3. By Dr S.RabieiBy Dr S.Rabiei 33
Hearing is the transduction of sound (Hearing is the transduction of sound (mechanicalmechanical
energy) intoenergy) into neuralneural impulses and theimpulses and the
interpretation of those impulses by the centralinterpretation of those impulses by the central
nervous systemnervous system
Hearing loss can result from aHearing loss can result from a defect at any leveldefect at any level
in this system.in this system.
The proper management of patients with hearingThe proper management of patients with hearing
loss requires an understanding of the normalloss requires an understanding of the normal
mechanisms.mechanisms.
4. By Dr S.RabieiBy Dr S.Rabiei 44
EVALUATION OF HEARINGEVALUATION OF HEARING
LOSSLOSS
Age of patient
Severity of loss
Duration
Onset - rapid vs. gradual (sudden hearing loss is an
emergency),constant vs. fluctuating.
Precipitating or exacerbating factors: trauma, noise,
drugs,prenatal infection, etc.
Associated symptoms: Vertigo, tinnitus, pain or
fullness in the ear, headache
Family history
History
5. By Dr S.RabieiBy Dr S.Rabiei 55
PhysicalPhysical
Emphasize the following:
Otologic exam
Systematic otoscopy
Tuning forks to grossly assess hearing and to
differentiate conductive vs. sensorineural
Exam of nasopharynx
Neurologic exam
Inspection, palpation, and auscultation of
neck
Look for associated anomalies
6. By Dr S.RabieiBy Dr S.Rabiei 66
TestsTests
Basic audiogram - all patients
Diagnostic audio, ENG, internal auditory
canal, x-rays, and/or CT scan if vertigo
present or neural lesion suspected
Electrocochleography if Meniere's
suspected
Appropriate blood tests.
All patients with sensorineural hearing
loss should have VDRL and FTA-ABS.
7. By Dr S.RabieiBy Dr S.Rabiei 77
DIFFERENTIAL DIAGNOSISDIFFERENTIAL DIAGNOSIS
Cerumen impaction
One of commonest causes of sudden
hearing loss
Treat by removing wax
External otitis - inflammation and
swelling of canal skin
Tumors of external canal
Congenital aural atresia
External ear:
8. By Dr S.RabieiBy Dr S.Rabiei 88
Middle ear
Otitis media
Acute - infectious or serous
Chronic - serous
Must always rule out possibility of nasopharyngeal
carcinoma
Tympanic membrane perforation or
cholesteatoma
Normal tympanic membrane with conductive
hearing loss
Suspect ossicular abnormality: otosclerosis, ossicular
dislocation, etc.
DIFFERENTIAL DIAGNOSISDIFFERENTIAL DIAGNOSIS
26. By Dr S.RabieiBy Dr S.Rabiei 2626
SensorineuralSensorineural
hearing losshearing loss
often associated with poor discrimination
out of proportion to degree of pure tone
sensitivity loss - this is due to distortion of
sound by cochlea or nerve
27. By Dr S.RabieiBy Dr S.Rabiei 2727
CongenitalCongenital
Hereditary
Isolated sensorineural hearing loss
Normal inner ear
Abnormal inner ear (Scheibe, Mondini-Michelle, etc.)
Hearing loss with associated anomalies
Acquired
Prenatal infection, especially syphilis, rubella, CMV
Prenatal drugs
Birth trauma
Developmental anomaly
Hereditary but delayed onset
Dominant or recessive
Numerous syndromes, some with associated anomalies
(example: Waardenburg's syndrome with white forelock,
hypertelorism, etc.)
