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Mixed, Central, and Functional
Hearing Loss
&
Tinnitus
DR.S.H.HASHEMI
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MIXED HEARING LOSS
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MIXED HEARING LOSS
 Whenever the hearing loss of a patient includes a mixture of both
conductive and sensorineural characteristics, is said to have a mixed
hearing loss.
 Hearing deficiency may have started originally as a conductive failure
(otosclerosis) and later developed a superimposed sensorineural
component.
 The difficulty may have been sensorineural in the beginning
( presbycusis ), and a conductive defect (middle-ear infection ) may
have developed subsequently.
 In some cases the conductive and the sensorineural elements may have
started simultaneously ( severe head injury affecting both the inner ear
and the middle ear ).
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MIXED HEARING LOSS . . .
 In clinical practice, most cases with an original sensorineural
etiology remain in that classification without an added
conductive element.
 In contrast, most cases that start as conductive hearing
impairment later develop some sensorineural involvement.
 Otosclerosis . . . + . . . presbycusis
 Chronic otitis media . . . + . . . Labyrinthitis
 Otosclerosis was at one time thought to retain its purely
conductive character for years; today it is recognized that this
condition develops sensorineural impairment in same cases.
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History: A 67-year-old man with insidious deafness for 25 years
No tinnitus or vertigo
Otologic: Normal
Audiologic: Reduced air and bone conduction thresholds with some air-bone
gap in the right ear
* Classification: Mixed hearing loss
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* Diagnosis: Otosclerosis with secondary sensorineural involvement
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History: A 62-year-old woman with severe deafness
Voice is normal. No tinnitus or vertigo
Otologic: Normal
Audiologic: Bone conduction is better than air, but patient denied hearing the
tuning fork on the mastoid or the forehead but heard it fairly well on the teeth
* Classification: Mixed hearing loss.
* Diagnosis: Otosclerosis with sensorineural hearing loss
* Comment: Both oval windows were overgrown with otosclerosis which
required drilling
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MIXED HEARING LOSS . . .
 Mixed hearing loss is becoming more common also in otosclerosis
after stapedectomy .
 The sensorineural deficit may be caused by penetration of the
oval window with exposure of the perilymph.
 Despite meticulous surgical care, the inner ear also can be
traumatized readily and made more susceptible to infection .
 In surgical trauma to the inner ear, high-frequency hearing loss
often falls below the preoperative level, and the patient may
complain of reduced discrimination though his pure-tone
threshold is improved.
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History: A 60-year-old man with bilateral chronic otorrhea for 40 years
Insidious hearing loss for many years . No tinnitus or vertigo
Otologic: Putrid discharge with evidence of cholesteatoma
Audiologic: Moderate to severe bilateral flat loss
Classification: Mixed hearing loss
Diagnosis: Chronic otitis media with neural or cochlear involvement
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MIXED HEARING LOSS . . .
 In chronic otitis media some toxic inflammatory metabolite
produces a cochleitis or labyrinthitis.
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History: A 45-year-old man with fullness in both ears and hearing loss for one week
No tinnitus or vertigo . No history of ear infections
Otologic: Bilateral impacted cerumen. Removed, and eardrums normal
Audiologic: Bilateral reduced air conduction thresholds with greater loss in high
frequencies
Classification: Mixed hearing loss before removal of cerumen. Sensorineural loss after
removal of cerumen
Diagnosis: Impacted cerumen with progressive nerve deafness
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MIXED HEARING LOSS . . .
 This example a warning to physicians to avoid assuring
any patient that his hearing loss can be corrected
merely by removing cerumen, because mixed hearing
loss may be found subsequently.
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MIXED HEARING LOSS . . .
 In every case of mixed hearing loss one should determine how much of
the deficit is conductive and how much is sensorineural.
 The prognosis depends largely on this estimate .
 The best way to approximate the conductive and the sensorineural
components of a hearing loss is to perform all possible tests for
estimating the patient’s sensorineural potential or “cochlear reserve.”
 In addition to routine bone conduction, speech discrimination scores
are essential .
 If the patient hears and discriminates well when speech is made
louder, then the conductive element probably is a major cause of the
hearing difficulty, and there is a good chance that surgery will improve
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the hearing.
MIXED HEARING LOSS . . .
 If the patient does not understand any better with a hearing aid
or when the voice is raised, hearing is not improved even if the
conductive portion of the mixed hearing loss is corrected.
