The ageing auditory system and its The ageing auditory system and its

implications for aural rehabilitation in implications for aural rehabilitation in

clinical practiceclinical practice

Part 1 Part 1

Liz RossLiz Ross

�� Part OnePart One of this session will discuss the of this session will discuss the anatomical and physiological changes in the anatomical and physiological changes in the auditory system that are seen with ageauditory system that are seen with age--related related hearing loss. hearing loss.

�� Part TwoPart Two will look at rehabilitation strategies will look at rehabilitation strategies which can be used in clinical practice for older which can be used in clinical practice for older people people -- including those who develop complex including those who develop complex needs with ageneeds with age--related conditions.related conditions.

�� What is ageing?What is ageing?

Changes with ageing

� Bones – loss of bone marrow and calcium , from about age 30

� Hair- receding hair line from about age 50

� Height – reduction in eight from about age 40

� Skin- sagging and wrinkles from age 40

� Teeth – discoloration as we age

AgeingAgeing

�� The process of growing old or developing the The process of growing old or developing the

appearance and characteristics of old age.appearance and characteristics of old age.

�� 1875 the Friendly Societies Act, defined old age 1875 the Friendly Societies Act, defined old age

as, any age after 50.as, any age after 50.

AgeingAgeing

�� 10 million people in the UK 10 million people in the UK are over 65 years old.are over 65 years old. The The latest projections are for 5latest projections are for 5½½million more elderly people million more elderly people in 20 years time and the in 20 years time and the number will have nearly number will have nearly doubled to around 19 million doubled to around 19 million by 2050 by 2050 ((CracknellCracknell, 2010). , 2010).

www.dailymail.com

Fauja Singh took up running marathons at age 89 and has recently

decided to retire from the sport at age 101.

AgeingAgeing

�� Employment ChangesEmployment Changes

�� Health ChangesHealth Changes

�� Economic ChangesEconomic Changes

�� Social ChangesSocial Changes

�� Lets think about the changes to the auditory Lets think about the changes to the auditory pathwayspathways

Age related changes Age related changes –– external earexternal ear

�� Degeneration of elastic fibres, decreased Degeneration of elastic fibres, decreased collagen collagen –– loss of elasticity in loss of elasticity in pinnapinna

�� Increase thickness and length of hair in external Increase thickness and length of hair in external auditory meatus (EAM)auditory meatus (EAM)

�� This causes cerumen tThis causes cerumen to o become harderbecome harder and and impactedimpacted

�� EAM more prone to traumaEAM more prone to trauma

�� Collapsed canalsCollapsed canals

�� Important for our practice Important for our practice -- care required in care required in impression taking and impression taking and audiometryaudiometry

Age related changes Age related changes –– middle earmiddle ear

�� Commonest disorders in over 65s Commonest disorders in over 65s --

�� InfectionInfection

�� Often linked with upper respiratory infections (URI)Often linked with upper respiratory infections (URI)

�� Other problems relate to changes within the Other problems relate to changes within the ossicularossicular

joints; reduction in elasticity in tympanic membrane (as joints; reduction in elasticity in tympanic membrane (as

described by described by GrattonGratton and Vazquez 2003).and Vazquez 2003).

�� Important for our practiceImportant for our practice-- older people can have older people can have

less effective immune system function. Check ME less effective immune system function. Check ME

function in this client group.function in this client group.

Age related changes Age related changes –– inner earinner ear

�� Presbycusis Presbycusis -- Age related hearing lossAge related hearing loss

�� Bilateral sensory neural hearing lossBilateral sensory neural hearing loss

�� Complex Complex ‘‘environmentalenvironmental--geneticgenetic’’ hearing losshearing loss

�� But But ……..

�� What exactly causes age related hearing loss?What exactly causes age related hearing loss?

�� Difficult to study causes because of other factorsDifficult to study causes because of other factors

�� Therefore problems in teasing out age related Therefore problems in teasing out age related causes from environmental factors ; male/ causes from environmental factors ; male/ female differences etc..female differences etc..

�� Previous work has suggested at Previous work has suggested at non industrial non industrial populations have no difference between male / populations have no difference between male / female hearing levels and noise is detrimental to female hearing levels and noise is detrimental to hearing (hearing (GoycooleaGoycoolea et al 1986)et al 1986)

�� Evidence from animal studies Evidence from animal studies -- mice bred to mice bred to

have genes disposing them to age related have genes disposing them to age related

hearing loss were also genetically disposed to hearing loss were also genetically disposed to

noise induced hearing loss (Davis et al., 2001)noise induced hearing loss (Davis et al., 2001)

�� Additionally, directly from research on humans, Additionally, directly from research on humans,

we know that other factors are influential in we know that other factors are influential in

hearing loss hearing loss -- smoking, elevated blood pressure smoking, elevated blood pressure

and cholesterol levelsand cholesterol levels..

