hearing loss, deaf child, hearing aids & cochlear implant

HEARING LOSS,DEAF CHILD HEARING AID

&COCHLEAR IMPAIRMENT

NUR HAMIMI ATIQAH MOHD ZABIDI012012100099

NUR HAMIMI ATIQAH MOHD ZABIDI012012100099

Hearing loss is impairment of hearing and its severity may vary from mild to severe or profound, while the term deafness is used, when there is little or no hearing at all

Degree of hearing loss1. Mild 26-40 dB2. Moderate 41-55 dB3. Moderately severe 56-70 dB4. Severe 71-91 dB5. Profound more than 91 dB

DEFINITION

Hearing loss

Organic

Inorganic

CLASSIFICATION

Hearing loss

Organic

Conductive

Sensorineural

Sensory (cochlear) Neural

Peripheral

Central

nonorganic

Any disease process which interfere with the conduction of sound to reach cochlea. The lesion may lie in the external ear and tympanic membrane, middle ear ossicles up to stapediovestibular joint.

CONDUCTIVE HEARING LOSS

1. Negative Rinne’s test ; BC>AC2. Weber lateralised to poorer ear3. Normal absolute bone conduction4. Low frequencies affected more5. Audiometry shows bone conduction better

than air conduction with air-bone gap. Greater the air-bone gap, more is the conductive loss

6. Loss is not more than 60 dB7. Speech discrimination is good

CHARACTERISTICS

CONGENITAL1. Meatal atresia2. Fixation of stapes footplate3. Fixation of malleus head4. Ossicular discontinuity5. Congenital cholesteatoma

AETIOLOGY

ACQUIRED1. External ear= any obstruction in the ear canal (ear wax, foreign body, furuncle, acute inflammatory swelling, tumor2. Middle eara) Perforation of tympanic membrane, traumatic, infectiveb) Fluid in middle ear ; acute otitis media, haemotympanumc) Mass in middle of ear ; tumord) Distruption of ossicles ; trauma to ossicle chain, CSOM,

cholesteatomae) Fixation of ossicles ; otosclerosisf) Eustachian tube blockage ; retracted tympanic membrane

1. Removal of canal obstruction2. Removal of fluid3. Removal of mass from middle era4. Stapedectomy5. Tympanoplasty6. Hearing aid

MANAGEMENT

CHARACTERISTICS1. A positive Rinne’s test ; AC>BC2. Weber lateralised to better ear3. Bone conduction reduced on Schawabach and

absolute bone conduction test4. More often involving high frequency5. No gap between air and bone conduction curve on

audiometry6. Loss may exceed 60db7. Speech discrimination is poor8. There is difficulty in hearing in the presence of

noise

SENSORINEURAL HEARING LOSS(SNHL)

CONGENITAL= present at birth and is the result of anomalies of the inner ear or damage to the hearing apparatus by prenatal or perinatal factor

ACQUIRED1. Infection of labyrinth-viral , bacterial or spirochaetal2. Trauma to labyrinth3. Noise-induced hearing loss4. Ototoxic drug5. Prebyscusis6. Meniere’s disease7. Acoustic neuroma8. Sudden hearing loss9. Familial progressive SNHL10. Systemic disorders ; DM, hypothyroidism, autoimmune

disorder

AETIOLOGY

1. Viral labyrinthitis = measles, ,mumps, CMV

2. Bacterial = meningitis3. Syphilitic = whether congenital or

acquired syphilis

A) Inflammation of labyrinth

Genetic disorder in which there is progressive degeneration of the cochlea starting in late childhood or early adult life

B) Familial Progressive SNHL

1. Aminoglycoside antibiotics Streptomycin Gentamicin Neomycin Amikacin

2. Diuretics Furosemide Ethacrynic acid

3. Anti malarial Quinine Chloroquine

4. Cytotoxic Cisplatin carboplatin

C) Ototoxicity

5. Analgesics Salicyclates Indomethacine Ibuprofen

6. Chemicals Alcohol Tobacco Marijuana

7. Miscellaneous Erytromycin Ampicillin Propranolol Deferoxamine

1. Acoustic trauma Permanent damage to hearing caused by

single brief exposure to very intense sound ; an explosion, gunfire

2. Noise-induced hearing loss Chronic exposure to less intense sound and

mainly hazard of noisy occupationsa) Temporary threshold shiftb) Permanent threshold shift

D) Noise Trauma

SNHL that has developed over a period of hours or a few days. Loss may be partial or complete Mostly unilateral

AETIOLOGYVIRAL , VASCULAR, RUPTURE OF COCHLEAR MEMBRANE1. Infection 2. Trauma3. Vascular4. Otologic5. Toxic6. Neoplastic7. Miscellaneous8. Psychogenic “ In The Very Ear Too No Major Pathology “

