1. Mary Beth Palomaki, MD February 17, 2011
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

5. Hearing Loss Conductive Sensorineural
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
OE: edema, inflammation, debris
OM:

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: >30 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: gentamycin>tobramycin>amikacin>neomycin
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: dB: misses up to 10% speech, may respond inappropriately, social interaction affected
Mild: dB: may miss up to 50% of speech
Moderate: dB: misses % of speech, speech quality poor, limited vocabulary
Severe: dB: 100% normal speech volume lost, delayed speech, social isolation
Profound: 90+ dB: sound vibrations felt rather than heard, need visual cues for communication
Decibels are lowest volumes patient can hear

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 <1500g
Apgar score <3 at 5 minutes, <6 at 10 minutes
Mechanical ventilation x 10 days or more
hyperbilirubinemia
After 28 days of age:
Parental concern
Persistent otitis media > 3 months
Head trauma
Bacterial meningitis
Demyelinating disorders
Syndromes
Gifford, KA et al. Hearing Loss in Children. Peds in Review 2009;30:

18. Universal Newborn Hearing Screening
Started in 1990’s 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 Jul;122(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
Cost of ABR and OAE is about the same, because more babies are referred for further audiologic testing
Electrophysiologic test 20

21. Newborn Hearing Screening
Otoacoustic emissions
Screening test
A sound is made by the baby’s ear
Cochlear hair cells generate sound waves (otoacoustic emission) in response to the sound
A tiny microphone by the baby’s 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
Not able to detect auditory nerve problems, infant must be quiet and still

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.”
The decision follows the recommendation from an outdated USPSTF document (1996) and that document was based on data from the early 1980’s
NYC department of education website: Accessed February

24. Weber test: Place the base of a struck tuning fork on the bridge of the forehead, nose or teeth. In a normal test there is no lateralization of sound. With conductive loss, sound lateralizes towards affected ear. With sensorineural loss, sound lateralizes to uninvolved side. Rinne test: Place the base of a struck tuning fork on the mastoid bone behind the ear. Have the patient indicate when sound is no longer heard. Move fork (held at base) beside ear and ask if now audible. In a normal test, AC > BC; patient can hear fork at ear. With conductive loss, BC > AC;patient will not hear fork at ear. AC: air conduction; BC: bone conduction 24

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
Normal hearing is from 20-20,000 Hz
Age 4 and up
Gives ear-specific results
Requires cooperation

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
Doesn’t test hearing, but just tests TM fxn, cannot do in neonates
Normal in sensorineural hearing loss,

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
Spondee: two syllable (pancake, dollhouse ect)

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
Need skilled examiner (esp, to avoid bias)

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
Need skilled examiner

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 years
Ear specific results
Atttention span can limit exam

32. Imaging CT scan: MRI 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
Family must agree about hearing aid
Improves language outcomes, if started before 6 months
Digital

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 > 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: Accessed February
US Preventive Services Task Force. Universal screening for hearing loss in newborns: US Preventive Services Task Force recommendation statement. Pediatrics 2008 Jul;122(1):143-8
Sanford, B and Weber, P. Treatment of hearing impairment in children. Access 16 Feb 2011.
Sanford B and Weber P. Etiology of hearing impairment in children. Access 7 Feb 2011
Adcock, L and Freysdottir, D. Screening the newborn for hearing loss. 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 2009;30: