1. Sensori-neural Hearing Loss (SNHL)
Size of the problem
WHO (2005)
• 278 million with disabling hearing impairment
• Disabling-moderate (41 d B +) or worse
• 364 million- mild hearing impairment
• 80 percent in low or middle income countries
• Among 20 leading global burden of the disease
Recent Increase is due to
• Improved diagnosis and early detection
• Longer survival of elderly
• Increase in NIHL
• Increase in ototoxicity
2. Sensori-neural Hearing Loss
Importance—profound effect
On individuals
• Hinder speech, language and cognitive skill
development in pre-lingual children
• Slow progress in schools
• Difficulty in obtaining, keeping and performing in
any occupation
• Significant social isolation and stigmatization-poor
interpersonal development
Social and economic
• Substantial cost of treatment and rehabilitation
• Loss of productivity
3. Causes of SNHL
A. Congenital
Genetic
Syndromic
Non-Syndromic
Non-genetic (Embryopathies)
B. Acquired
4. Causes of SNHL
Congenital-Genetic (Hereditary) SNHL-Syndromic
Waardenburg’s-White forelock,
heterochromia of iris
Usher- with retinitis pigmentosa
Alport’s- with nephritis
Pendred- with hypothyroidism
Marfan- skeletal defects
Jervill –Lange- with abnormal EEG
5. Causes of SNHL
Congenital-Genetic (Hereditary) SNHL-Non-
Syndromic
More common than syndromic
1. Autosomal dominant SNHL
2. X-linked SNHL
3. Autosomal recessive SNHL-more
common
9. Ototoxicity
Definition:
Tendency of certain therapeutic agents to cause
functional impairment of inner ear as a side
effect of pharmacotherapy
Route of administration:
Topical- creams, ointments, drops, sprays,
inhalation, irrigation
Systemic- IM/ IV
11. Aminoglycosides
• Streptomycin, dihydro-streptomycin,
kanamycin, neomycin, gentamicin,
tobramycin, sisomycin, amikacin, dibekacin,
netilmycin, paromycin, ispamicin
• Mechanism-effect on sensory neuro-epithelium
of the inner ear especially outer
hair cells of the organ of Corti and type I hair
cells of Crista ampulli
12. Aminoglycosides
• Widely used because potent and cheap
• Still used in drug resistance tuberculosis,
neonatal sepsis
• In 1-5% of patients exposed
• Factors influencing-dose, duration, liver and
kidney disease, bacteremia, concomitant use
of other agents, genetic predisposition
• Some are cochleotoxic, some vestibulotoxic
13. Cytotoxic Agents
Cisplatin, carboplatin
• Effective in solid head and neck squamous
cell carcinoma
• Highly ototoxic in about 50 % of patients
but the exposed population is low
• Loss of mainly outer hair cells
14. Loop Diuretics
Frusemide , ethacrynic acid, bumetanide
• Moderate to low percent of population at
risk
• Mechanism
Reversible reductions of endocochlear
potential
Electrolyte changes in inner ear fluids
Histologic changes in stria vascularis
15. Industrial Chemicals
• Toluene-used in printing and wood finishing,
• Benzene- used in plastic industry
Permanent hearing loss in animals but
inconclusive evidence in man
16. Polypeptide Antibiotics
Vancomycin, Viomycin
• Not aminoglycosides
• Less commonly used and less toxic
• Ototoxic when given at higher doses
for longer period of time
17. Macrolides
Erythromycin, azithromycin, clarithromycin
• Transient ototoxicity when used in
high doses
• Reduction in transient evoked
otoacoustic emissions
18. Salicylates
• Used for their anti-inflammatory,
antipyretic, analgesic and antiplatelet
effects
• In low doses protect inner ear from
gentamicin induced ototoxicity but ototoxic
in higher doses
19. Quinine Derivatives
• Widely used as antimalarial
• Exposed population at risk very high
20. Ototoxicity
Clinical features
• Tinnitus often the first symptom
• SNHL-high tone more than low ones
• Vertigo and disequilibrium
• Oscillopsia- with aminoglycosides