E) Sudden Hearing Loss

SNHL associated with physiological aging process in ear

It usually manifest at 65PATHOLOGY1. Sensory Degeneration of organ of corti Affected higher frequency Speech discrimination good

2. Neural Degeneration of cell of spiral ganglion High tone loss Speech disrimination poor

F) Prebyscusis

3. Strial or metabolic Atrophy of stria vascularis Speeech discrimination good

4. Cochlear conductive Stiffening of basilar membrane thus

affecting its movement

Hearing loss with no organic lesion It is either due malingering or psychogenic Some motive to claim some compensation

for being exposed to industrial noises, head injury, ototoxic medication

NON-ORGANIC HEARING LOSS(NOHL)

1. High index of suspicion Exaggerated efforts to hear, frequently

making request to repeat the question2. Inconsistent results on repeat pure tone and speech audiometry test3. Absence of shadow curve4. Inconsistence in PTA and SRT5. Stenger test6. Acoustic reflex threshold7. Electric response audiometry (ERA)

Asessment

DEAF CHILD

Nurul Husna Bt Ismail012013100283

EtiologyInvestigationManagement

0utlines

DEAF CHILD

PRENATAL CAUSES

INFANTFACTORS

MATERNAL FACTORS

PERINATAL CAUSES

POSTNATAL CAUSES

AETIOLOGY

INFANT FACTORSAnomalies affecting inner ear may involve membranous labyrinth, or both membranous and bony labyrinths Sheibe’s dyplasia Alexander’s dysplasia Bing-Siebenmann’s dysplasia Michel aplasia Mondini’s dysplasia Enlarged vestibular aqueduct Semicircular canal malformation

PRENATAL CAUSES

MATERNAL CAUSES Infections – TORCH Drugs during pregnancy :

◦Streptomycin, gentamicin, tobramycin, amikacin, quinine, chloroquine, thalidomide

◦Crosses placental barrier and damages the cochlea

Radiation to mother in first trimester Other factors :

◦Nutritional deficiency◦Diabetes◦Toxaemia◦Thyroid deficiency◦Alcohol

Foetal anoxia :◦Caused by placenta praevia, prolonged

labour, cord round the neck, prolapsed cord

◦Damages the cochlear nuclei and causes hemorrhage into the ear

Prematurity and low birth weight Birth injuries :

◦Forceps delivery - may cause intracranial hemorrhage with extravasation of blood into the inner ear

Neonatal jaundice :◦Bilirubin level greater than 20 mg%

damages the cochlear nuclei

PERINATAL CAUSES

Neonatal meningitisSepsisTime spent in neonatal ICU

Ototoxic drugs Used for neonatal meningitis or septicaemia

Genetic – Down’s syndrome, Alport’s syndrome, Hurler syndrome, etc

Non-genetic :◦Viral infections (measles, mumps, varicella, influenza), meningitis, encephalitis

◦Secretory otitis media◦Ototoxic drugs◦Trauma◦Noise-induced deafness

POSTNATAL CAUSES

FINDING THE CAUSE Detailed history of prenatal, perinatal

or postnatal causes, family history, physical examination and certain investigations

Suspicion of hearing loss :◦Child sleeps through loud noises unperturbed or fails to startle to loud sound

◦Fails to develop speech at 1-2 years

EVALUATION OF A DEAF CHILD

Risk factors for hearing loss in children :◦Family history◦Prenatal infections (TORCH)◦Craniofacial anomalies (including pinna and

ear canal)◦Low birth weight (< 1500 g)◦Hyperbilirubinemia requiring exchange

transfusion◦Ototoxic medications◦Bacterial meningitis◦Apgar score of 0-4 at 1 minute or 0-6 at 5

minutes◦Mechanical ventilation for 5 days or longer◦Stigmata or other findings associated with a

syndrome known to include sensorineural and/or conductive hearing loss

ASSESSMENT OF HEARING IN INFANTS AND CHILDREN

a)Neonatal screening procedures :1.Arousal test2.Auditory response cradle3.ABR (auditory brainstem

response) / OAE (otoacoustic emissions testing)

AROUSAL TEST AUDITORY RESPONSE CRADLE

A high frequency narrow band noise is presented for 2 seconds to the infant when baby in light sleep

Baby is placed in a cradle and his movement( trunk and limb, head jerk) in response to auditory stimulation are monitored

NORMAL : Infant aroused twice when 3 such stimuli are presented to him/her

ABR is the preferred screening method to evaluate hearing loss in NICU graduate.

