1. Presbyacusis
Dr. Vishal Sharma

2. Synonyms Age-related sensori-neural hearing loss
Age-associated hearing loss (AAHL)
Presbycusis (in USA)
No official agreed age above which a person suffers from presbyacusis & below which he/she does not. Arbitrary agreed age is 50 years.

3. Definitions
Presbyacusis: B/L symmetric, progressive SNHL due to aging, in absence of other etiologies
Socioacusis: B/L symmetric SNHL due to non- occupational noise, fatty diet & lack of exercise
Nosoacusis: B/L symmetric SNHL due to diseases with ototoxic effects
SNHL after 50 yrs age = presbyacusis + nosoacusis + socioacusis + occupational NIHL

4. Diagnosis of exclusion
Exclude other causes of hearing loss in elderly:
Noise induced hearing loss
Atherosclerosis (hyperlipidemia), diabetes, hypertension, myxoedema, Paget’s bone disease
CSOM, Meniere’s disease, acoustic neuroma, cochlear otosclerosis, ear trauma & ototoxic drug

5. History
Toynbee (1849) first wrote about age-related hearing loss & prescribed a treatment (application of silver nitrate solution to external auditory canal)
Zwaardemaker (1891) gave first accurate description of presbyacusis. He detected high frequency involvement & origin in cochlea.

6. Mechanism of Presbyacusis
Age-related arteriosclerosis
 hypo-perfusion &  oxygenation of cochlea
 formation of reactive oxygen metabolites & free radicals
 damage inner ear structures & mitochondrial DNA of inner ear
 Presbycusis

7. Genetic Predisposition
Genetic programming for early aging of parts of auditory system  early development of presbycusis
Genetically programmed susceptibility to environmental factors (noise, ototoxic drugs, stress) may be involved

8. Types of Presbyacusis (Gacek & Schuknecht, 1993)
Sensory
Neural
Metabolic or strial or vascular
Mechanical or cochlear conductive
Mixed
Indeterminate or intermediate

9. Sensory Presbyacusis
Loss of sensory hair cells in organ of Corti due to accumulation of lipofuscin pigment granules
Process originates in basal turn (for a length > 10 mm) & slowly progresses toward apex
Audiogram: abrupt, steep, high-frequency SNHL
Speech discrimination score: good

10. Sensory Presbyacusis

11. Neural Presbyacusis
Atrophy of spiral ganglion & cochlear neurons (> 50%) mainly in basal turn of cochlea
Slowly progressive HL (Pure Tone Average not affected until 90% neurons are destroyed)
Audiogram: ski-slope toward high frequencies
Speech discrimination score: poor (disproportionate)

12. Neural Presbyacusis

13. Metabolic Presbyacusis
Atrophy of stria vascularis (> 30% destroyed)
Stria vascularis maintains chemical + bioelectric balance & metabolic health of cochlea
Results in slowly progressive deafness
Audiogram: Flat (as entire cochlea is affected)
Speech discrimination score: good

14. Metabolic Presbyacusis

15. Mechanical Presbyacusis
Slowly progressive SNHL due to thickening & stiffening of basilar membrane of cochlea
More severe in basal turn of cochlea where basilar membrane is narrow
Audiogram: ski-slope toward high frequencies
Speech discrimination score: slightly impaired

16. Mechanical Presbyacusis

17. Other Types Mixed Presbyacusis:
Many ears have a combination of 4 pathologies
Indeterminate or Intermediate Presbyacusis:
SNHL which progresses with age, without light microscopic evidence of cochlear pathology
Pathology: altered cellular metabolism / ed synapse numbers / change in endolymph composition / central auditory pathway changes

18. Other age-related changes
Outer ear: ed cerumen formation, ed epithelial migration, ed hair growth, collapse of EAC
Middle ear: stiffening of TM, Arthritis + ossicular joints ossification, degeneration of middle ear muscles
They do not make marked contribution in deafness

19. Clinical Features Gradually progressive hearing loss
Difficulty in understanding conversation around high level of ambient background noise
Recruitment: abnormal growth in perception of loudness (at high intensity) in pt with hearing loss
Tinnitus (30-50%): indicate worsening of deafness
Social isolation & depression

20. Investigations Pure Tone Audiometry
Speech Audiometry: diminished scores
MRI: to rule out vestibular schwannoma
Indications of MRI in presbyacusis pt:
Asymmetry > 10 dB of PTA between both ears
Asymmetry > 20 dB of any single frequency
Unilateral tinnitus

21. Audiogram

22. Treatment Medical: no medical cure Diet modification & supplementation
Psychological counseling
Amplification devices or hearing aids
Lip reading & assisted listening devices
Cochlear Implantation
Tinnitus retraining therapy
Avoidance of aggravating factors

23. Dietary advice 30% caloric dietary restriction
Use of antioxidant dietary supplements (vitamins A, C, E; selenium) reduce production of reactive oxygen metabolites that harm inner ear & lead to age-related hearing loss
Neuro-vitamins & Gingko biloba have no role

24. Hearing Aids Binaural hearing aids give more benefit
Candidacy for hearing aids:
speech reception threshold > 30 dB in better ear
hearing level > 40 dB at 3 & 4 kHz in better ear
Pt with poor speech discrimination score are poor candidates for hearing aids

25. Body worn

26. Spectacle

27. Spectacle

31. Completely in canal

32. Completely in canal

33. Completely in canal

34. Behind the ear

35. In the ear

36. In the canal

37. Completely in canal

38. Lip reading or speech reading
Skill of understanding spoken message by
looking at speaker's lips, jaws, tongue, teeth,
facial expressions, gestures & body language
Lip reading is helpful in patients with diminished
speech discrimination & hearing aid users who
have hearing difficulty in noisy environments

41. Assisted Listening Devices
They are NOT hearing aids
They are NOT used instead of hearing aids
Help pt with hearing loss to function better in communication situations to overcome distance, background noise, or poor room acoustics
Can be used with or without hearing aids

42. Vibrating wrist watch & alarm clock

43. CO2 & smoke alarm with strobe light

44. Amplified & captioned telephone

45. T.V. & F.M. amplifiers

46. Personal & multi-user amplifier

47. Alerting Devices

48. Amplified Stethoscope

49. Cochlear Implantation
Patients with cochlear damage & relatively intact spiral ganglia + central pathways are best candidates
Cochlear implantation have been performed on patients up to 85 years old, with good results

51. Pawel Jastreboff: 1990

52. Tinnitus Retraining Therapy (TRT)
Based on neuro-physiological model of tinnitus
Blocks tinnitus-related neuronal activity from reaching cerebral cortex (where it is perceived) & from activating limbic & autonomic nervous systems
Uses combination of low level, broad-band noise & counseling to achieve habituation of tinnitus. Tinnitus never masked in TRT. Retraining takes months.
Success rate = %

53. Avoidance Avoid following aggravating factors: Noise exposure
Ototoxic drugs
Uncontrolled diabetes mellitus
Hyperlipidemia

54. Future research Gene therapy to avoid early hair cell death in cochlea
Medications to stimulate a genetic cascade for hair cell regeneration
Better programmed hearing aids

55. Alden, Alfred, Arthur, Eastman, Fletcher, Hisswald,
Luke, Matthew, Oom, Richard, Shirmer & Theodore