossicles show fixation or if there is considerable scarring with
adhesions, hearing might decrease somewhat further even though the perforation
is closed, as a result of the poorer transmission of sound and the cancellation
effect of sound striking both oval and round windows at the same time.
A perforation, per se, which allows for equalization of pressure
between the middle ear and the atmosphere does not affect flying. Sudden
cold or hot air or water and loud noise may cause vertigo
more easily in the perforated ear. Of course, water in a perforated ear
usually leads to infection and drainage. The principles of treatment are
meticulous cleaning of the canal perforation and middle ear, removal of
granulation tissue, and control of the infection with both systemic and
topical antibiotics solutions introduced into the middle ear. One technique
is to fill the canal with the solution and gently compress the tragus into
the meatus while swallowing. If the otorrhea is not too heavy, antibiotic
powders may be insufflated, or the older powder preparations, such as Sulzberger's
1% iodine and 1% boric acid, are often effective. For thick drainage and
debris, it may be necessary to irrigate with a 1.5-2% acetic acid solution.
The area should be suctioned clean and dry before using the antibiotic
drops or powders to increase their effectiveness.
Brown's sign : blanching of the tympanic membrane and of the area
behind it, seen with pneumatic pressure on the membrane; it indicates presence
of a vascular tumor or other lesion in the middle ear.
mastoiditis : inflammation of the mastoid
antrum and cells, sometimes as a result of otitis media.
Bezold's mastoiditis : a form in which the pus has escaped and formed
tracts into the neck
Complication : vonBezold's
abscess is an abscess in the neck in which pus tracts have formed deep
to the superior portion of the sternocleidomastoid muscle and along the
posterior belly of the digastric muscle
coalescent mastoiditis : a form in which the bony partitions between
the air cells erode so that air cells coalesce into large cavities; further
erosion of the temporal bone runs the risk of intracranial abscess.
sclerosing mastoiditis : mastoiditis attended with hardening and
condensation of the bone.
silent mastoiditis : a progressive destructive mastoiditis with
mild systemic and local manifestations.
Symptoms & signs :
Bezold's sign : an inflammatory swelling below the apex of the mastoid
process
Granger's sign : if in the radiograph of an infant < 2 years
old, the anterior wall of the lateral sinus is visible, extensive destruction
of the mastoid is indicated.
Bethea's sign or method : when the examiner, standing behind the
patient, places his fingertips on the upper surfaces of corresponding ribs
high in the patient's axillae, unilateral impairment of chest expansion
is indicated by less respiratory movement of the ribs on the side affected
Complication : mastoid or intramastoid
abscess : an abscess within the mastoid process and the air cells =>
mastoid
empyema : suppurative inflammation of the mucous lining of the cavities
of the mastoid process
diseases of inner ear
inner ear trauma : temporal bone
fractures
longitudinal or middle fossa fracture that parallels the long axis
of the petrous pyramid is usually due to forces applied to the temporoparietal
region. The middle ear is always damaged. The tympanic membrane is torn
and bleeds. The labyrinthine capsule is usually spared, as is the facial
nerve. Longitudinal temporal bone fractures are 4 times more frequent than
the transverse variety.
transverse or posterior fossa fractures usually result from forces
applied to the occipital or occipitomastoid region. There is essentially
a fracture of the labyrinth that spares the middle ear. There may be hemotympanum,
but rarely rupture of the tympanic membrane. Usually, there is both cochlear
and vestibular function loss, and the facial nerve is damaged in the internal
auditory meatus or horizontal portion. Only sterile ear instruments should
be used for examination, and dry ear precautions must be taken.
Treatment : cranial checks, prophylactic antibiotics,
and a complete neurological evaluation. A baseline audiogram is valuable
if the patient's condition permits.
Aetiology : overly aggressive use of the
Valsalva
maneuver to clear what the patient thought was an ear block. In reality,
the problem was an over-inflated middle ear and distended tympanic membrane,
which gives a similar blocked feeling, but usually has no pain
Symptoms & signs : when the round
window membrane ruptures, there may be variable degrees of tinnitus
and persistent or positional vertigo,
often with nausea and vomiting Laboratory examinations : calorics are
usually diminished on the involved side, and a sensorineural
hearing loss, often across the board, is present with poor discrimination
of words
Prognosis : most complete recoveries have
had repairs within 48 hours
otosclerosis
Aetiology :
hereditary (50%)
autosomal dominant inheritance with incomplete penetrance
polygenic inheritance
sporadic (50%)
Pathogenesis : primitive osteodystrophy of
labyrinthine capsula => bone demineralization => deposition of new bone
tissue (Schwartze's sign : pink blush behind the tympanic membrane
because of hyperemia of the mucous membrane around the promontory at otoscopy)
=> cartilagineous remnants in labyrinth => otospongiosis of the
bony labyrinth, especially adjacent to the footplate of the stapes; it
may cause stapedio-ovalar ankylosis resulting in conductive
hearing loss. Cochlear otosclerosis may also develop, resulting in
sensorineural
hearing loss. Endochochlear => periosteal => endoosteal.