Prognosis:
 In mixed hearing loss the prognosis depends on the relative proportion of
conductive and sensorineural pathology.
 If the sensorineural component is slight, the surgical prognosis is good , and
under favorable circumstances the hearing may approximate the level of the
bone conduction.
 However, the discrimination is not improved much, even after correction of
the conductive defect.
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CENTRAL HEARING LOSS
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CENTRAL HEARING LOSS
 If it is caused by a lesion that affects primarily the central nervous
system from the auditory nuclei to the cortex.(auditory pathway)
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CENTRAL HEARING LOSS . . .
 The auditory pathway consists of a series of transducers that
repeatedly change the speech stimulus so that it can be handled
effectively by the cortex.
 The eardrum and the ossicular chain modify the amplitude of the
sound waves .
 The cochlea analyzes these waves and reflects them as impulses
to the cortex.
 The chief function of the auditory cortex is to interpret and to
integrate these impulses and to provide the listener with the
exact meaningful information intended by the speaker, or to
permit the listener to react appropriately to the actual
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implication of the sound.
CENTRAL HEARING LOSS . . .
 In unilateral central hearing loss the contralateral ear can be affected.
 In unilateral central hearing loss (e.g. brain
tumor) the opposite ear, which presumably
hears normally may have much poorer
discrimination than the ear of a person who
has normal hearing.
 A similar adverse effect is noted in the ear
opposite the tumor when certain words are
interrupted periodically or accelerated.
 The patient with central hearing impairment has no difficulty perceiving highfrequency sounds such as the letter s and f that are affected so characteristically
in peripheral sensorineural lesions, but he/she has difficulty interpreting what is
heard.
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CENTRAL HEARING LOSS . . .
Characteristic Features of central hearing loss :
 Hearing tests do not indicate peripheral hearing impairment.
 pure-tone threshold is relatively good compared with the ability
of the patient to discriminate, and especially to interpret, what
he/she hears.
 The patient has difficulty interpreting complex information.
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CENTRAL HEARING LOSS . . .
 The prognosis for central hearing impairment is poor .
 There is no characteristic audiometric pattern, except that the
disparity between the hearing level and the speech interpretation
is quite marked.
 In certain cases, central hearing loss may mimic peripheral causes
of deafness, including occupational deafness.
 The spheroid cells of the superior ventral cochlear nucleus
(SVCN) show an anatomical frequency gradient, low ventral to
high dorsal.
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Superior ventral cochlear nucleus (SVCN)
 Erythroblastosis typically
causes hearing loss that
centers around 3000–4000 Hz.
 This may be caused by injury
to SVCN spheroid cells, the
second-order neurons of the
ascending auditory pathway ,
even in the presence
of
normal hair cells in the organ
of Corti .
 Central pathology must be
included in the differential
diagnosis of the hearing loss
producing a 4000-cycle dip
on the audiogram.
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Central Auditory Processing Disorders (CAPD)
 CAPD characterized by decreased understanding of speech in the presence of
background noise .
 Common complaints include inability to study or read in the presence of noise,
slowing of reading speed caused by noise(vacuum cleaners or air conditioners )
and suspicion by family members that the patient has a hearing loss.
 If people talk to a person with CAPD while he or she is involved in auditory
concentration such as listening to a television program, the person will often
“not hear.”
 However, if one gets the persons attention by calling his or her name before
speaking, the first sentence will not be missed, and hearing is normal.
 Treatment : altering the listening environment to obtain the best possible
signal-to-noise ratio .
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FUNCTIONAL HEARING LOSS
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FUNCTIONAL HEARING LOSS
 Functional or psychogenic hearing loss is the customary diagnosis when
there is no organic basis for the patient’s apparent deafness.
 The inability to hear results entirely or mainly from psychological or
emotional factors, and the peripheral hearing mechanism may be
essentially normal.
 The basis for functional hearing loss in most patients is psychogenic, the
product of emotional conflict, ( neurotic anxiety ) .
 Tinnitus is a characteristic feature of “hysterical deafness,” and patients
often claim that the noise is unbearable.
 Hearing acuity usually varies, depending on the patient’s emotional
state at the time of testing.
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FUNCTIONAL HEARING LOSS . . .
 Functional hearing loss is an unconscious device by which the
patient seeks to escape from an intolerable problem that he/she
cannot face consciously.