28. By Dr S.RabieiBy Dr S.Rabiei 2828
AcquiredAcquired
1.Noise induced - very common
2.Presbycusis - hearing loss of
old age
3.Head trauma - temporal bone
fracture, labyrinthine
concussion,central damage
29. 4. Meniere's disease or
syndrome
5. Luetic hearing loss (syphilis)
6. Ototoxic drugs
7. Oval or round window rupture
By Dr S.RabieiBy Dr S.Rabiei 2929
30. 8. Idiopathic sudden
sensorineural hearing loss
9. Acoustic nerve tumor
10.Infections
11.Otosclerosis
12.Surgical trauma
By Dr S.RabieiBy Dr S.Rabiei 3030
31. By Dr S.RabieiBy Dr S.Rabiei 3131
Noise induced - very commonNoise induced - very common
Due to single blast or repeated or prolongedDue to single blast or repeated or prolonged
exposure to loud noise (hunting, rock music)exposure to loud noise (hunting, rock music)
Affects high frequencies first (4 kHz); oftenAffects high frequencies first (4 kHz); often
progressiveprogressive
Frequently associated with tinnitusFrequently associated with tinnitus
No known treatment. Counsel patient to avoidNo known treatment. Counsel patient to avoid
noise in futurenoise in future
PREVENTION is key to reducing incidencePREVENTION is key to reducing incidence
33. By Dr S.RabieiBy Dr S.Rabiei 3333
Presbycusis - hearing loss of oldPresbycusis - hearing loss of old
ageage
Not universal, etiology not knownNot universal, etiology not known
Central interpretation deficit complicatesCentral interpretation deficit complicates
peripheral sensitivity lossperipheral sensitivity loss
No known cureNo known cure
Amplification can help, but hearing aidsAmplification can help, but hearing aids
must be carefully fitted Cochlear distortionmust be carefully fitted Cochlear distortion
and central processing may preclude usand central processing may preclude us
34. By Dr S.RabieiBy Dr S.Rabiei 3434
Meniere's disease or syndrome
FluctuatingFluctuating hearing losshearing loss
Characteristically associated with bouts of vertigoCharacteristically associated with bouts of vertigo
Anatomically correlated with endolymphaticAnatomically correlated with endolymphatic
hydropshydrops
Electrocochleograph (ECOG) frequently showsElectrocochleograph (ECOG) frequently shows
elevated summating potentialelevated summating potential
In active phase, glycerol may improve hearingIn active phase, glycerol may improve hearing
TreatmentTreatment
Medical: low-salt diet, diuretics, avoidance ofMedical: low-salt diet, diuretics, avoidance of
caffeine,anti-vertigo medication, psychological supportcaffeine,anti-vertigo medication, psychological support
Surgical: for selected patients with progressive diseaseSurgical: for selected patients with progressive disease
36. By Dr S.RabieiBy Dr S.Rabiei 3636
Oval or round window ruptureOval or round window rupture
Sudden onset of hearing lossSudden onset of hearing loss
FluctuatingFluctuating
Often accompanied by vertigoOften accompanied by vertigo
Definitive diagnosis can only be made byDefinitive diagnosis can only be made by
surgical exploration.surgical exploration.
Usually associated with sudden pressureUsually associated with sudden pressure
change: flying,Valsalva, scuba diving, sneeze,change: flying,Valsalva, scuba diving, sneeze,
etc.; but may be idiopathicetc.; but may be idiopathic
Treatment - initially, bed rest for suspectedTreatment - initially, bed rest for suspected
patients. If no recovery, explore and repair leak ifpatients. If no recovery, explore and repair leak if
foundfound
37. By Dr S.RabieiBy Dr S.Rabiei 3737
Ototoxic drugsOtotoxic drugs
Reversible: aspirin - associated withReversible: aspirin - associated with
tinnitustinnitus
Permanent: aminoglycosides, anti-Permanent: aminoglycosides, anti-
neoplastic drugs, etc.neoplastic drugs, etc.
