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Hearing Tests in Children Mr Stephen O'Hanlon MA(Oxon) MBBChir(Cantab) MRCS DOHNS MSc.

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Presentation on theme: "Hearing Tests in Children Mr Stephen O'Hanlon MA(Oxon) MBBChir(Cantab) MRCS DOHNS MSc."— Presentation transcript:

1 Hearing Tests in Children Mr Stephen O'Hanlon MA(Oxon) MBBChir(Cantab) MRCS DOHNS MSc

2 Case 1 Inpatient referred to ENT clinic by paediatrics team Inpatient referred to ENT clinic by paediatrics team 4 year old boy of Somali origin with tibial swelling 4 year old boy of Somali origin with tibial swelling Blood cultures, imaging; diagnosis of Osteomyelitis Blood cultures, imaging; diagnosis of Osteomyelitis Peripheral long line, 6/52 of IV ABX – Flucloxacillin and Benzylpenicillin Peripheral long line, 6/52 of IV ABX – Flucloxacillin and Benzylpenicillin

3 Case 1 3/52 into treatment, became unwell 3/52 into treatment, became unwell Temp 40, WCC 25, Neutrophilia, crp 200 Temp 40, WCC 25, Neutrophilia, crp 200 Erythema around peripheral line Erythema around peripheral line Line removed, started on Vancomycin and Gentamycin as per microbiology advice, presumed line sepsis Line removed, started on Vancomycin and Gentamycin as per microbiology advice, presumed line sepsis Blood cultures negative Blood cultures negative Good response after 24 hours Good response after 24 hours

4 Case 1 New peripheral line inserted, long term antibiotics resumed New peripheral line inserted, long term antibiotics resumed 2 days later, complained of blocked right ear 2 days later, complained of blocked right ear No other olologic/neuro symptoms No other olologic/neuro symptoms Dull TMs both sides Dull TMs both sides Rinne’s test normal both sides Rinne’s test normal both sides Weber’s test localises to the left side Weber’s test localises to the left side ?Antibiotic ototoxicity right ear ?Antibiotic ototoxicity right ear

5 Case 1 Seen by ENT. Agree with appearance of TMs and tuning fork tests. Seen by ENT. Agree with appearance of TMs and tuning fork tests. Hearing tests arranged Hearing tests arranged

6 Case 1

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8 Diagnosis : Bilateral Otitis Media with Effusion (Glue ear / Bilateral effusions) Diagnosis : Bilateral Otitis Media with Effusion (Glue ear / Bilateral effusions) Treatment : Wait and see Treatment : Wait and see Outcome : By three months, the hearing tests had returned to normal Outcome : By three months, the hearing tests had returned to normal

9 Case 1 Learning points Tuning fork tests are neither sensitive nor specific (around 70% for both) Tuning fork tests are neither sensitive nor specific (around 70% for both) Common problems occur commonly Common problems occur commonly Bilateral OME can present with unilateral symptoms Bilateral OME can present with unilateral symptoms OME usually resolves without surgical treatment OME usually resolves without surgical treatment

10 Case 2 GP referral to ENT clinic GP referral to ENT clinic 7 month old boy, parental concern about hearing. 7 month old boy, parental concern about hearing. FTND, normal response to hearing screening at birth FTND, normal response to hearing screening at birth 3/12 old, admitted with high temperature, diagnosis of ‘Viral meningitis’. Uneventful recovery 3/12 old, admitted with high temperature, diagnosis of ‘Viral meningitis’. Uneventful recovery

11 Case 2 Seen in clinic, happy 7 month old. Normal ENT on examination, but did not seem to respond to auditory cues. Seen in clinic, happy 7 month old. Normal ENT on examination, but did not seem to respond to auditory cues. ?Hearing loss due to meningitis ?Hearing loss due to meningitis Hearing tests Hearing tests

12 Case 2

13 Otoacoustic emissions Otoacoustic emissions No response at 40 db ISO left or right ear No response at 40 db ISO left or right ear

14 Case 2 Went on to have Brainstem Auditory Evoked Response testing under sedation Went on to have Brainstem Auditory Evoked Response testing under sedation Confirmed a bilateral moderate sensorineural hearing loss (45 db ISO both sides) Confirmed a bilateral moderate sensorineural hearing loss (45 db ISO both sides) Referred for hearing therapy, with a view for hearing aids Referred for hearing therapy, with a view for hearing aids

15 Case 2 Learning points Different hearing tests are required for children of different ages Different hearing tests are required for children of different ages Parental concern is one of the best indicators for hearing loss in children Parental concern is one of the best indicators for hearing loss in children

16 Hearing Tests in Children 1) Definitions – Anatomy, Physics, and Staff 1) Definitions – Anatomy, Physics, and Staff 2) Pure Tone Audiograms 2) Pure Tone Audiograms 3) Impedance Audiometry 3) Impedance Audiometry 4) Subjective Hearing Tests 4) Subjective Hearing Tests 5) Objective Hearing Tests 5) Objective Hearing Tests 6) Screening Programmes 6) Screening Programmes

