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AUDIOLOGY 03 Hearing assessment & the vestibular organ based on Adam Beckman’s* lecture 2015 *Head of Audiology Services, Plymouth Hospitals NHS trust Pedro Amarante Andrade, PhD LCSC06 BIOSCIENCES FOR SPEECH AND LANGUAGE THERAPY LCSC06 | Biosciences for SLT INTRODUCTION • Physics of sound • The ear (Anatomy and Physiology) • Hearing – How it works – How we measure it – Pathology • The vestibular system LCSC06 | Biosciences for SLT INTRODUCTION • The Ear • with reference to acoustics, anatomy and physiology – What goes wrong – pathology – How we test hearing and function • Year 2 – More detail in paediatrics • Year 3 – Adult acquired loss and its amelioration LCSC06 | Biosciences for SLT HEARING LOSS STATISTICS • There are more than 10,000,000 in the UK with some form of hearing loss, or 1/6 of the population. • From the total 3.7 million are of working age (16 – 64) and 6.3 million are of retirement age (65+). • By 2031, it is estimated that there will be 14.5 million people with hearing loss in the UK. • More than 800,000 people in the UK are severely or profoundly deaf. LCSC06 | Biosciences for SLT HEARING LOSS STATISTICS • About 2 million people in the UK have hearing aids, but only 1.4 million use them regularly. • At least 4 million people who don't have hearing aids would benefit from using them. • On average it takes ten years for people to address their hearing loss. • About one in ten adults in the UK have mild tinnitus and up to 1% have tinnitus that affects their quality of life. LCSC06 | Biosciences for SLT HEARING LOSS STATISTICS • There are more than 45,000 deaf children in the UK, plus many more who experience temporary hearing loss. • More than 70% of over 70 year-olds and 40% of over 50 year-olds have some form of hearing loss. • There are approximately 356,000 people with combined visual and hearing impairment in the UK. Action on Hearing Loss LCSC06 | Biosciences for SLT ASSESSMENT OF HEARING • Aim – to measure the quietest sound that person can hear at different frequencies and plot an audiogram for each ear • And – to establish where in the auditory pathway the problem lies i.e. type of hearing loss LCSC06 | Biosciences for SLT HEARING LOSS DESCRIPTORS • Degree of hearing loss – How bad is it? • Site of hearing loss – Where in the system is it? • High frequency speech sounds? – Consonants • “s”, “t” etc • Low frequency speech sounds? – Vowels • “oo”, “aa” LCSC06 | Biosciences for SLT DEGREES OF HEARING LOSS http://medicalaudiology.com.au/adult-hearing-assessments/ LCSC06 | Biosciences for SLT DEGREES OF HEARING LOSS Normal conversation level Right Ear (red circle) Left Ear (blue x) http://www.audina.net/en/content/view?id=11 LCSC06 | Biosciences for SLT TYPES OF HEARING LOSS • Conductive – outer ear – middle ear • Sensori-neural – cochlea (sensory) – auditory nerve (neural) • Mixed • Central – Not considered today LCSC06 | Biosciences for SLT SOME FACTS ABOUT HEARING LOSS • • • • Bilateral or Unilateral Symmetrical or Asymmetrical Can affect both ears in varying degrees Hearing results (Audiogram) does not indicate degree of disability • Patient can have more than one type of hearing problem • Hearing results can change LCSC06 | Biosciences for SLT MEASURING HEARING FUNCTION Two basic tests: – Pure tone audiometry – Tympanometry LCSC06 | Biosciences for SLT PURE TONE AUDIOMETRY • What is it? – Measure of hearing threshold, using air or bone conduction (across the normal speech frequencies) • How is threshold defined? – Psychometrically, based on method LCSC06 | Biosciences for SLT PURE TONE AUDIOMETRY • Method – Instruct patient – Remove obstructions • Examples… – Estimate hearing • How? – Ask for better hearing ear – Place headphones LCSC06 | Biosciences for SLT PURE TONE AUDIOMETRY • Method – Start with better ear • 1 kHz, 1-3 sec • 30dBHL above ‘threshold’ • Reduce intensity by 10dBHL – Until no response • Increase by 5dBHL – Until response • Reduce by 10, increase by 5 • Until: – 2 responses out of 2 LCSC06 | Biosciences for SLT PURE TONE AUDIOMETRY • Method – i.e. Threshold is defined as level at which patient responds at least 50% of time on ascending presentations (for clinical purposes) – Start at 1kHz – Repeat at 2, 4, 8, 0.5 & 0.25 kHz – Repeat 1 kHz – Test other ear LCSC06 | Biosciences for SLT PURE TONE AUDIOMETRY • Presentation – beware – Rhythm – Visual cues – Auditory cues – Unreliable responses • Non-organic • Tinnitus – Fatigue LCSC06 | Biosciences for SLT PURE TONE AUDIOMETRY • Method – Test bone conduction • • • • Remove obstructions Order: 1, 2, 4, 0.5 kHz Why not 8 kHz Why not 0.25 kHz LCSC06 | Biosciences for SLT PURE TONE AUDIOMETRY • Masking – Why? – When? – How? LCSC06 | Biosciences for SLT PURE TONE AUDIOMETRY • Masking – Why? • Sound can cross over to other cochlea – Ensure know which ear is hearing – When? • 40dB or greater difference in AC thresholds • 10dB or more air-bone gap • 40dB or greater gap between AC test ear and BC nontest ear – How? • Narrow band noise applied to the other ear LCSC06 | Biosciences for SLT PURE TONE AUDIOMETRY Degree of hearing loss • Basic classification – Mild • >20 and ≤40dBHL – Moderate • >40 and ≤60dBHL – Severe • >60 and ≤90dBHL – Profound • >90dBHL http://medicalaudiology.com.au/adult-hearing-assessments/ LCSC06 | Biosciences for SLT Walker et all, 2013. Audiometry screening and interpretation. Am Fam Physician. Jan 1;87(1):41-47. LCSC06 | Biosciences for SLT Walker et all, 2013. Audiometry screening and interpretation. Am Fam Physician. Jan 1;87(1):41-47. LCSC06 | Biosciences for SLT Walker et all, 2013. Audiometry screening and interpretation. Am Fam Physician. Jan 1;87(1):41-47. LCSC06 | Biosciences for SLT Walker et all, 2013. Audiometry screening and interpretation. Am Fam Physician. Jan 1;87(1):41-47. LCSC06 | Biosciences for SLT LCSC06 | Biosciences for SLT LCSC06 | Biosciences for SLT LCSC06 | Biosciences for SLT MEASURING HEARING FUNCTION Two basic tests: – Pure tone audiometry – Tympanometry LCSC06 | Biosciences for SLT TYMPANOMETRY • Why? – TM most flaccid when pressure in External Auditory Meatus equals pressure in Middle Ear – Most sound transmitted when Tympanic Membrane is most flaccid • How? – Apply sound of known level –226 Hz @ 85dBSPL • Measure reflected sound using pressure gradient LCSC06 | Biosciences for SLT TYMPANOMETRY Measures three factors: Size of ear canal cm3 Middle ear pressure daPa Maximum compliance cm3 https://commons.wikimedia.org/wiki/File:Tympanometry.svg. Scott Martin LCSC06 | Biosciences for SLT NORMAL TYMPANOMETRY www.aafp.org LCSC06 | Biosciences for SLT • A - Normal Overly Flexible • As - Otosclerosis or ossicular fixation • AD - Ossicular discontinuity • C - Eustachian tube dysfunction • B - Middle ear atelectasis (the TM is rigidly fixed to the middle ear) or otitis Inflexible media with effusion http://www.vrab-tacra.gc.ca/ Glue ear, wax blockage or (glue ear) perforation TM pushed out TM sucked in DIFFERENT TYMPANOMETRY RESULTS LCSC06 | Biosciences for SLT HEARING LOSS CAUSES LCSC06 | Biosciences for SLT CONDUCTIVE HEARING LOSS Outer ear – Congenital malformation • e.g. atresia, microtia • Gain none of the benefits of – Pinna, ear canal, ear drum • Sound transmitted via