1. Inner Ear Disorders
Lecture 14
Adults

2. Most common occurring causes of SNHL
Noise
Presbycusis
Meniere’s disease
Immune Disease
Ototoxicity
Diabetes

3. Noise Induced HL Most common form of preventable HL
Result from exposure to intense noise levels
Permanent threshold shift (PTS)
Temporary threshold shift (TTS) – recovers within hours
Acoustic Trauma: impulsive sound

4. Noise Induced Hearing Loss
More common in men with histories of noise exposure
Increasing incidence among children
Site of pathology: basal end hair cells- primarily OHC

5. http://www. neurophys. wisc

6. Symptoms of NIHL Tinnitus Difficulty understanding in noise
Difficulty understanding speech

7. Audiometric Results Otoscopy: Tympanometry: Pure tone Air and Bone OAE
Maximal HL between Hz – “Noise Notch”
OAE
ABR
Lowest Level for wave V
IWI

8. Safe vs. Unsafe Sound Levels
Noise levels measured in dB SPL
Any loud noise over 85dB is considered loud enough to cause NIHL.
80 dB ….shouting.
110 dB….concert or sporting event.
111 dB…. iPod on full volume.
130 dB …an airplane taking off 100m away.
140 dB ….level at which noise causes pain for most people

9. iPods Percent of Maximum Volume <= 40% 50% 60% 70% 80% 90% 100%
Equivalent Volume dB
<= 73dB
81dB
87dB
92dB
98dB
106dB
111dB
Time you can use before Hearing Loss WILL Occur
Unlimited
8 hours
4.5 hours
1.6 hours
23 minutes
4 minutes
1 minute

10. Metrics for Noise
Max sound level is the highest sound level recorded over a period of time
Average sound level is the average sound measured over a period of time
Noise dose is a percentage of the daily maximum permissible exposure. 100% dose is equivalent to an 85 dBA time-weighted average for 8 hours.
Noise Dose: 100%

11. Prevention of HL Walk Away Turn it down Use earplugs
Duration per Day, hours
Sound Level dBA 8 90 6 92
4.2 95 3 97 2
100
1.5
102 1
105 .5
110
.25
115
Walk Away
Turn it down
Use earplugs
Educate students about NIHL
OSHA NOISE guidelines

12. Education about Prevention of HL

13. Presbycusis The most common cause of SNHL associated w/ aging
Site of pathology: hair cell damage in cochlea
By years, pure tone thresholds show drop in hearing in the high frequencies
By years of age, the lower frequencies become affected

14. 6 Types of Presbycusis Schuknecht and Gacek 1993
Sensory
Neural
Strial
Cochlear Conductive
Mixed Presbycusis
Intermediate Presbycusis

15. Sensory Presbycusis (*Otle, Schukneckt & Kerr, 1978)
*Loss of inner and outer hair cells
Loss of supporting cell structure; degeneration of the Organ of Corti
Differential diagnosis is difficult
Aging vs acoustic trauma
SNHL begins in high frequency range
Possible mechanisms for intervention
Susceptibility of hair
cells to aminoglycosides
Genetics

16. Neural Presbycusis (*Otto, Schukneckt & Kerr 1978)
Loose 2,000 neurons per decade – S. Ganglion
less than 20,000 in adults years of age
*Loss of 50% of cochlear neurons, greater in
the elderly over 80 years of age = 15,000
from 30,000 as a young adult
Most consistent pathological change in older ear
Associated with poorer than expected word recognition

17. Stria Presbycusis Atrophy of the stria vascularis
Function also dependent on capillary beds
Stria Presbycusis
Atrophy of the stria vascularis
Affects production of endolymph – important to maintaining the electrochemical balance of inner ear fluids (ion transport mechanism )
Variable audiometric findings
Stria
Vascularis

18. Summary of Presbycusis
2 major age related structural changes
- Inner Ear
- Auditory Nerve
6 Classifications of Presbycusis affecting any or a combination of:
- hair cells, supporting structures
- stria vascularis
- spiral ganglia, neurons
- nerve fibers of the 8th cranial nerve

19. Audiometric Results Otoscopy: Tympanometry: Pure tone Air and Bone OAE
ABR
Lowest Level for wave V
IWI

20. Endolymphatic Hydrops/Meniere’s Disease
1/1000 persons suffers MD
Symptoms
Sudden attacks of vertigo, tinnitus, vomiting and Unilateral SNHL
Onset y/o

21. Endolymphatic Hydrops/Meniere’s Disease
Site of Pathology:
Vestibular system
Malfunction of ES - overproduction of endolymph in the inner ear
causes increased pressure on hair cells
Etiology: unknown, ES blockage, constriction in blood vessels, migraine, autoimmune reaction, genetic connection, viral infection etc.