 Hysterical blindness and paralysis are other examples of the same
type of somatization or “conversion reaction.”
 Military life during wartime
 Civilian life
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Functional Overlay
 It is entirely possible for hearing loss of functional origin to be
superimposed on true organic hearing impairment .
 The problem then is to recognize the two components in the
patient’s hearing impairment.
 The history and the otologic examination
important clues .
often provide
 (e.g. the patient may claim that his/her hearing was excellent
until a physician cleaned out his/her ears with such force that
he/she suddenly went stone deaf.)
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History: A 34-year-old woman with otosclerosis and hearing loss for over 10 years
Refuse to use hearing aids
She often says, “What?” even when addressed loudly. repeats a question before answering
She appears to be frustrated and emotionally disturbed and does not use her residual
hearing effectively
Diagnosis: functional overlay on an organic otosclerosis
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After positive suggestion this patient acquired a hearing aid and is doing much better
FUNCTIONAL HEARING LOSS . . .
Diagnosis by Specific Features:
 In an organic lesion, all tests must:
 Consistent results when they are repeated
 Correlate with one another
 A medical history could not possibly explain the patient’s
condition (e.g. Sudden onset of profound deafness following
instillation of drops into the ears ).
 Too spectacular an improvement with a hearing aid, especially
when the patient has set the controls at minimal amplification, or
a sudden disproportionate improvement in hearing after a simple
procedure such as drum massage or insufflating the eustachian
tube.
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FUNCTIONAL HEARING LOSS . . .
Diagnosis by Specific Features : . . .
 Decided fluctuations in hearing acuity as determined by any
single test.
 Inconsistency in the results of two or more tests.
 In complete deafness the presence of cochlear nerve reflexes
with loud noises indicates either malingering or hysteria.
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Psychogalvanic skin resistance test
Impedance audiometry
Otoacoustic emissions test
Evoked-response audiometry
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FUNCTIONAL HEARING LOSS . . .
 Psychogenically induced hearing loss usually is a uniform flattone loss in all frequencies, suggestive of a well-marked
conductive impairment.
 In a patient with unilateral functional deafness there may be
complete absence of bone conduction on the side of the bad ear,
though the good ear has normal acuity.
 Such a patient even may deny hearing shouts directed at the bad
ear in spite of the good hearing in the opposite ear.
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Audiometric Patterns in Functional Hearing Loss
 There is no characteristic audiometric pattern in functional
hearing loss , but the consistent inconsistencies serve to alert the
physician.
 Usually, the hearing impairment is bilateral, and the bone
conduction level is the same as the air conduction level.
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History: A 21-year-old woman with a series of emotional conflicts : breakup with her
fiance , flunking out of college, and pending divorce of her parents.
Otologic: Normal.
Audiologic: PTA: showed a severe hearing loss, she often seemed able to hear soft
voices behind her back. PGSR :showed normal hearing.
Classification: Functional
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Etiology: Emotional disturbance. Her hearing returned to normal after psychotherapy.
Malingering
 Malingering is the deliberate fabrication of symptoms that the
patient knows do not exist.
 The patient is motivated by the desire to seek some advantage:
 Financial compensation
 Escape from military service
 Evasion of responsibility for failure
 Characteristically, the malingerer abandons the symptoms when
he/she thinks he/she is no longer being observed.
 If the patient claims he has one “good” and one “bad” ear, and
the examiner obstructs his “good ear” with a finger, then shouts
into it loudly enough to be heard easily by bone conduction
alone, the malingerer claims he hears nothing.
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History: A 37-year-old construction worker knocked to ground by a beam
No unconsciousness, but left ear required sutures
Otologic: Normal. Normal caloric findings.
Audiologic: varying and inconsistent hearing levels during repeated audiograms
Classification: Functional hearing loss
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Etiology: Malingering
Tinnitus
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 Tinnitus is a term used to describe perceived sounds
that originate within the person rather than in the
outside world.
 Although nearly everyone experiences mild tinnitus
momentarily and intermittently, continuous tinnitus is
abnormal, but not unusual .
 The prevalence of tinnitus increases with age up
until 70 years and declines thereafter .
 This symptom is more common in people with otologic
problems, although tinnitus also can occur in patients
with normal hearing.
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DDx:
 Rushing of blood through the cranial arteries (certain
changes in the vascular walls : atherosclerosis )
 Pressing on various blood vessels in the neck occasionally stops this
type of tinnitus .
