TOPIC 2

CAUSES OF HEARINGIMPAIRMENT

Outer and Middle Ear Disorders

Structural defects due to embryologic malformations

Structural changes secondary to infection or trauma

Outer Ear Disorders

Microtia and atresia

Microtia

“an abnormal smallness of the auricle”

Atresia

“the absence of an opening of the external canal”

Outer Ear Disorders

Microtia and atresia Impacted cerumen Perforation of the tympanic

membrane

Perforation of the TM

n An example of the audiogram illustrating the flat, mild, conductive hearing loss that can occur with a perforated tympanic membrane

Outer Ear Disorders

Microtia and atresia Impacted cerumen Perforation of the tympanic

membrane Other

Middle Ear Disorders

Otitis Media Most common cause of transient conductive hearing loss in children

Inflamation of the middle ear

Caused by eustachian tube failure

Otitis Media

n Three examples of the usual characteristics of a conductive hearing loss arising from otitis media

Ways to Classify Otitis Media

With or without effusion Fluid type

Serous Suppurative Mucoid

Ways to Classify Otitis Media

With or without effusion Fluid type Duration

Acute Chronic Subacute Persistent Recurrent

Otitis Media Facts 76-95% of all kids will have one episode of OM by age

6 Prevalence is highest during the first two years of life 50% of all kids with one episode before their first

birthday will have 6 or more bouts within two years Most episodes occur in winter and spring Risk factors

Cleft palate Down syndrome Native Americans Urban poor Day care Secondhand smoke

Middle Ear Disorders Otitis media Otosclerosis

Otosclerosis

“a bone disorder that affects the stapes and the bony labyrinth of the inner ear. The disease process is characterized by resorption of bone and new spongy formation around the stapes and oval window”

Otosclerosis Facts:

Hereditary Women are more

likely to develop the disorder

Usually bilateral

progressive

Middle Ear Disorders Otitis media Otosclerosis Cholesteatoma

Cholesteatoma

“an epithelial pocket that forms on the tympanic membrane. Once the pocket forms, the normal shedding of epithelium results in growth of the tumor”

Middle Ear Disorders Otitis media Otosclerosis Cholesteatoma Other

Physical trauma

Physical Trauma of the Middle Ear

Here’s an example of an audiogram resulting from disarticulation of the ossicular chain

Middle Ear Disorders Otitis media Otosclerosis Cholesteatoma Other

Physical trauma Barotrauma Middle ear tumors

Glomus tumor

Cochlear Disorders Syndromes and inherited disorders

Syndromic disorders Nonsyndromal disorders

Syndromes and Inherited Disorders Resulting in Sensorineural Hearing Loss

Types of Nonsyndromic Disorders

Dominant Dominant progressive Dominant progressive with adult

onset Recessive hereditary SNHL X-linked

Cochlear Disorders

Syndromes and inherited disorders Noise induced hearing loss

Noise Induced Hearing Loss

The degree of SNHL depends on

The intensity of the noise

The spectral composition of the

noise

The duration of exposure

Individual susceptibility

OSHA Damage Risk Criteria

Noise Induced SNHL

Noise notch Cummulative Progressive

Cochlear Disorders

Syndromes and inherited disorders Noise induced hearing loss Other trauma Infections

Infections Congenital

Cytomegalovirus HIV Rubella Syphilis Toxoplasmosis

Infections Acquired

Herpes Zooster Oticus (Chicken Pox) Mumps Syphilis

Cochlear Disorders

Syndromes and inherited disorders Noise induced hearing loss Other trauma Infections Ototoxicity

Ototoxicity

Some antibiotics that are often ototoxic: Amikacin Dihydrostreptomycin Garamycin Gentamicin Kanamycin Neomycin Netilmicin Streptomycin Tobramycin Viomycin

Ototoxicity Chemotherapy

Carboplatin Cisplatin

Drugs that cause reversible hearing loss Quinine Salicylates (aspirin) Loop diuretics

Drugs that may be harmful during pregnancy Accutane Dilantin Quinine Thalidomide

Cochlear Disorders

Syndromes and inherited disorders Noise induced hearing loss Other trauma Infections Ototoxicity Meniere’s Disease

Meniere’s Disease

Symptoms Tinnitus Vertigo Unilateral

sensorineural hearing loss

Cochlear Disorders

Syndromes and inherited disorders Noise induced hearing loss Other trauma Infections Ototoxicity Meniere’s Disease Presbycusis

Presbycusis

Central Auditory Disorders

VIII Nerve tumors Other diseases of the VIII Nerve Neural disorders

Cochlear neuritis Diabetes mellitus

Brain Stem disorders Infarcts Gliomas Multiple sclerosis

Temporal Lobe disorders