deafness for undergraduates

Deafness

By Moustafa M. Dawoud

Assistant lecturer of ORLMFM 2015

Deafness

Definition:Diminution of hearing??

Drop of hearing threshold by 20dB or more.Mild >> 20-40 dB

Moderate>> 40-60 dB

Severe>> 60-80 dB

Profound>> more than 80 dB

Deafness

Types

Conductive Sensorineural

Mixed Functional

Deafness

Conductive deafness

•WaxEAC•Perforation either pathological

or traumaticTM•Otitis media.…

•Otosclerosis•Eustachian tube

ME

Ear wax

TM Perforation

Stapes removed

Deafness

SENSORINEURAL HEARING LOSS

SNHL

The defect is either Cochlear>> failure to convert sound waves

into electrical impulses.

Retrocochlear>> defect in transfer of impulses along the 8th nerve.

SNHL

Cochlear SNHL

1 -Congenital:Usher , Pendred $>>>Heridetary

Rubella & Drugs>>> Prenatal

Delivery trauma>>> Natal

Kernictrus & Neonatal infection>>> postnatal

Cochlear SNHL

2_ Traumatic:- Fracture skull base,- Acoustic trauma >>>acute or chronic exposure- Stapedectomy.

- 3- Inflammatory:- Infective: viral(MMR) , Syphilis.- Toxic: drugs , uremia , thyrotoxicosis.

Cochlear SNHL

4 -Vascular.>> spasm or embolus in internal auditory artery.

5 -Miscellaneous:-presbycausis.

-Meniere’s-Pure cochlear otosclerosis

-PLF

Retrocochlear SNHL

1 -Vestibulococchlear nerve affection:Acoustic neuroma, congenital cholesteatoma, Meningitis, vascular loop.

2 -Central lesions : e.g, MS, Brain tumors.

Comparison

SNHL CHL Character

High LOW Voice

Poor Good Speech discrimination

High frequenciesHears men better

Hears worse in noise

Low frequencies-Hears women

better-Hears better in

noise

Frequencies affected

Assessment

Subjective: Infants>> distraction method

2-5 years>> play-conditioned audiometryAbove 5 years & Adults>> PTA , Speech audiometry.Objective :ABR EChoGOAE

PTA

CHL Mixed Hearing loss

Synopsis

1 -Commonest cause of CD= ear wax.2 -CD in children= think of SOM first!

3 -Bil CD with intact TM= think otosclerosis!4 -Elderly , gradual hearing loss???

Presbyacusis.5 -Severe HL in children (MMM)

6 -unilateral SNHL, adult, very poor speech discrimination??? Think acoustic neuroma