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