HEARING LOSS

DR SUDEEP K.C.

CLASSIFICATION OF HEARING LOSS

AUDITORY PATHWAYS

CONDUCTIVE HEARING LOSS Characteristics of Conductive hearing loss

are:1) Negative Rinne test(BC>AC)2) Weber lateralised to defective ear.3) Normal absolute bone conduction.4) Low frequencies affected more.5) Audiometry shows bone conduction is better

than air conduction with A-B gap.6) Loss is more than 60 db.

Causes of Conductive loss1) Congenital causes.2) Acquired causes.

CONGENITAL CAUSES: Meatal atresia. Fixation of the stapes foot plate. Fixation of malleus head. Ossicular discontinuity

ACQUIRED CAUSES:Any obstruction in the ear canal E.g. Wax,

Foreign body, tumor etc.Perforation of TM- traumatic or infective.Fluid in the middle ear- Otitis media , Haemotympanum.Mass in the middle ear.Disruption of ossicles – Trauma, CSOM.Fixation of ossicles – Otosclerosis,

Tympanosclerosis.

Management1) Removal of Canal obstruction.2) Removal of the fluid.3) Removal of mass from middle ear.4) Stapedectomy - Otosclerotic fixation of

stapes footplate.5) Tympanoplasty.6) Hearing Aid.

TYMPANOPLASTYIt is an operation to :1) Eradicate disease in the middle ear.2) To reconstruct hearing mechanism. If there is only repairing of TM –

Myringoplasty. If there is reconstruction of Ossicular chain-

Ossiculoplasty. If both TM and Ossicular chain repair-

Tympanoplasty.

MYRINGOPLASTYIt is the repair of tympanic membrane .Graft material: Temporalis fascia or

perichondrium and sometimes from the cadaveric tympanic membrane, vein, fascia.

Repair can be done by two techniques:1) Under lay technique.2) Over lay technique.

OSSICULAR RECONSTRUCTIONIt is required when there is destruction or

fixation of Ossicular chain.Most common defect is long process of the

Incus.Repair of ossicular chain:Can be achieved by the use of autograft incus

or cartilage, or homograft ossicles or the prosthetic implants made of ceramic or teflon.

SENSORINEURAL HEARING LOSSCharacteristics of SNHL are:1) Positive Rinne test (AC>BC).2) Weber lateralised to better ear.3) Bone conduction reduced in ABC test.4) More often involving the high frequencies.5) No gap between the air and bone

conduction curve on audiometry.6) Loss may exceed 60 db.

CAUSES OF SNHL:1) Congenital.2) Acquired: Infection of the labyrinth. Trauma to the labyrinth or VIII nerve. Noise induced hearing loss. Ototoxic drugs. Presbycusis. Meniere’s disease. Acoustic Neuroma.

DIAGNOSIS:1) History.2) Severity of deafness.3) Types of audiogram-whether loss is of high

frequency or of low frequency.4) Site of the lesion- Cochlear , Retro –

Cochlear and Central.

MANAGEMENTEarly detection of SNHL is important as measures

can be taken to stop its progress, reverse it or to start an early rehabilitation programme.

SYPHILIS- High dose of penicillin and steroids.HYPOTHYROIDISM- Replacement therapy.SEROUS LABYRINTHITIS- Reverse by attention to

middle ear infection.MENIERE’S DISEASE- Early management can

prevent further episodes of vertigo and hearing loss.OTOTOXIC DRUGS should be discontinued.REHABILITATION.