Treat by prevention:Treat by prevention:
Careful monitoring of blood levels of toxicCareful monitoring of blood levels of toxic
drugsdrugs
Monitor hearing and vestibular functionMonitor hearing and vestibular function
38. By Dr S.RabieiBy Dr S.Rabiei 3838
Idiopathic sudden sensorineuralIdiopathic sudden sensorineural
hearing losshearing loss
Sudden hearing loss with no apparent causeSudden hearing loss with no apparent cause
Etiology obscure, could be viral, autoimmune,Etiology obscure, could be viral, autoimmune,
vascular,or allergic, to name a few suspectedvascular,or allergic, to name a few suspected
causescauses
Diagnostic evaluation - should be extensive toDiagnostic evaluation - should be extensive to
rule out other causesrule out other causes
Treatment - many therapies suggested - few areTreatment - many therapies suggested - few are
statistically proven except for bed rest andstatistically proven except for bed rest and
possibly 95% O2:5% CO2 inhalation and steroidpossibly 95% O2:5% CO2 inhalation and steroid
therapies. Patient is usually admitted to thetherapies. Patient is usually admitted to the
hospital for treatment.hospital for treatment.
39. By Dr S.RabieiBy Dr S.Rabiei 3939
Acoustic nerve tumorAcoustic nerve tumor
Uncommon tumor. Usually arises in vestibularUncommon tumor. Usually arises in vestibular
nerve and is schwannoma, or less often,nerve and is schwannoma, or less often,
neurilemmomaneurilemmoma
Usually present with hearing loss. Progression ofUsually present with hearing loss. Progression of
vestibular nerve involvement is so slow that it isvestibular nerve involvement is so slow that it is
not noticed by patient.not noticed by patient.
Characteristic audiometric results with abnormalCharacteristic audiometric results with abnormal
acoustic reflex, poor discrimination, and/oracoustic reflex, poor discrimination, and/or
abnormal ABR.abnormal ABR.
X-rays or CT show flaring of IAC in large tumors.X-rays or CT show flaring of IAC in large tumors.
Small tumors are seen with air contrast CTSmall tumors are seen with air contrast CT
Treatment - surgical excisionTreatment - surgical excision
40. By Dr S.RabieiBy Dr S.Rabiei 4040
InfectionsInfections
Viral infectionViral infection
Bacterial infection - labyrinthitis, meningitis, etc.Bacterial infection - labyrinthitis, meningitis, etc.
OtosclerosisOtosclerosis
SNHLoften seen in otosclerosis of footSNHLoften seen in otosclerosis of foot
plate, but occurrence of pureplate, but occurrence of pure
sensorineural hearing loss issensorineural hearing loss is
controversialcontroversial
Treatment with fluoride may be helpfulTreatment with fluoride may be helpful
41. By Dr S.RabieiBy Dr S.Rabiei 4141
Acoustic traumaAcoustic trauma
one-time, brief exposures followed byone-time, brief exposures followed by
immediate permanent hearing lossimmediate permanent hearing loss
exceed 140 dBexceed 140 dB and are often sustained for lessand are often sustained for less
thanthan 0.2 seconds0.2 seconds
tearing of membranes + disruption of cell wallstearing of membranes + disruption of cell walls
withwith mixing of perilymph and endolymph.mixing of perilymph and endolymph.
43. By Dr S.RabieiBy Dr S.Rabiei 4343
Gunshot (peak level)Gunshot (peak level)140 to 170 db140 to 170 db
Jet takeoffJet takeoff 140140
Rock concertRock concert 110 to 120110 to 120
stereo headphonesstereo headphones 110 to 120110 to 120
MotorcycleMotorcycle 9090
ConversationConversation 6060
Quiet roomQuiet room 5050
44. By Dr S.RabieiBy Dr S.Rabiei 4444
T.T.S : Temporary threshold shifts
decreased stiffness of the stereocilia ofdecreased stiffness of the stereocilia of
OHCs.OHCs.
TTS may be due to metabolic exhaustionTTS may be due to metabolic exhaustion
TTS is sometimes referred as "TTS is sometimes referred as "auditoryauditory
fatigue."fatigue."
prolonged periods of time : cell deathprolonged periods of time : cell death