Inability to focus sharply and jumping of
the distant objects
21. Ototoxicity
Prevention and Treatment
1. Avoidance of ototoxic agents as far as practicable
2. Careful monitoring and early recognition
3. Cessation of treatment and substitution by a
different agent
4. SNHL-hearing aid
5. Tinnitus-if disturbing-mild hypnotic and tinnitus
masker
6. Vertigo and disequilibrium –reassurance with
physiotherapy and head exercises
22. Presbyacusis
• New terminology--- age related sensori-neural
hearing impairment
• Result of aging process and inevitable
• Sixth decade onwards, if genetic predisposition and
NIHL earlier also
• Predisposition--Environmental factors
Noise exposure, smoking,
Alcoholism, high systolic blood pressure
Blood hyper viscosity
23. Presbyacusis
Histopathological changes in the inner
ear
• Sensory-Hair cell degeneration and loss
• Neural-degeneration of neurons and
ganglions
• Metabolic-Degeneration of stria vascularis
• Mechanical-degeneration of supporting
cells, membranes
24. Presbyacusis
Clinical features
• Hearing impairment – slow and
insidious, lack of clarity than loss of
volume
• “Don’t shout, I’m not deaf”
• Tinnitus often the presenting symptom
and sometimes may be troublesome
25. Presbyacusis
Management
• Speaking in a clear and articulated
voice close to the patients ear
• Hearing aid- but in some amplification
may not help
26. Noise induced hearing Loss (NIHL)
Reduction in auditory acuity associated with noise
exposure --social, recreational, occupational
Types
• Temporary threshold shift (TTS)- Lasting hours
to days, reversible
• Permanent threshold shift (PTS) - Irreversible
• Acoustic trauma- When a single exposure to
intense trauma leads to immediate hearing
loss
27. Noise induced hearing Loss (NIHL)
Pathology- various hypothesis
Metabolic changes- TTS
Excessive glutamase release, cochlear
hypoxia
Structural changes –PTS
Depolymerization of actin filaments in
sterocilia
Swelling of stria vascularis, nerve
endings, supporting cells- necrosis
29. Noise induced hearing Loss (NIHL)
Diagnosis—clinical
• Tinnitus is the usual initial symptom with or
without hearing impairment
• PTA-High tone hearing loss with a notch
centered on 4 kHz
30. Noise induced hearing Loss (NIHL)
Treatment
• “Prevention is better than cure”
• Awareness/Legal provisions
• Reduction of noise level at place of work
• Use of hearing protection devices
Intensity->85 dB, Duration- >8 hours per
day 5 days a week
31. Idiopathic Sudden Sensori-neural
Hearing Loss
Definition:
30 dB or more sensori-neural hearing loss at least in 3
consecutive frequencies occurring in less than 3 days
• Medical emergency
• Diagnosis by exclusion of other causes on the
basis of history, clinical examination,,
investigations and MRI
Causes- Postulated
• Viral, vascular, haematological, membrane rupture,
autoimmune etc.
32. Idiopathic Sudden Sensori-neural
Hearing Loss
Treatment- many agents, no single agent
universally popular
Steroids Antivirals
Carbogen Vasodilators
Vitamins Antioxidants
• TUTH-Hydrocotisone IV in high doses gradually
tapered over two weeks
33. Idiopathic Sudden Sensori-neural
Hearing Loss
Prognosis- Spontaneous remission common in
about 75%
• Complete recovery-hearing within < 10 dB
• Partial recovery-hearing within 50 % or
more of prehearing
• No recovery-less than 50 percent recovery
34. Non -Organic Hearing Loss (NOHL)
• Hysterical or malingnering- recruits or
prisoners
• Disproportionate and inconsistent
hearing test results
• Stenger tuning fork test
• Confirmed by stapedial reflex and evoked
response audiometry
35. Trauma to Inner Ear
• Fracture of temporal bone
Transverse-U/L Severe sudden SNHL
• Labyrinthine concussion
Head injury –chemical labyrinthitis
• Iatrogenic
Surgical damage to Oval Window,
Labyrinth