bone conduction only to inner ear LCSC06 | Biosciences for SLT AUDIOMETRY - TYMPANOMETRY LCSC06 | Biosciences for SLT CONDUCTIVE HEARING LOSS Outer ear – Blockage • Wax • Infection • Foreign body Sound transmission attenuated by blockage LCSC06 | Biosciences for SLT CONDUCTIVE HEARING LOSS • Outer ear – Exostosis • “Surfer’s ear” – Mild • Little effect on hearing • But trapped water and wax more prone to infection – Severe • Lose benefits of ear canal resonance (attenuates sound) LCSC06 | Biosciences for SLT CONDUCTIVE HEARING LOSS • Outer ear – Perforation • Small – mild hearing loss –Ear drum still works » Vibrates sounds, passes to ossicles » Smaller surface area » Less elastic –More prone to infections • Large – moderate hearing loss – Greater reduction in surface area – Does not vibrate ossicles well LCSC06 | Biosciences for SLT CONDUCTIVE HEARING LOSS • Middle ear – Eustachian tube dysfunction • Blocked Eustachian tube • Negative pressure in middle ear • TM “sucked in” –Less mobile –Sound not transmitted through as well LCSC06 | Biosciences for SLT CONDUCTIVE HEARING LOSS • Middle ear – Otitis media with effusion/glue ear • Eustachian tube blocked • Build up of fluid in middle ear • Sound not transmitted though well • Normally mild hearing loss –Can be moderate LCSC06 | Biosciences for SLT CONDUCTIVE HEARING LOSS • Middle ear – Infection • Fluid in middle ear • Acute infection –Build up of pressure –Painful +++ http://otitismedia.hawkelibrary.com/ • Discharge if ear drum perforates http://know-your-body.wonderhowto.com LCSC06 | Biosciences for SLT CONDUCTIVE HEARING LOSS • Middle ear – Cholesteatoma • Build up of debris in middle ear – Grows slowly – Erodes ossicles, skull – Needs to be surgically removed – Otosclerosis • Bony growth on ossicles – Normally footplate of stapes • Reduces movement of ossicles – Sound transmission to cochlea reduced LCSC06 | Biosciences for SLT CONDUCTIVE HEARING LOSS • Middle ear – Tympanosclerosis • Scarring on ear drum • Collagen deposition - plaques – Does not transmit sound as well – Ossicular malformation • Congenital • Ossicles do not transmit sound through as well – Ossicular fracture or discontinuity • Ossicles do not transmit sound through as well LCSC06 | Biosciences for SLT SENSORI-NEURAL HEARING LOSS LCSC06 | Biosciences for SLT SENSORI-NEURAL HEARING LOSS • Inner ear/nerve • What can go wrong? – Outer hair cells – Inner hair cells – Cochlear fluids – Neural transmission LCSC06 | Biosciences for SLT SENSORI-NEURAL HEARING LOSS • What are the causes? – Congenital • Syndromic • Non-syndromic – Infections • Prenatal • Postnatal – – – – Trauma Ototoxicity Noise induced Ageing LCSC06 | Biosciences for SLT EXAMPLES OF SYNDROMIC CAUSES Recessive syndromes Dominant syndromes X-linked syndromes Chromosomal disorders •Usher’s Waardenburg Alport’s Down Syndrome Syndrome Syndrome Syndrome •Pendred’s Treacher Collins Hunter Turner Syndrome Syndrome Syndrome Syndrome • Can effect different parts of the inner ear • Over 3000 – many rare problems can now be identified via genetic testing LCSC06 | Biosciences for SLT NON-SYNDROMIC • Genetic sensorineural hearing loss – Connexin 26 • Most common – Mitochondrial Connexin 26 (Cx26) is a protein found on the (GJB2) gene and is the most common cause of congenital sensorineural hearing loss LCSC06 | Biosciences for SLT PRENATAL INFECTIONS • STORCH – Syphilis – Toxoplasmosis – Rubella – Cytomegalovirus – Herpes LCSC06 | Biosciences for SLT PERINATAL PROBLEMS – Anoxia at birth – Assisted ventilation – Jaundice – Low birth weight – Mainly hair cell damage, but can effect other parts of the system as well • Including neural problems LCSC06 | Biosciences for SLT POSTNATAL INFECTIONS – Bacterial Meningitis – Meningococcal septicaemia – Mumps – Measles – Scarlet fever – Mainly hair cell damage LCSC06 | Biosciences for SLT TRAUMATIC • Skull fracture (temporal bone) – Can cause loss of fluids from cochlea • Acoustic trauma – explosions, fireworks, gunfire, rock concerts, and earphones – Can cause damage to: • Ear drum, hair cells, cochlear fluids • Barotrauma (differences in pressure) – Diving LCSC06 | Biosciences for SLT • Aminoglycoside antibiotics OTOTOXICITY – Gentamicin etc • Aspirin – large doses • Chloroquine (Antimalarial medications) – Quinine and derivatives • Chemotherapy – E.g. cistplatin • Mainly hair cell damage LCSC06 | Biosciences for SLT NOISE INDUCED - PROLONGED EXPOSURE • Leisure noise – Increasing • Increased levels at concerts/clubs • Personal listening devices • Industrial noise – Reducing • Noise at work regulations • Mainly outer hair cell damage LCSC06 | Biosciences for SLT SENSORINEURAL LOSSES - OTHER CAUSES • Age-related hearing loss – Most common – Variety of potential changes with time • • • • Outer hair cell Inner hair cell Electrolyte imbalance Neural conduction LCSC06 | Biosciences for SLT SENSORINEURAL LOSSES - OTHER CAUSES • Meniere’s disease – Associated with dizziness and tinnitus – Fluctuating symptoms – Problem with cochlear fluids • Infection – Inner ear • Ischaemia – Loss of blood supply – Hair cell damage LCSC06 | Biosciences for SLT NEURAL HEARING LOSSES • Acoustic Neuroma – Growth on the VIII Nerve • Multiple Sclerosis • Neurodegenerative disorders LCSC06 | Biosciences for SLT EFFECT OF HEARING LOSS • Depends on – Age of onset – Degree of loss • Will be covered in years 2 and 3 LCSC06 | Biosciences for SLT SUMMARY • Many conditions can effect hearing – Outer, middle or inner ear – VIII nerve • Basic tests will identify – If hearing loss is conductive or sensorineural – Likely cause of conductive losses • These provide that start of developing the appropriate management LCSC06 | Biosciences for SLT REFERENCES • Gelfand (2004) Hearing. An introduction to psychological and physiological acoustics (4th Ed) Chapter 4. Cochlear mechanisms and processes (p121177) • Katz (2002) Handbook of Clinical Audiology (5th Ed) • Moore (2003) An introduction to the psychology of hearing (5th Ed). Chapter 1: The nature of sound and the structure and function of the auditory system (p 1-54) • Lectures compiled from lectures provided by the Audiology team at QMU LCSC06 | Biosciences for SLT AUDIOLOGY 03 The vestibular organ based on Adam Beckman’s* lecture 2015 *Head of Audiology Services, Plymouth Hospitals NHS trust Pedro Amarante Andrade, PhD LCSC06 BIOSCIENCES FOR SPEECH AND LANGUAGE THERAPY LCSC06 | Biosciences for SLT THE VESTIBULAR SYSTEM Blausen.com staff. "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 20018762. - Own work. Licensed under CC BY 3.0 via Wikimedia LCSC06 | Biosciences for SLT THE VESTIBULAR SYSTEM "Sobo 1911 773" by Dr. Johannes Sobotta - Sobotta's Atlas and Text-book of Human Anatomy 1911. Licensed under Public LCSC06 | Biosciences for SLT THE VESTIBULAR SYSTEM LCSC06 | Biosciences for SLT SEMI-CIRCULAR CANALS • 3 canals orthogonally (at right angles) to each other – Horizontal or lateral semi-circular canal – Superior or anterior semi-circular canal – Posterior semi-circular canal LCSC06 | Biosciences for SLT SEMI-CIRCULAR CANALS • Filled with endolymph • End open up into bulge – Osseous ampulla – Inside this is the crista ampullaris LCSC06 | Biosciences for SLT SEMI-CIRCULAR CANALS "Vestibular system's semicircular canal- a