4. Hearing threshold in
better ear (average of
500,1000,2000 Hz)
Degree of
impairment(WHO)
Ability to understand
speech
0-25 dB Not significant No significant
26-40 dB Mild Difficulty with faint speech
41-55 dB Moderate Freq difficulty with normal
speech
56-70 dB Moderately severe Freq difficulty with loud
speech
71-90 dB Severe Can understand only
shouted or amplified
speech
91 above Profound Usually cannot understand
even amplified speech
6. CONDUCTIVE
HEARING LOSS
• Conduction of sound to
reach cochlea
• Characteristic:
– (-) Rinne test
– Weber lateralized to poorer
ear
– Normal BC
– Low f affected more
– Greater air-bone gap, more
conductive loss
– Loss not >60 dB
– Speech discrimination good
SENSORINEURAL
HEARING LOSS
• Lesion of cochlea, 8th nerve
• Characteristics:
• (+) Rinne test
• Weber lateralized to better
ear
• High f affected more
• No gap between air and
bone conduction
• loss >60dB
• Speech discrimination poor
• Difficult in hearing in
presence of noise
7.
8.
9. CONDUCTIVE HEARING LOSS
SENSORINEURAL HEARING
LOSS
CONGENITAL
•Meatal atresia
•Fixation of stapes footplate
•Fixation of malleus head
•Ossicular discontinuity
•Cong. cholesteatoma
ACQUIRED
• External ear:
– Obstruction
• Internal ear:
– Tympanic membrane
– Fluid
– Mass
– Ossicle
– Eustacian tube
CONGENITAL
•Anomalies (deaf child)
ACQUIRED
•Infection to labyrinth
•Trauma to labyrinth
•Noise-induced HL
•Ototoxic drugs
•Presbycusis
•Minere’s disease
•Acoustic neuroma
•Sudden hearing loss
•Familial progressive SNHL
10.
11. • Removal of canal
obstructions
• Removal of fluids
• Removal of mass from
middle ear
• Strapedectomy
• Tympanoplasty
• Hearing aid
• Myringoplasty
• Ossicular reconstruction
CONDUCTIVE HEARING LOSS
SENSORINEURAL HEARING
LOSS
• Treat the causes
• Antibiotics
• Replacement
therapy
(hypothyriodism)
12. TYMPANOPLASTY
• An operation to :
– Eradicate disease in middle ear
– Reconstruct hearing mechanism (may combined
with mastoidectomy)
14. SPECIFIC FORMS OF HEARING LOSS
1. INFLAMMATION OF LABYRINTH
– Viral labyrinthitis
– Viruses usually reach the inner ear by blood stream affecting
stria vascularis and the endolymph and organ of Corti.
– Few common organisms :
• Measles
• Mumps
• Cytomegalovirus
• Rubella
• Herpes zoster
• Herpes simplex
• Influenza
• Epstein-Barr
15. • BACTERIAL LABYRINTHITIS
– Bacterial infections reach labyrinth through the middle ear
(tympanogenic) or through the CSF (meningogenic)
– Meningitis usually causes sensorineural hearing loss (SNHL)
– Bacteria can invade the labyrinth along nerves, vessels, cochlear
aqueduct or the endolymphatic sac
• SYPHILITIC
– Congenital syphilis is of two types :
– Early form : Manifesting at age of 2 years old
– Late form : Manifesting at age of 8 – 20 years old
– Syphilitic involvement of the inner ear can cause :
• Sudden SNHL unilateral or bilateral
• Meniere syndrome-episodic vertigo, fluctuation hearing loss, tinnitus,
aural fullness
• Tullio phenomenon-loud sound induce vertigo
• Hennebert’s sign-positive fistula sign in the absence of
fistula(nystagmus)
17. 4. NOISE TRAUMA
– Hearing loss caused by excessive noise can be divided into two
groups
• Acoustic trauma-single brief exposure to very intense sound without
being preceded by a temporary threshold shift. Eg: gunshot
• Noise-induced hearing loss-chronic exposure to less intense sound Eg;
noisy occupations
– Temporary threshold shift (TTS)- hearing impaired immediately after exposure
to noise but recovers after interval of minutes to few hours to 2 weeks
– Permanent threshold shift (PTS)- hearing impairment is permanent and does
not recover at all
• Non auditory effects of noise-chronic fatigue, stress, hypertension,
peptic ulcer, laryngeal problems
5. AUTOIMMUNE (IMMUNE-MEDIATED INNER EAR DISEASE)
– Bilateral SNHL, age 40-50, episode of vestibular symptom,
evidence of autoimmune disease such as ulcerative colitis, SLE,
Rheumatoid arthritis or MS
18. • Investigations
– Audiogram
– Speech audiogram
– Evoked response audiometry
– Contrast-enhanced MRI
– Blood tests
• Treatment
– 1mg/kg/day up to total 60 mg/day for 4 weeks
– No response tapered for 12 days
