This document discusses various causes and characteristics of conductive and sensorineural hearing loss. Conductive hearing loss can be acquired from wax, foreign bodies, ear canal atresia, tympanic membrane perforations, or middle ear problems. Sensorineural hearing loss can be acquired from noise exposure, medications, infections, genetic syndromes, or presbycusis. Characteristics of conductive hearing loss include better bone conduction, negative Rinne test, and gap between air and bone conduction thresholds. Characteristics of sensorineural hearing loss include poorer bone conduction, positive Rinne test, and greater than 60 dB loss with poor speech discrimination. Treatment options are discussed depending on the cause.
See the 2,456 pharmacies on the National E-Pharmacy Platform
Causes and Evaluation of Conductive and Sensorineural Hearing Loss
1.
2.
3. CAUSES
ACQUIRED
WAX
FOREIGN BODY
FURUNCLE
ATRESIA OF EAR CANAL
PERFORATION OF TM
FLUID IN MIDDLE EAR
MASS IN MIDDLE EAR
EUSTACHIAN TUBE BLOCKAGE
OSSICULAR DISRUPTION
FIXATION OF STAPES
CONGENITAL
MEATAL ATRESIA
FIXATION OF MALLEUS
FIXATION OF STAPES
OSSICULAR DISCONTINUITY
CONGENITAL CHOLESTEATOMA
4. 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.
5. 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
6. Removal of canal obstruction
Removal of fluid
Removal of mass
Stapedectomy
Tympanoplasty
Hearing Aid
8. 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.
10. 2 TYPES
NOISE INDUCED
HEARING LOSS
TEMPORARY THRESHOLD SHIFT
(Immediate loss of hearing just
after exposure to noise which is
reversible)
PERMANENT THRESHOLD SHIFT
(Permanent hearing loss)
ACOUSTIC
TRAUMA
Permanent damage to hearing
caused by single brief exposure
to sound > 140 Db
11. 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
12. 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.
14. 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
15. 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