presbyacusis dr. vishal sharma. synonyms age-related sensori-neural hearing loss age-associated...
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PresbyacusisDr. Vishal Sharma
Synonyms
Age-related sensori-neural hearing loss
Age-associated hearing loss (AAHL)
Presbycusis (in USA)
No official agreed age above which a person
suffers from presbyacusis & below which he/she
does not. Arbitrary agreed age is 50 years.
Definitions
Presbyacusis: B/L symmetric, progressive SNHL
due to aging, in absence of other etiologies
Socioacusis: B/L symmetric SNHL due to non-
occupational noise, fatty diet & lack of exercise
Nosoacusis: B/L symmetric SNHL due to diseases
with ototoxic effects
SNHL after 50 yrs age = presbyacusis +
nosoacusis + socioacusis + occupational NIHL
Diagnosis of exclusion
Exclude other causes of hearing loss in elderly:
Noise induced hearing loss
Atherosclerosis (hyperlipidemia), diabetes,
hypertension, myxoedema, Paget’s bone disease
CSOM, Meniere’s disease, acoustic neuroma,
cochlear otosclerosis, ear trauma & ototoxic drug
History
Toynbee (1849) first wrote about age-related
hearing loss & prescribed a treatment (application
of silver nitrate solution to external auditory canal)
Zwaardemaker (1891) gave first accurate
description of presbyacusis. He detected high
frequency involvement & origin in cochlea.
Mechanism of Presbyacusis
Age-related arteriosclerosis
hypo-perfusion & oxygenation of cochlea
formation of reactive oxygen metabolites & free
radicals
damage inner ear structures & mitochondrial
DNA of inner ear
Presbycusis
Genetic Predisposition
Genetic programming for early aging of parts of
auditory system early development of
presbycusis
Genetically programmed susceptibility to
environmental factors (noise, ototoxic drugs,
stress) may be involved
Types of Presbyacusis (Gacek & Schuknecht, 1993)
Sensory
Neural
Metabolic or strial or vascular
Mechanical or cochlear conductive
Mixed
Indeterminate or intermediate
Sensory Presbyacusis
Loss of sensory hair cells in organ of Corti due to
accumulation of lipofuscin pigment granules
Process originates in basal turn (for a length > 10
mm) & slowly progresses toward apex
Audiogram: abrupt, steep, high-frequency SNHL
Speech discrimination score: good
Sensory Presbyacusis
Neural Presbyacusis
Atrophy of spiral ganglion & cochlear neurons (>
50%) mainly in basal turn of cochlea
Slowly progressive HL (Pure Tone Average not
affected until 90% neurons are destroyed)
Audiogram: ski-slope toward high frequencies
Speech discrimination score: poor (disproportionate)
Neural Presbyacusis
Metabolic Presbyacusis
Atrophy of stria vascularis (> 30% destroyed)
Stria vascularis maintains chemical + bioelectric
balance & metabolic health of cochlea
Results in slowly progressive deafness
Audiogram: Flat (as entire cochlea is affected)
Speech discrimination score: good
Metabolic Presbyacusis
Mechanical Presbyacusis
Slowly progressive SNHL due to thickening &
stiffening of basilar membrane of cochlea
More severe in basal turn of cochlea where basilar
membrane is narrow
Audiogram: ski-slope toward high frequencies
Speech discrimination score: slightly impaired
Mechanical Presbyacusis
Other Types
Mixed Presbyacusis:
Many ears have a combination of 4 pathologies
Indeterminate or Intermediate Presbyacusis:
SNHL which progresses with age, without light
microscopic evidence of cochlear pathology
Pathology: altered cellular metabolism / ed
synapse numbers / change in endolymph
composition / central auditory pathway changes
Other age-related changes
Outer ear: ed cerumen formation, ed epithelial
migration, ed hair growth, collapse of EAC
Middle ear: stiffening of TM, Arthritis + ossicular
joints ossification, degeneration of middle
ear muscles
They do not make marked contribution in deafness
Clinical Features
Gradually progressive hearing loss
Difficulty in understanding conversation around
high level of ambient background noise
Recruitment: abnormal growth in perception of
loudness (at high intensity) in pt with hearing loss
Tinnitus (30-50%): indicate worsening of deafness
Social isolation & depression
Investigations
Pure Tone Audiometry
Speech Audiometry: diminished scores
MRI: to rule out vestibular schwannoma
Indications of MRI in presbyacusis pt:
– Asymmetry > 10 dB of PTA between both ears
– Asymmetry > 20 dB of any single frequency
– Unilateral tinnitus
Audiogram
Treatment Medical: no medical cure
Diet modification & supplementation
Psychological counseling
Amplification devices or hearing aids
Lip reading & assisted listening devices
Cochlear Implantation
Tinnitus retraining therapy
Avoidance of aggravating factors
Dietary advice
30% caloric dietary restriction
Use of antioxidant dietary supplements (vitamins
A, C, E; selenium) reduce production of reactive
oxygen metabolites that harm inner ear & lead to
age-related hearing loss
Neuro-vitamins & Gingko biloba have no role
Hearing Aids
Binaural hearing aids give more benefit
Candidacy for hearing aids:
speech reception threshold > 30 dB in better ear
hearing level > 40 dB at 3 & 4 kHz in better ear
Pt with poor speech discrimination score are poor
candidates for hearing aids
Body worn
Spectacle
Spectacle
Completely in canal
Completely in canal
Completely in canal
Behind the ear
In the ear
In the canal
Completely in canal
Lip reading or speech reading
Skill of understanding spoken message by
looking at speaker's lips, jaws, tongue, teeth,
facial expressions, gestures & body language
Lip reading is helpful in patients with diminished
speech discrimination & hearing aid users who
have hearing difficulty in noisy environments
Assisted Listening Devices
They are NOT hearing aids
They are NOT used instead of hearing aids
Help pt with hearing loss to function better in
communication situations to overcome distance,
background noise, or poor room acoustics
Can be used with or without hearing aids
Vibrating wrist watch & alarm clock
CO2 & smoke alarm with strobe light
Amplified & captioned telephone
T.V. & F.M. amplifiers
Personal & multi-user amplifier
Alerting Devices
Amplified Stethoscope
Cochlear Implantation
Patients with cochlear damage & relatively intact
spiral ganglia + central pathways are best
candidates
Cochlear implantation have been performed on
patients up to 85 years old, with good results
Pawel Jastreboff: 1990
Tinnitus Retraining Therapy (TRT)
Based on neuro-physiological model of tinnitus
Blocks tinnitus-related neuronal activity from reaching
cerebral cortex (where it is perceived) & from activating
limbic & autonomic nervous systems
Uses combination of low level, broad-band noise &
counseling to achieve habituation of tinnitus. Tinnitus
never masked in TRT. Retraining takes 12 -18 months.
Success rate = 60 - 80%
Avoidance
Avoid following aggravating factors:
Noise exposure
Ototoxic drugs
Uncontrolled diabetes mellitus
Hyperlipidemia
Future research
Gene therapy to avoid early hair cell death in
cochlea
Medications to stimulate a genetic cascade for
hair cell regeneration
Better programmed hearing aids
Alden, Alfred, Arthur, Eastman, Fletcher, Hisswald,
Luke, Matthew, Oom, Richard, Shirmer & Theodore