 Noises made by muscles in the head during chewing
 Changes in temporal bone structure
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Tinnitus also may serve as an early sign of auditory
injury.(high-pitched ringing or hissing may be the first
indication of impending cochlear damage from ototoxic
drugs).
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Aspirin , Quinine( large dose )
Diuretics
Aminoglycoside antibiotics
Chemotherapy drugs
 These drugs should be used with extreme caution, especially
when kidney function is deficient.
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Tinnitus:
 Subjective (audible only to the patient)
 More common
 Unfortunately, it cannot be confirmed with current
methods of tinnitus detection.
 Usually difficult to document its presence and quantify its
severity .
 Objective (audible to the examiner )
 comparatively easy to detect and localize because it can be
heard by the examiner using a stethoscope or other
listening device.
 Glomus tumors, AV-malformations, Palatal myoclonus
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 DESCRIPTION OF TINNITUS:
 Ringing of bells
 Roar of the ocean
 Running motor
 Buzzing
 Machine shop noises
 Hissing of steam
 Localization:
 In the ears
 In the center head
 Not in the ears at all but inside the head
 Patients sometimes say that the ear noises are so loud that they
are unable to hear what is going on around them.
 Tinnitus rarely is louder than a very soft whisper (5–10 dB above
hearing threshold) .
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 Although the character of tinnitus is rarely diagnostic, certain
qualities are suggestive of specific problems :
 Seashell-like tinnitus(ocean-roaring type):
 Meniere’s syndrome (endolymphatic hydrops & swelling of the inner ear
membranes & ear fullness & fluctuating hearing loss unassociated with
straining or forceful nose blowing )
 Syphilitic labyrinthitis
 Trauma
 Unilateral ringing tinnitus:
 Acoustic neuroma
 Trauma
 Perilymph fistula (ringing tinnitus & fluctuating ear fullness & hearing loss
during straining )
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 Pulsatile tinnitus:
 A-V malformations
 Glomus jugulare tumors
 low-pitched type:
 Otosclerosis
 Other forms of conductive hearing loss
 Ringing & Hissing:
 Sensorineural hearing loss
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 When evaluating the history of a tinnitus (ear noise) problem, the
following questions should be asked:
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PHYSICAL EXAMINATION AND TESTING
 History
 physical examination:
 Complete head and neck assessments
 Examination of the cranial nerves
 Audiogram
 Routine audiogram
 Assessment of hearing at frequencies not tested routinely
 Brainstem evoked-response audiogram (BERA)
 Balance tests:
 Electronystagmogram (ENG)
 Computerized dynamic posturography (CDP)
 Otoacoustic emission (OAE) testing
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PHYSICAL EXAMINATION AND TESTING . . .
 Imaging studies:
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MRI
CT
Single photon emission computed tomography (SPECT)
Positron emission tomography (PET)
 Blood tests:
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Diabetes
Hypoglycemia
Hyperlipoproteinemia
Lyme disease
Syphilitic labyrinthitis
Thyroid dysfunction
Collagen vascular disease
Autoimmune inner-ear disease
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AUDIOMETRY IN THE PRESENCE OF TINNITUS
 May be the patient complains of inability to detect the tone
produced by the audiometer because of the tinnitus.
 It is best to present quickly interrupted or warbled tones so that the
patient can distinguish the discontinuous audiometer tone from the
constant tinnitus.
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TINNITUS WITH A NORMAL AUDIOGRAM
 Perform an audiogram on every patient who complains of
tinnitus.
 If the otoscopic findings are normal, and the audiogram shows
normal hearing from the lowest frequencies to 8000 Hz, and yet
the patient complains of tinnitus, several causes should be
considered :
(1) Hearing defects > 8000 Hz or at “in-between” frequencies not tested
during routine audiogram
(2) Vascular and neurologic disorders
(3) Functional causes
(4) Retrocochlear disease such as an acoustic neuroma
(5) Temporomandibular joint (TMJ) abnormality
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TINNITUS WITH HIDDEN HIGH-FREQUENCY HEARING LOSSES
 Many patients who complain of ringing or hissing tinnitus may
have perfectly normal hearing in the routine frequencies (250,
500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz).
 when the hearing is tested at higher frequencies up to 20,000 Hz, it is not
uncommon to find a hearing deficit.
