hearing loss

Hearing Loss

Dr. Utkal MishraPG (ENT)

VSS MEDICAL COLLEGE,BURLA

CLASSIFICATION

CONDUCTIVE HEARING LOSS

CAUSESACQUIRED

WAXFOREIGN BODY

FURUNCLEATRESIA OF EAR CANAL

PERFORATION OF TMFLUID IN MIDDLE EARMASS IN MIDDLE EAR

EUSTACHIAN TUBE BLOCKAGEOSSICULAR DISRUPTION

FIXATION OF STAPES

CONGENITALMEATAL ATRESIA

FIXATION OF MALLEUS FIXATION OF STAPES

OSSICULAR DISCONTINUITYCONGENITAL CHOLESTEATOMA

Characteristics of Conductive hearing loss

Negative Rinnie Test BC > AC Weber Lateralized to poorer ear Normal ABC Low frequencies affected more PTA – BC better than AC with A-B gap Loss is not more than 60 dB Speech discrimination is good.

Hearing Loss seen in different lesions

Complete Obstruction of ear canal – 30dB TM Perforation – 10 – 40 dB Ossicular disruption with intact TM – 54dB Ossicular disruption with TM Perforation – 38

dB Malleus Fixation – 10-25 dB Closure of Oval Window – 60dB

Management

Removal of canal obstruct ion Removal of fluid Removal of mass Stapedectomy Tympanoplasty Hear ing A id

SENSORINEURAL HEARING LOSSCAUSESACQUIRED

WARDENBURG SYNDROMEUSHER SYNDROMEALPORT SYNDROME

PENDRED SYNDROMECROUZON SYNDROME

LABYRINTHITISTEMPORAL BONE FRACTURE

NOISE INDUCED HEARING LOSSOTOTOXIC DRUGS

PRESBYCUSISACOUSTIC NEUROMA

DM, HTN, MS, HYPOTHYROID

CONGENITALSHIEBE DYSPLASIA (cochlea/ saccule)

ALEXANDER DYSPLASIA (basal turn of membranous cochlea)

TORCHES INFECTIONDRUGS

RADIATION

Characteristics of Sensorineural hearing loss

Positive Rinnie Test AC > BC Weber Lateralized to better ear Reduced ABC & Schwabach High frequencies affected more PTA – AC better than BC with no A-B gap Loss is more than 60 dB Speech discrimination is poor. Difficulty hearing in presence of noise.

OTOTOXICITY AMINOGLYCOSIDES – VESTIBULOTOXIC (type-1 hair cell) – Strepto /

Genta / Tobra

COCHLEOTOXIC (outer hair cell) – Neo / Kana / Amika

LOOP DIURETICS – (edema of stria vascularis) – Furosemide, Ethacrynic acid

SALICYLATES QUININE – vasospasm of stria vascularis CHLOROQUINE CYTOTOXIC DRUGS (outer hair cells) – Nitrogen Mustard, Cisplatin,

Carboplatin DESFERRIOXAMINE TOPICAL EAR DROPS – Chlorhexidine, Gentamycin, Polymyxin-B

NOISE TRAUMA2 TYPES

NOISE INDUCED HEARING LOSSTEMPORARY THRESHOLD SHIFT

(Immediate loss of hearing just after exposure to noise which is reversible)

PERMANENT THRESHOLD SHIFT(Permanent hearing loss)

ACOUSTIC TRAUMAPermanent damage to hearing caused by single

brief exposure to sound > 140 Db

NOISE TRAUMA

Frequency causing more damage – 2000 – 3000 Hz.

Maximum Safe Limit – 90 dB noise, 8h a day, 5 days a week

PTA – Typical Notch at 4kHz both for AC & BC.

Damage to hair cells start at Basal Coil of Cochlea

Outer Hair cells are first to be affected.

Maximum permissible impulse noise – 140dB

SUDDEN HEARING LOSS

DEFINATION – 30 dB or more SNHL at least 3 contiguous frequencies occuring

within a period of 3 days or less.

Mostly UNILATERAL.

Prognosis – 50 % spontaneous recovery within 15 days.

AETIOLOGY –

1. IDIOPATHIC - Viral, Vascular, Rupture of Cochlear membranes.

2. HEAD INJURY

3. MENIERE’S DISEASE

4. OTOTOXIC DRUGS

5. HEAMORHAGE/ THROMBOSIS OF LABYRINTHINE A.

SUDDEN HEARING LOSS MANAGEMENT

1. Bed Rest

2. Oral Steroid – Prednisolone 60mg O.D. morning dose for 1wk

3. Carbogen (5% CO2 + 95% O2) Inhalation

4. Vasodilators

5. Low salt diet & Diuretic

6. Intratympanic Steroid Therapy

7. Low molecular weight Dextran

8. Hyperbaric Oxygen Thearpy

PRESBYCUSIS Physiological SNHL after 65 yrs age.

4 Types –

1. Sensory – Degeneration of Organ of Corti

Speech discrimination good.

2. Neural - Degeneration of cells of Spiral Ganglion

Speech discrimination poor

3. Strial - Atrophy of Stria vascularis

Speech discrimination good.

4. Cochlear Conductive – Stiffening of Basillar membrane

Recruitment Phenomenon – Positive

Difficulty hearing in presence of background noise

NONORGANIC HEARING LOSS Malingering / Psychogenic

TESTS –

1. PTA - Inconsistent results (>5 dB) on repeatation

Absence of shadow curve of BC

2. SRT – Better than 10 dB than PTA

3. Stenger Test – Negative

4. Stapedial Reflex - Positive

2 vibrating tuning forks of 512 Hz. Placed 25 cm from both ear with patient blindfolded.

Patient will claim to hear it in normal ear

Now bring the deaf side TF closer

Now he will deny hearing anything

True Deafness – still hears on Normal side

No deafness – Hears on closer side