A simple presentation about hearing loss

1. By/ Mahmoud A. Aty
Hearing Loss:
Causes, Investigations and
Management

2.  Definition of HL.
 Types of HL.
 Causes of CHL.
 Causes of SNHL.
 Causes of Mixed HL.
 Investigations for Hearing Loss.
 History
 Otoscopic examination.
 Tuning Fork tests.
 Audiological Assessment.
 Pure Tone Audiometry.
 Tympanometry.
 Otoacoustic Emission.
 Evoked Response Audiometry.
 Treatment of Hearing loss.

3.  Diminution of hearing up
to complete loss of
hearing.
 It always indicate disease
in auditory pathway from
external ear up to cerebral
cortex.

4.  The tube is longer in
adult than in infant. Its
length in adults is about
3-4 cm.
 It forms an angle with
respect to the horizontal
plane (in adults 45
degrees while in infants it
is 10 degree angle).

5.  The lateral 1/3 is osseous arising from the
anterior wall of the tympanic cavity passing
through the squamous and petrous parts of
temporal bone and narrows gradually to form
the isthmus.
 The medial 2/3 is fibro-cartilegonous and
enters the nasopharynx to form the tubal
elevation.

6.  The Eustachian tube has three physiologic functions
with respect to the middle ear :
Ventilation Protection Drainage

7.  Ventilation of the middle ear is necessary to equilibrate air
pressure in the middle ear with atmospheric pressure for
maximal conduction of sound.

8.  The normal Eustachian tube is functionally collapsed at
rest, allowing slight negative pressure to exist in the middle
ear.
 It is kept closed by tissue factors (venus pressure, mucous
membrane properties, cartilaginous elasticity) and
structural factors (length and width of the lumen).
When the tube is opened?
 By contraction of tensor veli palatini muscle.
 When the intratympanic pressure exceeds 100-150
mm water above the ambient pressure.

9.  Protection of middle ear cavity from nasopharyngeal
secretions.
3- Drainage function:
 Drainage of fluids from middle ear cavity into the
nasopharynx.

10.  Interference of transmission of sound waves along
the conductive apparatus.
 Causes:
1. Occlusion of the external canal
2. Perforation of TM.
3. Causes in the Middle Ear.
4. Causes in the ET.

11.  It is defect either in conversion of sound energy into
electrical impulses in the cochlea or in transfer of
these impulses along auditory pathway.
 Causes:
1. Cochlear causes (Sensory).
2. Retro-cochlear Causes.

12.  It is defect in both conductive pathway and either
in the cochlea or auditory pathway.
 Causes:
1. Congenital as meatal atresia with anomalies either
in inner ear or 8th nerve.
2. Traumatic as fracture base of skull.
3. Complicated CSOM with Labyrinthitis.
4. Combined Otosclerosis (mixed otosclerosis).

13. I) History.
II) Otoscopic examination.
III) Tuning fork Tests.

14. II- Otoscopic examination

15. III- Tuning fork tests:
1-Rinne test
+ve, -ve, =, reduced
+ve, false negative
2- Weber test
3- Schwabachs test

16. Pure Tone
Audiometry
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20.  Type “A” Tympanogram
and its varieties: As, AD.
 Type “B “ Tympanogram
 Type “C” Tympanogram

21.  Normal middle ear pressure
 Normal eardrum movement
 Normal ear canal volume
Example:
 Normal middle ear
Type A

22.  Reduced Compliance
 Normal Middle-ear pressure
 Normal ear canal volume
Example:
 Fixation of ossicles
 Adhesive OM

23.  Increased compliance
 Normal middle-ear
pressure
 Normal ear canal volume
Example:
 Disarticulation of ossicles
 Scared TM

24.  “Flat”
 No compliance or pressure
peak indicated
 Decreased ear canal volume
Example:
 Occluding Wax
 Probe up against canal wall??

25.  “Flat”
 No compliance or pressure
peak indicated
 Increased ear canal volume
Example:
 Perforated TM
 Patent V. Tubes

26.  Excessive negative middle-ear
pressure
 Normal or reduced compliance
 Normal ear canal volume
Example:
 Eustachian tube dysfunction,
initiation or resolution of
middle-ear fluid

27. Objective measure of the integrity and function of
outer-hair cells of the cochlea.

28.  Provides objective information on the
condition of the cochlea.
 Otoacoustic emission is a result of active
movements of the hair cells in the cochlea
when sensing sound.

31. Evoked Response Audiometry
e. g (ABR)
It records the electrical activity in the auditory
pathway.
Clinical applications:
Threshold estimation
Neurodiagnosis:
to differentiate cochlear from
retrocochlear HL.

36. 1- Medical treatment:
 Mainly in CHL and to lesser extent in SNHL.
2- Surgical treatment:
 In CHL only.
3- Special Maneuvers:
4-Auditory Rehabilitation:

37.  Hearing aids can be fitted as
young as 3 months of age

38. Early Identification needs to be paired with early,
appropriate and consistent interventions.

39.  3-6 months trial with hearing aids;
lack of benefit
 Profound loss 90+dB (12 to 18
mos); >18 mos, Severe-to-
Profound 70 dB+
 No medical contraindications
 Rehab setting encouraging
auditory
 Family factors (motivation,
expectations)