DDx hearing loss

1. By Dr S.RabieiBy Dr S.Rabiei 11
HEARING LOSSHEARING LOSS
Dr Sohrab RabieiDr Sohrab Rabiei

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 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

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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.

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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:

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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

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25. SNHLSNHL
SNHLSNHL
By Dr S.RabieiBy Dr S.Rabiei 2525

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.)

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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

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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

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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

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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

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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.

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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

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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

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