 The hearing damage may well be at a point intermediate between these
routinely tested frequencies ( 40 dB loss at 3500 Hz )
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*History: a 38-year-old woman with fullness in her right ear and high-pitched
constant tinnitus for several months.
*Otologic: Normal
*Audiologic: Normal hearing with high-tone hearing loss > 8000 Hz
*Classification: High-tone sensory hearing loss
*Diagnosis: After further questioning the patient subsequently associated the
onset of tinnitus with a bad cold
*Hearing loss and subsequent tinnitus probably due to a viral cochleitis
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TINNITUS AND OTOSCLEROSIS
 Low-pitched
 Buzzing , roaring sound or pulsing noise timed to heartbeat
 In some patients with otosclerosis, the tinnitus is even more
disturbing than the hearing loss.
 Not all patients with otosclerosis have tinnitus
 In most instances, tinnitus will disappear or diminish during the
course of many years of hearing impairment.
 The fixation of the stapedial footplate may be eliminate the
tinnitus or may not .
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TINNITUS IN MENIERE’S DISEASE
 Ocean roar or a hollow seashell sound
 In the early stages of Meniere’s disease, tinnitus often persists all
the time and becomes the most disturbing symptom of the
disease.
 Many patients would even sacrifice their hearing to get rid of the
tinnitus.
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TINNITUS AFTER HEAD TRAUMA, EXPOSURE TO NOISE
 Ringing tinnitus
 After a blow to the external ear
 Close exposure to a sudden very loud noise ( explosion of a
firecracker or the firing of a gun ).
 Tinnitus is accompanied by a high-frequency hearing loss:
 If the hearing loss is temporary, the tinnitus usually subsides in a few hours
or days.
 If the hearing loss is permanent , the ringing tinnitus may persist for many
years or permanently.
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ACOUSTIC NEURITIS
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Acoustic nerve inflammation
High-tone deafness
High-pitched tinnitus
Hepatitis , influenza, other viral diseases
Infection of the middle ear.
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ACOUSTIC NEUROMA
 Benign tumor of the cerebellopontine angle
 Unilateral tinnitus ( often is the first symptom )
 Tinnitus may be caused by:
 Other Cerebellopontine angle neoplasms( meningioma, cholesteatoma,
vascular malformation)
 Anterior–inferior cerebellar artery(loop of blood vessel )
 Brainstem tumors
 MRI should be considered especially in any patient with unilateral
tinnitus.
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TM JOINT PROBLEMS
 Malocclusion or other TMJ disparity
 Tinnitus has resolved with adequate TMJ treatment
 Placing a plastic prosthesis (bite block) over the lower molars at night
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FUNCTIONAL CAUSES
 Diagnosis of functional or psychological tinnitus should be made
with great caution.
 Malingering:when the patient does not perceive an abnormal
noise and is aware of the fact, usually for secondary gain(lawsuit).
 True functional or “hysterical” tinnitus is psychiatric in etiology
and disappears following effective psychotherapy.
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MANAGING THE PATIENT WITH TINNITUS
 Tinnitus is usually not curable
 Unless a correctable, structural, or metabolic cause is found.
 In managing the patient with tinnitus, it is advisable to have a
forthright talk with the patient and to explain the most likely
cause of the tinnitus and the fact that as yet there is no specific
cure for it.
 Tinnitus maskers a re recommended by some physicians but their
value is also limited.
 Temporary method for relief from tinnitus
 They introduce a noise into the ear that the patient is able to control.
 Hearing aid-like instrument that produces a narrow band noise centered
around the pitch of the patient’s tinnitus.
 The level of masking noise is above the patient’s tinnitus.
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MANAGING THE PATIENT WITH TINNITUS . . .
 Habituators is a device somewhat similar to a tinnitus masker.
 Primarily used to treat patients with hyperacusis (hypersensitivity to noise)
 External masking with a radio, fan, music, vaporizer is helpful,
especially at night if the tinnitus interferes with their ability to fall
asleep.
 Tranquilizers : otosclerosis and Meniere’s disease
 Medical attention to related vascular abnormalities:
 Hypertension
 Buerger’s disease
 Atherosclerosis
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MANAGING THE PATIENT WITH TINNITUS . . .
 Hypnosis
 Psychotherapy
 SURGERY:
 Eighth nerve section
 Vascular loop (malpositioned blood vessel) compressing the eighth nerve,
microvascular decompression can be performed through the posterior
fossa.
THE END
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