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Hearing Loss

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Title: Hearing Loss


1
Hearing Loss
  • Mary Beth Palomaki, MD
  • February 17, 2011

2
Outline
  • Review anatomy and physiology of hearing
  • Etiology of hearing loss
  • Hearing screening
  • Evaluation of hearing loss
  • Treatment of hearing impairment

3
Anatomy of the Ear
4
(No Transcript)
5
Hearing Loss
  • Conductive
  • Obstruction of sound to inner ear
  • Sensorineural
  • Problem in inner ear, cochlea, auditory nerve
  • Mixed (both conductive and sensorineural)
  • Central
  • Problem in auditory centers in brain

6
Causes of Congenital Conductive Hearing Loss
  • Microtia
  • Absence or malformation of auricle
  • External ear canal atresia/stenosis
  • Most often unilateral
  • Usually with other craniofacial abnormalities
  • Treacher-Collins sndrome
  • Robin sequence
  • Crouzon syndrome
  • Tympanic membrane abnormality
  • Ossicular malformation
  • Most common is stapes malformation/atresia
  • Osteogenesis Imperfecta

7
Causes of Acquired Conductive Hearing Loss
  • Otitis Externa
  • Bacteria, fungi
  • Otitis media with effusion
  • Fluid obstructs TM movement
  • Effusion persists after therapy
  • Asymptomatic effusion is present in 40 of
    patients 1 month post treatment
  • Fluid present in 10 of patients 3 months post
    treatment
  • Hearing loss is 25dB and persists until fluid
    disappears

8
Causes of Acquired Conductive Hearing Loss
  • Foreign body
  • cerumen
  • Cholesteatoma
  • Benign growth made of cells and keratin
  • As it enlarges, it compresses ossicles, and
    occludes external auditory canal
  • Trauma
  • Temporal bone fractures
  • TM perforation
  • Otosclerosis
  • Overgrowth of bone (near stapes usually)

9
Causes of Congenital Sensorineural Hearing Loss
  • Prenatal infections
  • CMV infection
  • Leading cause of sensorineural hearing loss
  • Usually progressive/delayed onset
  • Toxoplasmosis
  • Delayed hearing loss
  • Can be prevented by treating with pyrimethamine
    and sulfonamide
  • Rubella
  • Usually bilateral
  • Syphilis
  • Hearing loss usually occurs around 2 years of age
  • Can be prevented by treatment of disease before 3
    months of age

10
Causes of Congenital Sensorineural Hearing Loss
  • Genetic Abnormalities
  • Autosomal Recessive (80 of genetic causes)
  • Syndromic Alport syndrome, Usher syndrome,
    Pendred syndrome, Jervell-Lange-Nielsen syndrome,
    Albinism, Hurler syndrome
  • Nonsyndromic gt30 loci identified most common on
    connexin 26 gene on chromosome 13
  • Autosomal Dominant (20 of genetic causes)
  • Syndromic Waardenburg syndrome,
    neurofibromatosis I and II, branchio-oto-renal
    syndrome, Jervell-Lange-Nielsen syndrome
  • Nonsyndromic immediate onset or delayed onset 2
    genes identified for delayed onset
  • Potassium channel in outer hair cells
  • Transcription factor
  • X-linked
  • Hunter syndrome, Alport syndrome, x-linked
    congenital hearing loss

11
Causes of Congenital Sensorineural Hearing Loss
  • Anatomic abnormalities
  • Michel complete lack of inner ear
  • Mondini partial development and malformation
    inner ear
  • Scheibe membranous cochleosaccular degeneration
    of the inner ear
  • Alexander malformation of the cochlear
    membranous system
  • Prenatal exposure to ototoxic drugs

12
Causes of Acquired Sensorineural Hearing Loss
  • Prematurity
  • Hypoxia, acidosis, incubator noise
  • Hyperbilirubinemia
  • Bilirubin toxic to cochlear nuclei and central
    auditory pathways
  • Ototoxic drugs
  • Aminoglycosides gentamycingttobramycingtamikacingtne
    omycin
  • Chemotherapy cisplatin, 5-FU, bleomycin,
    nitrogen mustard
  • Salicylates, quinines (reversible)