A response to a click stimulus of 40 nHL/less is the criterion of passing the test

HOW ? Neural signals are generated in VIII Cranial nerve & brain

stem in response to auditory stimuli. Electro encephalographic waves are recorded by

electrodes placed over the scalp. The audiologist measures the baby’s air conduction and

bone conduction thresholds and then evaluates the nerve’s response to sounds presented at a variety of intensity levels for each ear.

ABR (auditory brainstem response)

Moro’s reflex=Sudden movement of limbs and extension of head in response to sound of 80-90 dBCochleopalpebral reflex=Child responds by a blink to a loud soundCessation reflex=Infants stop activity or starts crying in response to sound of 90 dB

B)Behaviour observation audiometry

Used in children 6-7 months old Child is seated in his mothers’s lap, an

assistant distracts the child’s attention while examiner produce a sound from behind to see if the child tries to locate it

c)Distraction techniques

d) Conditioning techniques :Visual reinforcement audiometry (5m – 2y)

Play audiometry(2-5 y)

• Child is trained to look for an auditory stimulus by turning his head

• Reinforced by a flashing light/animated toys

Perform an act such as placing a marble in a box, putting a plastic block in a bucket each time he/she hears a sound signal

Ear specific thresholds can be determined by standard audiometric technique

E) OBECTIVE TESTS

ABR (Auditory brainstem response)

Otoacoustic emissions

Provides an ear specific information as sound stimulus can be presented to each ear separately by headphones

Screening test : response to a click stimulus of <40 nHL

Otoacoustic Emissions (OAE) - a test that checks the inner ear’s responses to sound. The person does not need to be awake during this test.

Parental guidance

-care of periodic replacement of hearing aids

-change of ear moulds as child growth-follow up visit for reevaluation

Hearing aids

MANAGEMENT

Development of speech and language

Education of the deaf Some deaf children with modeate hearing loss can

be integrated nto school wth preferential seating in the class

Vocational guidanceOpportunity to get employed

HEARING AIDS & COCHLEAR IMPLANTS

NUR ELLANI BT ABDUL WAHAB 012012100103

Device to amplify sounds reaching the ear Conventional hearing aids consists of 3

parts 1) Microphone – pick up sounds and converts

them into electrical impulses 2) Amplifier – magnifies electrical impulses 3) Receiver – converts electrical impulses

back to sound then carried through the earmould to the tympanic membrane

HEARING AIDS

Conventional hearing aids

Air conduction hearing aids- Amplified sound is transmitted via ear canal to the

tympanic membrane - Most of the aids are air conduction

Bone conduction hearing aids- Has a bone vibrator which fits on the mastoid and

directly stimulates the cochlear - Useful in person with actively draining ears, otitis

externa or atresia

Types of Hearing Aids

Body-worn types

Behind-the-ear (BTE) types

Spectacles types

In-the-ear (ITE) types

Canal types In the canal (ITC) Completely in the canal (CIC)

Sensorineural hearing loss

Deaf child – as early as possible for development of speech & learning

Conductive deafness – most of this cases can be helped by surgery, but it may prescribed when surgery is refused or failed

Indications

1. Degree of hearing loss2. Configuration of hearing loss (types of

frequencies affected) 3. Type of hearing loss (conductive or

sensorineural)4. Presence of recruitement5. Uncomfortable loudness level 6. Age & dexterity of patient

Consideration to fit a hearing loss

7. Condition of outer & middle ear 8. Cosmetic acceptance of aid9. Type of earmould 10. The types of fitting: whether it is - Monoaural (one aid only)- Binaural (one aid for each ear) - Biaural with y-connection (1 aid but 2

receivers, one for each ear) - Contralateral routing of signal types

Electronic device that can provide useful hearing and improved communication abilities for persons who have severe to profound sensorineural hearing loss and who cannot benefit from hearing aids

COCHLEAR IMPLANTS

Components: external & internal

How its work?

Criteria for cochlear implantation

Bilateral severe to profound sensorineural hearing loss Little or no benefit from hearing aids No medical contraindication for surgery Realistic expectation Good family and social support towards habilitation Adequate cognitive function to be able to use the devices

Previous auditory experience

(postlingual patients or prior use of hearing aids)

Younger age at

implantation

Shorter duration of deafness

Neural plasticity within the

auditory system

Factors for successful clinical outcome

Cosmetically unacceptable due to visibility Acoustic feedback Spectral distortion Occlusion of external auditory canal Collection of wax in the canal and blockage

of insert Sensitivity of canal skin to earmoulds Problem to use in discharging ears

Disadvantages

Complications of cochlear implant surgery

Early complications Late complications

• Facial paralysis • Wound infection• Wound dehiscence • Flap necrosis • Electrode migration• Device failure• CSF leak • Meningitis• Postoperative dizziness/vertigo

• Exposure of device and extrusion • Pain at the site of implants • Migration/displacement of device• Late device failure • Otitis media

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