17 Hearing Tests in Children For GP VTS trainees For GP VTS trainees Curriculum heading 8 : Care of Children and Young People Curriculum heading 8 : Care of Children and Young People Curriculum heading 15.4 : ENT and Facial Problems Curriculum heading 15.4 : ENT and Facial Problems

18 Definitions Pinna Pinna External auditory meatus and canal External auditory meatus and canal Tympanic membrane Tympanic membrane Middle ear cleft Middle ear cleft Cochlear Cochlear

19 Definitions Eighth Cranial Nerve Eighth Cranial Nerve Cochlear Nucleus Cochlear Nucleus Olivary complex (sup) Olivary complex (sup) Lateral lemniscus Lateral lemniscus Inferior colliculus Inferior colliculus (Auditory Cortex) (Auditory Cortex)

20 Definitions Sound level in dB = 10 log (intensity / Io) Sound level in dB = 10 log (intensity / Io) Io = W/m 2 Io = W/m 2 A doubling of sound intensity corresponds to a 3dB increase. A doubling of sound intensity corresponds to a 3dB increase. However, a 10db increase is perceived as only doubling the loudness. However, a 10db increase is perceived as only doubling the loudness.

21 Definitions Sound pressure level scale (dB SPL) is what engineers and journalists use. Sound pressure level scale (dB SPL) is what engineers and journalists use. Hearing scale level (dB HL or dB ISO) is what health professionals use. For a given frequency, 0 dB ISO is at the very limit of what a human is expected to be able to hear. The amount of energy ( and the dB SPL0 ) is not actually zero. Hearing scale level (dB HL or dB ISO) is what health professionals use. For a given frequency, 0 dB ISO is at the very limit of what a human is expected to be able to hear. The amount of energy ( and the dB SPL0 ) is not actually zero.

22 Definitions

23 Definitions Audiologists – Professionals who are trained to carry out subjective and objective hearing tests in patients. They also fit and maintain hearing aids. Audiologists – Professionals who are trained to carry out subjective and objective hearing tests in patients. They also fit and maintain hearing aids. Hearing therapists – Professionals who conduct therapy to help those with a hearing or a vestibular conditions. Hearing therapists – Professionals who conduct therapy to help those with a hearing or a vestibular conditions. Doctors – Include Ear, Nose, and Throat surgeons and Audiovestibular Physicians Doctors – Include Ear, Nose, and Throat surgeons and Audiovestibular Physicians

24 Pure Tone Audiogram The gold standard The gold standard Measures the hearing threshold at a range of frequencies Measures the hearing threshold at a range of frequencies Measures both ears Measures both ears Measures both air conduction and bone conduction Measures both air conduction and bone conduction Requires an Audiology booth and an Audiologist Requires an Audiology booth and an Audiologist Difficult to perform reliably in children under 60 months. Difficult to perform reliably in children under 60 months.

25 Pure Tone Audiogram

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27 -5 to 25 db ISONormal hearing -5 to 25 db ISONormal hearing 25 to 40 db ISOMild hearing loss 25 to 40 db ISOMild hearing loss 40 to 70 db ISOModerate hearing loss 40 to 70 db ISOModerate hearing loss 70 to 95 db ISOSevere hearing loss 70 to 95 db ISOSevere hearing loss 95 db ISO and above Profound hearing loss 95 db ISO and above Profound hearing loss

28 Impedance Audiometry A probe with a rubber seal is placed in the ear canal. A 220 Hz at 65 dB tone is played through an emitter on the probe. A probe with a rubber seal is placed in the ear canal. A 220 Hz at 65 dB tone is played through an emitter on the probe. Some of this sound is absorbed, some of it is reflected. Some of this sound is absorbed, some of it is reflected. The reflected sound is measured. The reflected sound is measured. This determines the compliance / impedance of the canal and middle ear. This determines the compliance / impedance of the canal and middle ear.

29 Impedance Audiometry This give information on how mobile the tympanic membrane is, and the volume of the canal. This give information on how mobile the tympanic membrane is, and the volume of the canal. This is frequently called 'Tympanometry'. This is frequently called 'Tympanometry'.

30 Impedance audiometry

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32 Is very good at showing middle ear effusions. Is very good at showing middle ear effusions. Is very good at demonstrating the existence of perforations. Is very good at demonstrating the existence of perforations. Is fairly good at showing tympanic membrane retraction. Is fairly good at showing tympanic membrane retraction. Does not give much info on the extent of the problem. Does not give much info on the extent of the problem.

