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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 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 Brain Stem disorders Cochlear neuritis Diabetes mellitus Infarcts Gliomas Multiple sclerosis Temporal Lobe disorders