Transcript PRESBYCUSIS - Isfahan University of Medical Sciences

PRESBYCUSIS
DR. SUPREET SINGH NAYYAR, AFMC
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DEFINITION
Hearing loss associated with ageing
Clinical features
Insiduous onset
Symmetric SNHL
Progressive loss with age
No other otologic diseases
Normal ear examination
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EPIDEMIOLOGY
Most common form of SNHL
Age
• 10% - 65 – 75yrs
• 25% - > 75yrs
Sex – no difference
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Race – no difference
EPIDEMIOLOGY
Rate of deterioration higher in males
Women show later onset
• In males – by age of 30yrs
Once clinically detectable
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• In males – better hearing at lower frequencies
• In females – at higher frequencies
ETIOLOGY
Not known
Multifactorial
Noise
Genetics
Diabetes / hyperlipidemia / heart diseases
Arteriosclerosis
Drugs & environmental chemical exposure
Stress
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NOISE
Rosen et al
• Sudanese tribe – noise free environment – significant hearing
preservation
Goycolea et al
• Study on three groups of islanders
• Group 1 – subjects who had always lived on island
• Group 2 – islanders who had lived in industrialised
environment for 3 to 5 years
• Group 3 – individuals who had lived in an industrialised
environment for > 5 years
Rosen F, Bergman M, Plester D, El Mufti A, Sati MH. Presbycusis: study of a relatively noise free population in
the Sudan. Ann Otol 1962;71:727-743.
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Goycolea HV, Goycolea HG, Faran C, Rodrigues L, Martinez GC, Vidal R. Effect of life in industrialised
societies of hearing in natives of Eastern Island. Laryngoscope 1986;96:1391-1396.
NOISE
Studies on industrial workers & military personnel
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• Some show additivity of noise & age in development of
presbycusis
• Others don’t
GENETICS
Genetic programming for early aging of parts of auditory
system
Genetically programmed susceptibility to environmental
factors
Sank D, Kallman RJ. The role of heredity in total deafness. Volta Rev 1963;68:461-470.
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Paparella MM, Hanson DG, Rao KN, Olvestad R. Genetic sensorineural deafness in adults. Ann of Otol Rhinol
Laryngol 1975;84:459-472.
DEGENERATIVE
CHANGES
Factors
Peripheral & Central ischaemia
Cochlear nerve compression by hyperostosis
Neurochemical changes
Intracellular accumulation of catabolites
Mitochondrial DNA deletions
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LIGHT MICROSCOPIC
FINDINGS IN AGING EAR
Cochlear
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• Decrease in population of spiral ganglion cells
• Diffuse atrophy of organ of corti & stria vascularis
• Atrophy of Reissner’s membrane – presence of vacuoles /
blebs or rupture
• Degenerative changes of spiral ligament
LIGHT MICROSCOPIC ….
Central
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• Atrophy of ganglion cells
• Ventral cochlear nucleus
• Loss of spheroid cells / reparative gliosis
• Dorsal involvement – high frequency loss
• Inferior colliculus – loss of neuronal elements, glial increase
• Cellular degeneration – medial geniculate body & auditory
cortex
LIGHT MICROSCOPIC ….
Vascular
• Degenerative changes of internal auditory artery
• Plugging of vascular channels in otic capsule (Gussen)
• Progressive thickening of tunica adventitia (Fisch et al)
• Secondary strial atrophy (Graton et al) - segmental
(Igarishi et al)
Osseous
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• Increased apposition of bone in otic capsule
• Hyperostosis of lamina cribrosa in IAM
ULTRASTRUCTURAL FINDINGS
• In the organ of corti
• Marked loss of outer hair cells
• Mild loss of inner hair cells
• Soucek et al
• In surviving cells – “Giant sterociliary degeneration”
• Engstrom et al
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• Fused or modified steriocilia
• A clustering of osmophilic structres of lysosomes &
lipofuscin (pigment of aging)
• In familial lipofuscinosis – early deterioration of
sensory organs & dementia
NEUROCHEMICAL
CHANGES
Kaspary et al
• Postulated neurochemical basis
GABA
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• Significant role in sound processing mechanism in central
nucleus of inferior colliculus
• Aging animal models
• Decrease in number of GABA immunoreactive neurons
• Abnormalities in GABA receptor binding sites
• Overall decrease in concentration of GABA
PRESBYCUSIS AT
MOLECULAR LEVEL
Dys-differentiation theory
• A preprogrammed activation of genes noxious to cells
Membrane theory
• Progressive accumulation of oxidative damage
• Reduction in levels of glutathione and superoxide dismutase
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Ates NA, Unal M, Tamer L, Derici E, Karakas S, Ercan B, Pata YS, Akbas Y, Vayisoglu Y, Camdeviren H .