33 Subjective hearing tests Measure overall functionality. Many variables can confuse the results. Easier to carry out. Measure overall functionality. Many variables can confuse the results. Easier to carry out. Behavioural techniques Behavioural techniques Distraction techniques Distraction techniques Conditioned reflex audiology Conditioned reflex audiology Speech discrimination tests Speech discrimination tests Bedside testing Bedside testing

34 Subjective hearing tests Behavioural techniques Behavioural techniques Useful 0-6 months Useful 0-6 months Present a loud sound and observe child's response Present a loud sound and observe child's response Startle, blinking, crying, or cessation of activity Startle, blinking, crying, or cessation of activity Highly subjective Highly subjective

35 Subjective hearing tests Distraction techniques Distraction techniques Useful 6-18 months Useful 6-18 months Child sits on mother's lap while assistant distracts (i.e., with toy) Child sits on mother's lap while assistant distracts (i.e., with toy) Tester makes sounds of varying intensity behind one side of the child, out of visual field Tester makes sounds of varying intensity behind one side of the child, out of visual field Positive response is when child turns to look at sound Positive response is when child turns to look at sound Sound can be simple tone, conversant speech or sibilant speech. Sound can be simple tone, conversant speech or sibilant speech.

36 Subjective hearing tests Conditioned reflex audiology (also called performance testing) Conditioned reflex audiology (also called performance testing) Useful months Useful months Child is trained to perform a simple task, such as putting a marble in a cup, after hearing a specific auditory stimulus Child is trained to perform a simple task, such as putting a marble in a cup, after hearing a specific auditory stimulus The intensity of this stimulus is changed, with no visual cues. The intensity of this stimulus is changed, with no visual cues. Closer to a pure tone audiogram, but still subjective Closer to a pure tone audiogram, but still subjective

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38 Subjective hearing tests Speech discrimination tests Speech discrimination tests Useful months Useful months Child is asked to point to a variety of toys. These toys are selected to cover a variety of speech patterns. Child is asked to point to a variety of toys. These toys are selected to cover a variety of speech patterns. Cup / Duck or Key / Tree. Cup / Duck or Key / Tree. Speech level with 80% of guesses correct. Speech level with 80% of guesses correct.

39 Subjective hearing tests Bedside tests Bedside tests Rinne/Weber test only 70% specific Rinne/Weber test only 70% specific A good tragal rub causes 30 db of masking A good tragal rub causes 30 db of masking A whisper at 60cm requires 20 db threshold to detect A whisper at 60cm requires 20 db threshold to detect Don't forget history and examination Don't forget history and examination

40 Objective Hearing Tests Otoacoustic emissions Otoacoustic emissions Evoked response audiometry Evoked response audiometry

41 Objective Hearing Tests Otoacoustic emissions Otoacoustic emissions The cochlear is an excellent echo chamber. The cochlear is an excellent echo chamber. Outer hair cells make a noise as they vibrate. This noise can be measured while a series of clicks are played via a probe in the ear canal. Outer hair cells make a noise as they vibrate. This noise can be measured while a series of clicks are played via a probe in the ear canal. The noise is almost always absent in children with hearing loss greater than 40 db ISO. The noise is almost always absent in children with hearing loss greater than 40 db ISO. Probe is more expensive that impedance audiometry, and of limited use in children over 6 months. Probe is more expensive that impedance audiometry, and of limited use in children over 6 months.

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43 Objective Hearing Tests Evoked response audiometry Evoked response audiometry Electrical signals are produced by various parts of the auditory system in response to sound stimuli Electrical signals are produced by various parts of the auditory system in response to sound stimuli Measurement of these signals can show where the hearing loss occurs Measurement of these signals can show where the hearing loss occurs No conscious effort is required from the patient No conscious effort is required from the patient

44 Objective Hearing Tests Evoked response audiometry Evoked response audiometry Electrocochleogram Electrocochleogram Brainstem electrical response Brainstem electrical response Cortical electrical response Cortical electrical response Requires electrode placement and sometimes sedation or anaesthetic Requires electrode placement and sometimes sedation or anaesthetic Complex data needs careful interpretation Complex data needs careful interpretation

45 Objective Hearing Tests

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47 Screening Programmes 1 in 1,000 children are born with severe hearing loss 1 in 1,000 children are born with severe hearing loss Important to screen children from birth Important to screen children from birth Also, screening is important after ITU stay, meningitis, severe head injury, etc Also, screening is important after ITU stay, meningitis, severe head injury, etc Parental concern Parental concern

48 Screening Programmes Suggested routine screening Suggested routine screening Neonatal Universal screening (OAE with BSER if indicated) Neonatal Universal screening (OAE with BSER if indicated) 6 to 8 monthsDistraction techniques 6 to 8 monthsDistraction techniques 2 to 4 yearsDistraction techniques or conditioned reflex audiometry 2 to 4 yearsDistraction techniques or conditioned reflex audiometry Pre-schoolPure tone audiometry Pre-schoolPure tone audiometry

49 Any questions?

50 Further reading


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