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TOPIC 2. CAUSES OF HEARING IMPAIRMENT. 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.
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TOPIC 2 CAUSES OF HEARING IMPAIRMENT
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 • 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
Otitis Media Most common cause of transient conductive hearing loss in children Inflamation of the middle ear Caused by eustachian tube failure Middle Ear Disorders
Otitis Media • 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
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
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