Assesment of Hearing in Infants & Children

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ASSESMENT OF HEARINGIN INFANTS & CHILDREN

PRESENTED BY : DR. PRIYANJAL GAUTAMPG- 2nd Yr. (M.S. - E.N.T.)NIMS MEDICAL COLLEGE & HOSPITAL, JAIPUR


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INTRODUCTION

In developed countries routine screening of

newborn child for hearing impairment is anorm.

But in developing countries, it is usually theparents who suspect hearing impairment &bring child to the physician.

Early diagnosis & timely intervention givesbest result in rehabilitating such children.


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Speech & hearing are inter-related.

For normal speech child must hears sounds.Later child understands the sounds of the

words & intimates the words & talks.


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CAUSES OF CONGENITALDEAFNESS

1. Genetic defects : affects inner ear & causedeafness.

(i) Michel aplasia : Complete failure of innerear development.

(ii) Mondini aplasia : Cochlea has 1 turnsinstead of 2 turns.


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Causes of permanent childhood hearingimpairment :

(A) Congenital disorders:

(i) Genetic- Syndromic Autosomalrecessive

Autosomal

dominantNonsyndromic X-linked

Mitochondrial


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(B) Environmental causes:

(i) Perinatal causes: Hypoxia

Hyperbilirubinemia

Low birth weight

(ii) Acquired disorders: Infections Chronicotitis media

Meningitis

Mumps

AIDS


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RISK FACTORS FORCONGENITAL HEARING LOSS

An illness/condition requiring admission of48hrs or greater to a NICU Auditoryneuropathy/dys-synchrony.

Stigmata associated with a syndrome knownto include a sensorineural or conductive

hearing loss.

Family H/O early childhood deafness.


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TEMPORARY CHILDHOODHEARING LOSS

Risk factors:

Otitis media with effusion (OME)

Passive smoking Bottle feeding

URTI

Admission to NICU as a newborn Day care

Siblings having had OME


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IDENTIFICATION OFDEAFNESS IN CHILDREN

1. HISTORY:

. A thorough history taking from parents ofsuspected deaf child is very important. Eg.

H/O Attack of Measles, Herpes, Syphilis etc.to mother during early part of pregnancy isimportant.

. Body wt. below 1.5 kg at birth, H/O drugtaken during pregnancy is important.


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2. Normal Responses of hearing children:

(A) Neonatal Period- Birth to 2 months

(i) Moros Reflex: Stimulation of the sleeping

baby with a loud sound produces startleresponse in a normal child.

(i) Auriculo palpebral response :Stimulation of the child with loud soundproduces closure ofpalpebral fissures ina normal hearing children.


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NEWBORN HEARING SCREENING:

Tests used for newborn hearing screening are -:

Automated otoacoustic emissions (AOAE)

Transient evoked otoacoustic emissions(TEOAE)

Distortion product otoacoustic emissions(DPOAE)


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T i t k d i i


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Transient-evoked emissions(TEOAEs):

These are typicallypresented as anamplitude/timeplot of acoustic

waveformrecorded from theear canal.

TEOAEs greaterthan 20 db soundpressure level

(SPL) can be


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s or on pro uc em ss ons(DPOAEs):

These aregenerated in thecochlea in response

to 2 simultaneouspure-tone stimuli.

This tonal responseis not present in the

eliciting stimuli &therefore referredto as distortion.


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Hearing tests in children:

(A) Electrophysiological testing (0-6 months)

(A) Behavioural observation audiometry (0-6

month)

(A) The distraction test (6-18 months)

(A) Visual reinforcement audiometry (6-36months)


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VISUAL REINFORCEMENTAUDIOMETRY (VRA)


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BERA

BERA stands for Brain Stem EvokedResponse Audiometry.

It is an important clinical tool & morestandard parameter in the diagnosis ofhearing problems.

It is an accurate measure of auditoryfunction & measures the electrical activity inthe auditory pathways.


