HEARING LOSS ENT

HEARING LOSS
BY: NURRASHIDAH BT ABDURAHMAN
NABILAH IFFAH BT MD. ARIF

ANATOMY OF EAR

The ear is made up of three parts
1.
Outer ear – consists of pinna and external auditory canal
2.
middle ear – consists of tympanic membrane and ossicles (3 tiny bones that are attached to the tympanic membrane which are malleus, incus and stapes) 3. inner ear – consists of oval window, semicircular ducts, cochlea and auditory tube 

HEARING – transduction of sound to neural impulses and its interpretation by the CNS
 HEARING LOSS – defect of any level from transduction of sound to the interpretation of sound
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NORMAL HEARING PHYSIOLOGY
Conductive Pathway
Neural Pathway

Conductive Pathway
(External auditory canal to cochlea) Neural Pathway
(nerve to brain)
Stimulation of bipolar neurons in the spiral ganglion of the cochlear division of CN VIII

Sylvian fissure of temporal lobe Cochlear nucleus Superior olivary nucleus

Inferior colliculus Lateral leminiscus TYPES OF HEARING LOSS
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CONDUCTIVE HEARING LOSS (CHL)
The conduction of sound to the cochlea is impaired Can be caused by external and middle ear diseases SENSORINEURAL HEARING LOSS (SNHL)
Due to a defect in the conversion of sound into neural signs or in the transmission of those signal to the cortex
Can be caused by the disease in cochlea, acoustic nerve(CN 8), brainstem or cortex
MIXED HEARING LOSS
The conduction of sound to the cochlea is impaired, as well as transmission through cochlea to the cortex

CAUSES OF HEARING LOSS
CONDUCTIVE HEARING LOSS
1.
EXTERNAL EAR CANAL
 Impacted earwax
 Otitis externa
 Foreign body
 Congenital atresia
2.
MIDDLE EAR
 Acute otitis media
 Otitis media with effusion
 Perforation of tympanic membrane
 Otosclerosis
 Tumour (cholesteatoma)
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SENSORINEURAL HEARING LOSS
1.
CONGENITAL
 Hereditary defects
 TORCH infection
 Perinatal and postnatal infection
2.
ACQUIRED
 Presbycusis
 Noise induced hearing loss
 Meniere’s disease
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