Glutathione S- transferase gene polymorphisms in presbycusis. Otol Neurootol. 2005 May;26(3):392-7.
PRESBYCUSIS AT
MOLECULAR LEVEL
Enzyme N-acetyltransferase (NAT)
• Involved in detoxification of cytotoxic and carcinogenic
compounds as well as reactive oxygen species (ROS)
• NAT2*6A - the risk of presbycusis was 15.2-fold more in
individuals with mutant allele
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Unal, Murat MD; Tamer, Lulufer PhD; Dogruer, Zeynep Nil MSc; Yildirim, Hatice MSc;
Vayisoglu, Yusuf MD; Camdeviren, Handan PhD. N-Acetyltransferase 2 Gene Polymorphism
and Presbycusis. Laryngoscope. 115(12):2238-2241, December 2005.
PRESBYCUSIS AT
MOLECULAR LEVEL
Mitochondrial DNA deletions
• mtDNA genome – 4977base pair deletion
Ueda, Oshima T, Ikeda K, Abe K, Aoki M, Takasaka T. Mitochondrial DNA deletion is a predisposing cause for
sensorineural hearing loss. Laryngoscope. 1998 Apr;108(4 Pt 1):580-4
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Kong W, Wang Q, Zheng X, Cheng H. Mitochondrial DNA mutations and non-syndromic sensorineural hearing
loss. Zhonghua Er Bi Yan Hou Ke Za Zhi. 2002 Oct;37(5):338-42.
SCHUKNECHT’S CLASSIFICATION
Sensory
Neural
Strial (metabolic)
Cochlear conductive (mechanical)
Mixed
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Indeterminate
SENSORY PRESBYCUSIS
Atrophy of organ of corti
• Basal end of cochlea
Audiometrically
• Speech frequencies –
rarely involved
• Initially abrupt high
frequency hearing loss (68kHz)
• Progresses –mid
frequencies
Speech discrimination
• Good
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NEURAL PRESBYCUSIS
Preservation of relatively
normal pure tone thresholds
with progressive drop in
word discrimination scores
Losses of upto 50% compatible with near normal
speech discrimination
90% of cochlear neurons must
be lost before puretone
thresholds are affected
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NEURAL
PRESBYCUSIS
Pauler et al
Studied neuronal counts from base to apex of four regions of
cochlea
Loss in 15-22mm region
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Correlated with loss of
speech discrimination
NEURAL
PRESBYCUSIS
Other degenerative changes of central nervous system
Lack of coordination
Weakness of extremities
Tremors
Irritability
Intellectual deterioration
Memory loss
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STRIAL PRESBYCUSIS
Role of stria vascularis
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• Production of endocochlear potential 80mV in scala media
• Endolymph production
• Contains oxidising enzymes –metabolism of glucose
STRIAL PRESBYCUSIS
Types of strial atrophy
• Patchy type
• Affects predominantly marginal cells
• Most severe in apical and middle turns
• Diffuse type
• Widening of intracellular spaces
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30% loss of strial tissue results in hearing
loss
STRIAL PRESBYCUSIS
Audiologic features
• Flat / slightly sloping
• Symmetric
• SDS – mild loss
Onset –4th to 6th
decade
Progresses slowly
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COCHLEAR CONDUCTIVE
Lacks definitive
histologic correlate
Temporal bone studies
• Hair cells
• Cochlear neurons
• Stria vascularis
Normal
Middle age, symmetric
SNHL
Gradually increases in
severity from low to
high frequencies
SDS - mild loss
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COCHLEAR
CONDUCTIVE
Schuknecht postulated
• Mechanical alteration in cochlear function (stiffening of basilar
membrane)
• Hearing loss increments show a linear relationship to sound
frequencies
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They are caused by changes in resonance
frequency of cochlear duct which
determines the distribution of sound frequency
MIXED PRESBYCUSIS
Site of lesion – any combination
Hearing loss – any combination
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Speech discrimination – mild loss
INDETERMINATE
PRESBYCUSIS
No distinct lesions
Flat or abrupt high frequency hearing loss
• Similar to strial or sensory presbycusis