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Uses of BERA :

1. Detection of deafness in the difficult-to-testpatients like infants, mentally retarded ormalingering subjects.

1. Assessment of nature of deafness whetherconductive or sensory or neural.

1. Identification of the site of lesion inretrocochlear pathologies.


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Principle of BERA :

v When a sound reaches cochlea, it isconverted

into an electric impulse & passes fromcochlea

to auditory cortex.

P th


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Pathway :

Sound

Spiral ganglion (cochlea)

Ventral & Dorsal cochlear nuclei (brainstem)

Superior Olivary complex (midbrain)

Lateral Lemniscus (midbrain)


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BERA MACHINE


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BERA MACHINE

ELECTRODE PLACEMENTS


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ELECTRODE PLACEMENTSIN BERA

1. Over the vertex orscalp (activeelectrode).

2. Over the mastoid orearlobe of ipsilateralear (reference

electrode).

3. Over the forehead

just above the nasion


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Sound stimulus nearly 60 dB abovethreshold is given to patient via headphoneswhich deliveres a broad band click sound of

100 micro sec. (0.1 milli sec.) duration.

The click sound is fed into the ear to be

tested by a headphone and the contralateralear is masked.

A series of rapid sounds provide a stimulus& events are recorded during the 1st 10 millisec. following the sound stimulus.


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Each of these waves represents aneuroelecritical activity generated by theneural generators at some site in the

auditory pathway in b/w the cochlea & thebrainstem.

WAVE SITE OF NEURALGENERATOR

1st Cochlear Nerve (distalend)

2nd Cochlear Nucleus

3rd Superior Olivary


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INTERPRETATION OF BERA RESPONSE :


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A normal BERA recording has 5 prominentpeaks & 2 small peaks.

These peaks are BERA potentials & sincethey have troughs & crests, they are knownas BERA waves.

Each wave give information about a specificsegment of the auditory pathway from the

cochlea to the brainstem region.

Hence especially I, III, & V wave have to be

accurately identified.


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Wave 5th :

It is to be identified before all the otherwaves.

It is most reliable & easily identifiable wavein BERA tracing.

The hallmark of 5th wave is that there is asharp negative deflection (downward)imediating following the peak.


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Wave 4th :

It is identified as a peak just preceding wave5th. So, once 5th wave is identified, it is notdifficult to recognize wave 4th.

Wave 3rd :

It is the wave preceding wave 4th. So, oncewave 4th has been recognized wave 3rd isidentified as upward peak b/w wave 2nd &4th at or beyond 3 milli sec. mark on the

graph.


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Wave 2nd :

It is the peak immediately preceding thewave 3rd. This wave has a latency of appox.2 milisec. & hence it is difficult to identify.

So, it should be looked for at or just beyond2 milisec. mark on BERA graph.


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Wave 1st :

It has to be recognized properly because itgive an idea whether the stimulus hascrossed over from the cochlea & the distalauditory nerve.

If wave 1st is present & other waves 2nd,3rd, 4th & 5th are absent, it suggest that the

stimulus has reached the cochlea wellenough but not able to proceed further. Thismeans there is retrocochlear pathology.


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STUDY OF WAVEMORPHOLOGY

In case of newborns the graph has 3 peaks(instead of 5 to 7 peaks in adults) & wave2nd & 4th are absent.

Moreover the graph in newborns has a largerwave 1st & much smaller wave 5th than in

adults.

Note: Other pathological conditions which altersthe morphology of the graph includes- Acousticneuromas on which the time interval b/w eak

BERA GRAPH IN


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BERA GRAPH INACOUSTIC NEUROMA


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BIBILOGRAPHY

1. SCOTT BROWNS17TH EDITION,

VOL - I

AUDIO-VESTIBULOMETRY ANIRBAN bISWAS


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THANK YOU !

DR. S. P. SRIVASTAVA (Prof. & HOD)

DR. AMIT MODWAL (Assoc. Prof.)

DR. PRADEEP SHARMA (Assoc. Prof.)

DR. RAKESH SABOO (Asst. Prof.)

DR. GURLEEN KAUR (P.G. 2nd Yr.)

Assesment of Hearing in Infants & Children

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