13
Causes of Acquired Sensorineural Hearing Loss
  • Infection
  • Bacterial meningitis
  • Trauma
  • Blunt or penetrating trauma to the temporal bone
  • Radiation to head and neck
  • Tumor acoustic neuroma
  • Neurodegenerative/demyelinating disorders

14
Causes of Acquired Sensorineural Hearing Loss
Noise Exposure
  • Noise causes direct damage to cochlear structures
  • Noise causes over-stimulation of cochlear
    structures
  • increased metabolic demand causes increased
    nitric oxide release--toxic to hair cells
  • Increased metabolic demand causes generation of
    free radicals

15
Degrees of Hearing
  • Normal 0-15 dB detects all speech
  • Minimal 16-25 dB misses up to 10 speech, may
    respond inappropriately, social interaction
    affected
  • Mild 26-40 dB may miss up to 50 of speech
  • Moderate 41-55 dB misses 50-100 of speech,
    speech quality poor, limited vocabulary
  • Severe 56-90 dB 100 normal speech volume
    lost, delayed speech, social isolation
  • Profound 90 dB sound vibrations felt rather
    than heard, need visual cues for communication

16
Evaluation of Hearing Loss
  • History
  • Physical exam
  • Newborn screening
  • Auditory Brainstem Response
  • Otoacoustic Emissions testing
  • In office screening
  • Rinne, Weber tests
  • Pure tone audiometry
  • Formal audiologic evaluation
  • Tympanometry
  • Behavioral audiometry
  • Speech audiometry
  • Imaging

17
History Risk Factors for Hearing Loss
  • Neonate
  • Family History
  • In utero infections
  • Birth weight lt1500g
  • Apgar score lt3 at 5 minutes, lt6 at 10 minutes
  • Mechanical ventilation x 10 days or more
  • hyperbilirubinemia
  • After 28 days of age
  • Parental concern
  • Persistent otitis media gt 3 months
  • Head trauma
  • Bacterial meningitis
  • Demyelinating disorders
  • Syndromes

Gifford, KA et al. Hearing Loss in Children.
Peds in Review 200930 207-215.
18
Universal Newborn Hearing Screening
  • Started in 1990s due to availability of
    screening tools
  • United States Preventative Services Task Force
    recommended universal newborn hearing screening
    in 2008
  • Universal screening improves language outcomes

19
USPSTF Recommendations
  • All newborns should be screened before 1 month of
    age
  • If the newborn fails screening, the newborn
    should have audiologic assessment by 3 months of
    age
  • Intervention should be given to families by 6
    months of age for hearing impaired children

US Preventive Services Task Force. Universal
screening for hearing loss in newborns US
Preventive Services Task Force recommendation
statement. Pediatrics 2008 Jul122(1)143-8
20
Newborn Hearing Screening
  • Auditory Brain Stem Response
  • Screening test
  • Click stimulus near ear
  • Electrodes on forehead, nape of neck, mastoid
  • Measurement of action potentials from 8th cranial
    nerve
  • Can detect conductive and sensorineural hearing
    loss
  • Duration 4-15 min
  • Is appropriate for infants up to 9 months

21
Newborn Hearing Screening
  • Otoacoustic emissions
  • Screening test
  • A sound is made by the babys ear
  • Cochlear hair cells generate sound waves
    (otoacoustic emission) in response to the sound
  • A tiny microphone by the babys ear detects the
    otoacoustic emissions
  • Duration 5-8 minutes
  • Vernix should be cleaned out of ear canal prior
    to testing
  • Babies at risk for developing sensorineural
    hearing loss need to have ABR screening
  • Appropriate for all ages

22
Child Hearing Screening
  • No recommendations for screening after newborn
    screen up to age 4
  • Unless risk factors present
  • Recommended age for screening 4,5,6,8,10 yrs
  • No screening in NYC schools