Symptoms & signs : asymptomatic =>
monolateral
conductive hypoacusia =toxic enzymes diffuse to cochlea via perilymph=>
mixed
hypoacusia (75%) => progressive bilateral hypoacusia => Willis
paracusia; rarely vestibular disorders
Laboratory examinations : type
B tympanogram . Bezold's triad : prolonged bone conduction (negative
Rinne test) and lessened perception of low tones
Therapy :
ankylosis of the stapes by post-inflammatory osteogenesis (syndrome
of Coyle Shea Jr) is a pathologic entity still not well known, often
confounded with otosclerosis. If surgical treatment is the same as for
otosclerosis (stapedectomy,
platinectomy, veinous graft and piston), the prognosis is not the same
and a great carefulness is necessary, as well in operatory indications
as in operatory procedure itselfref.
Scheibe's deafness : congenital deafness due to partial aplasia
of the saccule and cochlear duct (Scheibe's aplasia), Corti's ganglion
hypoplasia, ectasia of cochlear canal
Michel's deafness : congenital deafness due to total lack of development
of the inner ear (Michel's aplasia) and sometimes even rocca petrosa
Mondini-Alexander deafness : development only of a single curved
tube representing the cochlea, and similar immaturity of the vestibular
canals; a high-frequency hearing loss results
Bing-Siebenmann deafness : bony labyrinth well formed but membranous
part and particularly the sense organ poorly developed. This type is often
associated with retinitis pigmentosa
Siebenmann deafness : changes mainly in middle ear and often due
to thyroid hormone deficiency
Prognosis : there is usually return of labyrinthine
function over weeks or months. With fistulas, there is often a permanent
nerve-type hearing loss, and some patients have chronic positional
vertigo.
acute suppurative, bacterial
or purulent labyrinthitis : labyrinthitis in which pus enters the labyrinth
Aetiology : bacteria
tympanogenic labyrinthitis : acute suppurative labyrinthitis that
results from invasion from the tympanic cavity through a fistula.
hematogenic labyrinthitis : acute suppurative labyrinthitis that
results from invasion by bacteria from septicemia
meningogenic labyrinthitis : acute suppurative labyrinthitis that
results from invasion of meningitis through an erosion of the temporal
bone.
Symptoms & signs : severe and often permanent
vertigo
and sensorineural hearing
loss Complications such as meningitis or brain
abscess lead to toxic symptoms of headache,
malaise, and fever.
Therapy : antibiotics and surgery
Prognosis : some small mortality can be
expected even with treatment. For those who recover, there is usually no
recovery of the cochlear or vestibular responses, and 3-5 weeks are required
for compensation. It is often impossible to be sure of complete eradication
of disease, and there is questionable compensation for loss of hearing
and labyrinthine function and occasional residual ataxia.
Symptoms & signs : vestibular symptoms
(spontaneous nystagmus
to the opposite ear, nausea
and vomiting,
true vertigo, ataxia, past-pointing)
usually preceding the cochlear depression (loss of hearing) by a
few hours to several days
Laboratory examinations : in patients
with cholesteatoma, if exerting pressure and then suction using a pneumo-otoscope
produces nystagmus
and vertigo, a labyrinthine fistula is present
vascular or neuritic => Citelli sudden hearing loss or acute cochlear
lock (continue, fluctuating, partial, pantonal)
acute serous, sterile or toxic labyrinthitis
: a type caused by chemical or toxic irritants that invade the labyrinth,
usually from the middle ear
circumscribed labyrinthitis / labyrinthine fistula / perilabyrinthitis
: acute serous labyrinthitis in a discrete area, due to erosion of the
bony wall of a semicircular canal with exposure of the membranous labyrinth
Gerlier's disease : an acute disease seen in farm workers and stablemen,
characterized by vertigo, ptosis, and motor disorders; it is probably a
form of vestibular neuronitis
Aetiology : antecedent or concomitant infection
in the URT, maxillary sinuses, or teeth
Symptoms & signs : sudden, debilitating
vertigo,
nausea
and vomiting,
and spontaneous nystagmus. The cochlea is spared,
but one or both of the labyrinths have abnormal calorics. Vestibular symptoms
decrease somewhat after a few hours, but they remain fairly severe for
the first week, slowly decreasing over the next 4-8 weeks. About 70% of
these patients have permanent, decreased caloric function.
Therapy : supportive and reeducation
Prognosis : self-limiting disease, recurrent
attacks even as long as 4 years after the initial attack.
Hennebert's sign : rotatory nystagmus
when positive or negative pressure is applied to the tympanic membrane,
indicative of labyrinthitis with leakage of perilymph; positive pressure
(air compression) causes nystagmus toward the affected side, and negative
pressure (air rarefaction) causes nystagmus away from the affected side.
Babinski-Weil test : the patient, with eyes shut, walks forward
and backward 10 times. A person with labyrinthine disease deviates from
the straight path, bending to one side when walking forward and to the
other side when walking backward
Mittelmeyer's test : the patient tries to march in place with eyes
closed; in vestibular disorder he will turn to the side ipsilateral to
vestibular loss, or contralateral to vestibular excitation
Hitzig test (for vestibular apparatus): the positive electrode of
a galvanic current is applied just in front of the ear being examined while
the negative electrode is held in the patient's hand, the patient standing
with feet together and eyes closed. A current of 5 mA causes a leaning
toward the positive pole in normal persons.
Búrúny's symptom : in disturbances of equilibrium
of the vestibular apparatus, the direction of the fall is influenced by
changing the position of the patient's head.
Complications : Voltolini's disease
: acute, painful inflammation of the inner ear followed by meningitis
with deafness and unconsciousness
Web resources :
Noise at National Center
for Environental Health (NCEH), CDC
Hearing loss at National
Center on Birth Defects and Developmental Disabilities (NCBDDD), CDC