– Maintenance dose for every other day 10-20mg/day for 6 months
– Alternative-methotrexate 15mg/week for 6-8 weeks
– Response continue 6 months
– Alternative cyclophosphamide, intratympanic steroid inj, systemic IgG inj,
plasmapheresis
19. 6. SUDDEN HEARING LOSS
– It is defined as 30 dB or more of SNHL over at least three
contiguous frequencies occurring within a period of 3 days or
less
– Mostly it is unilateral
– It may be accompanied by tinnitus or temporary spell of
vertigo
– Etiology
• Infections : Mumps, herpes zoster, meningitis, encephalitis,
syphilis, otitis media
• Trauma : Head injury, ear operation, noise trauma, barotrauma,
spontaneous rupture
• Vascular :Haemorrhage, embolism or thromboembolism of
labyrinthine or cochlear artery
• Ear : Meniere’s disease, Cogan’s syndrome, large vestibular
aqueduct
• Toxic : Ototoxic drugs, insecticides
• Neoplastic : Acoustic neuroma, carcinomatous neuropathy
• Miscellaneous : MS, hypothyroidism, sarcoidosis
• Psychogenic
20. • Management
– A detailed history, physical examination and laboratory
investigations are done to find the etiology.
– Laboratory investigations : Audiometry, imaging studies,
test for syphilis, diabetes, hypothyroidism and blood
disorders.
– Treat accordingly.
– Empirical therapy : (Idiopathic)
• Bed rest
• Steroid therapy : Anti-inflammatory and edema-40-60mg for 1
week and tailed off for 3 weeks
• Inhalation of carbogen (5% CO2 + 95% O2)
• Low molecular weight dextran
• Vasodilator drugs
• Hyperbaric oxygen therapy
• Low-salt diet and a diuretic
• Intratympanic steroid therapy
21. • Prognosis
– Half of patients (idiopathic) recover
spontaneously within 15 days
– Poor prognosis :
• Disease has been there for 1 month
• Severe hearing loss and is associated with vertigo
• Older patients
– Better prognosis :
• Younger patients below 40 with moderate losses
• Early treatment
22. 7. PRESBYCUSIS
– SNHL associated with physiological aging
process in the ear.
– Four pathological type
1. Sensory : Degeneration of organ of Corti.
2. Neural : Degeneration of cells of spiral ganglion or
higher auditory pathways.
3. Strial or metabolic : Atrophy of stria vascularis in all
turns of cochlea. Audiogram is flat.
4. Cochlear conductive : Due to stiffening of the
basilar membrane thus affecting its movements.
Audiogram is sloping type
23. NONORGANIC HEARING LOSS
• There is no organic lesion. It is either due to
malingering or psychogenic.
• Patient may present with :
– Total hearing loss in both ears
– Total loss in only one ear
– Exaggerated loss in one or both ears
24. DEAF CHILD
• Children with profound (>90dB loss) or total
deafness fail to develop speech “deaf-mute”
or “deaf and dumb”
• These children have no defect in developing
speech
• Hearing loss was observed and managed
<6 mo has better scores of vocabulary, better
expressive and comprehensive language skills
27. HEARING AID
• Instrumental devices
1. Hearing aids
• Conventional hearing aids
• Bone-anchored hearing aids
• Implantable hearing aids
2. Implants
• Cochlear implant
• Auditory brainstem implants
3. Assistive devices for the deaf
• Training
– Speech reading(lip)
– Auditory training
– Speech conservation
28. CONVENTIONAL HEARING AIDS
• Amplify sounds reaching the ear
• 3 parts: microphone, amplifier, receiver
• Types: air conduction HA, bone conduction HA
• Most are air conduction:
29. BONE CONDUCTION TYPE
INDICATION
•conductive hearing loss
•Unilateral hearing loss
•Mixed hearing loss
•Chronic infection of ear
canal
COMPONENTS
1. Titanium fixture
2. Titanium abutment
3. Sound processore
30. COCHLEAR IMPLANTS
• Electronic device that can provide useful hearing
and improved communication abilities for
persons who have severe to profound SNHL and
who cannot benefit from hearing aids
• Producing meaningful electrical stimulation of
the auditory nerve where degeneration of the
hair cells in the cochlear has progressed to a
point such that amplification provided by hearing
aids is no longer effective
31.
32.
33. REFERENCE : Diseases of ear, nose and throat & neck and neck
surgery, PL Dhingra 6th edition