23
NY City School Hearing Screening Discontinued in
Fall 2009
  • The Office of School Health has discontinued
    hearing screening in elementary schools.  This
    decision follows the recommendation of The United
    States Preventive Services Task Force, the group
    charged by the federal government with making
    recommendations on screening and preventive
    health services.
  •  The reasons behind this recommendation are as
    follows
  • 1) There are no high quality research trials
    which demonstrate that hearing screening in this
    age group leads to better functional or
    educational outcomes
  • 2) The vast majority of children who fail a
    hearing screen have hearing loss due to fluid in
    the middle ear or wax in the external ear canal. 
    These are temporary conditions. 
  • In addition, because of the State requirement for
    universal neonatal hearing screening, (since
    2000) most severe hearing deficiencies are
    detected in infancy.  This is important because
    the impact of hearing loss is greatest in the 0-3
    age group when children are acquiring basic
    language skills.

NYC department of education website
http//schools.nyc.gov/Offices/Health/HearingVisio
nScreening/default.htm. Accessed February 13.
2011
24
(No Transcript)
25
Pure Tone Audiometry (Conventional Audiometry)
  • Tests air and bone conduction at different
    frequencies, from 250 Hz-8000 Hz
  • Measured in decibels
  • Tones played into ear to measure air conduction
  • An oscillator on the mastoid is used to measure
    bone conduction
  • Relies on patient response, typically raising a
    hand
  • Gives ear-specific results
  • It is appropriate for older children, adolescents
    (age 4 and up)
  • Can be done in pediatric office

26
Tympanometry
  • Compliance of the TM is measured as air pressure
    in the external ear canal is varied
  • Used to detect abnormalities of the tympanic
    membrane and middle ear
  • Can help differentiate between conductive and
    sensorineural hearing loss
  • Is normal in SNHL
  • Tests function of TM, not hearing
  • Most useful when combined with pneumatic otoscopy
  • Appropriate for all ages except neonates

27
Linden-Jerger Classification
28
Speech Audiometry
  • Speech threshold decibel level at which patient
    can repeat 50 of words accurately
  • Test uses spondee words
  • Speech discrimination percent of words a patient
    can identify at approximately 40 dB above
    threshold
  • Can help determine central lesions/neuropathies

29
Behavioral Testing Behavioral Observation
Audiometry
  • Auditory stimulus provided
  • Voice
  • Warbled tones
  • Response to stimulus is observed
  • Startle
  • Movement of limb
  • Cessation movement, e.g. sucking pacifier
  • cry
  • No reinforcement of behaviors
  • Appropriate for infants up to 8 months, patients
    with multiple handicaps

30
Behavioral Testing Visual Reinforcement
Audiometry
  • Child placed between two speakers with light-up
    toys
  • Child is conditioned to look towards active
    speaker by a toy that lights up when patient
    looks toward correct speaker
  • Patient is rewarded visually for looking at the
    active speaker
  • Appropriate for ages 9 mo-2.5 years

31
Behavioral Testing Play Audiometry
  • Patient is conditioned to perform a certain play
    action in response to an auditory stimulus
  • Drop a block in a cup
  • Place peg in board
  • Similar to pure tone audiometry varying
    frequencies and or oscillation on mastoid
  • Appropriate for children ages 2.5-4 years

32
Imaging
  • CT scan
  • Inner ear abnormalities
  • Tumors
  • Bony structure abnormalities temporal bone and
    ossicles
  • MRI
  • tumor

33
Treatment of Hearing Loss
  • Team effort
  • Audiologists
  • Otolaryngologists
  • Speech pathologists
  • Geneticists
  • Educational specialists
  • Pediatric ophthalmologist

34
Hearing Aids
  • Types analog, digital
  • Digital has better sound quality, flexible
    settings
  • Digital more expensive
  • Style bone conduction, behind-the-ear,
    in-the-ear, completely-in-the-canal
  • Behind-the-ear are easiest as child grows the
    aid can be re-molded
  • In-ear models appropriate for mild-moderate
    hearing loss only
  • Adjustment
  • Computer programs can tell if hearing aid is
    correct fit and volume
  • Not necessary to rely on child reporting

35
Hearing Aids
36
Assistive listening devices
  • Person talking has a microphone
  • An FM transmitter wirelessly sends sound to
    receiver
  • Listener wears receiver
  • Provides sound amplification
  • Eliminates background noise
  • Most commonly used for educational purposes

37
Bone Conduction Hearing Devices
  • For children with air conduction hearing loss
    (atresia, chronic infections)
  • Types
  • Steel headband
  • Uncomfortable, poor sound quality
  • Implantable
  • bone-anchored implantable hearing aid system
  • BAHA
  • Titanium screw in skull attaches to hearing aid

38
Cochlear Implants
  • Prosthetic device that stimulates the cochlear
    nerve
  • For patients with severe-profound hearing loss
  • All models approved for children gt 18 months
  • One model approved in 12 month old children
  • How does it work?
  • Microphone receives sound (placed in external ear
    canal)
  • A speech processor arranges/selects sounds (above
    skin-looks like hearing aid)
  • Receiver coil (placed below scalp) converts
    sounds to electrical impulses
  • Electrical impulses transmitted to electrode in
    cochlea/auditory nerve

39
Cochlear Implant
40
Cochlear Implants
  • Patients learn to hear sounds in environment
  • Require extensive therapy to learn interpretation
    of sounds, words
  • Early implantation puts children at risk of
    losing any remaining cochlea function but can
    improve language outcomes

41
Development in Children with Hearing Loss
  • Children with hearing loss who are not diagnosed
    appropriately
  • lack sensory stimuli from sounds of language
  • fail to develop synapses in auditory and language
    centers of the brain
  • Development of language is related to timing of
    intervention
  • If child is identified before 6 months, no
    connection exists between level of hearing loss
    and degree of language development
  • If child is identified before 6 months of age,
    language is related closely to cognitive
    abilities
  • Children diagnosed late, suffer from delayed
    language skills in relation to cognitive
    abilities, poor overall academic achievement, and
    poor social skills

42
Healthy People 2010 initiative
  • 1. Increase the percent of newborns screened for
    hearing loss by 1 month of age
  • 2. Increase the number of at-risk patients
    evaluated by audiologist by 3 months of age
  • 3. Increase the number of children with hearing
    loss enrolled in special services by 6 months of
    age

43
Which of the following statements regarding
hearing loss in infants and children is true?
  • A. Children born with external ear anomalies
    experience SNHL more commonly than conductive
    hearing loss
  • B. Cholesteatoma is the most common cause of
    conductive hearing loss
  • C. Language delay does not occur unless hearing
    loss is severe or profound
  • D. Newborn screen is reserved for preterm infants
    or those who have a positive family history
  • E. Parental concern regarding language delay or
    hearing loss is sufficient cause for auditory
    testing

44
Answer
  • E

45
References
  • NIDCD.nih.gov/hearing/coch. Accessed 2 Feb 2011.
  • Tierney, CD and Brown, PJ. Development of
    children who have hearing impairment. Peds in
    Review 2009 29 e72-73.
  • NYC department of education website
    http//schools.nyc.gov/Offices/Health/HearingVisio
    nScreening/default.htm. Accessed February 13.
    2011
  • US Preventive Services Task Force. Universal
    screening for hearing loss in newborns US
    Preventive Services Task Force recommendation
    statement. Pediatrics 2008 Jul122(1)143-8
  • Sanford, B and Weber, P. Treatment of hearing
    impairment in children. www.UpToDate.com.
    Access 16 Feb 2011.
  • Sanford B and Weber P. Etiology of hearing
    impairment in children. www.UpToDate.com.
    Access 7 Feb 2011
  • Adcock, L and Freysdottir, D. Screening the
    newborn for hearing loss. www.uptodate.com
    Access 6 Feb 2011.
  • Recommendations for Preventitive Pediatric Health
    Care. AAP.org. Access 13 Feb 2011.
  • Gifford, KA et al. Hearing Loss in Children.
    Peds in Review 200930 207-215.
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