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PRESBYCUSIS

DR. SUPREET SINGH NAYYAR, AFMC

FOR MORE .PPT, VISIT WWW.NAYYARENT.COM

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DEFINITIONHearing loss associated with ageingClinical features

• Insiduous onset• Symmetric SNHL• Progressive loss with age• No other otologic diseases• Normal ear examination

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EPIDEMIOLOGYMost common form of SNHLAge

• 10% - 65 – 75yrs• 25% - > 75yrs

Sex – no differenceRace – no difference

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EPIDEMIOLOGYRate of deterioration higher in malesWomen show later onset

• In males – by age of 30yrsOnce clinically detectable

• In males – better hearing at lower frequencies• In females – at higher frequencies

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ETIOLOGYNot knownMultifactorial

• Noise • Genetics• Diabetes / hyperlipidemia / heart diseases• Arteriosclerosis• Drugs & environmental chemical exposure• Stress

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NOISERosen 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.

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.

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NOISEStudies on industrial workers & military personnel

• Some show additivity of noise & age in development of presbycusis

• Others don’t

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GENETICSGenetic programming for early aging of parts of auditory systemGenetically programmed susceptibility to environmental factors

Sank D, Kallman RJ. The role of heredity in total deafness. Volta Rev 1963;68:461-470.

Paparella MM, Hanson DG, Rao KN, Olvestad R. Genetic sensorineural deafness in adults. Ann of Otol Rhinol Laryngol 1975;84:459-472.

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DEGENERATIVE CHANGESFactors

• 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 EARCochlear

• 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

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LIGHT MICROSCOPIC ….Central

• 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

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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• Increased apposition of bone in otic capsule• Hyperostosis of lamina cribrosa in IAM

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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 • Fused or modified steriocilia• A clustering of osmophilic structres of lysosomes &

lipofuscin (pigment of aging)• In familial lipofuscinosis – early deterioration of

sensory organs & dementia

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NEUROCHEMICAL CHANGES Kaspary et al

• Postulated neurochemical basisGABA

• 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

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PRESBYCUSIS AT MOLECULAR LEVELDys-differentiation theory

• A preprogrammed activation of genes noxious to cellsMembrane theory

• Progressive accumulation of oxidative damage• Reduction in levels of glutathione and superoxide dismutase

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.

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PRESBYCUSIS AT MOLECULAR LEVELEnzyme 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

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.

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PRESBYCUSIS AT MOLECULAR LEVELMitochondrial 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

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.

   

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SCHUKNECHT’S CLASSIFICATIONSensoryNeuralStrial (metabolic)Cochlear conductive (mechanical)MixedIndeterminate

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SENSORY PRESBYCUSISAtrophy of organ of corti

• Basal end of cochlea

Audiometrically• Speech frequencies –

rarely involved • Initially abrupt high

frequency hearing loss (6-8kHz)

• Progresses –mid frequencies

Speech discrimination • Good

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NEURAL PRESBYCUSISPreservation 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 PRESBYCUSISPauler et al

Studied neuronal counts from base to apex of four regions of cochlea

Loss in 15-22mm region

Correlated with loss of speech discrimination

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NEURAL PRESBYCUSISOther degenerative changes of central nervous system

• Lack of coordination• Weakness of extremities• Tremors• Irritability • Intellectual deterioration• Memory loss

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STRIAL PRESBYCUSISRole of stria vascularis

• Production of endocochlear potential 80mV in scala media• Endolymph production• Contains oxidising enzymes –metabolism of glucose

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STRIAL PRESBYCUSISTypes of strial atrophy

• Patchy type • Affects predominantly marginal cells • Most severe in apical and middle turns

• Diffuse type• Widening of intracellular spaces

30% loss of strial tissue results in hearing loss

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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

correlateTemporal bone studies

• Hair cells• Cochlear neurons • Stria vascularis

Middle age, symmetric SNHL

Gradually increases in severity from low to high frequencies

SDS - mild loss

Normal

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COCHLEAR CONDUCTIVESchuknecht postulated

• Mechanical alteration in cochlear function (stiffening of basilar membrane)

• Hearing loss increments show a linear relationship to sound frequencies

They are caused by changes in resonance frequency of cochlear duct which determines the distribution of sound frequency

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MIXED PRESBYCUSISSite of lesion – any combinationHearing loss – any combinationSpeech discrimination – mild loss

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INDETERMINATE PRESBYCUSISNo distinct lesionsFlat or abrupt high frequency hearing loss

• Similar to strial or sensory presbycusis• Without histopath correlate

Speech – mild loss

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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 CLASSIFICATIONPresbycusis

• >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)• <65yrs / family history• Flat or basin shaped curve• Good speech discrimination score

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EVALUATION AND D/DDetailed history

• to rule out any specific etiology• Noise exposure / Trauma / ear infections• Ototoxicity• Vit –D deficiency• Neurologic disorders – multiple sclerosis• Advanced vascular disease- TIAs, related brain stem

ischemia• Genetic

PTA, TympanometryIf asymmetric – ABR, MRI

Loss of outer hair cells

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IMPACT OF PRESBYCUSISNo visible infirmityThose interacting with him may not take helpful measuresForces him to continually ask for help Fosters a sense of disabilityVoluntarily remain in isolation at parties May eventually withdraw from social situations

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PREVENTION & TREATMENTPrevention

• 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• No effective medical or surgical treatment

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ALTERNATIVE MEDICINE30% dietary caloric restrictionAntioxidant therapy – Vit A supplementsControl diabetes / hyperlipidemia

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PROGNOSISMajority

• Slow deterioration Neural presbycusis

• Worsen more rapidly

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REHABILITATION

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REHABILITATIONPrecise hearing aid fittingHearing assistive devicesLip reading classesPossible cochlear implantation

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ASSISTIVE DEVICESTelephone devices

• Telecoils• Telephone amplifiers• Buzzer• Visual alert

Television, Radio & Stereo amplifiers• Wireless infrared devices• FM systems• Audio loop systems

Source: from a brochure published by the American Academy of Otolaryngology - Head and Neck Surgery. 200224-07-2012

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ASSISTIVE DEVICESSignaling devices

• Visual alerts• Vibrator

Personal amplification devicesDevices for professional people

• Electronic stethoscope• Amplifier for a nurse looking after hearing impaired

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CURRENT & FUTURE AREAS OF INVESTIGATION

Influence of • 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• Relevant journal articles

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THANK YOU

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