cross-section" by United States government - http://www.cami.jccbi.gov/aam400/phys_intro.htm.. Licensed under Public Domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/ LCSC06 | Biosciences for SLT SEMI-CIRCULAR CANALS • Rotational movement – Displaces hair cells • Semi-circular canals in action • Push-pull system – Left and right – Excitatory on one side = inhibitory on the other side LCSC06 | Biosciences for SLT SEMI-CIRCULAR CANALS • Horizontal or lateral semi-circular canal – 12-15mm long – Arched horizontally – laterally and backwards – Head rotating sideways • E.g. “No”, crossing road • Superior or anterior semi-circular canal – 15-20mm long – Arched upwards – Head rotating front-back • E.g. nodding “yes” LCSC06 | Biosciences for SLT SEMI-CIRCULAR CANALS • Posterior semi-circular canal – 18-22mm long – Arched upwards at the back – Rotation • Head tilting onto shoulder LCSC06 | Biosciences for SLT SEMI-CIRCULAR CANALS • Movement stops – Endolymph continues to move • Lag • Endolymph moving • Continuous movement – Habituates • No longer aware turning LCSC06 | Biosciences for SLT OTOLITH ORGANS LCSC06 | Biosciences for SLT OTOLITH ORGANS • Utricle and saccule • Sensitive to – Linear acceleration – Gravity LCSC06 | Biosciences for SLT OTOLITH ORGANS "Bigotolith" by Original uploader was Password at en.wikipedia - Transferred from en.wikipedia; Transfer was stated to be made by User:Padawane.. Licensed under Public Domain via Wikimedia Commons http://commons.wikimedia.org/wiki/ LCSC06 | Biosciences for SLT OTOLITH ORGANS • Endolymph • Hair cells • Otoliths – Calcium carbonate crystals in gelatinous material • Change of direction of force – Otoliths move, shearing motion on hair cells • Otolith video LCSC06 | Biosciences for SLT OTOLITH ORGANS • Utricle – Larger otolith organ – Linear acceleration • Start in a car – Crystals have more mass – Take longer to start moving – drag the stereocilia • Stop in a car – Crystals have intertia – Continue to move – drag the stereocilia in the opposite direction LCSC06 | Biosciences for SLT OTOLITH ORGANS • Saccule – Smaller otolith organ – Vertical acceleration • Gravity • Going up or down in a lift LCSC06 | Biosciences for SLT OTOLITH ORGANS • Information utilised from – Left and right organs – Proprioception • Neck – Eyes – example; • Tilt head backwards – Is head tilting or body tilting? – We know head is tilting from combined information from neck and otolith organs LCSC06 | Biosciences for SLT VESTIBULO-OCULAR REFLEX • When we walk, why doesn’t this happen? • Film trailer..... LCSC06 | Biosciences for SLT VESTIBULO-OCULAR REFLEX • Steadicam • Tracking shot with steadicam...... LCSC06 | Biosciences for SLT VESTIBULO-OCULAR REFLEX • Image stabilised on retina • When head moves, eyes move in opposite direction – Head move right, eyes move left and vice versa • Head moving all the time – So essential LCSC06 | Biosciences for SLT VESTIBULO-OCULAR REFLEX LCSC06 | Biosciences for SLT VOR – ROTATION TO THE LEFT • Movement of endolymph in semi-circular canal – Signal to: • VIII nerve • Nucleus vestibularis • Contralateral VI nerve – Nucleus abducens • Lateral rectus AND also medial longitudinal fasciculus of contraleteral eye • Medial rectus muscle of each eye • Eyes move to the right LCSC06 | Biosciences for SLT LCSC06 | Biosciences for SLT VESTIBULO-OCULAR REFLEX • Problems with VOR will make everyday activities challenging – Reading – Driving – Walking down stairs – ……….. LCSC06 | Biosciences for SLT SUMMARY • Summary video • Vestibular system – Semi-circular canals – Otolith organs – Vestibulo-ocular reflex (VOR) LCSC06 | Biosciences for SLT