PRESBYCUSIS

1. PRESBYCUSIS Dr. supreet singh nayyar, afmc For more .ppt, visit www.nayyarent.com www.nayyarENT.com

2. Definition • Hearing loss associated with ageing • Clinical features • Insiduous onset • Symmetric SNHL • Progressive loss with age • No other otologic diseases • Normal ear examination www.nayyarENT.com

3. Epidemiology • Most common form of SNHL • Age • 10% - 65 – 75yrs • 25% - > 75yrs • Sex – no difference • Race – no difference www.nayyarENT.com

4. Epidemiology • Rate of deterioration higher in males • Women show later onset • In males – by age of 30yrs • Once clinically detectable • In males – better hearing at lower frequencies • In females – at higher frequencies www.nayyarENT.com

5. Etiology • Not known • Multifactorial • Noise • Genetics • Diabetes / hyperlipidemia / heart diseases • Arteriosclerosis • Drugs & environmental chemical exposure • Stress www.nayyarENT.com

6. 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 Otol1962;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. www.nayyarENT.com

7. Noise • Studies on industrial workers & military personnel • Some show additivity of noise & age in development of presbycusis • Others don’t www.nayyarENT.com

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

9. Degenerative Changes • Factors • Peripheral & Central ischaemia • Cochlear nerve compression by hyperostosis • Neurochemical changes • Intracellular accumulation of catabolites • Mitochondrial DNA deletions www.nayyarENT.com

10. Light Microscopic Findings in Aging Ear • Cochlear • 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 www.nayyarENT.com

11. 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 www.nayyarENT.com

12. 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 www.nayyarENT.com

13. 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 osmophilicstructres of lysosomes & lipofuscin (pigment of aging) • In familial lipofuscinosis – early deterioration of sensory organs & dementia www.nayyarENT.com

14. Neurochemical Changes • Kaspary et al • Postulated neurochemical basis • GABA • 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 www.nayyarENT.com

15. 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 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. www.nayyarENT.com

16. 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 mutantallele 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. www.nayyarENT.com

17. 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 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. www.nayyarENT.com

18. Schuknecht’s Classification • Sensory • Neural • Strial (metabolic) • Cochlear conductive (mechanical) • Mixed • Indeterminate www.nayyarENT.com

19. Sensory Presbycusis • Atrophy 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 www.nayyarENT.com

20. 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 www.nayyarENT.com

21. Neural Presbycusis • Pauler 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 www.nayyarENT.com

22. Neural Presbycusis • Other degenerative changes of central nervous system • Lack of coordination • Weakness of extremities • Tremors • Irritability • Intellectual deterioration • Memory loss www.nayyarENT.com

23. Strial Presbycusis • Role of stria vascularis • Production of endocochlear potential 80mV in scala media • Endolymph production • Contains oxidising enzymes –metabolism of glucose www.nayyarENT.com

24. 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 • 30% loss of strial tissue results in hearing loss www.nayyarENT.com

25. StrialPresbycusis • Audiologic features • Flat / slightly sloping • Symmetric • SDS – mild loss • Onset –4th to 6th decade • Progresses slowly www.nayyarENT.com

26. Cochlear Conductive • Lacks definitive histologic correlate • Temporal bone studies • Hair cells • Cochlear neurons • Striavascularis • Middle age, symmetric SNHL • Gradually increases in severity from low to high frequencies • SDS - mild loss Normal www.nayyarENT.com

27. Cochlear Conductive • Schuknecht 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 www.nayyarENT.com

28. Mixed Presbycusis • Site of lesion – any combination • Hearing loss – any combination • Speech discrimination – mild loss www.nayyarENT.com

29. Indeterminate Presbycusis • No distinct lesions • Flat or abrupt high frequency hearing loss • Similar to strial or sensory presbycusis • Without histopath correlate • Speech – mild loss www.nayyarENT.com

30. Indeterminate Presbycusis • Probable etiologies • Impaired cellular metabolism • Diminished synaptic function • Chemical alterations of endolymph • Dysfunction in central auditory pathway www.nayyarENT.com

31. 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) • <65yrs / family history • Flat or basin shaped curve • Good speech discrimination score www.nayyarENT.com

32. Evaluation and D/D • Detailed 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, Tympanometry • If asymmetric – ABR, MRI Loss of outer hair cells www.nayyarENT.com

33. 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 • May eventually withdraw from social situations www.nayyarENT.com

34. 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 • No effective medical or surgical treatment www.nayyarENT.com

35. Alternative Medicine • 30% dietary caloric restriction • Antioxidant therapy – Vit A supplements • Control diabetes / hyperlipidemia www.nayyarENT.com

36. Prognosis • Majority • Slow deterioration • Neural presbycusis • Worsen more rapidly www.nayyarENT.com

37. Rehabilitation www.nayyarENT.com

38. Rehabilitation • Precise hearing aid fitting • Hearing assistive devices • Lip reading classes • Possible cochlear implantation www.nayyarENT.com

39. Assistive Devices • Telephone 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.2002 www.nayyarENT.com

40. Assistive Devices • Signaling devices • Visual alerts • Vibrator • Personal amplification devices • Devices for professional people • Electronic stethoscope • Amplifier for a nurse looking after hearing impaired www.nayyarENT.com

41. Current & Future Areas of Investigation • Influence of • Demographics & socioeconomic conditions • Dietary habits • Tobacco use • Alcohol consumption • Diabetes / hypertension / hyperlipidemia www.nayyarENT.com

42. References • Rinaldo F Canalis, Paul R Lambert. Comprehensive otology. • Scott-Brown 3rd Volume 7thedition • Schuknecht. Pathology of Ear • Relevant journal articles www.nayyarENT.com

43. Thank you • For more topisc & presentations in ENT, visit www.nayyarENT.com www.nayyarENT.com