Presbyacusis Dr. Vishal Sharma

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.

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

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

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.

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

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

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

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

Sensory Presbyacusis

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)

Neural Presbyacusis

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

Metabolic Presbyacusis

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

Mechanical Presbyacusis

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

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

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

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

Audiogram

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

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

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

Body worn

Spectacle

Spectacle

Completely in canal

Completely in canal

Completely in canal

Behind the ear

In the ear

In the canal

Completely in canal

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

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

Vibrating wrist watch & alarm clock

CO2 & smoke alarm with strobe light

Amplified & captioned telephone

T.V. & F.M. amplifiers

Personal & multi-user amplifier

Alerting Devices

Amplified Stethoscope

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

Pawel Jastreboff: 1990

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 12 -18 months. Success rate = 60 - 80%

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

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

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