22. Endolymphatic Sac ES – important for keeping fluid levels constant
Research ongoing to ID mechanisms that regulate
endolymph production

23. Endolymph Hydrops/ Meniere’s Disease
2 parts to the labyrinth: the bony and membranous labyrinth.
Membranous labyrinth is filled endolymph
Increased production of endolymph alters chemical balance of inner ear
The release of endolymph results in a major disturbance of the normal chemical composition of the perilymph in scala vestibuli. As scala vestibuli has a wide communication with perilymph of the vestibule, the chemical disturbance will spread into the vestibular system. The high-potassium endolymph is highly toxic to cells not specialized to deal with it. Cells become depolarized (activating transmitter release and afferent nerve fiber activity) and swell in a high-potassium environment, resulting in auditory and vestibular dysfunction.
Perilymph (Na)
Endolymph (K+)

24. Endolymph Hydrops/ Meniere’s
If head moves> endolymph moves and sends vestibular sensory info to the brain
Increase in endolymph > the membranous labyrinth dilates> vertigo > “endolymphatic hydrops”

25. Meniere’s Disease
Ménière's disease thought to be more than E. Hydrops.
Possible rupture of the membranous labyrinth> endolymph mixes with perilymph.
The mix of perilymph and endolymph is thought to cause symptoms of Ménière's disease

26. Treatment for Meniere’s
No known cure > management of symptoms
Acute
Vasodialators, Corticosteroids – improve blood flow to cochlea, anti-inflammatory effect
Anti vertigo medications
Phenergen, dramamine ,antivert,valium
Maintenance
Diuretics
limit sodium in diet
Amplification
Vestibular rehabilitation Tx

27. Surgical Treatment
Endolymphatic Sac Surgery – decompress the sac/shunt insertion (not common today)
Aggressive Tx approaches
Labyrinthectomy – removal of vestibular organ- causes total deafness in affected ear
Vestibular Neurectomy – partially sever the affected nerve
Current approach: Infusion of TM with corticosteroids

28. Audiometric Findings Onset starts with unilateral LF SNHL
Fluctuations in hearing and “Flattening” of shape of audiogram as disease progresses n

29. Audiometric Results Otoscopy: Tympanometry: Pure tone Air and Bone OAE
ABR
Lowest Level for wave V
IWI

30. Tests to assist with Differential Diagnosis
Auditory Brainstem Response (ABR) test
Electronystagmography: ENG
VEMPs
MRI

31. Autoimmune inner ear disease (AIED)
Inflammatory condition of the inner ear
Inner ear proteins are recognized as foreign
Primary process
Secondary to trauma or inflammation
Occurs when the body's immune system attacks cells in the inner ear that are mistaken for a virus or bacteria

32. Symptoms & Incidence Incidence:
<1% of the 28 million Americans with a HL
2/3 females, middle aged
Sudden SNHL in one ear but becomes bilat
progressing rapidly to second ear (<3 mos)
Aural fullness
Dizziness/vertigo

33. Theory and Symptoms of AIED
Cochlea is devoid of immune cells
Antibodies/ rogue T-cells (type of white blood cell) that circulate around body to look for cell abnormalities and infections
T-cells essential for immunity
Rogue T-cells cause inner ear damage

34. Treatment
Drug therapy: steroids, prednisone and methotrexate – (used in chemotherapy)
If received early in disease, very helpful
Often results in severe to profound bilateral SNHL
Amplification
Cochlear implant

36. Differential Testing ABR ENG Blood Tests Immunofluorescence
labeling of antibodies with fluorescent dyes
Audiometric Evaluations

37. Audiometric Results Otoscopy: Tympanometry: Pure tone Air and Bone OAE
ABR
Lowest Level for wave V
IWI

38. Ototoxicity Consider Toxicity is related to
Sometimes the medicine is worse than the disease
Sometimes there is no choice when presented with life threatening conditions
Toxicity is related to
Dosage
Duration of administration

40. Common ototoxic drugs Aminoglycosides antibiotics Antineoplastic drugs
Treat infections
Gentamicin, kanamycin, neomycin, streptomycin, tobramycin
Antineoplastic drugs
Treatment of cancer and tumors
Cisplatin,carboplatin, nitorgen mustard

41. Common ototoxic drugs Diuretics and loop diruetics Salicylates Quinine
Treatment of congestive heart failure, pulmonary edema
Lasix, bumetanide
Salicylates
Treatment of arthritis, rheumatic fever, connective tissue disorders
Aspirin
Quinine
Uncommon- Tx malaria

42. Common ototoxic drugs
Environmental chemicals
Arsenic
Mercury
Tin
Lead

43. Common Symptoms Impaired renal function
Permanent SNHL – bilateral and mostly high frequencies
Tinnitus
Can occur suddenly
Speech recognition reduced

44. Main mechanism
Free radicals form and anti-oxidant inhibition result in HL
Damages cells in cochlea
Apoptosis – cell death

45. Audiometric Results Otoscopy: Tympanometry: Pure tone Air and Bone OAE
ABR
Lowest Level for wave V
IWI

46. Treatments Avoid or reduce doses of ototoxic agents as possible
Monitor hearing
Substitute with a different agent
SNHL – HA

47. Diabetes Elevated blood glucose levels affect inner ear hair cells
Progressive bilateral SNHL
Often affects visual acuity
Dual Sensory loss

48. Treatment Audiologic Monitoring
Pure tone audiometry – esp in high freq
Speech audiometry – discrim may be very poor when compared to pure tone thresholds
Otoacoustic emissions – most sensitive and earliest detector of cochlear damage

49. Audiometric Results Otoscopy: Tympanometry: Pure tone Air and Bone OAE
ABR
Lowest Level for wave V
IWI

50. AMA Criteria for Medical Referral
visible congenital, traumatic deformity
history active drainage/bleeding from the ear
sudden, rapidly progressive loss (90 days)
acute/chronic dizziness
unilateral loss of sudden, recent onset (90 days)
ABG ≥ , 1000, 2000 Hz
significant cerumen accumulation, foreign body
Ear pain or discomfort