�� Important for our practiceImportant for our practice-- There are complex There are complex

interactions of many factors which contribute to interactions of many factors which contribute to

age related hearing lossage related hearing loss

Lets go back to considering PresbycusisLets go back to considering Presbycusis

�� Bilateral sensory neural hearing lossBilateral sensory neural hearing loss

�� Affecting high frequencies initially then loss Affecting high frequencies initially then loss

spreads to mid and lower frequencies spreads to mid and lower frequencies –– not not

linear and great variability between individualslinear and great variability between individuals

�� Poorer speech discrimination Poorer speech discrimination

�� And additionally affects quality of life And additionally affects quality of life

�� Importance of central processingImportance of central processing

Cochlea functionCochlea function

�� Importance of the Spiral Importance of the Spiral Ligament/ Ligament/ StriaStria VascularisVascularisstructurestructure

�� Outer hair cells (approx Outer hair cells (approx 12000) 12000) –– with pressure wave with pressure wave in cochlea the cells shorten in cochlea the cells shorten then elongate.then elongate.

�� Ion channels in the Ion channels in the stereociliastereocilia of the hair cells of the hair cells open as the result of bending open as the result of bending of of stereocilia'sstereocilia's membranemembrane

Hair CellsHair Cells�� EndolymphEndolymph is rich in is rich in

potassium potassium

�� Displacement of the Displacement of the stereociliastereocilia causes the causes the channels to openchannels to open

�� Potassium (K+) enters the Potassium (K+) enters the hair cell causing it to hair cell causing it to depolarise.depolarise.

�� Releases neurotransmitter Releases neurotransmitter initiating the signals being initiating the signals being passed on , ultimately, to passed on , ultimately, to the the VIIIthVIIIth nerve and on up nerve and on up through the central through the central pathwayspathways

http://www.cochlea.eu/en/hair-cells

�� Outer hair cells tuning function Outer hair cells tuning function

�� Inner hair cells Inner hair cells transducetransduce movement into neural movement into neural

activityactivity

�� Hair cell excitement modulates action potentials Hair cell excitement modulates action potentials

in in VIIIthVIIIth nervenerve

Classification of Classification of PPresbycusisresbycusis

�� Sensory Sensory –– loss of sensory hair cells and loss of sensory hair cells and supporting cells in the organ of supporting cells in the organ of CortiCorti

�� Neural Neural –– loss cochlear neuronsloss cochlear neurons

�� Metabolic (Metabolic (StrialStrial) ) -- loss loss strialstrial tissuetissue

�� Cochlear conductive Cochlear conductive –– changes in mechanical changes in mechanical properties in basilar membraneproperties in basilar membrane

�� Mixed Mixed –– significant pathological change in more significant pathological change in more than one structurethan one structure

�� Intermediate Intermediate –– through different structures , through different structures , suggested spiral ganglion cell involvement suggested spiral ganglion cell involvement

[Adapted from [Adapted from SchuknechtSchuknecht and and GacekGacek (1993); (1993); MeisamiMeisami et al. (2004)] et al. (2004)]

Older adults Older adults

�� Apart from the biological ageing of cells what Apart from the biological ageing of cells what

other conditions may give rise to SN hearing loss other conditions may give rise to SN hearing loss

in older adults?in older adults?

�� Several other factors we need to think about in Several other factors we need to think about in

general terms rather than for an individual clientgeneral terms rather than for an individual client

�� Pure tone audiograms cannot Pure tone audiograms cannot ‘‘pick outpick out’’ potential potential

coco--morbid factors within individualsmorbid factors within individuals

�� ……and as we discussed different external/ and as we discussed different external/

internal factors may interact with presbycusisinternal factors may interact with presbycusis

�� OtotoxicityOtotoxicity ––

�� different absorption of different absorption of

drug in the drug in the

gastrointestinal systemgastrointestinal system

�� Changes in renal function Changes in renal function

altering excretion of altering excretion of

drugsdrugs

�� Many changes in function Many changes in function

within the older adult within the older adult

may make them may make them

susceptible to adverse susceptible to adverse

reactionsreactions

�� Noise exposureNoise exposure ––

�� damage to outer then inner damage to outer then inner

hair cellshair cells

�� Generally bilateral (unless Generally bilateral (unless

noise exposure specific to noise exposure specific to

one side) one side)

�� Multi damage process Multi damage process

(presbycusis + noise (presbycusis + noise

exposure + other factors)exposure + other factors)

�� Metabolic conditions Metabolic conditions ––

diabetes , diabetes , nuerochemicalnuerochemical

imbalance, imbalance, ‘‘risk factorrisk factor’’ of of

SN hearing lossSN hearing loss

�� Vascular disease Vascular disease ––

changes to blood supply changes to blood supply

to organs, to organs, ‘‘risk factorrisk factor’’ in in

SN hearing lossSN hearing loss

�� Genetic factorsGenetic factors

�� Dementia Dementia –– this brings this brings

us on to consider..us on to consider..

Changes in central processingChanges in central processing

�� After the cochlea the After the cochlea the signal is passed signal is passed through different through different relay stations in the relay stations in the central auditory central auditory pathways.pathways.

�� Signal information Signal information contains contains -- frequency; frequency; intensity and locationintensity and location

�� So what does age do So what does age do to processing to processing abilities?abilities?

https://www.healthtap.com/user_questions/166457-how-is-auditory-processing-disorder-different-from-other-hearing-loss

�� Slowing in temporal processingSlowing in temporal processing

�� General cognitive declineGeneral cognitive decline

�� Clients who have had stokes; myocardial Clients who have had stokes; myocardial infraction; Parkinson's infraction; Parkinson's

�� Important for our practice Important for our practice -- PTA PTA cannot differentiate between cannot differentiate between peripheral (cochlear) and neural peripheral (cochlear) and neural hearing loss hearing loss

Tinnitus, Vestibular Dysfunction and Tinnitus, Vestibular Dysfunction and

Dizziness in ageingDizziness in ageing

�� Along with hearing loss prevalence of Along with hearing loss prevalence of

tinnitus increases with agetinnitus increases with age

�� Vestibular imbalance increases with age Vestibular imbalance increases with age

and and ‘‘dizzinessdizziness’’ from other changes from other changes

associated with ageing (blood pressure, associated with ageing (blood pressure,

visual acuity; falls etc.) visual acuity; falls etc.)

SummarySummary

�� Ageing effects can be seen through out the Ageing effects can be seen through out the auditory pathwaysauditory pathways

�� Audiometric tests have valuable functionAudiometric tests have valuable function

�� But do not always reflect actual real world But do not always reflect actual real world difficultiesdifficulties

�� We need to understand ageing We need to understand ageing –– but not take on but not take on the stereotypes the stereotypes

�� Next, [in Part 2], we will look at thinking about Next, [in Part 2], we will look at thinking about the management options for older adultthe management options for older adult

ReferencesReferences

�� CracknellCracknell, R. (2010). The ageing population: the UK's ageing population h, R. (2010). The ageing population: the UK's ageing population has considerable as considerable consequences for public services. In, Mellowsconsequences for public services. In, Mellows--Facer, Facer, A.(edA.(ed), ), Key Issues for the New Parliament Key Issues for the New Parliament 20102010, House of Commons Library: London, pp 44, House of Commons Library: London, pp 44--45.45.

�� Davis, R. R., Davis, R. R., NewlanderNewlander, J. K., Ling, X. B., , J. K., Ling, X. B., CortopassiCortopassi, G. A., Krieg, E. F., & , G. A., Krieg, E. F., & ErwayErway, L. C. (2001). , L. C. (2001). Genetic basis for susceptibility to noiseGenetic basis for susceptibility to noise--induced hearing loss in mice. induced hearing loss in mice. Hearing ResearchHearing Research, 155(1), , 155(1), 8282--90.90.

�� GoycooleaGoycoolea, M.V., , M.V., GoycooleaGoycoolea, H.G., Rodriguez, L.G., , H.G., Rodriguez, L.G., FarfanFarfan, C.R., Martinez, G.C. and Vidal, R. , C.R., Martinez, G.C. and Vidal, R. 1986. Effect of life in industrialized societies on hearing in n1986. Effect of life in industrialized societies on hearing in natives of atives of eastereaster island. island. The The LaryngoscopeLaryngoscope, 96 (12) pp.1391, 96 (12) pp.1391--1396. 1396.

�� GrattonGratton, M. A. and A. E. Vazquez (2003).Age, M. A. and A. E. Vazquez (2003).Age--related hearing loss: current research. Current related hearing loss: current research. Current Opinion in Opinion in Otolaryngology & Head and Neck SurgeryOtolaryngology & Head and Neck Surgery 11(5): 36711(5): 367--371.371.

�� SchuknechtSchuknecht and and GacekGacek (1993) Cochlear pathology in presbycusis, (1993) Cochlear pathology in presbycusis, Ann Ann OtolOtol RhinolRhinol LaryngolLaryngol..Jan;102(1 Pt 2):1Jan;102(1 Pt 2):1--1616

�� MeisamiMeisami E. ; Brown, C. E. ; Brown, C. EmerleEmerle, H. (2003) Sensory systems : normal aging, disorders, and , H. (2003) Sensory systems : normal aging, disorders, and treatments of vision and hearing in humans in treatments of vision and hearing in humans in TimirasTimiras PS eds. PS eds. Physiological Basis of Aging and Physiological Basis of Aging and GeriatricsGeriatrics, Fourth Edition, Fourth Edition