• Without histopath correlate
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Speech – mild loss
INDETERMINATE
PRESBYCUSIS
Probable etiologies
Impaired cellular metabolism
Diminished synaptic function
Chemical alterations of endolymph
Dysfunction in central auditory pathway
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LOWELL & PAPARELLA
CLASSIFICATION
Presbycusis
• >65yrs / no etiology
• Gradually / abruptly descending SNHL
Familial presbycusis
• >65yrs / no etiology / having family history
• Gradually declining SNHL / occasional basin
configuration
• Speech discrimination score of 70% to 80%
Familial hearing loss (Genetic presbycusis)
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• <65yrs / family history
• Flat or basin shaped curve
• Good speech discrimination score
EVALUATION AND D/D
Detailed history
• to rule out any specific etiology
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Noise exposure / Trauma / ear infections
Ototoxicity
Loss of outer hair cells
Vit –D deficiency
Neurologic disorders – multiple sclerosis
Advanced vascular disease- TIAs, related brain stem
ischemia
• Genetic
PTA, Tympanometry
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If asymmetric – ABR, MRI
IMPACT OF
PRESBYCUSIS
No visible infirmity
Those interacting with him may not take helpful
measures
Forces him to continually ask for help
Fosters a sense of disability
Voluntarily remain in isolation at parties
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May eventually withdraw from social situations
PREVENTION &
TREATMENT
Prevention
• Counseling - Important for young patients with genetic or
familial pattern
• Periodic otologic examination
• Annual audiograms in high risk patients
• Career or life-style change
Treatment
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• No effective medical or surgical treatment
ALTERNATIVE
MEDICINE
30% dietary caloric restriction
Antioxidant therapy – Vit A supplements
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Control diabetes / hyperlipidemia
PROGNOSIS
Majority
• Slow deterioration
Neural presbycusis
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• Worsen more rapidly
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REHABILITATION
REHABILITATION
Precise hearing aid fitting
Hearing assistive devices
Lip reading classes
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Possible cochlear implantation
ASSISTIVE DEVICES
Telephone devices
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Telecoils
Telephone amplifiers
Buzzer
Visual alert
Television, Radio & Stereo amplifiers
Source: from a brochure published by the American Academy of Otolaryngology - Head and Neck Surgery.
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• Wireless infrared devices
• FM systems
• Audio loop systems
ASSISTIVE DEVICES
Signaling devices
• Visual alerts
• Vibrator
Personal amplification devices
Devices for professional people
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• Electronic stethoscope
• Amplifier for a nurse looking after hearing impaired
CURRENT & FUTURE AREAS OF
INVESTIGATION
Influence of
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Demographics & socioeconomic conditions
Dietary habits
Tobacco use
Alcohol consumption
Diabetes / hypertension / hyperlipidemia
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REFERENCES
• Rinaldo F Canalis, Paul R Lambert. Comprehensive
otology.
• Scott-Brown 3rd Volume 7th edition
• Schuknecht. Pathology of Ear
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• Relevant journal articles
Decline in Hearing Sensitivity
Decibel
80
1 khz
2 khz
4 khz
8 khz
60
40
20
0
30
40 50
60 70 80
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Age
Percent of Adults with Disabilities (National
Center for Health Statistics, 1999)
60
50
Percent
40
30
20
10
0
70-74
75-79
Age Group
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80-84
85+
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65-69
THANK YOU
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