3. • Hearing impairment means a person who is not able to hear as well as someone
with normal hearing – hearing thresholds of 25 dB or better in both ears
• Deafness is used, when there is little or no hearing at all.
4. 1. Conductive Hearing Loss
• It is caused by any disease process interfering with the conduction of sound from
the external ear to the stapediovestibular joint.
• Thus the cause may lie in the external ear (obstructions), tympanic membrane
(perforation), middle ear (fluid), ossicles (fixation or disruption) or the eustachian
tube (obstruction).
5. 2. Sensorineural (SN) Hearing Loss
• It results from lesions of the cochlea (sensory type) or VIIIth nerve and its central
connections (neural type).
• The term retrocochlear is used when hearing loss is due to lesions of VIIIth nerve,
and central deafness, when it is due to lesions of central auditory connections.
6. 3. Mixed Hearing Loss
• In this type, elements of both conductive and sensorineural deafness are present in
the same ear.
• There is air-bone gap indicating conductive element, and impairment of bone
conduction indicating sensorineural loss.
• Mixed hearing loss is seen in some cases of otosclerosis and chronic suppurative
otitis media.
7. Assessment of Hearing
Tuning Fork Tests
• These tests are performed with tuning forks of different frequencies such as 128,
256, 512, 1024, 2048 and 4096 Hz, but for routine clinical practice, tuning fork of
512 Hz is ideal.
8.
9. Rinne Test.
• In this test air conduction of the ear is compared with its bone conduction.
• AC > BC –Normal or SNHL
• BC > AC - CD
Weber Test.
• In this test, a vibrating tuning fork is placed in the middle of the forehead or the
vertex and the patient is asked in which ear the sound is heard.
• CENTRAL- Normal
• CD-lateralized to poor ear, SNHL- lateralized to better ear
10.
11. Pure Tone Audiometry
• An audiometer is an electronic device which produces pure tones, the intensity of
which can be increased or decreased in 5 dB steps.
• Usually air conduction thresholds are measured for tones of 125, 250, 500, 1000,
2000, 4000 and 8000 Hz and bone conduction thresholds for 250, 500, 1000, 2000
and 4000 Hz.
12.
13.
14.
15.
16.
17. Causes of SNHL
Congenital
• It is present at birth and is the result of anomalies of the inner ear or damage to the
hearing apparatus by prenatal or perinatal factors.
20. B. FAMILIAL PROGRESSIVE SENSORINEURAL HEARING LOSS
• It is a genetic disorder in which there is progressive degeneration of the cochlea
starting in late childhood or early adult life.
• Hearing loss is bilateral with flat or basin-shaped audiogram but an excellent
speech discrimination.
22. D. NOISE TRAUMA
• Hearing loss associated with exposure to noise has been well-known in boiler
makers, iron- and coppersmiths, and artillery men. Lately, noise trauma has
assumed greater significance because of its being an occupational hazard.
1. Acoustic Trauma
• Permanent damage to hearing can be caused by a single brief exposure explosion,
gun fire or a powerful cracker and may reach or cross 140 dB.
• Noise level of a gun or rifle may reach 140–170 dB SPL (sound pressure level).
23. 2. Noise-Induced Hearing Loss (NIHL)
(a) Temporary threshold shift (TTS)
• The hearing is impaired immediately after exposure to noise but recovers after an
interval of a few minutes to a few hours even up to 2 weeks.
(b) Permanent threshold shift (PTS)
• The hearing impairment is permanent and does not recover at all.
A noise of 90 dB (A) SPL, 8 h a day for 5 days per week is the maximum safe
limit as recommended by Ministry of Labour, Govt.
24.
25.
26. E. AUTOIMMUNE (IMMUNE-MEDIATED) INNER EAR
DISEASE
• Immune-mediated inner ear disease (Syn. Autoimmune SNHL) causes progressive
bilateral sensorineural hearing loss.
• It occurs between 40 and 50 years with equal incidence in both sexes.
27. F. SUDDEN HEARING LOSS
• Sudden SNHL is defined as 30 dB or more of SNHL over at least three contiguous
frequencies occurring within a period of 3 days or less.
• Mostly it is unilateral. It may be accompanied by tinnitus or temporary spell of
vertigo.
29. • 1. Bed rest.
• 2. Steroid therapy. Prednisolone 40–60 mg in a single morning dose for 1 week
and then tailed off in a period of 3 weeks. Steroids are anti-inflammatory and
relieve oedema. They have been found useful in idiopathic sudden hearing loss of
moderate degree.
• 3. Inhalation of carbogen (5% CO2 + 95% O2). It increases cochlear blood flow
and improves oxygenation.
• 4. Vasodilator drugs.
• 5. Low molecular weight dextran. It decreases blood viscosity. It is
contraindicated in cardiac failure and bleeding disorders.
• 6. Hyperbaric oxygen therapy.
30. • 7. Low-salt diet and a diuretic
It is empirical and has same benefit as in cases of Ménière’s disease.
• 8. Intratympanic steroids therapy
31.
32. G. PRESBYCUSIS
• Sensorineural hearing loss associated with physiological aging process in the ear
is called presbycusis.
• It usually manifests at the age of 65 years but may do so early if there is hereditary
predisposition, chronic noise exposure or generalized vascular disease.
33. NONORGANIC HEARING LOSS (NOHL)
• In this type of hearing loss, there is no organic lesion.
• It is either due to malingering or is psychogenic.
34. • The Deaf Child
• Children with profound (>90 dB loss) or total deafness fail
• to develop speech and have often been termed deaf-mute
• or deaf and dumb.
• The period from birth to
• 5 years of life is critical for the development of speech and
• language, therefore, there is need for early identification
• and assessment of hearing loss and early rehabilitation in
• infants and children.
35. AETIOLOGY
• Hearing loss in a child may develop from causes before birth (prenatal), during
birth (perinatal) or thereafter (postnatal).
A. PRENATAL CAUSES
1. INFANT FACTORS
• An infant may be born with inner ear anomalies due to genetic or nongenetic
causes.
• Anomalies may affect inner ear alone (nonsyndromic) or may form part of a
syndrome (syndromic).
2.MATERNAL FACTORS
(a) Infections during pregnancy.
(b) Drugs during pregnancy.
(c) Radiation to mother in the first trimester.
36. B. PERINATAL CAUSES
1. ANOXIA
2. PREMATURITY AND Low BIRTH WEIGHT
3. BIRTH INJURIES
4. Neonatal Jaundice
5. Neonatal Meningitis
6. Time Spent in Neonatal ICU
7. Ototoxic Drugs
37. C. POSTNATAL CAUSES
1. Genetic
• Though deafness is genetic, it manifests later in childhood or adult life.
• Deafness may occur alone as in familial progressive sensorineural deafness or in
association with certain syndromes, e.g. Alport, Klippel-Feil, Hurler, etc.
2. Nongenetic.
• They are essentially same as in adults.
